The Variation of Animals and Plants under Domestication

by Charles Darwin M.A., F.R.S., ETC.

VOLUMES ONE AND TWO


CONTENTS.

FOREWORD

PREFACE TO THE SECOND EDITION

INTRODUCTION

CHAPTER I.—DOMESTIC DOGS AND CATS.

ANCIENT VARIETIES OF THE DOG—RESEMBLANCE OF DOMESTIC DOGS IN VARIOUS
COUNTRIES TO NATIVE CANINE SPECIES—ANIMALS NOT ACQUAINTED WITH MAN AT
FIRST FEARLESS—DOGS RESEMBLING WOLVES AND JACKALS—HABIT OF BARKING
ACQUIRED AND LOST—FERAL DOGS—TAN-COLOURED EYE-SPOTS—PERIOD OF
GESTATION—OFFENSIVE ODOUR—FERTILITY OF THE RACES WHEN
CROSSED—DIFFERENCES IN THE SEVERAL RACES IN PART DUE TO DESCENT FROM
DISTINCT SPECIES—DIFFERENCES IN THE SKULL AND TEETH—DIFFERENCES IN THE
BODY, IN CONSTITUTION—FEW IMPORTANT DIFFERENCES HAVE BEEN FIXED BY
SELECTION—DIRECT ACTION OF CLIMATE—WATER-DOGS WITH PALMATED
FEET—HISTORY OF THE CHANGES WHICH CERTAIN ENGLISH RACES OF THE DOG HAVE
GRADUALLY UNDERGONE THROUGH SELECTION—EXTINCTION OF THE LESS IMPROVED
SUB-BREEDS.

CATS, CROSSED WITH SEVERAL SPECIES—DIFFERENT BREEDS FOUND ONLY IN
SEPARATED COUNTRIES—DIRECT EFFECTS OF THE CONDITIONS OF LIFE—FERAL
CATS—INDIVIDUAL VARIABILITY.

CHAPTER II.—HORSES AND ASSES.

HORSE. DIFFERENCES IN THE BREEDS—INDIVIDUAL VARIABILITY OF—DIRECT
EFFECTS OF THE CONDITIONS OF LIFE—CAN WITHSTAND MUCH COLD—BREEDS MUCH
MODIFIED BY SELECTION—COLOURS OF THE HORSE—DAPPLING—DARK STRIPES ON THE
SPINE, LEGS, SHOULDERS, AND FOREHEAD—DUN-COLOURED HORSES MOST
FREQUENTLY STRIPED—STRIPES PROBABLY DUE TO REVERSION TO THE PRIMITIVE
STATE OF THE HORSE.

ASSES. BREEDS OF—COLOUR OF—LEG- AND SHOULDER-STRIPES—SHOULDER-STRIPES
SOMETIMES ABSENT, SOMETIMES FORKED.

CHAPTER III.—PIGS—CATTLE—SHEEP—GOATS.

PIGS BELONG TO TWO DISTINCT TYPES, SUS SCROFA AND
INDICUS—TORFSCHWEIN—JAPAN PIGS—FERTILITY OF CROSSED PIGS—CHANGES IN THE
SKULL OF THE HIGHLY CULTIVATED RACES—CONVERGENCE OF
CHARACTER—GESTATION—SOLID-HOOFED SWINE—CURIOUS APPENDAGES TO THE
JAWS—DECREASE IN SIZE OF THE TUSKS—YOUNG PIGS LONGITUDINALLY
STRIPED—FERAL PIGS—CROSSED BREEDS.

CATTLE—ZEBU A DISTINCT SPECIES—EUROPEAN CATTLE PROBABLY DESCENDED FROM
THREE WILD FORMS—ALL THE RACES NOW FERTILE TOGETHER—BRITISH PARK
CATTLE—ON THE COLOUR OF THE ABORIGINAL SPECIES—CONSTITUTIONAL
DIFFERENCES—SOUTH AFRICAN RACES—SOUTH AMERICAN RACES—NIATA
CATTLE—ORIGIN OF THE VARIOUS RACES OF CATTLE.

SHEEP —REMARKABLE RACES OF—VARIATIONS ATTACHED TO THE MALE
SEX—ADAPTATIONS TO VARIOUS CONDITIONS—GESTATION OF—CHANGES IN THE
WOOL—SEMI-MONSTROUS BREEDS.

GOATS —REMARKABLE VARIATIONS OF.

CHAPTER IV.—DOMESTIC RABBITS.

DOMESTIC RABBITS DESCENDED FROM THE COMMON WILD RABBIT—ANCIENT
DOMESTICATION—ANCIENT SELECTION—LARGE LOP-EARED RABBITS—VARIOUS
BREEDS—FLUCTUATING CHARACTERS—ORIGIN OF THE HIMALAYAN BREED—CURIOUS
CASE OF INHERITANCE—FERAL RABBITS IN JAMAICA AND THE FALKLAND
ISLANDS—PORTO SANTO FERAL RABBITS—OSTEOLOGICAL CHARACTERS—SKULL—SKULL
OF HALF-LOP RABBITS—VARIATIONS IN THE SKULL ANALOGOUS TO DIFFERENCES IN
DIFFERENT SPECIES OF HARES—VERtebræ—STERNUM—SCAPULA—EFFECTS OF USE AND
DISUSE ON THE PROPORTIONS OF THE LIMBS AND BODY—CAPACITY OF THE SKULL
AND REDUCED SIZE OF THE BRAIN—SUMMARY ON THE MODIFICATIONS OF
DOMESTICATED RABBITS.

CHAPTER V.—DOMESTIC PIGEONS.

ENUMERATION AND DESCRIPTION OF THE SEVERAL BREEDS—INDIVIDUAL
VARIABILITY—VARIATIONS OF A REMARKABLE NATURE—OSTEOLOGICAL CHARACTERS:
SKULL, LOWER JAW, NUMBER OF vertebræ—CORRELATION OF GROWTH: TONGUE WITH
BEAK; EYELIDS AND NOSTRILS WITH WATTLED SKIN—NUMBER OF WING-FEATHERS,
AND LENGTH OF WING—COLOUR AND DOWN—WEBBED AND FEATHERED FEET—ON THE
EFFECTS OF DISUSE—LENGTH OF FEET IN CORRELATION WITH LENGTH OF
BEAK—LENGTH OF STERNUM, SCAPULA, AND FURCULUM—LENGTH OF WINGS—SUMMARY
ON THE POINTS OF DIFFERENCE IN THE SEVERAL BREEDS.

CHAPTER VI.—PIGEONS—_continued._

ON THE ABORIGINAL PARENT-STOCK OF THE SEVERAL DOMESTIC RACES—HABITS OF
LIFE—WILD RACES OF THE ROCK-PIGEON—Dovecot-PIGEONS—PROOFS OF THE
DESCENT OF THE SEVERAL RACES FROM COLUMBA LIVIA—FERTILITY OF THE RACES
WHEN CROSSED—REVERSION TO THE PLUMAGE OF THE WILD
ROCK-PIGEON—CIRCUMSTANCES FAVOURABLE TO THE FORMATION OF THE
RACES—ANTIQUITY AND HISTORY OF THE PRINCIPAL RACES—MANNER OF THEIR
FORMATION—SELECTION—UNCONSCIOUS SELECTION—CARE TAKEN BY FANCIERS IN
SELECTING THEIR BIRDS—SLIGHTLY DIFFERENT STRAINS GRADUALLY CHANGE INTO
WELL-MARKED BREEDS—EXTINCTION OF INTERMEDIATE FORMS—CERTAIN BREEDS
REMAIN PERMANENT, WHILST OTHERS CHANGE—SUMMARY.

CHAPTER VII.—FOWLS.

BRIEF DESCRIPTIONS OF THE CHIEF BREEDS—ARGUMENTS IN FAVOUR OF THEIR
DESCENT FROM SEVERAL SPECIES—ARGUMENTS IN FAVOUR OF ALL THE BREEDS
HAVING DESCENDED FROM GALLUS BANKIVA—REVERSION TO THE PARENT-STOCK IN
COLOUR—ANALOGOUS VARIATIONS—ANCIENT HISTORY OF THE FOWL—EXTERNAL
DIFFERENCES BETWEEN THE SEVERAL BREEDS—EGGS—CHICKENS—SECONDARY SEXUAL
CHARACTERS—WING-AND TAIL-FEATHERS, VOICE, DISPOSITION, ETC—OSTEOLOGICAL
DIFFERENCES IN THE SKULL, VERTEBRÆ, ETC—EFFECTS OF USE AND DISUSE ON
CERTAIN PARTS—CORRELATION OF GROWTH.

CHAPTER
VIII.—DUCK—GOOSE—PEACOCK—TURKEY—GUINEA-FOWL—CANARY-BIRD—GOLD-FISH—RIVER
-BEES—SILK-MOTHS.

DUCKS, SEVERAL BREEDS OF—PROGRESS OF DOMESTICATION—ORIGIN OF FROM THE
COMMON WILD-DUCK—DIFFERENCES IN THE DIFFERENT BREEDS—OSTEOLOGICAL
DIFFERENCES—EFFECTS OF USE AND DISUSE ON THE LIMB-BONES.

GOOSE, ANCIENTLY DOMESTICATED—LITTLE VARIATION OF—SEBASTOPOL BREED.

PEACOCK, ORIGIN OF BLACK-SHOULDERED BREED.

TURKEY,BREEDS OF—CROSSED WITH THE UNITED STATES SPECIES—EFFECTS OF
CLIMATE ON.

GUINEA-FOWL, CANARY-BIRD, GOLD-FISH, HIVE-BEES.

SILK-MOTHS, SPECIES AND BREEDS OF—ANCIENTLY DOMESTICATED—CARE IN THEIR
SELECTION—DIFFERENCES IN THE DIFFERENT RACES—IN THE EGG, CATERPILLAR,
AND COCOON STATES—INHERITANCE OF CHARACTERS—IMPERFECT WINGS—LOST
INSTINCTS—CORRELATED CHARACTERS.

CHAPTER IX.—CULTIVATED PLANTS: CEREAL AND CULINARY PLANTS.

PRELIMINARY REMARKS ON THE NUMBER AND PARENTAGE OF CULTIVATED
PLANTS—FIRST STEPS IN CULTIVATION—GEOGRAPHICAL DISTRIBUTION OF
CULTIVATED PLANTS.

CEREALIA. DOUBTS ON THE NUMBER OF SPECIES—WHEAT: VARIETIES
OF—INDIVIDUAL VARIABILITY—CHANGED HABITS—SELECTION—ANCIENT HISTORY OF
THE VARIETIES—MAIZE: GREAT VARIATION OF—DIRECT ACTION OF CLIMATE ON.

CULINARY PLANTS.—CABBAGES: VARIETIES OF, IN FOLIAGE AND STEMS, BUT NOT
IN OTHER PARTS—PARENTAGE OF—OTHER SPECIES OF BRASSICA—PEAS: AMOUNT OF
DIFFERENCE IN THE SEVERAL KINDS, CHIEFLY IN THE PODS AND SEED—SOME
VARIETIES CONSTANT, SOME HIGHLY VARIABLE—DO NOT
INTERCROSS—BEANS—POTATOES: NUMEROUS VARIETIES OF—DIFFERING LITTLE
EXCEPT IN THE TUBERS—CHARACTERS INHERITED.

CHAPTER X.—PLANTS _continued_—FRUITS—ORNAMENTAL TREES—FLOWERS.

FRUITS. GRAPES: VARY IN ODD AND TRIFLING PARTICULARS—MULBERRY: THE
ORANGE GROUP—SINGULAR RESULTS FROM CROSSING— PEACH AND NECTARINE: BUD
VARIATION—ANALOGOUS VARIATION—RELATION TO THE ALMOND—APRICOT—PLUMS:
VARIATION IN THEIR STONES— CHERRIES: SINGULAR VARIETIES
OF—APPLE—PEAR—STRAWBERRY: INTERBLENDING OF THE ORIGINAL
FORMS—GOOSEBERRY: STEADY INCREASE IN SIZE OF THE FRUIT—VARIETIES
OF—WALNUT—NUT—CUCURBITACEOUS PLANTS: WONDERFUL VARIATION OF.

ORNAMENTAL TREES. THEIR VARIATION IN DEGREE AND
KIND—ASH-TREE—SCOTCH-FIR—HAWTHORN.

FLOWERS. MULTIPLE ORIGIN OF MANY KINDS—VARIATION IN CONSTITUTIONAL
PECULIARITIES—KIND OF VARIATION—ROSES: SEVERAL SPECIES
CULTIVATED—PANSY—DAHLIA—HYACINTH: HISTORY AND VARIATION OF.

CHAPTER XI.—ON BUD-VARIATION, AND ON CERTAIN ANOMALOUS MODES OF
REPRODUCTION AND VARIATION.

BUD-VARIATION IN THE PEACH, PLUM, CHERRY, VINE, GOOSEBERRY, CURRANT,
AND BANANA, AS SHOWN BY THE MODIFIED FRUIT—IN FLOWERS: CAMELLIAS,
AZALEAS, CHRYSANTHEMUMS, ROSES, ETC—ON THE RUNNING OF THE COLOUR IN
CARNATIONS—BUD-VARIATIONS IN LEAVES—VARIATIONS BY SUCKERS, TUBERS, AND
BULBS—ON THE BREAKING OF TULIPS—BUD-VARIATIONS GRADUATE INTO CHANGES
CONSEQUENT ON CHANGED CONDITIONS OF LIFE—GRAFT-HYBRIDS—ON THE
SEGREGATION OF THE PARENTAL CHARACTERS IN SEMINAL HYBRIDS BY
BUD-VARIATION—ON THE DIRECT OR IMMEDIATE ACTION OF FOREIGN POLLEN ON
THE MOTHER-PLANT—ON THE EFFECTS IN FEMALE ANIMALS OF A PREVIOUS
IMPREGNATION ON THE SUBSEQUENT OFFSPRING—CONCLUSION AND SUMMARY.

CHAPTER XII.—INHERITANCE.

WONDERFUL NATURE OF INHERITANCE—PEDIGREES OF OUR DOMESTICATED
ANIMALS—INHERITANCE NOT DUE TO CHANCE—TRIFLING CHARACTERS
INHERITED—DISEASES INHERITED—PECULIARITIES IN THE EYE
INHERITED—DISEASES IN THE HORSE—LONGEVITY AND VIGOUR—ASYMMETRICAL
DEVIATIONS OF STRUCTURE—POLYDACTYLISM AND REGROWTH OF SUPERNUMERARY
DIGITS AFTER AMPUTATION—CASES OF SEVERAL CHILDREN SIMILARLY AFFECTED
FROM NON-AFFECTED PARENTS—WEAK AND FLUCTUATING INHERITANCE: IN WEEPING
TREES, IN DWARFNESS, COLOUR OF FRUIT AND FLOWERS—COLOUR OF
HORSES—NON-INHERITANCE IN CERTAIN CASES—INHERITANCE OF STRUCTURE AND
HABITS OVERBORNE BY HOSTILE CONDITIONS OF LIFE, BY INCESSANTLY
RECURRING VARIABILITY, AND BY REVERSION—CONCLUSION.

CHAPTER XIII.—INHERITANCE _continued_—REVERSION OF ATAVISM.

DIFFERENT FORMS OF REVERSION—IN PURE OR UNCROSSED BREEDS, AS IN
PIGEONS, FOWLS, HORNLESS CATTLE AND SHEEP, IN CULTIVATED
PLANTS—REVERSION IN FERAL ANIMALS AND PLANTS—REVERSION IN CROSSED
VARIETIES AND SPECIES—REVERSION THROUGH BUD-PROPAGATION, AND BY
SEGMENTS IN THE SAME FLOWER OR FRUIT—IN DIFFERENT PARTS OF THE BODY IN
THE SAME ANIMAL—THE ACT OF CROSSING A DIRECT CAUSE OF REVERSION,
VARIOUS CASES OF, WITH INSTINCTS—OTHER PROXIMATE CAUSES OF
REVERSION—LATENT CHARACTERS—SECONDARY SEXUAL CHARACTERS—UNEQUAL
DEVELOPMENT OF THE TWO SIDES OF THE BODY—APPEARANCE WITH ADVANCING AGE
OF CHARACTERS DERIVED FROM A CROSS—THE GERM, WITH ALL ITS LATENT
CHARACTERS, A WONDERFUL OBJECT—MONSTROSITIES—PELORIC FLOWERS DUE IN
SOME CASES TO REVERSION.

CHAPTER XIV.—INHERITANCE _continued_—FIXEDNESS OF
CHARACTER—PREPOTENCY—SEXUAL LIMITATION—CORRESPONDENCE OF AGE.

FIXEDNESS OF CHARACTER APPARENTLY NOT DUE TO ANTIQUITY OF
INITANCE—PREPOTENCY OF TRANSMISSION IN INDIVIDUALS OF THE SAME FAMILY,
IN CROSSED BREEDS AND SPECIES; OFTEN STRONGER IN ONE SEX THAN THE
OTHER; SOMETIMES DUE TO THE SAME CHARACTER BEING PRESENT AND VISIBLE IN
ONE BREED AND LATENT IN THE OTHER—INHERITANCE AS LIMITED BY
SEX—NEWLY-ACQUIRED CHARACTERS IN OUR DOMESTICATED ANIMALS OFTEN
TRANSMITTED BY ONE SEX ALONE, SOMETIMES LOST BY ONE SEX
ALONE—INHERITANCE AT CORRESPONDING PERIODS OF LIFE—THE IMPORTANCE OF
THE PRINCIPLE WITH RESPECT TO EMBRYOLOGY; AS EXHIBITED IN DOMESTICATED
ANIMALS: AS EXHIBITED IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED
DISEASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN IN THE
PARENT—SUMMARY OF THE THREE PRECEDING CHAPTERS.

CHAPTER XV.—ON CROSSING.

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED
BREEDS—WHEN THE NUMBERS OF TWO COMMINGLING BREEDS ARE UNEQUAL, ONE
ABSORBS THE OTHER—THE RATE OF ABSORPTION DETERMINED BY PREPOTENCY OF
TRANSMISSION, BY THE CONDITIONS OF LIFE, AND BY NATURAL SELECTION—ALL
ORGANIC BEINGS OCCASIONALLY INTERCROSS; APPARENT EXCEPTIONS—ON CERTAIN
CHARACTERS INCAPABLE OF FUSION; CHIEFLY OR EXCLUSIVELY THOSE WHICH HAVE
SUDDENLY APPEARED IN THE INDIVIDUAL—ON THE MODIFICATION OF OLD RACES,
AND THE FORMATION OF NEW RACES BY CROSSING—SOME CROSSED RACES HAVE BRED
TRUE FROM THEIR FIRST PRODUCTION—ON THE CROSSING OF DISTINCT SPECIES IN
RELATION TO THE FORMATION OF DOMESTIC RACES.

CHAPTER XVI.—CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF
VARIETIES—INFLUENCE OF DOMESTICATION ON FERTILITY.

DIFFICULTIES IN JUDGING OF THE FERTILITY OF VARIETIES WHEN CROSSED.
VARIOUS CAUSES WHICH KEEP VARIETIES DISTINCT, AS THE PERIOD OF BREEDING
AND SEXUAL PREFERENCE—VARIETIES OF WHEAT SAID TO BE STERILE WHEN
CROSSED—VARIETIES OF MAIZE, VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND
TOBACCO, RENDERED IN SOME DEGREE MUTUALLY STERILE—DOMESTICATION
ELIMINATES THE TENDENCY TO STERILITY NATURAL TO SPECIES WHEN CROSSED—ON
THE INCREASED FERTILITY OF UNCROSSED ANIMALS AND PLANTS FROM
DOMESTICATION AND CULTIVATION.

CHAPTER XVII.—ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL EFFECTS
OF CLOSE INTERBREEDING.

DEFINITION OF CLOSE INTERBREEDING—AUGMENTATION OF MORBID
TENDENCIES—GENERAL EVIDENCE OF THE GOOD EFFECTS DERIVED FROM CROSSING,
AND ON THE EVIL EFFECTS FROM CLOSE INTERBREEDING—CATTLE, CLOSELY
INTERBRED; HALF-WILD CATTLE LONG KEPT IN THE SAME
PARKS—SHEEP—FALLOW-DEER—DOGS, RABBITS, PIGS—MAN, ORIGIN OF HIS
ABHORRENCE OF INCESTUOUS MARRIAGES—FOWLS—PIGEONS—HIVE-BEES—PLANTS,
GENERAL CONSIDERATIONS ON THE BENEFITS DERIVED FROM CROSSING—MELONS,
FRUIT-TREES, PEAS, CABBAGES, WHEAT, AND FOREST-TREES—ON THE INCREASED
SIZE OF HYBRID PLANTS, NOT EXCLUSIVELY DUE TO THEIR STERILITY—ON
CERTAIN PLANTS WHICH EITHER NORMALLY OR ABNORMALLY ARE SELF-IMPOTENT,
BUT ARE FERTILE, BOTH ON THE MALE AND FEMALE SIDE, WHEN CROSSED WITH
DISTINCT INDIVIDUALS EITHER OF THE SAME OR ANOTHER SPECIES—CONCLUSION.

CHAPTER XVIII.—ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED
CONDITIONS OF LIFE: STERILITY FROM VARIOUS CAUSES.

ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE CONDITIONS OF
LIFE—STERILITY FROM CHANGED CONDITIONS, IN ANIMALS, IN THEIR NATIVE
COUNTRY AND IN MENAGERIES—MAMMALS, BIRDS, AND INSECTS—LOSS OF SECONDARY
SEXUAL CHARACTERS AND OF INSTINCTS—CAUSES OF STERILITY—STERILITY OF
DOMESTICATED ANIMALS FROM CHANGED CONDITIONS—SEXUAL INCOMPATIBILITY OF
INDIVIDUAL ANIMALS—STERILITY OF PLANTS FROM CHANGED CONDITIONS OF
LIFE—CONTABESCENCE OF THE ANTHERS—MONSTROSITIES AS A CAUSE OF
STERILITY—DOUBLE FLOWERS—SEEDLESS FRUIT—STERILITY FROM THE EXCESSIVE
DEVELOPMENT OF THE ORGANS OF VEGETATION—FROM LONG-CONTINUED PROPAGATION
BY BUDS—INCIPIENT STERILITY THE PRIMARY CAUSE OF DOUBLE FLOWERS AND
SEEDLESS FRUIT.

CHAPTER XIX.—SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS ON
HYBRIDISM.

ON THE GOOD DERIVED ON THE EFFECTS OF CROSSING—THE INFLUENCE OF
DOMESTICATION ON FERTILITY—CLOSE INTERBREEDING—GOOD AND EVIL RESULTS
FROM CHANGED CONDITIONS OF LIFE—VARIETIES WHEN CROSSED NOT INVARIABLY
FERTILE—ON THE DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND
VARIETIES—CONCLUSIONS WITH RESPECT TO HYBRIDISM—LIGHT THROWN ON
HYBRIDISM BY THE ILLEGITIMATE PROGENY OF HETEROSTYLED PLANTS—STERILITY
OF CROSSED SPECIES DUE TO DIFFERENCES CONFINED TO THE REPRODUCTIVE
SYSTEM—NOT ACCUMULATED THROUGH NATURAL SELECTION—REASONS WHY DOMESTIC
VARIETIES ARE NOT MUTUALLY STERILE—TOO MUCH STRESS HAS BEEN LAID ON THE
DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND CROSSED
VARIETIES—CONCLUSION.

CHAPTER XX.—SELECTION BY MAN.

SELECTION A DIFFICULT ART—METHODICAL, UNCONSCIOUS, AND NATURAL
SELECTION—RESULTS OF METHODICAL SELECTION—CARE TAKEN IN
SELECTION—SELECTION WITH PLANTS—SELECTION CARRIED ON BY THE ANCIENTS
AND BY SEMI-CIVILISED PEOPLE—UNIMPORTANT CHARACTERS OFTEN ATTENDED
TO—UNCONSCIOUS SELECTION—AS CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR
DOMESTICATED ANIMALS CHANGED THROUGH THE ACTION OF UNCONSCIOUS
SELECTION—INFLUENCE OF DIFFERENT BREEDERS ON THE SAME
SUB-VARIETY—PLANTS AS AFFECTED BY UNCONSCIOUS SELECTION—EFFECTS OF
SELECTION AS SHOWN BY THE GREAT AMOUNT OF DIFFERENCE IN THE PARTS MOST
VALUED BY MAN.

CHAPTER XXI.—SELECTION, _continued_

NATURAL SELECTION AS AFFECTING DOMESTIC PRODUCTIONS—CHARACTERS WHICH
APPEAR OF TRIFLING VALUE OFTEN OF REAL IMPORTANCE—CIRCUMSTANCES
FAVOURABLE TO SELECTION BY MAN—FACILITY IN PREVENTING CROSSES, AND THE
NATURE OF THE CONDITIONS—CLOSE ATTENTION AND PERSEVERANCE
INDISPENSABLE—THE PRODUCTION OF A LARGE NUMBER OF INDIVIDUALS
ESPECIALLY FAVOURABLE—WHEN NO SELECTION IS APPLIED, DISTINCT RACES ARE
NOT FORMED—HIGHLY-BRED ANIMALS LIABLE TO DEGENERATION—TENDENCY IN MAN
TO CARRY THE SELECTION OF EACH CHARACTER TO AN EXTREME POINT, LEADING
TO DIVERGENCE OF CHARACTER, RARELY TO CONVERGENCE—CHARACTERS CONTINUING
TO VARY IN THE SAME DIRECTION IN WHICH THEY HAVE ALREADY
VARIED—DIVERGENCE OF CHARACTER, WITH THE EXTINCTION OF INTERMEDIATE
VARIETIES, LEADS TO DISTINCTNESS IN OUR DOMESTIC RACES—LIMIT TO THE
POWER OF SELECTION—LAPSE OF TIME IMPORTANT—MANNER IN WHICH DOMESTIC
RACES HAVE ORIGINATED—SUMMARY.

CHAPTER XXII.—CAUSES OF VARIABILITY.

VARIABILITY DOES NOT NECESSARILY ACCOMPANY REPRODUCTION—CAUSES ASSIGNED
BY VARIOUS AUTHORS—INDIVIDUAL DIFFERENCES—VARIABILITY OF EVERY KIND DUE
TO CHANGED CONDITIONS OF LIFE—ON THE NATURE OF SUCH CHANGES—CLIMATE,
FOOD, EXCESS OF NUTRIMENT—SLIGHT CHANGES SUFFICIENT—EFFECTS OF GRAFTING
ON THE VARIABILITY OF SEEDLING-TREES—DOMESTIC PRODUCTIONS BECOME
HABITUATED TO CHANGED CONDITIONS—ON THE ACCUMULATIVE ACTION OF CHANGED
CONDITIONS—CLOSE INTERBREEDING AND THE IMAGINATION OF THE MOTHER
SUPPOSED TO CAUSE VARIABILITY—CROSSING AS A CAUSE OF THE APPEARANCE OF
NEW CHARACTERS—VARIABILITY FROM THE COMMINGLING OF CHARACTERS AND FROM
REVERSION—ON THE MANNER AND PERIOD OF ACTION OF THE CAUSES WHICH EITHER
DIRECTLY, OR INDIRECTLY THROUGH THE REPRODUCTIVE SYSTEM, INDUCE
VARIABILITY.




CHAPTER XXIII.—DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF
LIFE.

SLIGHT MODIFICATIONS IN PLANTS FROM THE DEFINITE ACTION OF CHANGED
CONDITIONS, IN SIZE, COLOUR, CHEMICAL PROPERTIES, AND IN THE STATE OF
THE TISSUES—LOCAL DISEASES—CONSPICUOUS MODIFICATIONS FROM CHANGED
CLIMATE OR FOOD, ETC—PLUMAGE OF BIRDS AFFECTED BY PECULIAR NUTRIMENT,
AND BY THE INOCULATION OF POISON—LAND-SHELLS—MODIFICATIONS OF ORGANIC
BEINGS IN A STATE OF NATURE THROUGH THE DEFINITE ACTION OF EXTERNAL
CONDITIONS—COMPARISON OF AMERICAN AND EUROPEAN TREES—GALLS—EFFECTS OF
PARASITIC FUNGI—CONSIDERATIONS OPPOSED TO THE BELIEF IN THE POTENT
INFLUENCE OF CHANGED EXTERNAL CONDITIONS—PARALLEL SERIES OF
VARIETIES—AMOUNT OF VARIATION DOES NOT CORRESPOND WITH THE DEGREE OF
CHANGE IN THE CONDITIONS—BUD-VARIATION—MONSTROSITIES PRODUCED BY
UNNATURAL TREATMENT—SUMMARY.

CHAPTER XXIV.—LAWS OF VARIATION—USE AND DISUSE, ETC.

NISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF THE ORGANISATION—ON THE
EFFECTS OF THE INCREASED USE AND DISUSE OF ORGANS—CHANGED HABITS OF
LIFE—ACCLIMATISATION WITH ANIMALS AND PLANTS—VARIOUS METHODS BY WHICH
THIS CAN BE EFFECTED—ARRESTS OF DEVELOPMENT—RUDIMENTARY ORGANS.

CHAPTER XXV.—LAWS OF VARIATION, _continued._—CORRELATED VARIABILITY.

EXPLANATION OF TERM CORRELATION—CONNECTED WITH
DEVELOPMENT—MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED
SIZE OF PARTS—CORRELATED VARIATION OF HOMOLOGOUS PARTS—FEATHERED FEET
IN BIRDS ASSUMING THE STRUCTURE OF THE WINGS—CORRELATION BETWEEN THE
HEAD AND THE EXTREMITIES—BETWEEN THE SKIN AND DERMAL APPENDAGES—BETWEEN
THE ORGANS OF SIGHT AND HEARING—CORRELATED MODIFICATIONS IN THE ORGANS
OF PLANTS—CORRELATED MONSTROSITIES—CORRELATION BETWEEN THE SKULL AND
EARS—SKULL AND CREST OF FEATHERS—SKULL AND HORNS—CORRELATION OF GROWTH
COMPLICATED BY THE ACCUMULATED EFFECTS OF NATURAL SELECTION—COLOUR AS
CORRELATED WITH CONSTITUTIONAL PECULIARITIES.

CHAPTER XXVI.—LAWS OF VARIATION, _continued._—SUMMARY.

THE FUSION OF HOMOLOGOUS PARTS—THE VARIABILITY OF MULTIPLE AND
HOMOLOGOUS PARTS—COMPENSATION OF GROWTH—MECHANICAL PRESSURE—RELATIVE
POSITION OF FLOWERS WITH RESPECT TO THE AXIS, AND OF SEEDS IN THE
OVARY, AS INDUCING VARIATION—ANALOGOUS OR PARALLEL VARIETIES—SUMMARY OF
THE THREE LAST CHAPTERS.

CHAPTER XXVII.—PROVISIONAL HYPOTHESIS OF PANGENESIS.

PRELIMINARY REMARKS—FIRST PART: THE FACTS TO BE CONNECTED UNDER A
SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS OF
REPRODUCTION—RE-GROWTH OF AMPUTATED PARTS—GRAFT-HYBRIDS—THE DIRECT
ACTION OF THE MALE ELEMENT ON THE FEMALE—DEVELOPMENT—THE FUNCTIONAL
INDEPENDENCE OF THE UNITS OF THE
BODY—VARIABILITY—INHERITANCE—REVERSION—SECOND PART: STATEMENT OF THE
HYPOTHESIS—HOW FAR THE NECESSARY ASSUMPTIONS ARE IMPROBABLE—EXPLANATION
BY AID OF THE HYPOTHESIS OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN
THE FIRST PART—CONCLUSION.

CHAPTER XXVIII.—CONCLUDING REMARKS.

DOMESTICATION—NATURE AND CAUSES OF VARIABILITY—SELECTION—DIVERGENCE AND
DISTINCTNESS OF CHARACTER—EXTINCTION OF RACES—CIRCUMSTANCES FAVOURABLE
TO SELECTION BY MAN—ANTIQUITY OF CERTAIN RACES—THE QUESTION WHETHER
EACH PARTICULAR VARIATION HAS BEEN SPECIALLY PREORDAINED.

INDEX

LIST OF ILLUSTRATIONS

 Figure 1. Dun Devonshire pony, with shoulder, spinal, and leg stripes.
 Figure 2. Head of Japan or masked pig.
 Figure 3. Head of wild boar, and of “golden days,” a pig of the Yorkshire large breed.
 Figure 4. Old Irish pig with jaw-appendages.
 Figure 5. Half-lop rabbit.
 Figure 6. Skull of wild rabbit.
 Figure 7. Skull of large lop-eared rabbit.
 Figure 8. Part of zygomatic arch, showing the projecting end of the malar bone of the auditory meatus, of rabbits.
 Figure 9. Posterior end of skull, showing the inter-parietal bone, of rabbits.
 Figure 10. Occipital foramen of rabbits.
 Figure 11. Skull of half-lop rabbit.
 Figure 12. Atlas vertebrae of rabbits.
 Figure 13. Third cervical vertebrae of rabbits.
 Figure 14. Dorsal vertebrae, from sixth to tenth inclusive, of rabbits.
 Figure 15. Terminal bone of sternum of rabbits.
 Figure 16. Acromion of scapula of rabbits.
 Figure 17. The rock-pigeon, or columba livia.
 Figure 18. English pouter.
 Figure 19. English carrier.
 Figure 20. English barb.
 Figure 21. English fantail.
 Figure 22. African owl.
 Figure 23. Short-faced English tumbler.
 Figure 24. Skulls of pigeons, viewed laterally.
 Figure 25. Lower jaws of pigeons, seen from above.
 Figure 26. Skull of runt, seen from above.
 Figure 27. Lateral view of jaws of pigeons.
 Figure 28. Scapulæ of pigeons.
 Figure 29. Furcula of pigeons.
 Figure 30. Spanish fowl.
 Figure 31. Hamburgh fowl.
 Figure 32. Polish fowl.
 Figure 33. Occipital foramen of the skulls of fowls.
 Figure 34. Skulls of fowls, viewed from above, a little obliquely.
 Figure 35. Longitudinal sections of skulls of fowls, viewed laterally.
 Figure 36. Skull of horned fowl, viewed from above, a little obliquely.
 Figure 37. Sixth cervical vertebræ of fowls, viewed laterally.
 Figure 38. Extremity of the furcula of fowls, viewed laterally.
 Figure 39. Skulls of ducks, viewed laterally, reduced to two-thirds of the natural size.
 Figure 40. Cervical vertebræ of ducks, of natural size.
 Figure 41. Pods of the common pea.
 Figure 42. Peach and almond stones, of natural size, viewed edgeways.
 Figure 43. Plum stones, of natural size, viewed laterally.
FOREWORD

_Harriet Ritvo_

Charles Darwin wrote _On the Origin of Species_ in a hurry. He had, it
was true, been formulating his ideas and arguments for several
decades—since his round-the-world _Beagle_ voyage of 1831-1836. These
ideas and arguments had been slow to take definitive shape; Darwin had
nurtured and reworked them, amassing evidence for what he projected to
be a weighty magnum opus. Although he had shared his developing
evolutionary speculations with his closest professional colleagues,
Darwin was reluctant to publish them on several grounds. He was aware
that his theory of evolution by natural selection (or descent with
modification) was complex, that it rested on vast but not
incontrovertible evidence, and that the chain of his reasoning was not
uniformly strong. Further, his conclusions challenged not only the
scientific assumptions of many fellow specialists but also the
theological convictions of a much wider circle of fellow citizens.

In 1859, Darwin did not feel quite ready to expose his cherished theory
to the harsh light of public scrutiny. In the introduction to the
_Origin_ he confessed that although his work on evolution by natural
selection was “nearly finished,” he would need “two or three more years
to complete it.” The _ Origin_ was, he suggested, merely a stopgap, a
schematic “abstract” of a much longer and more fully supported treatise
yet to come. He had been moved to preview his labors in this way, he
explained, because his health was “far from strong” and, perhaps more
importantly, because Alfred Russel Wallace, a younger naturalist
working in isolation in southeast Asia, had sent a paper to the Linnean
Society of London in which he “arrived at almost exactly the same
general conclusions that I have on the origin of species.” If Darwin
had not gone public with his theory at this point, he would have risked
losing credit for the work of many years.

As its reception showed immediately and has continued to show, the
_Origin_ benefited from the succinctness imposed by circumstances.
Darwin himself may have appreciated this point; at any rate, he never
produced the massive treatise, although he repeatedly issued revised
editions of the _ Origin._ But he did not abandon his intention to
buttress his initial schematic presentation with additional evidence.
In the course of the next two decades he published several full-length
elaborations of topics summarily discussed in the _Origin: The
Variation of Animals and Plants under Domestication; The Descent of
Man, and Selection in Relation to Sex;_ and _The Expression of the
Emotions in Man and Animals._ In addition to fleshing out the _Origin,_
these subsequent studies bolstered its arguments and responded to
questions raised by critical readers, especially pragmatic questions
about the way that descent with modification actually operated.

In _The Variation of Animals and Plants under Domestication,_ which
appeared first in 1868 and in a revised edition in 1875, Darwin
developed a theme to which he had accorded great rhetorical and
evidentiary significance. He had begun the _ Origin_ with a description
of artificial selection as practiced by farmers, stock breeders, and
pet fanciers, thus using a reassuringly homely example—one recognizable
by the general public as well as by members of the scientific
community—to introduce the most innovative component of his
evolutionary theory. In addition, domesticated animals and plants,
because they were numerous and available for constant observation,
provided a readily available body of evidence.

Reassuring as it was, the analogy between natural and artificial
selection was far from perfect. The point of Darwin’s analogy was to
make the idea of natural selection seem plausible by characterizing it
as a grander version of a well-known process while emphasizing its
efficiency and shaping power. He noted, for example, that some of the
prize birds bred by London pigeon fanciers diverged so strikingly in
size, plumage, beak shape, flying technique, vocalizations. bone
structure, and many other attributes, that if they had been presented
to an ornithologist as wild specimens, they would unquestionably have
been considered to represent distinct species, perhaps even distinct
genera. Darwin argued that if the relatively brief and constrained
selective efforts of human breeders had produced such impressive
results, it was likely that the more protracted and thorough-going
efforts of nature would work still more efficaciously.

But as Darwin acknowledged, there were some fairly obvious reasons why
the two processes might diverge. The superior power of natural
selection—“Man can act only on external and visible characters: nature
. . . can act on . . . the whole machinery of life. Man selects only
for his own good; Nature only for that of the being which she tends”
(_Origin,_ chap. 5)—might constitute a difference of kind rather than
of degree, as might the much greater stretches of time available for
natural selection. Further, although the mechanism of the two processes
appeared superficially similar, their outcomes tended to be rather
different. Natural selection produced a constantly increasing and
diversifying variety of forms; it never reversed or exactly repeated
itself. Anyone familiar with artificial selection would have realized
that, although new breeds were constantly being developed and although
neither improved wheat nor improved cattle showed any tendency to
revert to the condition of their aboriginal wild ancestors, the strains
produced by human selection were neither as prolific nor as durable as
those produced by nature. Indeed, the animals and plants celebrated as
the noblest achievements of the breeder’s art were especially liable to
delicacy and infertility. Highly bred strains, long isolated from
others of their species to preserve their genealogical purity, far from
serving as a springboard for further variation, often had to be
revivified with infusions of less-rarefied blood. Yet any relaxation of
reproductive boundaries threatened subsidence into the common run of
conspecifics.

Darwin firmly connected _Variation_ to the _Origin_ by devoting its
introduction to an overview of his theory of evolution by natural
selection. In particular, the two volumes of _Variation,_ cumbersomely
organized and packed with zoological and botanical detail, addressed
some of the difficulties inherent in the attractive but paradoxical
analogy between natural selection and artificial selection. For
selection of any sort to operate, diversity already had to exist. With
wild populations living under natural conditions, however, diversity
was difficult to discern. It was widely believed that a heightened
propensity to vary (at least in ways obvious to human observers) was
one of the few general characteristics that differentiated domestic
animals as a group from their wild relatives. This point was
conventionally illustrated with reference to coat color and design.
American bison, for example, were, on the whole, brown, and all
Burchell’s zebras shared similar black and white stripes. A single herd
of either _Bos tauras_ or _Equus caballus_ (domestic cattle or horses),
on the other hand, could display colors ranging from white through
yellow, red, and brown to black, as well as a variety of spotted and
blotched patterns.

In order to demonstrate that such populations spontaneously produced
sufficient variation to support artificial selection, Darwin devoted
most of the first volume of _ Variation_ to a species-by-species survey
of domesticated plants and animals. He began with the dog, the breeds
of which differed so greatly in size, shape, disposition, talents, and
every other characteristic that Darwin attributed its exemplary
plasticity to its derivation from several different species of wild
canines. Domestic cats, on the other hand, differed relatively little
from one another, at least, their variation tended to be individual,
rather than consolidated into breeds. Darwin attributed this to the
minimal influence exerted by cat owners over the mating behavior of
their animals, so that, alone among fully domesticated animals, cats
could not be said to have undergone a genuine process of artificial
selection.

Farmyard ungulates, however, had all proved more susceptible to human
manipulation, whether through the gradual enhancement of inherent
tendencies, such as the relatively early maturation that distinguished
shorthorn cattle, or through the preservation of spontaneously arising
monstrosities, such as the short, broad foreheads and protruding lower
jaws of the niata cattle of South America, the bulldogs of the bovine
world. Among animals, fancy pigeons, with their short generations,
devoted breeders, and lack of any pragmatic constraints on their
extravagant deformations, provided Darwin with his most abundant
material. He allotted less space to his survey of domesticated plants,
although, with the exception of trees, they tended to he much shorter
lived and more variable even than pigeons. For example, as Darwin
pointed out, a single long-cultivated species—_Brassica oleracea,_ the
ordinary cabbage—had given rise to strains as distinctive as Brussels
sprouts, cauliflower, broccoli, and kohl-rabi.

Darwin crammed in so much information of this sort that, in order to
confine _Variation_ to two volumes of manageable size, less crucial
evidence was relegated to a smaller typeface. And so compendious was
his survey of domesticates that he felt constrained to deny that it was
intended to he an exhaustive catalog. After all, many such catalogs,
devoted merely to the accumulation of species- or breed-specific data,
existed already; Darwin cited them generously in his footnotes. The
material included in _Variation_ had been chosen to fulfill a more
focused argumentative purpose. Darwin’s theory of descent with
modification required something further than the simple demonstration
that abundant variation existed among domesticated animals and plants.
The accumulated experience of naturalists and breeders offered no clear
explanation of the causes of variation; indeed, no consensus existed on
this issue. Variation under domestication was frequently attributed to
accidental external influences, especially climate and food. But
environmentally induced variation was not of much use to Darwin.
Instead, he sought evidence not only that the tendency to vary was
inherent in domesticated animals and plants but also that specific
variations were inherited.

As a result, Darwin’s wealth of detail in _ Variation_
disproportionately featured strong—as well as puzzling, problematic, or
even questionable—versions of inheritance, in addition to the
unsurprising, if still not completely understood, likelihood that
children would resemble their parents. For example, he devoted an
entire chapter to what he termed “atavism” or “reversion”—that is, the
tendency for offspring to manifest traits apparently derived from their
grandparents, collateral relations, or even remote ancestors, rather
than from their mothers or their fathers. The existence of this
tendency in the lineages of individuals, he argued, incontrovertibly
demonstrated the fact of heritability; and in an extended or
exaggerated version it also demonstrated evolutionary relations between
species. Thus, many breeds of domesticated chickens revealed their
ultimate ancestry by producing occasional sports with the red and
orange plumage of the original _Callus bankiva,_ or jungle fowl.

Like many other naturalists of his time, Darwin was receptive to the
idea of telegony, also known as “the influence of the previous sire.”
He retailed the famous story of Lord Morton’s mare, a chestnut of
seven-eighths Arabian blood, whose first foal had been sired by a
quagga (a now-extinct relative of the zebra) her owner was attempting
to domesticate. It was not surprising that the young hybrid faintly
echoed his father’s stripes, but the fact that her next two foals, both
sired by a black Arabian horse, also seemed to resemble the quagga in
this regard, was more remarkable. Darwin pointed out that atavism
offered one possible explanation of this phenomenon—infant horses and
donkeys often showed evanescent striping, which might indicate the
pattern of their ancient shared progenitor—but he was also drawn to the
notion that the first male to impregnate a female left some permanent,
heritable trace of himself behind. He offered analogous examples from
the vegetable kingdom, where the pollen of related varieties of apples,
corn, or orchids, could not only produce hybrid offspring but
occasionally also physically alter the reproductive tract of the
female. Plants also, and more regularly, demonstrated a kind of
variability that could arise independently of sexual reproduction, such
as “bud variation,” whereby what Darwin called a “monstrosity” might
appear on a single branch or flower and then be transmitted, sexually
or asexually, to future generations.

As he documented the profusion of variation among domesticated animals
and plants, and the tendency of organisms to transmit these variations
down the generations, Darwin did more than demonstrate that there was
ample grist for the mill of natural selection. He also addressed the
most serious weakness in the argument of the _Origin._ Despite the
incompleteness of the fossil record, plenty of evidence suggested that
evolution had taken place; indeed the idea of evolution had been
current in one form or another for a century before 1859. Darwin’s
explanation of the way that natural selection should operate was also
widely persuasive. The competitive metaphors with which he
characterized it, especially the “struggle for life” prominently
featured in the _Origin_’s subtitle, fit well with Victorian
understandings about how things worked in the human arenas of industry,
commerce, and geopolitics. There was, however, a problem that troubled
those inclined to sympathize with Darwin’s reasoning as well as those
inclined to reject it. The efficacy of natural selection, like that of
artificial selection, depended on the inheritance of particular traits.
But before the modern understanding of genetics became available, no
satisfactory mechanism had been adduced to explain this phenomenon. No
consensus yet existed about the way that sexual reproduction worked, so
there was also disagreement about which characteristics were inherited
and which were the result of environment, and what could he contributed
by the male as opposed to the female parent, let alone why offspring
sometimes resembled a grandparent or some more distant relative rather
than their parents. The special difficulty of accounting for the sudden
emergence of monstrosities, or even less dramatically novel traits, led
Darwin, in later editions of the _Origin_ as well as in _Variation,_ to
become increasingly receptive to the notion that characteristics
acquired by one generation might he inherited by the next.

In the penultimate chapter of _Variation,_ Darwin attempted to
strengthen the weak link in his chain of argument by proposing a
mechanism for inheritance. He called his theory “pangenesis,” and he
claimed that it explained not only ordinary inheritance—the influence
of parents on their children—but also reversion, telegony, the
regeneration of amputated limbs in some kinds of animals, the
inheritance of acquired characteristics, and the relationship between
sexual and asexual modes of reproduction and inheritance. The operation
of pangenesis depended on the posited existence of unobservable units
that Darwin called “gemmules,” tiny granules that were thrown off by
individual cells and then circulated through the body. They had,
however, an affinity for each other, which led to their aggregation in
the reproductive organs or in parthenogenetic buds. They could remain
latent for years, until an organism reached a certain stage of
development, or for generations, until they encountered other gemmules
to which they bore some special relationship. In this way a
long-dormant greatgrandparental gemmule might suddenly manifest itself
in a child. Since gemmules could he altered by environmental
influences, they could convert acquired characteristics into the stuff
of heredity. And since they were vulnerable to error, they could
occasionally make mistakes, causing organs, such as limbs or tails or
even heads, to develop in inappropriate numbers or in the wrong places.

It has doubtless been fortunate for Darwin’s reputation that his theory
of pangenesis is not as well remembered as his theory of evolution by
natural selection. As vague in detail as it was ambitious and
comprehensive in scope, it was unpersuasive at the time and has since
been proven completely wrong. But like _Variation_ as a whole, which
similarly illustrated the limitations of its author as well as his
strengths, pangenesis does not therefore lack interest or significance.
Despite recent excellent and well-appreciated studies of his entire
life and extended _oeuvre_ (Janet Browne, _Charles Darwin: Voyaging_
[New York: Knopf, 1995] and Adrian Desmond and James Moore, _Darwin_
[London: Michael Joseph, 1991], Darwin is known primarily as the author
of the _Origin,_ which is unrepresentative in its economy of structure,
argument, and evidence, as well as on account of its historical
notoriety. Its enforced streamlining has helped to preserve the
_Origin_’s accessibility, but its relative paucity of examples was
particularly uncharacteristic of Darwin. _Variation,_ with its
accumulation of evidence about everything from the webbing between
dogs’ toes to the weight of gooseberries, was much more typical; in
addition, it placed Darwin firmly—indeed, irretrievably—within his
time, rather than in an achronological limbo reserved for intellectual
heroes. As a graduate student from the People’s Republic of China told
me several years ago, after having participated in a seminar that read
excerpts from _Variation_ and _The Expression of the Emotions,_ if the
leaders of his government knew that Darwin had written such books, he
would not be officially admired.

In science as in politics the victors tend to write the history books.
As a result, the record of the past is edited, intentionally or
unintentionally, so that it focuses mainly on the precursors of
contemporary orthodoxy. Such a focus may accurately represent the
genealogy of modem ideas, but it almost inevitably misrepresents the
historical experience of their progenitors. Viewed without the benefit
of hindsight, the marketplace of Victorian ideas seemed much more
competitive than it does to us. Even the powerful, persuasive, and
ultimately triumphant theory of evolution by natural selection required
not only defense, but repeated buttressing and revision. _ Variation_
showed Darwin hard at work on this rearguard action, using the
materials he had at hand—for the most part, homely details about the
domesticated animals and plants with which his audience was most
familiar. His information was gleaned from the observations of
fanciers, breeders, and amateur naturalists, as well as from the
treatises of those on the cutting edge of zoology and botany. As
hindsight narrows the historical spotlight, it imposes its own sense of
hierarchy on the preoccupations of the past. But Darwin was interested
in all of these topics, valued all of these sources, and belonged, to a
greater or lesser extent, to all of these communities.

The author of _Variation_ was a Victorian country gentleman, a lover of
dogs and horses, a breeder of pigeons and peas. He was also, and
equally, the author of _On the Origin of Species._


PREFACE TO THE SECOND EDITION

During the seven years which have elapsed since the publication in 1868
of the first edition of this Work, I have continued to attend to the
same subjects, as far as lay in my power; and I have thus accumulated a
large body of additional facts, chiefly through the kindness of many
correspondents. Of these facts I have been able here to use only those
which seemed to me the more important. I have omitted some statements,
and corrected some errors, the discovery of which I owe to my
reviewers. Many additional references have been given. The eleventh
chapter, and that on Pangenesis, are those which have been most
altered, parts having been remodelled; but I will give a list of the
more important alterations for the sake of those who may possess the
first edition of this book.

          TABLE OF PRINCIPAL ADDITIONS AND CORRECTIONS IN SECOND
          EDITION



              First
              Edition
              Vol. I

              Second
              Edition
              Vol. I



            
              First

              Edition

              Vol. I
            
               
            
              Second

              Edition

              Vol. I
            
               
                                               
_Page_     _Chapter_      
34     I     Dr. Burt Wilder’s observations on the brains
          of different breeds of the Dog.
38     I     Degeneracy of Dogs imported into
          Guinea.
51     II     Difference in the number of lumbar
          vertebræ in the races or species of the Horse.
102     III     Hairy appendages to the throats of
          Goats.
162     V     Sexual differences in colour in the domestic
          Pigeon.
217     VI     Movements like those of the Tumbler-pigeon,
          caused by injury to the brain.
290     VIII     Additional facts with respect to the
          Black-shouldered Peacock.
296     VIII     Ancient selection of Gold-fish in
          China.
314     IX     Major Hallett’s ‘Pedigree Wheat.’
326     IX     The common radish descended from _Raphanus
          raphanistrum._
374     XI     Several additional cases of bud-variation
          given.
396     XI     An abstract of all the cases recently
          published of graft-hybrids in the potato, together with a
          general summary on graft-hybridisation.
399     XI     An erroneous statement with respect to the
          pollen of the date-palm affecting the fruit of the
          Chamærops omitted.
400     XI     New cases of the direct action of pollen on
          the mother-plant.
404     XI     Additional and remarkable instances of the
          actions of the male parent on the future progeny of the
          female.
Vol.II            
14     XII     An erroneous statement corrected, with
          respect to the regrowth of supernumerary digits after
          amputation.
23     XII     Additional facts with respect to the
          inherited effects of circumcision.
23     XII     Dr. Brown-Séquard on the inherited
          effects of operations on the Guinea-pig.
24     XII     Other cases of inherited mutilations.
      Vol. II      
43     XIII     An additional case of reversion due to a
          cross.
72     XIV     Inheritance as limited by sex.
105     XVI     Two varieties of maize which cannot be
          crossed.
120     XVII     Some additional facts on the advantages of
          cross-breeding in animals.
123     XVII     Discussion on the effects of the close
          interbreeding in the case of man.
135

          to

          141      

          XVII

                Additional cases of plants sterile with
          pollen from the same plant.
149     XVIII     Mr. Sclater on the infertility of animals
          under confinement.
152     XVIII     The Aperea a distinct species from the
          Guinea-pig.
230     XXI     Prof. Jäger on hawks killing
          light-coloured pigeons.
273     XXIII     Prof. Wisemann on the effects of isolation
          in the development of species.
281     XXIII     The direct action of the conditions of life
          in causing variation.
317     XXIV     Mr. Romanes on rudimentary parts.
324

          to

          328      

          XXV

                Some additional cases of correlated
          variability.
339     XXVI     On Geoffrey St. Hilaire’s law of _“soi
          pour soi.”_
357

          to

          404      

          XXVII

                The chapter on Pangenesis has been largely
          altered and re-modelled; but the essential principles remain
          the same.




INTRODUCTION


The object of this work is not to describe all the many races of
animals which have been domesticated by man, and of the plants which
have been cultivated by him; even if I possessed the requisite
knowledge, so gigantic an undertaking would be here superfluous. It is
my intention to give under the head of each species only such facts as
I have been able to collect or observe, showing the amount and nature
of the changes which animals and plants have undergone whilst under
man’s dominion, or which bear on the general principles of variation.
In one case alone, namely in that of the domestic pigeon, I will
describe fully all the chief races, their history, the amount and
nature of their differences, and the probable steps by which they have
been formed. I have selected this case, because, as we shall hereafter
see, the materials are better than in any other; and one case fully
described will in fact illustrate all others. But I shall also describe
domesticated rabbits, fowls, and ducks, with considerable fulness.

The subjects discussed in this volume are so connected that it is not a
little difficult to decide how they can be best arranged. I have
determined in the first part to give, under the heads of the various
animals and plants, a large body of facts, some of which may at first
appear but little related to our subject, and to devote the latter part
to general discussions. Whenever I have found it necessary to give
numerous details, in support of any proposition or conclusion, small
type has been used. The reader will, I think, find this plan a
convenience, for, if he does not doubt the conclusion or care about the
details, he can easily pass them over; yet I may be permitted to say
that some of the discussions thus printed deserve attention, at least
from the professed naturalist.

It may be useful to those who have read nothing about Natural
Selection, if I here give a brief sketch of the whole subject and of
its bearing on the origin of species.[1] This is the more desirable, as
it is impossible in the present work to avoid many allusions to
questions which will be fully discussed in future volumes.

From a remote period, in all parts of the world, man has subjected many
animals and plants to domestication or culture. Man has no power of
altering the absolute conditions of life; he cannot change the climate
of any country; he adds no new element to the soil; but he can remove
an animal or plant from one climate or soil to another, and give it
food on which it did not subsist in its natural state. It is an error
to speak of man “tampering with nature” and causing variability. If a
man drops a piece of iron into sulphuric acid, it cannot be said
strictly that he makes the sulphate of iron, he only allows their
elective affinities to come into play. If organic beings had not
possessed an inherent tendency to vary, man could have done nothing.[2]
He unintentionally exposes his animals and plants to various conditions
of life, and variability supervenes, which he cannot even prevent or
check. Consider the simple case of a plant which has been cultivated
during a long time in its native country, and which consequently has
not been subjected to any change of climate. It has been protected to a
certain extent from the competing roots of plants of other kinds; it
has generally been grown in manured soil; but probably not richer than
that of many an alluvial flat; and lastly, it has been exposed to
changes in its conditions, being grown sometimes in one district and
sometimes in another, in different soils. Under such circumstances,
scarcely a plant can be named, though cultivated in the rudest manner,
which has not given birth to several varieties. It can hardly be
maintained that during the many changes which this earth has undergone,
and during the natural migrations of plants from one land or island to
another, tenanted by different species, that such plants will not often
have been subjected to changes in their conditions analogous to those
which almost inevitably cause cultivated plants to vary. No doubt man
selects varying individuals, sows their seeds, and again selects their
varying offspring. But the initial variation on which man works, and
without which he can do nothing, is caused by slight changes in the
conditions of life, which must often have occurred under nature. Man,
therefore, may be said to have been trying an experiment on a gigantic
scale; and it is an experiment which nature during the long lapse of
time has incessantly tried. Hence it follows that the principles of
domestication are important for us. The main result is that organic
beings thus treated have varied largely, and the variations have been
inherited. This has apparently been one chief cause of the belief long
held by some few naturalists that species in a state of nature undergo
change.

I shall in this volume treat, as fully as my materials permit, the
whole subject of variation under domestication. We may thus hope to
obtain some light, little though it be, on the causes of
variability,—on the laws which govern it, such as the direct action of
climate and food, the effects of use and disuse, and of correlation of
growth,—and on the amount of change to which domesticated organisms are
liable. We shall learn something of the laws of inheritance, of the
effects of crossing different breeds, and on that sterility which often
supervenes when organic beings are removed from their natural
conditions of life, and likewise when they are too closely interbred.
During this investigation we shall see that the principle of Selection
is highly important. Although man does not cause variability and cannot
even prevent it, he can select, preserve, and accumulate the variations
given to him by the hand of nature almost in any way which he chooses;
and thus he can certainly produce a great result. Selection may be
followed either methodically and intentionally, or unconsciously and
unintentionally. Man may select and preserve each successive variation,
with the distinct intention of improving and altering a breed, in
accordance with a preconceived idea; and by thus adding up variations,
often so slight as to be imperceptible by an uneducated eye, he has
effected wonderful changes and improvements. It can, also, be clearly
shown that man, without any intention or thought of improving the
breed, by preserving in each successive generation the individuals
which he prizes most, and by destroying the worthless individuals,
slowly, though surely, induces great changes. As the will of man thus
comes into play, we can understand how it is that domesticated breeds
show adaptation to his wants and pleasures. We can further understand
how it is that domestic races of animals and cultivated races of plants
often exhibit an abnormal character, as compared with natural species;
for they have been modified not for their own benefit, but for that of
man.

In another work I shall discuss, if time and health permit, the
variability of organic beings in a state of nature; namely, the
individual differences presented by animals and plants, and those
slightly greater and generally inherited differences which are ranked
by naturalists as varieties or geographical races. We shall see how
difficult, or rather how impossible it often is, to distinguish between
races and sub-species, as the less well-marked forms have sometimes
been denominated; and again between sub-species and true species. I
shall further attempt to show that it is the common and widely ranging,
or, as they may be called, the dominant species, which most frequently
vary; and that it is the large and flourishing genera which include the
greatest number of varying species. Varieties, as we shall see, may
justly be called incipient species.

But it may be urged, granting that organic beings in a state of nature
present some varieties,—that their organisation is in some slight
degree plastic; granting that many animals and plants have varied
greatly under domestication, and that man by his power of selection has
gone on accumulating such variations until he has made strongly marked
and firmly inherited races; granting all this, how, it may be asked,
have species arisen in a state of nature? The differences between
natural varieties are slight; whereas the differences are considerable
between the species of the same genus, and great between the species of
distinct genera. How do these lesser differences become augmented into
the greater difference? How do varieties, or as I have called them
incipient species, become converted into true and well-defined species?
How has each new species been adapted to the surrounding physical
conditions, and to the other forms of life on which it in any way
depends? We see on every side of us innumerable adaptations and
contrivances, which have justly excited the highest admiration of every
observer. There is, for instance, a fly (Cecidomyia)[3] which deposits
its eggs within the stamens of a Scrophularia, and secretes a poison
which produces a gall, on which the larva feeds; but there is another
insect (Misocampus) which deposits its eggs within the body of the
larva within the gall, and is thus nourished by its living prey; so
that here a hymenopterous insect depends on a dipterous insect, and
this depends on its power of producing a monstrous growth in a
particular organ of a particular plant. So it is, in a more or less
plainly marked manner, in thousands and tens of thousands of cases,
with the lowest as well as with the highest productions of nature.

This problem of the conversion of varieties into species,—that is, the
augmentation of the slight differences characteristic of varieties into
the greater differences characteristic of species and genera, including
the admirable adaptations of each being to its complex organic and
inorganic conditions of life,—has been briefly treated in my ‘Origin of
Species.’ It was there shown that all organic beings, without
exception, tend to increase at so high a ratio, that no district, no
station, not even the whole surface of the land or the whole ocean,
would hold the progeny of a single pair after a certain number of
generations. The inevitable result is an ever-recurrent Struggle for
Existence. It has truly been said that all nature is at war; the
strongest ultimately prevail, the weakest fail; and we well know that
myriads of forms have disappeared from the face of the earth. If then
organic beings in a state of nature vary even in a slight degree, owing
to changes in the surrounding conditions, of which we have abundant
geological evidence, or from any other cause; if, in the long course of
ages, inheritable variations ever arise in any way advantageous to any
being under its excessively complex and changing relations of life; and
it would be a strange fact if beneficial variations did never arise,
seeing how many have arisen which man has taken advantage of for his
own profit or pleasure; if then these contingencies ever occur, and I
do not see how the probability of their occurrence can be doubted, then
the severe and often-recurrent struggle for existence will determine
that those variations, however slight, which are favourable shall be
preserved or selected, and those which are unfavourable shall be
destroyed.

This preservation, during the battle for life, of varieties which
possess any advantage in structure, constitution, or instinct, I have
called Natural Selection; and Mr. Herbert Spencer has well expressed
the same idea by the Survival of the Fittest. The term “natural
selection” is in some respects a bad one, as it seems to imply
conscious choice; but this will be disregarded after a little
familiarity. No one objects to chemists speaking of “elective
affinity;” and certainly an acid has no more choice in combining with a
base, than the conditions of life have in determining whether or not a
new form be selected or preserved. The term is so far a good one as it
brings into connection the production of domestic races by man’s power
of selection, and the natural preservation of varieties and species in
a state of nature. For brevity sake I sometimes speak of natural
selection as an intelligent power;—in the same way as astronomers speak
of the attraction of gravity as ruling the movements of the planets, or
as agriculturists speak of man making domestic races by his power of
selection. In the one case, as in the other, selection does nothing
without variability, and this depends in some manner on the action of
the surrounding circumstances on the organism. I have, also, often
personified the word Nature; for I have found it difficult to avoid
this ambiguity; but I mean by nature only the aggregate action and
product of many natural laws,—and by laws only the ascertained sequence
of events.

It has been shown from many facts that the largest amount of life can
be supported on each area, by great diversification or divergence in
the structure and constitution of its inhabitants. We have, also, seen
that the continued production of new forms through natural selection,
which implies that each new variety has some advantage over others,
inevitably leads to the extermination of the older and less improved
forms. These latter are almost necessarily intermediate in structure,
as well as in descent, between the last-produced forms and their
original parent-species. Now, if we suppose a species to produce two or
more varieties, and these in the course of time to produce other
varieties, the principal of good being derived from diversification of
structure will generally lead to the preservation of the most divergent
varieties; thus the lesser differences characteristic of varieties come
to be augmented into the greater differences characteristic of species,
and, by the extermination of the older intermediate forms, new species
end by being distinctly defined objects. Thus, also, we shall see how
it is that organic beings can be classed by what is called a natural
method in distinct groups—species under genera, and genera under
families.

As all the inhabitants of each country may be said, owing to their high
rate of reproduction, to be striving to increase in numbers; as each
form comes into competition with many other forms in the struggle for
life,—for destroy any one and its place will be seized by others; as
every part of the organisation occasionally varies in some slight
degree, and as natural selection acts exclusively by the preservation
of variations which are advantageous under the excessively complex
conditions to which each being is exposed, no limit exists to the
number, singularity, and perfection of the contrivances and
co-adaptations which may thus be produced. An animal or a plant may
thus slowly become related in its structure and habits in the most
intricate manner to many other animals and plants, and to the physical
conditions of its home. Variations in the organisation will in some
cases be aided by habit, or by the use and disuse of parts, and they
will be governed by the direct action of the surrounding physical
conditions and by correlation of growth.

On the principles here briefly sketched out, there is no innate or
necessary tendency in each being to its own advancement in the scale of
organisation. We are almost compelled to look at the specialisation or
differentiation of parts or organs for different functions as the best
or even sole standard of advancement; for by such division of labour
each function of body and mind is better performed. And as natural
selection acts exclusively through the preservation of profitable
modifications of structure, and as the conditions of life in each area
generally become more and more complex from the increasing number of
different forms which inhabit it and from most of these forms acquiring
a more and more perfect structure, we may confidently believe, that, on
the whole, organisation advances. Nevertheless a very simple form
fitted for very simple conditions of life might remain for indefinite
ages unaltered or unimproved; for what would it profit an infusorial
animalcule, for instance, or an intestinal worm, to become highly
organised? Members of a high group might even become, and this
apparently has often occurred, fitted for simpler conditions of life;
and in this case natural selection would tend to simplify or degrade
the organisation, for complicated mechanism for simple actions would be
useless or even disadvantageous.

The arguments opposed to the theory of Natural Selection, have been
discussed in my ‘Origin of Species,’ as far as the size of that work
permitted, under the following heads: the difficulty in understanding
how very simple organs have been converted by small and graduated steps
into highly perfect and complex organs; the marvellous facts of
Instinct; the whole question of Hybridity; and, lastly, the absence in
our known geological formations of innumerable links connecting all
allied species. Although some of these difficulties are of great
weight, we shall see that many of them are explicable on the theory of
natural selection, and are otherwise inexplicable.

In scientific investigations it is permitted to invent any hypothesis,
and if it explains various large and independent classes of facts it
rises to the rank of a well-grounded theory. The undulations of the
ether and even its existence are hypothetical, yet every one now admits
the undulatory theory of light. The principle of natural selection may
be looked at as a mere hypothesis, but rendered in some degree probable
by what we positively know of the variability of organic beings in a
state of nature,—by what we positively know of the struggle for
existence, and the consequent almost inevitable preservation of
favourable variations,—and from the analogical formation of domestic
races. Now this hypothesis may be tested,—and this seems to me the only
fair and legitimate manner of considering the whole question,—by trying
whether it explains several large and independent classes of facts;
such as the geological succession of organic beings, their distribution
in past and present times, and their mutual affinities and homologies.
If the principle of natural selection does explain these and other
large bodies of facts, it ought to be received. On the ordinary view of
each species having been independently created, we gain no scientific
explanation of any one of these facts. We can only say that it has so
pleased the Creator to command that the past and present inhabitants of
the world should appear in a certain order and in certain areas; that
He has impressed on them the most extraordinary resemblances, and has
classed them in groups subordinate to groups. But by such statements we
gain no new knowledge; we do not connect together facts and laws; we
explain nothing.

It was the consideration of such large groups of facts as these which
first led me to take up the present subject. When I visited during the
voyage of H.M.S. _Beagle,_ the Galapagos Archipelago, situated in the
Pacific Ocean about 500 miles from South America, I found myself
surrounded by peculiar species of birds, reptiles, and plants, existing
nowhere else in the world. Yet they nearly all bore an American stamp.
In the song of the mocking-thrush, in the harsh cry of the
carrion-hawk, in the great candlestick-like opuntias, I clearly
perceived the neighbourhood of America, though the islands were
separated by so many miles of ocean from the mainland, and differed
much in their geological constitution and climate. Still more
surprising was the fact that most of the inhabitants of each separate
island in this small archipelago were specifically different, though
most closely related to each other. The archipelago, with its
innumerable craters and bare streams of lava, appeared to be of recent
origin; and thus I fancied myself brought near to the very act of
creation. I often asked myself how these many peculiar animals and
plants had been produced: the simplest answer seemed to be that the
inhabitants of the several islands had descended from each other,
undergoing modification in the course of their descent; and that all
the inhabitants of the archipelago were descended from those of the
nearest land, namely America, whence colonists would naturally have
been derived. But it long remained to me an inexplicable problem how
the necessary degree of modification could have been effected, and it
would have thus remained for ever, had I not studied domestic
productions, and thus acquired a just idea of the power of Selection.
As soon as I had fully realised this idea, I saw, on reading Malthus on
Population, that Natural Selection was the inevitable result of the
rapid increase of all organic beings; for I was prepared to appreciate
the struggle for existence by having long studied the habits of
animals.

Before visiting the Galapagos I had collected many animals whilst
travelling from north to south on both sides of America, and
everywhere, under conditions of life as different as it is possible to
conceive, American forms were met with—species replacing species of the
same peculiar genera. Thus it was when the Cordilleras were ascended,
or the thick tropical forests penetrated, or the fresh waters of
America searched. Subsequently I visited other countries, which in all
their conditions of life were incomparably more like parts of South
America, than the different parts of that continent are to each other;
yet in these countries, as in Australia or Southern Africa, the
traveller cannot fail to be struck with the entire difference of their
productions. Again the reflection was forced on me that community of
descent from the early inhabitants of South America would alone explain
the wide prevalence of American types throughout that immense area.

To exhume with one’s own hands the bones of extinct and gigantic
quadrupeds brings the whole question of the succession of species
vividly before one’s mind; and I found in South America great pieces of
tesselated armour exactly like, but on a magnificent scale, that
covering the pigmy armadillo; I had found great teeth like those of the
living sloth, and bones like those of the cavy. An analogous succession
of allied forms had been previously observed in Australia. Here then we
see the prevalence, as if by descent, in time as in space, of the same
types in the same areas; and in neither the case does the similarity of
the conditions by any means seem sufficient to account for the
similarity of the forms of life. It is notorious that the fossil
remains of closely consecutive formations are closely allied in
structure, and we can at once understand the fact if they are closely
allied by descent. The succession of the many distinct species of the
same genus throughout the long series of geological formations seems to
have been unbroken or continuous. New species come in gradually one by
one. Ancient and extinct forms of life are often intermediate in
character, like the words of a dead language with respect to its
several offshoots or living tongues. All these facts seemed to me to
point to descent with modification as the means of production of new
species.

The innumerable past and present inhabitants of the world are connected
together by the most singular and complex affinities, and can be
classed in groups under groups, in the same manner as varieties can be
classed under species and sub-varieties under varieties, but with much
higher grades of difference. These complex affinities and the rules for
classification, receive a rational explanation on the theory of
descent, combined with the principle of natural selection, which
entails divergence of character and the extinction of intermediate
forms. How inexplicable is the similar pattern of the hand of a man,
the foot of a dog, the wing of a bat, the flipper of a seal, on the
doctrine of independent acts of creation! how simply explained on the
principle of the natural selection of successive slight variations in
the diverging descendants from a single progenitor! So it is with
certain parts or organs in the same individual animal or plant, for
instance, the jaws and legs of a crab, or the petals, stamens, and
pistils of a flower. During the many changes to which in the course of
time organic beings have been subjected, certain organs or parts have
occasionally become at first of little use and ultimately superfluous;
and the retention of such parts in a rudimentary and useless condition
is intelligible on the theory of descent. It can be shown that
modifications of structure are generally inherited by the offspring at
the same age at which each successive variation appeared in the
parents; it can further be shown that variations do not commonly
supervene at a very early period of embryonic growth, and on these two
principles we can understand that most wonderful fact in the whole
circuit of natural history, namely, the close similarity of the embryos
within the same great class—for instance, those of mammals, birds,
reptiles, and fish.

It is the consideration and explanation of such facts as these which
has convinced me that the theory of descent with modification by means
of natural selection is in the main true. These facts have as yet
received no explanation on the theory of independent Creation; they
cannot be grouped together under one point of view, but each has to be
considered as an ultimate fact. As the first origin of life on this
earth, as well as the continued life of each individual, is at present
quite beyond the scope of science, I do not wish to lay much stress on
the greater simplicity of the view of a few forms or of only one form
having been originally created, instead of innumerable miraculous
creations having been necessary at innumerable periods; though this
more simple view accords well with Maupertuis’s philosophical axiom of
“least action.”

In considering how far the theory of natural selection may be extended,
—that is, in determining from how many progenitors the inhabitants of
the world have descended,—we may conclude that at least all the members
of the same class have descended from a single ancestor. A number of
organic beings are included in the same class, because they present,
independently of their habits of life, the same fundamental type of
structure, and because they graduate into each other. Moreover, members
of the same class can in most cases be shown to be closely alike at an
early embryonic age. These facts can be explained on the belief of
their descent from a common form; therefore it may be safely admitted
that all the members of the same class are descended from one
progenitor. But as the members of quite distinct classes have something
in common in structure and much in common in constitution, analogy
would lead us one step further, and to infer as probable that all
living creatures are descended from a single prototype.

I hope that the reader will pause before coming to any final and
hostile conclusion on the theory of natural selection. The reader may
consult my ‘Origin of Species’ for a general sketch of the whole
subject; but in that work he has to take many statements on trust. In
considering the theory of natural selection, he will assuredly meet
with weighty difficulties, but these difficulties relate chiefly to
subjects—such as the degree of perfection of the geological record, the
means of distribution, the possibility of transitions in organs,
etc.—on which we are confessedly ignorant; nor do we know how ignorant
we are. If we are much more ignorant than is generally supposed, most
of these difficulties wholly disappear. Let the reader reflect on the
difficulty of looking at whole classes of facts from a new point of
view. Let him observe how slowly, but surely, the noble views of Lyell
on the gradual changes now in progress on the earth’s surface have been
accepted as sufficient to account for all that we see in its past
history. The present action of natural selection may seem more or less
probable; but I believe in the truth of the theory, because it
collects, under one point of view, and gives a rational explanation of,
many apparently independent classes of facts.[4]

REFERENCES

 [1] To any one who has attentively read my ‘Origin of Species’ this
 Introduction will be superfluous. As I stated in that work that I
 should soon publish the facts on which the conclusions given in it
 were founded, I here beg permission to remark that the great delay in
 publishing this first work has been caused by continued ill-health.

 [2] M. Pouchet has recently (‘Plurality of Races,’ Eng. Translat.,
 1864, p. 83, etc.) insisted that variation under domestication throws
 no light on the natural modification of species. I cannot perceive the
 force of his arguments, or, to speak more accurately, of his
 assertions to this effect.

 [3] Léon Dufour in ‘Annales des Science. Nat.’ (3rd series, Zoolog.),
 tom. v. p. 6.

 [4] In treating the several subjects included in the present and my
 other works I have continually been led to ask for information from
 many zoologists, botanists, geologists, breeders of animals, and
 horticulturists, and I have invariably received from them the most
 generous assistance. Without such aid I could have effected little. I
 have repeatedly applied for information and specimens to foreigners,
 and to British merchants and officers of the Government residing in
 distant lands, and, with the rarest exceptions, I have received
 prompt, open-handed, and valuable assistance. I cannot express too
 strongly my obligations to the many persons who have assisted me, and
 who, I am convinced, would be equally willing to assist others in any
 scientific investigation.




CHAPTER I. DOMESTIC DOGS AND CATS.

ANCIENT VARIETIES OF THE DOG—RESEMBLANCE OF DOMESTIC DOGS IN VARIOUS
COUNTRIES TO NATIVE CANINE SPECIES—ANIMALS NOT ACQUAINTED WITH MAN AT
FIRST FEARLESS—DOGS RESEMBLING WOLVES AND JACKALS—HABIT OF BARKING
ACQUIRED AND LOST—FERAL DOGS—TAN-COLOURED EYE-SPOTS—PERIOD OF
GESTATION—OFFENSIVE ODOUR—FERTILITY OF THE RACES WHEN
CROSSED—DIFFERENCES IN THE SEVERAL RACES IN PART DUE TO DESCENT FROM
DISTINCT SPECIES—DIFFERENCES IN THE SKULL AND TEETH—DIFFERENCES IN THE
BODY, IN CONSTITUTION—FEW IMPORTANT DIFFERENCES HAVE BEEN FIXED BY
SELECTION—DIRECT ACTION OF CLIMATE—WATER-DOGS WITH PALMATED
FEET—HISTORY OF THE CHANGES WHICH CERTAIN ENGLISH RACES OF THE DOG HAVE
GRADUALLY UNDERGONE THROUGH SELECTION—EXTINCTION OF THE LESS IMPROVED
SUB-BREEDS.

CATS, CROSSED WITH SEVERAL SPECIES—DIFFERENT BREEDS FOUND ONLY IN
SEPARATED COUNTRIES—DIRECT EFFECTS OF THE CONDITIONS OF LIFE—FERAL
CATS—INDIVIDUAL VARIABILITY.


    The first and chief point of interest in this chapter is, whether
    the numerous domesticated varieties of the dog have descended from
    a single wild species, or from several. Some authors believe that
    all have descended from the wolf, or from the jackal, or from an
    unknown and extinct species. Others again believe, and this of late
    has been the favourite tenet, that they have descended from several
    species, extinct and recent, more or less commingled together. We
    shall probably never be able to ascertain their origin with
    certainty. Palæontology[1] does not throw much light on the
    question, owing, on the one hand, to the close similarity of the
    skulls of extinct as well as living wolves and jackals, and owing,
    on the other hand, to the great dissimilarity of the skulls of the
    several breeds of the domestic dogs. It seems, however, that
    remains have been found in the later tertiary deposits more like
    those of a large dog than of a wolf, which favours the belief of De
    Blainville that our dogs are the descendants of a single extinct
    species. On the other hand, some authors go so far as to assert
    that every chief domestic breed must have had its wild prototype.
    This latter view is extremely improbable: it allows nothing for
    variation; it passes over the almost monstrous character of some of
    the breeds; and it almost necessarily assumes that a large number
    of species have become extinct since man domesticated the dog;
    whereas we plainly see that wild members of the dog-family are
    extirpated by human agency with much difficulty; even so recently
    as 1710 the wolf existed in so small an island as Ireland.

    The reasons which have led various authors to infer that our dogs
    have descended from more than one wild species are as follows.[2]
    Firstly, the great difference between the several breeds; but this
    will appear of comparatively little weight, after we shall have
    seen how great are the differences between the several races of
    various domesticated animals which certainly have descended from a
    single parent-form. Secondly, the more important fact, that, at the
    most anciently known historical periods, several breeds of the dog
    existed, very unlike each other, and closely resembling or
    identical with breeds still alive.

    We will briefly run back through the historical records. The
    materials are remarkably deficient between the fourteenth century
    and the Roman classical period.[3] At this latter period various
    breeds, namely hounds, house-dogs, lapdogs, etc, existed; but, as
    Dr. Walther has remarked, it is impossible to recognise the greater
    number with any certainty. Youatt, however, gives a drawing of a
    beautiful sculpture of two greyhound puppies from the Villa of
    Antoninus. On an Assyrian monument, about 640 B.C., an enormous
    mastiff[4] is figured; and according to Sir H. Rawlinson (as I was
    informed at the British Museum), similar dogs are still imported
    into this same country. I have looked through the magnificent works
    of Lepsius and Rosellini, and on the Egyptian monuments from the
    fourth to the twelfth dynasties (i.e. from about 3400 B.C. to 2100 
    B.C.) several varieties of the dog are represented; most of them
    are allied to greyhounds; at the later of these periods a dog
    resembling a hound is figured, with drooping ears, but with a
    longer back and more pointed head than in our hounds. There is,
    also, a turnspit, with short and crooked legs, closely resembling
    the existing variety; but this kind of monstrosity is so common
    with various animals, as with the ancon sheep, and even, according
    to Rengger, with jaguars in Paraguay, that it would be rash to look
    at the monumental animal as the parent of all our turnspits:
    Colonel Sykes[5] also has described an Indian pariah dog as
    presenting the same monstrous character. The most ancient dog
    represented on the Egyptian monuments is one of the most singular;
    it resembles a greyhound, but has long pointed ears and a short
    curled tail: a closely allied variety still exists in Northern
    Africa; for Mr. E. Vernon Harcourt[6] states that the Arab
    boar-hound is “an eccentric hieroglyphic animal, such as Cheops
    once hunted with, somewhat resembling the rough Scotch deer-hound;
    their tails are curled tight round on their backs, and their ears
    stick out at right angles.” With this most ancient variety a
    pariah-like dog coexisted.

    We thus see that, at a period between four and five thousand years
    ago, various breeds, viz. pariah dogs, greyhounds, common hounds,
    mastiffs, house-dogs, lapdogs, and turnspits, existed, more or less
    closely resembling our present breeds. But there is not sufficient
    evidence that any of these ancient dogs belonged to the same
    identical sub-varieties with our present dogs.[7] As long as man
    was believed to have existed on this earth only about 6000 years,
    this fact of the great diversity of the breeds at so early a period
    was an argument of much weight that they had proceeded from several
    wild sources, for there would not have been sufficient time for
    their divergence and modification. But now that we know, from the
    discovery of flint tools embedded with the remains of extinct
    animals in districts which have since undergone great geographical
    changes, that man has existed for an incomparably longer period,
    and bearing in mind that the most barbarous nations possess
    domestic dogs, the argument from insufficient time falls away
    greatly in value.

    Long before the period of any historical record the dog was
    domesticated in Europe. In the Danish Middens of the Neolithic or
    Newer Stone period, bones of a canine animal are embedded, and
    Steenstrup ingeniously argues that these belonged to a domestic
    dog; for a very large proportion of the bones of birds preserved in
    the refuse consists of long bones, which it was found on trial dogs
    cannot devour.[8] This ancient dog was succeeded in Denmark during
    the Bronze period by a larger kind, presenting certain differences,
    and this again during the Iron period, by a still larger kind. In
    Switzerland, we hear from Prof. Rütimeyer,[9] that during the
    Neolithic period a domesticated dog of middle size existed, which
    in its skull was about equally remote from the wolf and jackal, and
    partook of the characters of our hounds and setters or spaniels
    (Jagdhund und Wachtelhund). Rütimeyer insists strongly on the
    constancy of form during a very long period of time of this the
    most ancient known dog. During the Bronze period a larger dog
    appeared, and this closely resembled in its jaw a dog of the same
    age in Denmark. Remains of two notably distinct varieties of the
    dog were found by Schmerling in a cave;[10] but their age cannot be
    positively determined.

    The existence of a single race, remarkably constant in form during
    the whole Neolithic period, is an interesting fact in contrast with
    what we see of the changes which the races underwent during the
    period of the successive Egyptian monuments, and in contrast with
    our existing dogs. The character of this animal during the
    Neolithic period, as given by Rütimeyer, supports De Blainville’s
    view that our varieties have descended from an unknown and extinct
    form. But we should not forget that we know nothing with respect to
    the antiquity of man in the warmer parts of the world. The
    succession of the different kinds of dogs in Switzerland and
    Denmark is thought to be due to the immigration of conquering
    tribes bringing with them their dogs; and this view accords with
    the belief that different wild canine animals were domesticated in
    different regions. Independently of the immigration of new races of
    man, we know from the wide-spread presence of bronze, composed of
    an alloy of tin, how much commerce there must have been throughout
    Europe at an extremely remote period, and dogs would then probably
    have been bartered. At the present time, amongst the savages of the
    interior of Guiana, the Taruma Indians are considered the best
    trainers of dogs, and possess a large breed which they barter at a
    high price with other tribes.[11]

    The main argument in favour of the several breeds of the dog being
    the descendants of distinct wild stocks, is their resemblance in
    various countries to distinct species still existing there. It
    must, however, be admitted that the comparison between the wild and
    domesticated animal has been made but in few cases with sufficient
    exactness. Before entering on details, it will be well to show that
    there is no a priori difficulty in the belief that several canine
    species have been domesticated. Members of the dog family inhabit
    nearly the whole world; and several species agree pretty closely in
    habits and structure with our several domesticated dogs. Mr. Galton
    has shown[12] how fond savages are of keeping and taming animals of
    all kinds. Social animals are the most easily subjugated by man,
    and several species of Canidæ hunt in packs. It deserves notice, as
    bearing on other animals as well as on the dog, that at an
    extremely ancient period, when man first entered any country, the
    animals living there would have felt no instinctive or inherited
    fear of him, and would consequently have been tamed far more easily
    than at present. For instance, when the Falkland Islands were first
    visited by man, the large wolf-like dog (_Canis antarcticus_)
    fearlessly came to meet Byron’s sailors, who, mistaking this
    ignorant curiosity for ferocity, ran into the water to avoid them:
    even recently a man, by holding a piece of meat in one hand and a
    knife in the other, could sometimes stick them at night. On a
    island in the Sea of Aral, when first discovered by Butakoff, the
    saigak antelopes, which are “generally very timid and watchful, did
    not fly from us, but on the contrary looked at us with a sort of
    curiosity.” So, again, on the shores of the Mauritius, the manatee
    was not at first in the least afraid of man, and thus it has been
    in several quarters of the world with seals and the morse. I have
    elsewhere shown[13] how slowly the native birds of several islands
    have acquired and inherited a salutary dread of man: at the
    Galapagos Archipelago I pushed with the muzzle of my gun hawks from
    a branch, and held out a pitcher of water for other birds to alight
    on and drink. Quadrupeds and birds which have seldom been disturbed
    by man, dread him no more than do our English birds, the cows, or
    horses grazing in the fields.

It is a more important consideration that several canine species evince
(as will be shown in a future chapter) no strong repugnance or
inability to breed under confinement; and the incapacity to breed under
confinement is one of the commonest bars to domestication. Lastly,
savages set the highest value, as we shall see in the chapter on
Selection, on dogs: even half-tamed animals are highly useful to them:
the Indians of North America cross their half-wild dogs with wolves,
and thus render them even wilder than before, but bolder: the savages
of Guiana catch and partially tame and use the whelps of two wild
species of _Canis,_ as do the savages of Australia those of the wild
Dingo. Mr. Philip King informs me that he once trained a wild Dingo
puppy to drive cattle, and found it very useful. From these several
considerations we see that there is no difficulty in believing that man
might have domesticated various canine species in different countries.
It would indeed have been a strange fact if one species alone had been
domesticated throughout the world.

    We will now enter into details. The accurate and sagacious
    Richardson says, “The resemblance between the Northern American
    wolves (_Canis lupus,_ var. _occidentalis_) and the domestic dogs
    of the Indians is so great that the size and strength of the wolf
    seems to be the only difference. I have more than once mistaken a
    band of wolves for the dogs of a party of Indians; and the howl of
    the animals of both species is prolonged so exactly in the same key
    that even the practised ear of the Indian fails at times to
    discriminate them.” He adds that the more northern Esquimaux dogs
    are not only extremely like the grey wolves of the Arctic circle in
    form and colour, but also nearly equal them in size. Dr. Kane has
    often seen in his teams of sledge-dogs the oblique eye (a character
    on which some naturalists lay great stress), the drooping tail, and
    scared look of the wolf. In disposition the Esquimaux dogs differ
    little from wolves, and, according to Dr. Hayes, they are capable
    of no attachment to man, and are so savage that when hungry they
    will attack even their masters. According to Kane they readily
    become feral. Their affinity is so close with wolves that they
    frequently cross with them, and the Indians take the whelps of
    wolves “to improve the breed of their dogs.” The half-bred wolves
    sometimes (Lamare-Picquot) cannot be tamed, “though this case is
    rare;” but they do not become thoroughly well broken in till the
    second or third generation. These facts show that there can be but
    little, if any, sterility between the Esquimaux dog and the wolf,
    for otherwise they would not be used to improve the breed. As Dr.
    Hayes says of these dogs, “reclaimed wolves they doubtless
    are.”[14]

    North America is inhabited by a second kind of wolf, the
    prairie-wolf (_Canis latrans_), which is now looked at by all
    naturalists as specifically distinct from the common wolf; and is,
    according to Mr. J.K. Lord, in some respects intermediate in habits
    between a wolf and a fox. Sir J. Richardson, after describing the
    Hare Indian dog, which differs in many respects from the Esquimaux
    dog, says, “It bears the same relation to the prairie-wolf that the
    Esquimaux dog does to the great grey wolf.” He could, in fact,
    detect no marked difference between them; and Messrs. Nott and
    Gliddon give additional details showing their close resemblance.
    The dogs derived from the above two aboriginal sources cross
    together and with the wild wolves, at least with the _C.
    occidentalis,_ and with European dogs. In Florida, according to
    Bartram, the black wolf-dog of the Indians differs in nothing from
    the wolves of that country except in barking.[15]

    Turning to the southern parts of the new world, Columbus found two
    kinds of dogs in the West Indies; and Fernandez[16] describes three
    in Mexico: some of these native dogs were dumb—that is, did not
    bark. In Guiana it has been known since the time of Buffon that the
    natives cross their dogs with an aboriginal species, apparently the
    _Canis cancrivorus._ Sir R. Schomburgk, who has so carefully
    explored these regions, writes to me, “I have been repeatedly told
    by the Arawaak Indians, who reside near the coast, that they cross
    their dogs with a wild species to improve the breed, and individual
    dogs have been shown to me which certainly resembled the _C.
    cancrivorus_ much more than the common breed. It is but seldom that
    the Indians keep the _C. cancrivorus_ for domestic purposes, nor is
    the Ai, another species of wild dog, and which I consider to be
    identical with the _Dusicyon silvestris_ of H. Smith, now much used
    by the Arecunas for the purpose of hunting. The dogs of the Taruma
    Indians are quite distinct, and resemble Buffon’s St. Domingo
    greyhound.” It thus appears that the natives of Guiana have
    partially domesticated two aboriginal species, and still cross
    their dogs with them; these two species belong to a quite different
    type from the North American and European wolves. A careful
    observer, Rengger,[17] gives reasons for believing that a hairless
    dog was domesticated when America was first visited by Europeans:
    some of these dogs in Paraguay are still dumb, and Tschudi[18]
    states that they suffer from cold in the Cordillera. This naked dog
    is, however quite distinct from that found preserved in the ancient
    Peruvian burial-places, and described by Tschudi, under the name of
    _Canis ingæ,_ as withstanding cold well and as barking. It is not
    known whether these two distinct kinds of dog are the descendants
    of native species, and it might be argued that when man first
    migrated into America he brought with him from the Asiatic
    continent dogs which had not learned to bark; but this view does
    not seem probable, as the natives along the line of their march
    from the north reclaimed, as we have seen, at least two N. American
    species of Canidæ.

    Turning to the Old World, some European dogs closely resemble the
    wolf; thus the shepherd dog of the plains of Hungary is white or
    reddish-brown, has a sharp nose, short, erect ears, shaggy coat,
    and bushy tail, and so much resembles a wolf that Mr. p.t, who
    gives this description, says he has known a Hungarian mistake a
    wolf for one of his own dogs. Jeitteles, also, remarks on the close
    similarity of the Hungarian dog and wolf. Shepherd dogs in Italy
    must anciently have closely resembled wolves, for Columella (vii.
    12) advises that white dogs be kept, adding, “pastor album probat,
    ne pro lupo canem feriat.” Several accounts have been given of dogs
    and wolves crossing naturally; and Pliny asserts that the Gauls
    tied their female dogs in the woods that they might cross with
    wolves.[19] The European wolf differs slightly from that of North
    America, and has been ranked by many naturalists as a distinct
    species. The common wolf of India is also by some esteemed as a
    third species, and here again we find a marked resemblance between
    the pariah dogs of certain districts of India and the Indian
    wolf.[20]

    With respect to Jackals, Isidore Geoffroy Saint-Hilaire[21] says
    that not one constant difference can be pointed out between their
    structure and that of the smaller races of dogs. They agree closely
    in habits: jackals, when tamed and called by their master, wag
    their tails, lick his hands, crouch, and throw themselves on their
    backs; they smell at the tails of other dogs, and void their urine
    sideways; they roll on carrion or on animals which they have
    killed; and, lastly, when in high spirits, they run round in
    circles or in a figure of eight, with their tails between their
    legs.[22] A number of excellent naturalists, from the time of
    Güldenstädt to that of Ehrenberg, Hemprich, and Cretzschmar, have
    expressed themselves in the strongest terms with respect to the
    resemblance of the half-domestic dogs of Asia and Egypt to jackals.
    M. Nordmann, for instance, says, “Les chiens d’Awhasie ressemblent
    étonnamment à des chacals.” Ehrenberg[23] asserts that the domestic
    dogs of Lower Egypt, and certain mummied dogs, have for their wild
    type a species of wolf (_C. lupaster_) of the country; whereas the
    domestic dogs of Nubia and certain other mummied dogs have the
    closest relation to a wild species of the same country, viz. _C.
    sabbar,_ which is only a form of the common jackal. Pallas asserts
    that jackals and dogs sometimes naturally cross in the East; and a
    case is on record in Algeria.[24] The greater number of naturalists
    divide the jackals of Asia and Africa into several species, but
    some few rank them all as one.

    I may add that the domestic dogs on the coast of Guinea are
    fox-like animals, and are dumb.[25] On the east coast of Africa,
    between latitude 4° and 6° south, and about ten days’ journey in
    the interior, a semi-domestic dog, as the Rev. S. Erhardt informs
    me, is kept, which the natives assert is derived from a similar
    wild animal. Lichtenstein[26] says that the dogs of the Bosjemans
    present a striking resemblance even in colour (excepting the black
    stripe down the back) with the _C. mesomelas_ of South Africa. Mr.
    E. Layard informs me that he has seen a Caffre dog which closely
    resembled an Esquimaux dog. In Australia the Dingo is both
    domesticated and wild; though this animal may have been introduced
    aboriginally by man, yet it must be considered as almost an endemic
    form, for its remains have been found in a similar state of
    preservation and associated with extinct mammals, so that its
    introduction must have been ancient.[27]

    From this resemblance of the half-domesticated dogs in several
    countries to the wild species still living there,—from the facility
    with which they can often be crossed together,—from even half-tamed
    animals being so much valued by savages,—and from the other
    circumstances previously remarked on which favour their
    domestication, it is highly probable that the domestic dogs of the
    world are descended from two well-defined species of wolf (viz. _C.
    lupus_ and _C. latrans),_ and from two or three other doubtful
    species (namely, the European, Indian, and North African wolves);
    from at least one or two South American canine species; from
    several races or species of jackal; and perhaps from one or more
    extinct species. Although it is possible or even probable that
    domesticated dogs, introduced into any country and bred there for
    many generations, might acquire some of the characters proper to
    the aboriginal Canidæ of the country, we can hardly thus account
    for introduced dogs having given rise to two breeds in the same
    country, resembling two of its aboriginal species, as in the
    above-given cases of Guiana and of North America.[28]

    It cannot be objected to the view of several canine species having
    been anciently domesticated, that these animals are tamed with
    difficulty: facts have been already given on this head, but I may
    add that the young of the _Canis primævus_ of India were tamed by
    Mr. Hodgson,[29] and became as sensible of caresses, and manifested
    as much intelligence, as any sporting dog of the same age. There is
    not much difference, as we have already shown and shall further
    see, in habits between the domestic dogs of the North American
    Indians and the wolves of that country, or between the Eastern
    pariah dogs and jackals, or between the dogs which have run wild in
    various countries and the several natural species of the family.
    The habit of barking, however, which is almost universal with
    domesticated dogs, forms an exception, as it does not characterise
    a single natural species of the family, though I am assured that
    the _Canis latrans_ of North America utters a noise which closely
    approaches a bark. But this habit is soon lost by dogs when they
    become feral and is soon reacquired when they are again
    domesticated. The case of the wild dogs on the island of Juan
    Fernandez having become dumb has often been quoted, and there is
    reason to believe[30] that the dumbness ensued in the course of
    thirty-three years; on the other hand, dogs taken from this island
    by Ulloa slowly reacquired the habit of barking. The
    Mackenzie-river dogs, of the _Canis latrans_ type, when brought to
    England, never learned to bark properly; but one born in the
    Zoological Gardens[31] “made his voice sound as loudly as any other
    dog of the same age and size.” According to Professor Nillson,[32]
    a wolf-whelp reared by a bitch barks. I. Geoffroy Saint-Hilaire
    exhibited a jackal which barked with the same tone as any common
    dog.[33] An interesting account has been given by Mr. G. Clarke[34]
    of some dogs run wild on Juan de Nova, in the Indian Ocean; “they
    had entirely lost the faculty of barking; they had no inclination
    for the company of other dogs, nor did they acquire their voice”
    during a captivity of several months. On the island they
    “congregate in vast packs, and catch sea-birds with as much address
    as foxes could display.” The feral dogs of La Plata have not become
    dumb; they are of large size, hunt singly or in packs, and burrow
    holes for their young.[35] In these habits the feral dogs of La
    Plata resemble wolves and jackals; both of which hunt either singly
    or in packs, and burrow holes.[36] These feral dogs have not become
    uniform in colour on Juan Fernandez, Juan de Nova, or La Plata.[37]
    In Cuba the feral dogs are described by Poeppig as nearly all
    mouse-coloured, with short ears and light-blue eyes. In St.
    Domingo, Col. Ham. Smith says[38] that the feral dogs are very
    large, like greyhounds, of a uniform pale blue-ash, with small
    ears, and large light-brown eyes. Even the wild Dingo, though so
    anciently naturalised in Australia, “varies considerably in
    colour,” as I am informed by Mr. P.P. King: a half-bred Dingo
    reared in England[39] showed signs of wishing to burrow.

    From the several foregoing facts we see that reversion in the feral
    state gives no indication of the colour or size of the aboriginal
    parent-species. One fact, however, with respect to the colouring of
    domestic dogs, I at one time hoped might have thrown some light on
    their origin; and it is worth giving, as showing how colouring
    follows laws, even in so anciently and thoroughly domesticated an
    animal as the dog. Black dogs with tan-coloured feet, whatever
    breed they may belong to, almost invariably have a tan-coloured
    spot on the upper and inner corners of each eye, and their lips are
    generally thus coloured. I have seen only two exceptions to this
    rule, namely, in a spaniel and terrier. Dogs of a light-brown
    colour often have a lighter, yellowish-brown spot over the eyes;
    sometimes the spot is white, and in a mongrel terrier the spot was
    black. Mr. Waring kindly examined for me a stud of fifteen
    greyhounds in Suffolk: eleven of them were black, or black and
    white, or brindled, and these had no eye-spots; but three were red
    and one slaty-blue, and these four had dark-coloured spots over
    their eyes. Although the spots thus sometimes differ in colour,
    they strongly tend to be tan-coloured; this is proved by my having
    seen four spaniels, a setter, two Yorkshire shepherd dogs, a large
    mongrel, and some fox-hounds, coloured black and white, with not a
    trace of tan-colour, excepting the spots over the eyes, and
    sometimes a little on the feet. These latter cases, and many
    others, show plainly that the colour of the feet and the eye-spots
    are in some way correlated. I have noticed, in various breeds,
    every gradation, from the whole face being tan-coloured, to a
    complete ring round the eyes, to a minute spot over the inner and
    upper corners. The spots occur in various sub-breeds of terriers
    and spaniels; in setters; in hounds of various kinds, including the
    turnspit-like German badger-hound; in shepherd dogs; in a mongrel,
    of which neither parent had the spots; in one pure bulldog, though
    the spots were in this case almost white; and in greyhounds,—but
    true black-and-tan greyhounds are excessively rare; nevertheless I
    have been assured by Mr. Warwick, that one ran at the Caledonian
    Champion meeting of April 1860, and was “marked precisely like a
    black-and-tan terrier.” This dog, or another exactly the same
    colour, ran at the Scottish National Club on the 21st of March,
    1865; and I hear from Mr. C. M. Browne, that “there was no reason
    either on the sire or dam side for the appearance of this unusual
    colour.” Mr. Swinhoe at my request looked at the dogs in China, at
    Amoy, and he soon noticed a brown dog with yellow spots over the
    eyes. Colonel H. Smith[40] figures the magnificent black mastiff of
    Thibet with a tan-coloured stripe over the eyes, feet, and chaps;
    and what is more singular, he figures the Alco, or native domestic
    dog of Mexico, as black and white, with narrow tan-coloured rings
    round the eyes; at the Exhibition of dogs in London, May 1863, a
    so-called forest dog from North-West Mexico was shown, which had
    pale tan-coloured spots over the eyes. The occurrence of these
    tan-coloured spots in dogs of such extremely different breeds,
    living in various parts of the world, makes the fact highly
    remarkable.

    We shall hereafter see, especially in the chapter on Pigeons, that
    coloured marks are strongly inherited, and that they often aid us
    in discovering the primitive forms of our domestic races. Hence, if
    any wild canine species had distinctly exhibited the tan-coloured
    spots over the eyes, it might have been argued that this was the
    parent-form of nearly all our domestic races. But after looking at
    many coloured plates, and through the whole collection of skins in
    the British Museum, I can find no species thus marked. It is no
    doubt possible that some extinct species was thus coloured. On the
    other hand, in looking at the various species, there seems to be a
    tolerably plain correlation between tan-coloured legs and face; and
    less frequently between black legs and a black face; and this
    general rule of colouring explains to a certain extent the
    above-given cases of correlation between the eye-spots and the
    colour of the feet. Moreover, some jackals and foxes have a trace
    of a white ring round their eyes, as in _C. mesomelas, C. aureus,_
    and (judging from Colonel H. Smith’s drawing) in _C. alopex,_ and
    _C. thaleb._ Other species have a trace of a black line over the
    corners of the eyes, as in _C. variegatus, cinereo-variegatus,_ and
    _fulvus,_ and the wild Dingo. Hence I am inclined to conclude that
    a tendency for tan-coloured spots to appear over the eyes in the
    various breeds of dogs, is analogous to the case observed by
    Desmarest, namely, that when any white appears on a dog the tip of
    the tail is always white, “de manière à rappeler la tache terminale
    de même couleur, qui caractérise la plupart des Canidés
    sauvages.”[41] This rule, however, as I am assured by Mr. Jesse,
    does not invariably hold good.

    It has been objected that our domestic dogs cannot be descended
    from wolves or jackals, because their periods of gestation are
    different. The supposed difference rests on statements made by
    Buffon, Gilibert, Bechstein, and others; but these are now known to
    be erroneous; and the period is found to agree in the wolf, jackal,
    and dog, as closely as could be expected, for it is often in some
    degree variable.[42] Tessier, who has closely attended to this
    subject, allows a difference of four days in the gestation of the
    dog. The Rev. W. D. Fox has given me three carefully recorded cases
    of retrievers, in which the bitch was put only once to the dog; and
    not counting this day, but counting that of parturition, the
    periods were fifty-nine, sixty-two, and sixty-seven days. The
    average period is sixty-three days; but Bellingeri states that this
    applies only to large dogs; and that for small races it is from
    sixty to sixty-three days; Mr. Eyton of Eyton, who has had much
    experience with dogs, also informs me that the time is apt to be
    longer with large than with small dogs.

    F. Cuvier has objected that the jackal would not have been
    domesticated on account of its offensive smell; but savages are not
    sensitive in this respect. The degree of odour, also, differs in
    the different kinds of jackal;[43] and Colonel H. Smith makes a
    sectional division of the group with one character dependent on not
    being offensive. On the other hand, dogs— for instance, rough and
    smooth terriers—differ much in this respect; and M. Godron states
    that the hairless so-called Turkish dog is more odoriferous than
    other dogs. Isidore Geoffroy[44] gave to a dog the same odour as
    that from a jackal by feeding it on raw flesh.

    The belief that our dogs are descended from wolves, jackals, South
    American Canidæ, and other species, suggests a far more important
    difficulty. These animals in their undomesticated state, judging
    from a widely-spread analogy, would have been in some degree
    sterile if intercrossed; and such sterility will be admitted as
    almost certain by all those who believe that the lessened fertility
    of crossed forms is an infallible criterion of specific
    distinctness. Anyhow these animals keep distinct in the countries
    which they inhabit in common. On the other hand, all domestic dogs,
    which are here supposed to be descended from several distinct
    species, are, as far as is known, mutually fertile together. But,
    as Broca has well remarked,[45] the fertility of successive
    generations of mongrel dogs has never been scrutinised with that
    care which is thought indispensable when species are crossed. The
    few facts leading to the conclusion that the sexual feelings and
    reproductive powers differ in the several races of the dog when
    crossed are (passing over mere size as rendering propagation
    difficult) as follows: the Mexican Alco[46] apparently dislikes
    dogs of other kinds, but this perhaps is not strictly a sexual
    feeling; the hairless endemic dog of Paraguay, according to
    Rengger, mixes less with the European races than these do with each
    other; the Spitz dog in Germany is said to receive the fox more
    readily than do other breeds; and Dr. Hodgkin states that a female
    Dingo in England attracted the male wild foxes. If these latter
    statements can be trusted, they prove some degree of sexual
    difference in the breeds of the dog. But the fact remains that our
    domestic dogs, differing so widely as they do in external
    structure, are far more fertile together than we have reason to
    believe their supposed wild parents would have been. Pallas
    assumes[47] that a long course of domestication eliminates that
    sterility which the parent-species would have exhibited if only
    lately captured; no distinct facts are recorded in support of this
    hypothesis; but the evidence seems to me so strong (independently
    of the evidence derived from other domesticated animals) in favour
    of our domestic dogs having descended from several wild stocks,
    that I am inclined to admit the truth of this hypothesis.

    There is another and closely allied difficulty consequent on the
    doctrine of the descent of our domestic dogs from several wild
    species, namely, that they do not seem to be perfectly fertile with
    their supposed parents. But the experiment has not been quite
    fairly tried; the Hungarian dog, for instance, which in external
    appearance so closely resembles the European wolf, ought to be
    crossed with this wolf: and the pariah dogs of India with Indian
    wolves and jackals; and so in other cases. That the sterility is
    very slight between certain dogs and wolves and other Canidæ is
    shown by savages taking the trouble to cross them. Buffon got four
    successive generations from the wolf and dog, and the mongrels were
    perfectly fertile together.[48] But more lately M. Flourens states
    positively as the result of his numerous experiments that hybrids
    from the wolf and dog, crossed _inter se,_ become sterile at the
    third generation, and those from the jackal and dog at the fourth
    generation.[49] But these animals were closely confined; and many
    wild animals, as we shall see in a future chapter, are rendered by
    confinement in some degree or even utterly sterile. The Dingo,
    which breeds freely in Australia with our imported dogs, would not
    breed though repeatedly crossed in the Jardin des Plantes.[50] Some
    hounds from Central Africa, brought home by Major Denham, never
    bred in the Town of London;[51] and a similar tendency to sterility
    might be transmitted to the hybrid offspring of a wild animal.
    Moreover, it appears that in M. Flourens’ experiments the hybrids
    were closely bred in and in for three or four generations; and this
    circumstance would most certainly increase the tendency to
    sterility. Several years ago I saw confined in the Zoological
    Gardens of London a female hybrid from an English dog and jackal,
    which even in this the first generation was so sterile that, as I
    was assured by her keeper, she did not fully exhibit her proper
    periods; but this case was certainly exceptional, as numerous
    instances have occurred of fertile hybrids from these two animals.
    In almost all experiments on the crossing of animals there are so
    many causes of doubt, that it is extremely difficult to come to any
    positive conclusion. It would, however, appear, that those who
    believe that our dogs are descended from several species will have
    not only to admit that their offspring after a long course of
    domestication generally lose all tendency to sterility when crossed
    together; but that between certain breeds of dogs and some of their
    supposed aboriginal parents a certain degree of sterility has been
    retained or possibly even acquired.

Notwithstanding the difficulties in regard to fertility given in the
last two paragraphs, when we reflect on the inherent improbability of
man having domesticated throughout the world one single species alone
of so widely distributed, so easily tamed, and so useful a group as the
Canidæ; when we reflect on the extreme antiquity of the different
breeds; and especially when we reflect on the close similarity, both in
external structure and habits, between the domestic dogs of various
countries and the wild species still inhabiting these same countries,
the balance of evidence is strongly in favour of the multiple origin of
our dogs.

    _Differences between the several Breeds of the Dog.—_If the several
    breeds have descended from several wild stocks, their difference
    can obviously in part be explained by that of their parent species.
    For instance, the form of the greyhound may be partly accounted for
    by descent from some such animal as the slim Abyssinian _Canis
    simensis,_[52] with its elongated muzzle; that of the larger dogs
    from the larger wolves, and the smaller and slighter dogs from the
    jackals: and thus perhaps we may account for certain constitutional
    and climatal differences. But it would be a great error to suppose
    that there has not been in addition[53] a large amount of
    variation. The intercrossing of the several aboriginal wild stocks,
    and of the subsequently formed races, has probably increased the
    total number of breeds, and, as we shall presently see, has greatly
    modified some of them. But we cannot explain by crossing the origin
    of such extreme forms as thoroughbred greyhounds, bloodhounds,
    bulldogs, Blenheim spaniels, terriers, pugs, etc., unless we
    believe that forms equally or more strongly characterised in these
    different respects once existed in nature. But hardly any one has
    been bold enough to suppose that such unnatural forms ever did or
    could exist in a wild state. When compared with all known members
    of the family of Canidæ they betray a distinct and abnormal origin.
    No instance is on record of such dogs as bloodhounds, spaniels,
    true greyhounds having been kept by savages: they are the product
    of long-continued civilisation.

    The number of breeds and sub-breeds of the dog is great; Youatt for
    instance, describes twelve kinds of greyhounds. I will not attempt
    to enumerate or describe the varieties, for we cannot discriminate
    how much of their difference is due to variation, and how much to
    descent from different aboriginal stocks. But it may be worth while
    briefly to mention some points. Commencing with the skull, Cuvier
    has admitted[54] that in form the differences are “plus fortes que
    celles d’aucunes espèces sauvages d’un même genre naturel.” The
    proportions of the different bones; the curvature of the lower jaw,
    the position of the condyles with respect to the plane of the teeth
    (on which F. Cuvier founded his classification), and in mastiffs
    the shape of its posterior branch; the shape of the zygomatic arch,
    and of the temporal fossae; the position of the occiput—all vary
    considerably.[55] The difference in size between the brains of dogs
    belonging to large and small breeds “is something prodigious.”
    “Some dogs’ brains are high and rounded, while others are low,
    long, and narrow in front.” In the latter, “the olfactory lobes are
    visible for about half their extent, when the brain is seen from
    above, but they are wholly concealed by the hemispheres in other
    breeds.”[56] The dog has properly six pairs of molar teeth in the
    upper jaw, and seven in the lower; but several naturalists have
    seen not rarely an additional pair in the upper jaw;[57] and
    Professor Gervais says that there are dogs “qui ont sept paires de
    dents supérieures et huit inférieures.” De Blainville[58] has given
    full particulars on the frequency of these deviations in the number
    of the teeth, and has shown that it is not always the same tooth
    which is supernumerary. In short-muzzled races, according to H.
    Müller,[59] the molar teeth stand obliquely, whilst in long-muzzled
    races they are placed longitudinally, with open spaces between
    them. The naked, so-called Egyptian or Turkish dog is extremely
    deficient in its teeth,[60] —sometimes having none except one molar
    on each side; but this, though characteristic of the breed, must be
    considered as a monstrosity. M. Girard,[61] who seems to have
    attended closely to the subject, says that the period of the
    appearance of the permanent teeth differs in different dogs, being
    earlier in large dogs; thus the mastiff assumes its adult teeth in
    four or five months, whilst in the spaniel the period is sometimes
    more than seven or eight months. On the other hand small dogs are
    mature, and the females have arrived at the best age for breeding,
    when one year old, whereas large dogs “are still in their puppyhood
    at this time, and take fully twice as long to develop their
    proportions.”[62]

    With respect to minor differences little need be said. Isidore
    Geoffroy has shown[63] that in size some dogs are six times as long
    (the tail being excluded) as others; and that the height relatively
    to the length of the body varies from between one to two, and one
    to nearly four. In the Scotch deer-hound there is a striking and
    remarkable difference in the size of the male and female.[64] Every
    one knows how the ears vary in size in different breeds, and with
    their great development their muscles become atrophied. Certain
    breeds of dogs are described as having a deep furrow between the
    nostrils and lips. The caudal vertebrae, according to F. Cuvier, on
    whose authority the two last statements rest, vary in number; and
    the tail in English cattle and some shepherd dogs is almost absent.
    The mammae vary from seven to ten in number; Daubenton, having
    examined twenty-one dogs, found eight with five mammae on each
    side; eight with four on each side; and the others with an unequal
    number on the two sides.[65] Dogs have properly five toes in front
    and four behind, but a fifth toe is often added; and F. Cuvier
    states that, when a fifth toe is present, a fourth cuneiform bone
    is developed; and, in this case, sometimes the great cuneiform bone
    is raised, and gives on its inner side a large articular surface to
    the astragalus; so that even the relative connection of the bones,
    the most constant of all characters, varies. These modifications,
    however, in the feet of dogs are not important, because they ought
    to be ranked, as De Blainville has shown[66] as monstrosities.
    Nevertheless they are interesting from being correlated with the
    size of the body, for they occur much more frequently with mastiffs
    and other large breeds than with small dogs. Closely allied
    varieties, however, sometimes differ in this respect; thus Mr.
    Hodgson states that the black-and-tan Lassa variety of the Thibet
    mastiff has the fifth digit, whilst the Mustang sub-variety is not
    thus characterised. The extent to which the skin is developed
    between the toes varies much; but we shall return to this point.
    The degree to which the various breeds differ in the perfection of
    their senses, dispositions, and inherited habits is notorious to
    every one. The breeds present some constitutional differences: the
    pulse, says Youatt[67] “varies materially according to the breed,
    as well as to the size of the animal.” Different breeds of dogs are
    subject in different degrees to various diseases. They certainly
    become adapted to different climates under which they have long
    existed. It is notorious that most of our best European breeds
    deteriorate in India.[68] The Rev R. Everest[69] believes that no
    one has succeeded in keeping the Newfoundland dog long alive in
    India; so it is, according to Lichtenstein,[70] even at the Cape of
    Good Hope. The Thibet mastiff degenerates on the plains of India,
    and can live only on the mountains.[71] Lloyd[72] asserts that our
    bloodhounds and bulldogs have been tried, and cannot withstand the
    cold of the northern European forests.

    Seeing in how many characters the races of the dog differ from each
    other, and remembering Cuvier’s admission that their skulls differ
    more than do those of the species of any natural genus, and bearing
    in mind how closely the bones of wolves, jackals, foxes, and other
    Canidæ agree, it is remarkable that we meet with the statement,
    repeated over and over again, that the races of the dog differ in
    no important characters. A highly competent judge, Prof.
    Gervais,[73] admits “si l’on prenait sans contrôle les alterations
    dont chacun de ces organes est susceptible, on pourrait croire
    qu’il y a entre les chiens domestiques des différences plus grandes
    que celles qui séparent ailleurs les espèces, quelquefois même les
    genres.” Some of the differences above enumerated are in one
    respect of comparatively little value, for they are not
    characteristic of distinct breeds: no one pretends that such is the
    case with the additional molar teeth or with the number of mammae;
    the additional digit is generally present with mastiffs, and some
    of the more important differences in the skull and lower jaw are
    more or less characteristic of various breeds. But we must not
    forget that the predominant power of selection has not been applied
    in any of these cases; we have variability in important parts, but
    the differences have not been fixed by selection. Man cares for the
    form and fleetness of his greyhounds, for the size of his mastiffs,
    and formerly for the strength of the jaw in his bulldogs, etc.; but
    he cares nothing about the number of their molar teeth or mammae or
    digits; nor do we know that differences in these organs are
    correlated with, or owe their development to, differences in other
    parts of the body about which man does care. Those who have
    attended to the subject of selection will admit that, nature having
    given variability, man, if he so chose, could fix five toes to the
    hinder feet of certain breeds of dogs, as certainly as to the feet
    of his Dorking fowls: he could probably fix, but with much more
    difficulty, an additional pair of molar teeth in either jaw, in the
    same way as he has given additional horns to certain breeds of
    sheep; if he wished to produce a toothless breed of dogs, having
    the so-called Turkish dog with its imperfect teeth to work on, he
    could probably do so, for he has succeeded in making hornless
    breeds of cattle and sheep.

    With respect to the precise causes and steps by which the several
    races of dogs have come to differ so greatly from each other, we
    are, as in most other cases, profoundly ignorant. We may attribute
    part of the difference in external form and constitution to
    inheritance from distinct wild stocks, that is to changes effected
    under nature before domestication. We must attribute something to
    the crossing of the several domestic and natural races. I shall,
    however, soon recur to the crossing of races. We have already seen
    how often savages cross their dogs with wild native species; and
    Pennant gives a curious account[74] of the manner in which
    Fochabers, in Scotland, was stocked “with a multitude of curs of a
    most wolfish aspect” from a single hybrid-wolf brought into that
    district.

    It would appear that climate to a certain extent directly modifies
    the forms of dogs. We have lately seen that several of our English
    breeds cannot live in India, and it is positively asserted that
    when bred there for a few generations they degenerate not only in
    their mental faculties, but in form. Captain Williamson,[75] who
    carefully attended to this subject, states that “hounds are the
    most rapid in their decline;” “greyhounds and pointers, also,
    rapidly decline.” But spaniels, after eight or nine generations,
    and without a cross from Europe, are as good as their ancestors.
    Dr. Falconer informs me that bulldogs, which have been known, when
    first brought into the country, to pin down even an elephant by its
    trunk, not only fall off after two or three generations in pluck
    and ferocity, but lose the under-hung character of their lower
    jaws; their muzzles become finer and their bodies lighter. English
    dogs imported into India are so valuable that probably due care has
    been taken to prevent their crossing with native dogs; so that the
    deterioration cannot be thus accounted for. The Rev. R. Everest
    informs me that he obtained a pair of setters, born in India, which
    perfectly resembled their Scotch parents: he raised several litters
    from them in Delhi, taking the most stringent precautions to
    prevent a cross, but he never succeeded, though this was only the
    second generation in India, in obtaining a single young dog like
    its parents in size or make; their nostrils were more contracted,
    their noses more pointed, their size inferior, and their limbs more
    slender. So again on the coast of Guinea, dogs, according to
    Bosman, “alter strangely; their ears grow long and stiff like those
    of foxes, to which colour they also incline, so that in three or
    four years, they degenerate into very ugly creatures; and in three
    or four broods their barking turns into a howl.”[76] This
    remarkable tendency to rapid deterioration in European dogs
    subjected to the climate of India and Africa, may be largely
    accounted for by reversion to a primordial condition which many
    animals exhibit, as we shall hereafter see, when their
    constitutions are in any way disturbed.

    Some of the peculiarities characteristic of the several breeds of
    the dog have probably arisen suddenly, and, though strictly
    inherited, may be called monstrosities; for instance, the shape of
    the legs and body in the turnspit of Europe and India; the shape of
    the head and the under-hanging jaw in the bull-and pug-dog, so
    alike in this one respect and so unlike in all others. A
    peculiarity suddenly arising, and therefore in one sense deserving
    to be called a monstrosity, may, however, be increased and fixed by
    man’s selection. We can hardly doubt that long-continued training,
    as with the greyhound in coursing hares, as with water-dogs in
    swimming—and the want of exercise, in the case of lapdogs—must have
    produced some direct effect on their structure and instincts. But
    we shall immediately see that the most potent cause of change has
    probably been the selection, both methodical and unconscious, of
    slight individual differences,—the latter kind of selection
    resulting from the occasional preservation, during hundreds of
    generations, of those individual dogs which were the most useful to
    man for certain purposes and under certain conditions of life. In a
    future chapter on Selection I shall show that even barbarians
    attend closely to the qualities of their dogs. This unconscious
    selection by man would be aided by a kind of natural selection; for
    the dogs of savages have partly to gain their own subsistence: for
    instance, in Australia, as we hear from Mr. Nind,[77] the dogs are
    sometimes compelled by want to leave their masters and provide for
    themselves; but in a few days they generally return. And we may
    infer that dogs of different shapes, sizes, and habits, would have
    the best chance of surviving under different circumstances,—on open
    sterile plains, where they have to run down their own prey,—on
    rocky coasts, where they have to feed on crabs and fish left in the
    tidal pools, as in the case of New Guinea and Tierra del Fuego. In
    this latter country, as I am informed by Mr. Bridges, the Catechist
    to the Mission, the dogs turn over the stones on the shore to catch
    the crustaceans which lie beneath, and they “are clever enough to
    knock off the shell-fish at a first blow;” for if this be not done,
    shell-fish are well-known to have an almost invincible power of
    adhesion.

    It has already been remarked that dogs differ in the degree to
    which their feet are webbed. In dogs of the Newfoundland breed,
    which are eminently aquatic in their habits, the skin, according to
    Isidore Geoffroy,[78] extends to the third phalanges whilst in
    ordinary dogs it extends only to the second. In two Newfoundland
    dogs which I examined, when the toes were stretched apart and
    viewed on the under side, the skin extended in a nearly straight
    line between the outer margins of the balls of the toes; whereas,
    in two terriers of distinct sub-breeds, the skin viewed in the same
    manner was deeply scooped out. In Canada there is a dog which is
    peculiar to the country and common there, and this has “half-webbed
    feet and is fond of the water.”[79] English otter-hounds are said
    to have webbed feet: a friend examined for me the feet of two, in
    comparison with the feet of some harriers and bloodhounds; he found
    the skin variable in extent in all, but more developed in the
    otter-hounds than in the others.[80] As aquatic animals which
    belong to quite different orders have webbed feet, there can be no
    doubt that this structure would be serviceable to dogs that
    frequent the water. We may confidently infer that no man ever
    selected his water-dogs by the extent to which the skin was
    developed between their toes; but what he does, is to preserve and
    breed from those individuals which hunt best in the water, or best
    retrieve wounded game, and thus he unconsciously selects dogs with
    feet slightly better webbed. The effects of use from the frequent
    stretching apart of the toes will likewise aid in the result. Man
    thus closely imitates Natural Selection. We have an excellent
    illustration of this same process in North America, where,
    according to Sir J. Richardson,[81] all the wolves, foxes, and
    aboriginal domestic dogs have their feet broader than in the
    corresponding species of the Old World, and “well calculated for
    running on the snow” Now, in these Arctic regions, the life or
    death of every animal will often depend on its success in hunting
    over the snow when soft; and this will in part depend on the feet
    being broad; yet they must not be so broad as to interfere with the
    activity of the animal when the ground is sticky, or with its power
    of burrowing holes, or with other necessary habits of life.

    As changes in domestic breeds which take place so slowly are not to
    be noticed at any one period, whether due to the selection of
    individual variations or of differences resulting from crosses, are
    most important in understanding the origin of our domestic
    productions, and likewise in throwing indirect light on the changes
    effected under nature, I will give in detail such cases as I have
    been able to collect. Lawrence,[82] who paid particular attention
    to the history of the foxhound, writing in 1829, says that between
    eighty and ninety years before “an entirely new foxhound was raised
    through the breeder’s art,” the ears of the old southern hound
    being reduced, the bone and bulk lightened, the waist increased in
    length, and the stature somewhat added to. It is believed that this
    was effected by a cross with a greyhound. With respect to this
    latter dog, Youatt,[83] who is generally cautious in his
    statements, says that the greyhound within the last fifty years,
    that is before the commencement of the present century, “assumed a
    somewhat different character from that which he once possessed. He
    is now distinguished by a beautiful symmetry of form, of which he
    could not once boast, and he has even superior speed to that which
    he formerly exhibited. He is no longer used to struggle with deer,
    but contends with his fellows over a shorter and speedier course.”
    An able writer[84] believes that our English greyhounds are the
    descendants, _progressively improved,_ of the large rough
    greyhounds which existed in Scotland so early as the third century.
    A cross at some former period with the Italian greyhound has been
    suspected; but this seems hardly probable, considering the
    feebleness of this latter breed. Lord Orford, as is well-known,
    crossed his famous greyhounds, which failed in courage, with a
    bulldog—this breed being chosen from being erroneously supposed to
    be deficient in the power of scent; “after the sixth or seventh
    generation,” says Youatt, “there was not a vestige left of the form
    of the bulldog, but his courage and indomitable perseverance
    remained.”

    Youatt infers, from a comparison of an old picture of King
    Charles’s spaniels with the living dog, that “the breed of the
    present day is materially altered for the worse:” the muzzle has
    become shorter, the forehead more prominent, and the eyes larger;
    the changes in this case have probably been due to simple
    selection. The setter, as this author remarks in another place, “is
    evidently the large spaniel improved to his present peculiar size
    and beauty, and taught another way of marking his game. If the form
    of the dog were not sufficiently satisfactory on this point, we
    might have recourse to history:” he then refers to a document dated
    1685 bearing on this subject, and adds that the pure Irish setter
    shows no signs of a cross with the pointer, which some authors
    suspect has been the case with the English setter. The bulldog is
    an English breed, and as I hear from Mr. G. R. Jesse,[85] seems to
    have originated from the mastiff since the time of Shakspeare; but
    certainly existed in 1631, as shown by Prestwick Eaton’s letters.
    There can be no doubt that the fancy bulldogs of the present day,
    now that they are not used for bull-baiting, have become greatly
    reduced in size, without any express intention on the part of the
    breeder. Our pointers are certainly descended from a Spanish breed,
    as even their present names, Don, Ponto, Carlos, etc., show; it is
    said that they were not known in England before the Revolution in
    1688;[86] but the breed since its introduction has been much
    modified, for Mr. Borrow, who is a sportsman and knows Spain
    intimately well, informs me that he has not seen in that country
    any breed “corresponding in figure with the English pointer; but
    there are genuine pointers near Xeres which have been imported by
    English gentlemen.” A nearly parallel case is offered by the
    Newfoundland dog, which was certainly brought into England from
    that country, but which has since been so much modified that, as
    several writers have observed, it does not now closely resemble any
    existing native dog in Newfoundland.[87]

These several cases of slow and gradual changes in our English dogs
possess some interest; for though the changes have generally, but not
invariably, been caused by one or two crosses with a distinct breed,
yet we may feel sure, from the well-known extreme variability of
crossed breeds, that rigorous and long-continued selection must have
been practised, in order to improve them in a definite manner. As soon
as any strain or family became slightly improved or better adapted to
alter circumstances, it would tend to supplant the older and less
improved strains. For instance, as soon as the old foxhound was
improved by a cross with the greyhound, or by simple selection, and
assumed its present character—and the change was probably desired owing
to the increased fleetness of our hunters—it rapidly spread throughout
the country, and is now everywhere nearly uniform. But the process of
improvement is still going on for every one tries to improve his strain
by occasionally procuring dogs from the best kennels. Through this
process of gradual substitution the old English hound has been lost;
and so it has been with the Irish wolf-dog, the old English bulldog,
and several other breeds, such as the alaunt, as I am informed by Mr.
Jesse. But the extinction of former breeds is apparently aided by
another cause; for whenever a breed is kept in scanty numbers, as at
present with the bloodhound, it is reared with some difficulty,
apparently from the evil effects of long-continued close interbreeding.
As several breeds of the dog have been slightly but sensibly modified
within so short a period as the last one or two centuries, by the
selection of the best individuals, modified in many cases by crosses
with other breeds; and as we shall hereafter see that the breeding of
dogs was attended to in ancient times, as it still is by savages, we
may conclude that we have in selection, even if only occasionally
practised, a potent means of modification.

DOMESTIC CATS.

    Cats have been domesticated in the East from an ancient period; Mr.
    Blyth informs me that they are mentioned in a Sanskrit writing 2000
    years old, and in Egypt their antiquity is known to be even
    greater, as shown by monumental drawings and their mummied bodies.
    These mummies, according to De Blainville,[88] who has particularly
    studied the subject, belong to no less than three species, namely,
    _F. caligulata,_ bubastes, and _chaus._ The two former species are
    said to be still found, both wild and domesticated, in parts of
    Egypt. _F. caligulata_ presents a difference in the first inferior
    milk molar tooth, as compared with the domestic cats of Europe,
    which makes De Blainville conclude that it is not one of the
    parent-forms of our cats. Several naturalists, as Pallas, Temminck,
    Blyth, believe that domestic cats are the descendants of several
    species commingled: it is certain that cats cross readily with
    various wild species, and it would appear that the character of the
    domestic breeds has, at least in some cases, been thus affected.
    Sir W. Jardine has no doubt that, “in the north of Scotland, there
    has been occasional crossing with our native species (_F.
    sylvestris_), and that the result of these crosses has been kept in
    our houses. I have seen,” he adds, “many cats very closely
    resembling the wild cat, and one or two that could scarcely be
    distinguished from it.” Mr. Blyth[89] remarks on this passage, “but
    such cats are never seen in the southern parts of England; still,
    as compared with any Indian tame cat, the affinity of the ordinary
    British cat to _F. sylvestris_ is manifest; and due I suspect to
    frequent intermixture at a time when the tame cat was first
    introduced into Britain and continued rare, while the wild species
    was far more abundant than at present.” In Hungary, Jeitteles[90]
    was assured on trustworthy authority that a wild male cat crossed
    with a female domestic cat, and that the hybrids long lived in a
    domesticated state. In Algiers the domestic cat has crossed with
    the wild cat (_F. lybica_) of that country.[91] In South Africa as
    Mr. E. Layard informs me, the domestic cat intermingles freely with
    the wild _F. caffra_; he has seen a pair of hybrids which were
    quite tame and particularly attached to the lady who brought them
    up; and Mr. Fry has found that these hybrids are fertile. In India
    the domestic cat, according to Mr. Blyth, has crossed with four
    Indian species. With respect to one of these species, _F. chaus,_
    an excellent observer, Sir W. Elliot, informs me that he once
    killed, near Madras, a wild brood, which were evidently hybrids
    from the domestic cat; these young animals had a thick lynx-like
    tail and the broad brown bar on the inside of the forearm
    characteristic of _F. chaus._ Sir W. Elliot adds that he has often
    observed this same mark on the forearms of domestic cats in India.
    Mr. Blyth states that domestic cats coloured nearly like _ F.
    chaus,_ but not resembling that species in shape, abound in Bengal;
    he adds, “such a colouration is utterly unknown in European cats,
    and the proper tabby markings (pale streaks on a black ground,
    peculiarly and symmetrically disposed), so common in English cats,
    are never seen in those of India.” Dr. D. Short has assured Mr.
    Blyth[92] that, at Hansi, hybrids between the common cat and _F.
    ornata_ (or _ torquata_) occur, “and that many of the domestic cats
    of that part of India were undistinguishable from the wild _F.
    ornata._” Azara states, but only on the authority of the
    inhabitants, that in Paraguay the cat has crossed with two native
    species. From these several cases we see that in Europe, Asia,
    Africa, and America, the common cat, which lives a freer life than
    most other domesticated animals, has crossed with various wild
    species; and that in some instances the crossing has been
    sufficiently frequent to affect the character of the breed.

Whether domestic cats have descended from several distinct species, or
have only been modified by occasional crosses, their fertility, as far
as is known, is unimpaired. The large Angora or Persian cat is the most
distinct in structure and habits of all the domestic breeds; and is
believed by Pallas, but on no distinct evidence, to be descended from
the _F. manul_ of middle Asia; and I am assured by Mr. Blyth that the
Angora cat breeds freely with Indian cats, which, as we have already
seen, have apparently been much crossed with _F. chaus._ In England
half-bred Angora cats are perfectly fertile with one another.

    Within the same country we do not meet with distinct races of the
    cat, as we do of dogs and of most other domestic animals; though
    the cats of the same country present a considerable amount of
    fluctuating variability. The explanation obviously is that, from
    their nocturnal and rambling habits, indiscriminate crossing cannot
    without much trouble be prevented. Selection cannot be brought into
    play to produce distinct breeds, or to keep those distinct which
    have been imported from foreign lands. On the other hand, in
    islands and in countries completely separated from each other, we
    meet with breeds more or less distinct; and these cases are worth
    giving, showing that the scarcity of distinct races in the same
    country is not caused by a deficiency of variability in the animal.
    The tailless cats of the Isle of Man are said to differ from common
    cats not only in the want of a tail, but in the greater length of
    their hind legs, in the size of their heads, and in habits. The
    Creole cat of Antigua, as I am informed by Mr. Nicholson, is
    smaller, and has a more elongated head, than the British cat. In
    Ceylon, as Mr. Thwaites writes to me, every one at first notices
    the different appearance of the native cat from the English animal;
    it is of small size, with closely lying hairs; its head is small,
    with a receding forehead; but the ears are large and sharp;
    altogether it has what is there called a “low-caste” appearance.
    Rengger[93] says that the domestic cat, which has been bred for 300
    years in Paraguay, presents a striking difference from the European
    cat; it is smaller by a fourth, has a more lanky body, its hair is
    short, shining, scanty and lies close, especially on the tail: he
    adds that the change has been less at Ascension, the capital of
    Paraguay, owing to the continual crossing with newly imported cats;
    and this fact well illustrates the importance of separation. The
    conditions of life in Paraguay appear not to be highly favourable
    to the cat, for, though they have run half-wild, they do not become
    thoroughly feral, like so many other European animals. In another
    part of South America, according to Roulin,[94] the introduced cat
    has lost the habit of uttering its hideous nocturnal howl. The Rev.
    W.D. Fox purchased a cat in Portsmouth, which he was told came from
    the coast of Guinea; its skin was black and wrinkled, fur
    bluish-grey and short, its ears rather bare, legs long, and whole
    aspect peculiar. This “negro” cat was fertile with common cats. On
    the opposite coast of Africa, at Mombas, Captain Owen,  R.N.,[95]
    states that all the cats are covered with short stiff hair instead
    of fur: he gives a curious account of a cat from Algoa Bay, which
    had been kept for some time on board and could be identified with
    certainty; this animal was left for only eight weeks at Mombas, but
    during that short period it “underwent a complete metamorphosis,
    having parted with its sandy-coloured fur.” A cat from the Cape of
    Good Hope has been described by Desmarest as remarkable from a red
    stripe extending along the whole length of its back. Throughout an
    immense area, namely, the Malayan archipelago, Siam, Pegu, and
    Burmah, all the cats have truncated tails about half the proper
    length,[96] often with a sort of knot at the end. In the Caroline
    archipelago the cats have very long legs, and are of a
    reddish-yellow colour.[97] In China a breed has drooping ears. At
    Tobolsk, according to Gmelin, there is a red-coloured breed. In
    Asia, also, we find the well-known Angora or Persian breed.

    The domestic cat has run wild in several countries, and everywhere
    assumes, as far as can be judged by the short recorded
    descriptions, a uniform character. Near Maldonado, in La Plata, I
    shot one which seemed perfectly wild; it was carefully examined by
    Mr. Waterhouse,[98] who found nothing remarkable in it, excepting
    its great size. In New Zealand according to Dieffenbach, the feral
    cats assume a streaky grey colour like that of wild cats; and this
    is the case with the half-wild cats of the Scotch Highlands.

We have seen that distant countries possess distinct domestic races of
the cat. The differences may be in part due to descent from several
aboriginal species, or at least to crosses with them. In some cases, as
in Paraguay, Mombas, and Antigua, the differences seem due to the
direct action of different conditions of life. In other cases some
slight effect may possibly be attributed to natural selection, as cats
in many cases have largely to support themselves and to escape diverse
dangers. But man, owing to the difficulty of pairing cats, has done
nothing by methodical selection; and probably very little by
unintentional selection; though in each litter he generally saves the
prettiest, and values most a good breed of mouse- or rat-catchers.
Those cats which have a strong tendency to prowl after game, generally
get destroyed by traps. As cats are so much petted, a breed bearing the
same relation to other cats, that lapdogs bear to larger dogs, would
have been much valued; and if selection could have been applied, we
should certainly have had many breeds in each long-civilised country,
for there is plenty of variability to work upon.

    We see in this country considerable diversity in size, some in the
    proportions of the body, and extreme variability in colouring. I
    have only lately attended to this subject, but have already heard
    of some singular cases of variation; one of a cat born in the West
    Indies toothless, and remaining so all its life. Mr. Tegetmeier has
    shown me the skull of a female cat with its canines so much
    developed that they protruded uncovered beyond the lips; the tooth
    with the fang being .95, and the part projecting from the gum .6 of
    an inch in length. I have heard of several families of six-toed
    cats, in one of which the peculiarity had been transmitted for at
    least three generations. The tail varies greatly in length; I have
    seen a cat which always carried its tail flat on its back when
    pleased. The ears vary in shape, and certain strains, in England,
    inherit a pencil-like tuft of hairs, above a quarter of an inch in
    length, on the tips of their ears; and this same peculiarity,
    according to Mr. Blyth, characterises some cats in India. The great
    variability in the length of the tail and the lynx-like tufts of
    hairs on the ears are apparently analogous to differences in
    certain wild species of the genus. A much more important
    difference, according to Daubenton,[99] is that the intestines of
    domestic cats are wider, and a third longer, than in wild cats of
    the same size; and this apparently has been by their less strictly
    carnivorous diet.

REFERENCES

 [1] Owen ‘British Fossil Mammals,’ pp. 123 to 133. Pictet’s ‘Traité de
 Pal.,’ 1853, tom. i. p. 202. De Blainville in his ‘Ostéographie,
 Canidæ,’ p. 142, has largely discussed the whole subject, and
 concludes that the extinct parent of all domesticated dogs came
 nearest to the wolf in organisation, and to the jackal in habits. _See
 also_ Boyd Dawkins, ‘Cave Hunting,’ 1874, p. 131, etc., and his other
 publications. Jeitteles has discussed in great detail the character of
 the breeds of pre-historic dogs: ‘Die vorgeschichtlichen Alterthümer
 der Stadt Olmütz,’ II. Theil, 1872, p. 44 to end.

 [2] Pallas, I believe, originated this doctrine in ‘Act. Acad. St.
 Petersburgh,’ 1780, Part ii. Ehrenberg has advocated it, as may be
 seen in De Blainville’s ‘Ostéographie,’ p. 79. It has been carried to
 an extreme extent by Col. Hamilton Smith in the ‘Naturalist Library,’
 vols ix and x. Mr. W. C. Martin adopts it in his excellent ‘History of
 the Dog,’ 1845; as does Dr. Morton, as well as Nott and Gliddon, in
 the United States. Prof. Low, in his ‘Domesticated Animals,’ 1845, p.
 666, comes to this same conclusion. No one has argued on this side
 with more clearness and force than the late James Wilson, of
 Edinburgh, in various papers read before the Highland Agricultural and
 Wernerian Societies. Isidore Geoffroy Saint-Hilaire (‘Hist. Nat.
 Gén.,’ 1860, tom. iii. p. 107), though he believes that most dogs have
 descended from the jackal, yet inclines to the belief that some are
 descended from the wolf. Prof. Gervais (‘Hist. Nat. Mamm.’ 1855, tom.
 ii. p. 69, referring to the view that all the domestic races are the
 modified descendants of a single species, after a long discussion,
 says, “Cette opinion est, suivant nous du moins, la moins probable.”

 [3] Berjeau, ‘The Varieties of the Dog; in old Sculptures and
 Pictures,’ 1863. ‘Der Hund,’ von Dr. F. L. Walther, Giessen, 1817, s.
 48: this author seems carefully to have studied all classical works on
 the subject. _See also_ Volz, ‘Beiträge zur Kulturgeschichte,’
 Leipzig, 1852, s. 115, ‘Youatt on the Dog,’ 1845, p. 6. A very full
 history is given by De Blainville in his ‘Ostéographie, Canidæ.’

 [4] I have seen drawings of this dog from the tomb of the son of Esar
 Haddon, and clay models in the British Museum. Nott and Gliddon, in
 their ‘Types of Mankind,’ 1854, p. 393, give a copy of these drawings.
 This dog has been called a Thibetan mastiff, but Mr. H. A. Oldfield,
 who is familiar with the so-called Thibet mastiff, and has examined
 the drawings in the British Museum, informs me that he considers them
 different.

 [5] ‘Proc. Zoolog. Soc.,’ July 12th, 1831.

 [6] ‘Sporting in Algeria,’ p. 51.

 [7] Berjeau gives facsimiles of the Egyptian drawings. Mr. C. L.
 Martin in his ‘History of the Dog,’ 1845, copies several figures from
 the Egyptian monuments, and speaks with much confidence with respect
 to their identity with still living dogs. Messrs. Nott and Gliddon
 (‘Types of Mankind,’ 1854, p. 388) give still more numerous figures.
 Mr. Gliddon asserts that a curl-tailed greyhound, like that
 represented on the most ancient monuments, is common in Borneo; but
 the Rajah, Sir J. Brooke, informs me that no such dog exists there.

 [8] These, and the following facts on the Danish remains, are taken
 from M. Morlot’s most interesting memoir in ‘Soc. Vaudoise des Sc.
 Nat.’ tom. vi., 1860, pp. 281, 299, 320.

 [9] ‘Die Fauna der Pfahlbauten,’ 1861, s. 117, 162.

 [10] De Blainville ‘Ostéographie, Canidæ.’

 [11] Sir R. Schomburgk has given me information on this head. _See
 also_ ‘Journal of R. Geographical Soc.’ vol. xiii. 1843, p. 65.

 [12] ‘Domestication of Animals:’ Ethnological Soc., Dec. 22nd, 1863.

 [13] ‘Journal of Researches,’ etc., 1845, p. 393. With respect to
 _Canis antarcticus, see_ p. 193. For the case of the antelope, _see_
 ‘Journal Royal Geograph. Soc.,’ vol. xxiii. p. 94.

 [14] The authorities for the foregoing statements are as
 follow:—Richardson in ‘Fauna Boreali-Americana,’ 1829, pp. 64, 75; Dr.
 Kane ‘Arctic Explorations,’ 1856, vol. i. pp. 398, 455; Dr. Hayes
 ‘Arctic Boat Journey,’ 1860, p. 167. Franklin’s ‘Narrative,’ vol. i.
 p. 269, gives the case of three whelps of a black wolf being carried
 away by the Indians. Parry, Richardson, and others, give accounts of
 wolves and dogs naturally crossing in the eastern parts of North
 America. Seeman in his ‘Voyage of H.M.S. _Herald_,’ 1853, vol. ii. p.
 26, says the wolf is often caught by the Esquimaux for the purpose of
 crossing with their dogs, and thus adding to their size and strength.
 M. Lamare-Picquot in ‘Bull. de la Soc. d’Acclimat,’ tom. vii., 1860,
 p. 148, gives a good account of the half-bred Esquimaux dogs.

 [15] ‘Fauna Boreali-Americana,’ 1829, pp. 73, 78, 80. Nott and
 Gliddon, ‘Types of Mankind,’ p. 383. The naturalist and traveller
 Bartram is quoted by Hamilton Smith, in ‘Naturalist Lib.,’ vol. x. p.
 156. A Mexican domestic dog seems also to resemble a wild dog of the
 same country; but this may be the prairie-wolf. Another capable judge,
 Mr. J. K. Lord (‘The Naturalist in Vancouver Island,’ 1866, vol. ii.
 p. 218), says that the Indian dog of the Spokans, near the Rocky
 Mountains, “is beyond all question nothing more than a tamed Cayote or
 prairie-wolf,” or _Canis latrans._)

 [16] I quote this from Mr. R. Hill’s excellent account of the Alco or
 domestic dog of Mexico, in Gosse’s ‘Naturalist’s Sojourn in Jamaica,’
 1851, p. 329.

 [17] ‘Naturgeschichte der Säugethiere von Paraguay,’ 1830, s. 151.

 [18] Quoted in Humboldt’s ‘Aspects of Nature’ (Eng. trans.), vol. i.
 p. 108.

 [19] p.t’s ‘Travels in Hungary and Transylvania,’ vol. i. p. 501.
 Jeitteles ‘Fauna Hungariæ Superioris,’ 1862, s. 13. _See_ Pliny ‘Hist.
 of the World’ (Eng. trans.), 8th book, ch. xl., about the Gauls
 crossing their dogs. _See also_ Aristotle ‘Hist. Animal.’lib. viii. c.
 28. For good evidence about wolves and dogs naturally crossing near
 the Pyrenees, _see_ M. Mauduyt ‘Du Loup et de ses Races,’ Poitiers,
 1851; also Pallas in ‘Acta Acad. St. Petersburgh,’ 1780, part ii. p.
 94.

 [20] I give this on excellent authority, namely Mr. Blyth (under the
 signature of Zoophilus), in the ‘Indian Sporting Review,’ Oct. 1856,
 p. 134. Mr. Blyth states that he was struck with the resemblance
 between a brush-tailed race of pariah-dogs, north-west of Cawnpore,
 and the Indian wolf. He gives corroborative evidence with respect to
 the dogs of the valley of the Nerbudda.

 [21] For numerous and interesting details on the resemblance of dogs
 and jackals _see_ Isid. Geoffroy St.-Hilaire ‘Hist. Nat. Gén.,’ 1860,
 tom. iii. p. 101. _ See also_ ‘Hist. Nat. des Mammifères,’ par Prof.
 Gervais, 1855, tom. ii. p. 60.

 [22] Also Güldenstädt ‘Nov. Comment. Acad. Petrop.,’ tom. xx., pro
 anno 1775, p. 449. Also Salvin in ‘Land and Water,’ Oct. 1869.

 [23] Quoted by De Blainville in his ‘Ostéographie, Canidæ,’ pp. 79,
 98.

 [24] _See_ Pallas in ‘Act. Acad. St. Petersburgh,’ 1780, part ii. p.
 91. For Algeria, _see_ Isid. Geoffroy St.-Hilaire ‘Hist. Nat. Gén.,’
 tom. iii. p. 177. In both countries it is the male jackal which pairs
 with female domestic dogs.

 [25] John Barbut’s ‘Description of the Coast of Guinea in 1746.’

 [26] ‘Travels in South Africa,’ vol. ii. p. 272.

 [27] Selwyn, Geology of Victoria; ‘Journal of Geolog. Soc.,’ vol.
 xiv., 1858, p. 536, and vol. xvi., 1860, p. 148; and Prof. M’Coy, in
 ‘Annals and Mag. of Nat. Hist.’ (3rd series) vol. ix., 1862, p. 147.
 The Dingo differs from the dogs of the central Polynesian islands.
 Dieffenbach remarks (‘Travels,’ vol. ii. p. 45) that the native New
 Zealand dog also differs from the Dingo.

 [28] These latter remarks afford, I think, a sufficient answer to some
 criticisms by Mr. Wallace, on the multiple origin of dogs, given in
 Lyell’s ‘Principles of Geology,’ 1872, vol. ii. p. 295.

 [29] ‘Proceedings Zoolog. Soc.,’ 1833, p. 112. _ See also,_ on the
 taming of the common wolf, L. Lloyd, ‘Scandinavian Adventures,’ 1854,
 vol. i. p. 460. With respect to the jackal, _see_ Prof. Gervais ‘Hist.
 Nat. Mamm.’ tom. ii. p. 61. With respect to the aguara of Paraguay
 _see_ Rengger’s work.

 [30] Roulin, in ‘Mém. présent. par divers Savans,’ tom. vi. p. 341.

 [31] Martin, ‘History of the Dog,’ p. 14.

 [32] Quoted by L. Lloyd in ‘Field Sports of North of Europe,’ vol. i.
 p. 387.

 [33] Quatrefages, ‘Soc. d’Acclimat.,’ May 11th, 1863, p. 7.

 [34] ‘Annals and Mag. of Nat. Hist.’ vol. xv., 1845, p. 140.

 [35] Azara, ‘Voyages dans l’Amér. Mérid.’ tom. i. p. 381; his account
 is fully confirmed by Rengger. Quatrefages gives an account of a bitch
 brought from Jerusalem to France which burrowed a hole and littered in
 it. _ See_ ‘Discours, Exposition des Races Canines,’ 1865, p. 3.

 [36] With respect to wolves burrowing holes _ see_ Richardson, ‘Fauna
 Boreali-Americana,’ p. 64; and Bechstein ‘Naturgeschichte
 Deutschlands,’ B. i. s. 617.

 [37] _See_ Poeppig, ‘Reise in Chile,’ B. i. s. 290; Mr. G. Clarke, as
 above; and Rengger, s. 155.

 [38] Dogs, ‘Nat. Library,’ vol. x. p. 121; an endemic South American
 dog seems also to have become feral in this island. _See_ Gosse’s
 ‘Jamaica,’ p. 340.

 [39] Low ‘Domesticated Animals,’ p. 650.

 [40] ‘The Naturalist Library,’ Dogs, vol. x. pp. 4, 19.

 [41] Quoted by Prof. Gervais, ‘Hist. Nat. Mamm.,’ tom. ii. p. 66.

 [42] J. Hunter shows that the long period of seventy-three days given
 by Buffon is easily explained by the bitch having received the dog
 many times during a period of sixteen days (‘Phil. Transact.,’ 1787,
 p. 353). Hunter found that the gestation of a mongrel from wolf and
 dog (‘Phil. Transact.,’ 1789, p. 160) apparently was sixty-three days,
 for she received the dog more than once. The period of a mongrel dog
 and jackal was fifty-nine days. Fred. Cuvier found the period of
 gestation of the wolf to be (‘Dict. Class. d’Hist. Nat.’ tom. iv. p.
 8) two months and a few days, which agrees with the dog. Isid G.
 St.-Hilaire, who has discussed the whole subject, and from whom I
 quote Bellingeri, states (‘Hist. Nat. Gén.,’ tom. iii. p. 112) that in
 the Jardin des Plantes the period of the jackal has been found to be
 from sixty to sixty-three days, exactly as with the dog.

 [43] _See_ Isid. Geoffroy St.-Hilaire ‘Hist. Nat. Gén.,’ tom. iii. p.
 112, on the odour of jackals. Col. Ham. Smith in ‘Nat. Lib.,’ vol. x.
 p. 289.

 [44] Quoted by Quatrefages in ‘Bull. Soc. d’Acclimat.,’ May 11th,
 1863.

 [45] ‘Journal de la Physiologie,’ tom. ii. p. 385.

 [46] _See_ Mr. R. Hill’s excellent account of this breed in Gosse’s
 ‘Jamaica,’ p. 338; Rengger ‘Säugethiere von Paraguay,’ s. 153. With
 respect to Spitz dogs, _see_ Bechstein’s ‘Naturgesch. Deutschlands,’
 1801, B. i. s. 638. With respect to Dr. Hodgkin’s statement made
 before Brit. Assoc. _see_ ‘The Zoologist,’ vol. iv. for 1845-46 p.
 1097.

 [47] ‘Acta Acad. St. Petersburgh,’ 1780, part ii. pp. 84, 100.

 [48] M. Broca has shown (‘Journal de Physiologie,’ tom. ii. p. 353)
 that Buffon’s experiments have been often misrepresented. Broca has
 collected (pp. 390-395) many facts on the fertility of crossed dogs,
 wolves, and jackals.

 [49] ‘De la Longévité Humaine,’ par M. Flourens, 1855, p. 143. Mr.
 Blyth says (‘Indian Sporting Review,’ vol. 2 p. 137) that he has seen
 in India several hybrids from the pariah-dog and jackal; and between
 one of these hybrids and a terrier. The experiments of Hunter on the
 jackal are well-known. _See also_ Isid. Geoffroy St.-Hilaire, ‘Hist.
 Nat. Gén.,’ tom. iii. p. 217, who speaks of the hybrid offspring of
 the jackal as perfectly fertile for three generations.

 [50] On authority of F. Cuvier quoted in Bronn’s ‘Geschichte der
 Natur,’ B ii. s. 164.

 [51] W. C. L. Martin ‘History of the Dog,’ 1845, p. 203. Mr. Philip P.
 King, after ample opportunities of observation, informs me that the
 Dingo and European dogs often cross in Australia.

 [52] Rüppel ‘Neue Wirbelthiere von Abyssinien,’ 1835-40 ‘Mammif.,’ s.
 39 pl. xiv. There is a specimen of this fine animal in the British
 Museum.

 [53] Even Pallas admits this; _see_ ‘Act. Acad. St. Petersburgh,’
 1780, p. 93.

 [54] Quoted by I. Geoffroy, ‘Hist. Nat. Gén.,’ tom. iii. p. 453.

 [55] F. Cuvier in ‘Annales du Muséum,’ tom. xviii. p. 337; Godron ‘De
 l’Espèce,’ tom. i. p. 342; and Col. H. Smith in ‘Nat. Library,’ vol.
 ix. p. 101. _See also_ some observations on the degeneracy of the
 skull in certain breeds, by Prof. Bianconi, ‘La Theorie Darwinienne,’
 1874, p. 279.

 [56] Dr. Burt Wilder, ‘American Assoc. Advancement of Science,’ 1873,
 pp. 236, 239.

 [57] Isid. Geoffroy Saint-Hilaire ‘Hist. des Anomalies,’ 1832, tom. i.
 p. 660, Gervais ‘Hist. Nat. des Mammifères,’ tom. ii., 1855, p. 66. De
 Blainville (‘Ostéographie, Canidæ,’ p. 137) has also seen an extra
 molar on both sides.

 [58] ‘Ostéographie, Canidæ,’ p. 137.

 [59] Würzburger ‘Medecin. Zeitschrift,’ 1860, B. i. s. 265.

 [60] Mr. Yarrell in ‘Proc. Zoolog. Soc.,’ Oct. 8th, 1833. Mr.
 Waterhouse showed me a skull of one of these dogs, which had only a
 single molar on each side and some imperfect incisors.

 [61] Quoted in ‘The Veterinary,’ London, vol. viii. p. 415.

 [62] This is quoted from Stonehenge, a great authority, ‘The Dog,’
 1867, p. 187.

 [63] ‘Hist. Nat. Général,’ tom. iii. p. 448.

 [64] W. Scrope ‘Art of Deer-Stalking,’ p. 354.

 [65] Quoted by Col. Ham. Smith in ‘Nat. Lib.,’ vol. x. p. 79.

 [66] De Blainville ‘Ostéographie, Canidæ,’ p. 134. F. Cuvier ‘Annales
 du Muséum,’ tom. xviii. p. 342. In regard to mastiffs, _see_ Col. H.
 Smith ‘Nat. Lib.’ vol. x. p. 218. For the Thibet mastiff, _see_ Mr.
 Hodgson in ‘Journal of As. Soc. of Bengal,’ vol. i., 1832, p. 342.

 [67] ‘The Dog,’ 1845, p. 186. With respect to diseases Youatt asserts
 (p. 167) that the Italian greyhound is “strongly subject” to polypi in
 the matrix or vagina. The spaniel and pug (p. 182) are most liable to
 bronchocele. The liability to distemper (p. 232) is extremely
 different in different breeds. On the distemper, _see also_ Col.
 Hutchinson on ‘Dog Breaking,’ 1850, p. 279.

 [68] _See_ Youatt on the Dog, p. 15; ‘The Veterinary,’ London, vol.
 xi. p. 235.

 [69] ‘Journal of As. Soc. of Bengal,’ vol. iii. p. 19.

 [70] ‘Travels,’ vol. ii. p. 15.

 [71] Hodgson in ‘Journal of As. Soc. of Bengal,’ vol. i. p. 342.

 [72] ‘Field Sports of the North of Europe,’ vol. ii. p. 165.

 [73] ‘Hist. Nat. des Mammif.,’ 1855, tom. ii. pp. 66, 67.

 [74] ‘History of Quadrupeds,’ 1793, vol. i. p. 238.

 [75] ‘Oriental Field Sports,’ quoted by Youatt, ‘The Dog,’ p. 15.

 [76] A. Murray gives this passage in his ‘Geographical Distribution of
 Mammals,’ 4to, 1866, p. 8.

 [77] Quoted by Mr. Galton, ‘Domestication of Animals,’ p. 13.

 [78] ‘Hist. Nat. Gén.,’ tom. iii. p. 450.

 [79] Mr. Greenhow on the Canadian Dog in Loudon’s ‘Mag. of Nat.
 Hist.,’ vol. vi., 1833, p. 511.

 [80] _See_ Mr. C. O. Groom-Napier on the webbing of the hind feet of
 Otterhounds in ‘Land and Water,’ Oct. 13, 1866, p. 270.

 [81] ‘Fauna Boreali-Americana,’ 1829, p. 62.

 [82] ‘The Horse in all his Varieties,’ etc., 1829, pp. 230, 234.

 [83] ‘The Dog,’ 1845, pp. 31, 35; with respect to King Charles’s
 spaniel, p. 45; for the setter, p. 90.

 [84] In the ‘Encyclop. of Rural Sports,’ p. 557.

 [85] Author of ‘Researches into the History of the British Dog.’

 [86] _See_ Col. Hamilton Smith on the antiquity of the Pointer, in
 ‘Nat. Lib.’ vol. x. p. 196.

 [87] The Newfoundland dog is believed to have originated from a cross
 between the Esquimaux dog and a large French hound. _See_ Dr. Hodgkin
 ‘British Assoc.,’ 1844; Bechstein ‘Naturgesch. Deutschland,’ B. i. s.
 574; ‘Nat. Lib.,’ vol. x. p. 132; also Mr. Jukes’ ‘Excursion in and
 about Newfoundland.’

 [88] De Blainville ‘Ostéographie, Felis,’ p. 65, on the character of
 _F. caligulata_; pp. 85, 89, 90, 175, on the other mummied species. He
 quotes Ehrenberg on _F. maniculata_ being mummied.

 [89] Asiatic Soc. of Calcutta; Curator’s Report, Aug. 1856. The
 passage from Sir W. Jardine is quoted from this Report. Mr. Blyth, who
 has especially attended to the wild and domestic cats of India, has
 given in this Report a very interesting discussion on their origin.

 [90] ‘Fauna Hungariæ Sup.,’ 1862, s. 12.

 [91] Isid. Geoffroy Saint-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. p.
 177.

 [92] ‘Proc. Zoolog. Soc.,’ 1863, p. 184.

 [93] ‘Säugethiere von Paraguay,’ 1830, s. 212.

 [94] ‘Mem. présentés par divers Savans: Acad. Roy. des Sciences,’ tom.
 vi. p. 346. Gomara first noticed this fact in 1554.

 [95] ‘Narrative of Voyages,’ vol. ii. p. 180.

 [96] J. Crawfurd ‘Descript. Dict. of the Indian Islands,’ p. 255. The
 Madagascar cat is said to have a twisted tail; _see_ Desmarest in
 ‘Encyclop. Nat. Mamm.,’ 1820, p. 233, for some of the other breeds.

 [97] Admiral Lutké’s Voyage, vol. iii. p. 308.

 [98] ‘Zoology of the Voyage of the Beagle, Mammalia,’ p. 20.
 Dieffenbach ‘Travels in New Zealand,’ vol. ii. p. 185. Ch. St. John
 ‘Wild Sports of the Highlands,’ 1846, p. 40.

 [99] Quoted by Isid. Geoffroy ‘Hist. Nat. Gén.,’ tom. iii. p. 427.




CHAPTER II. HORSES AND ASSES.

HORSE. DIFFERENCES IN THE BREEDS—INDIVIDUAL VARIABILITY OF—DIRECT
EFFECTS OF THE CONDITIONS OF LIFE—CAN WITHSTAND MUCH COLD—BREEDS MUCH
MODIFIED BY SELECTION—COLOURS OF THE HORSE—DAPPLING—DARK STRIPES ON THE
SPINE, LEGS, SHOULDERS, AND FOREHEAD—DUN-COLOURED HORSES MOST
FREQUENTLY STRIPED—STRIPES PROBABLY DUE TO REVERSION TO THE PRIMITIVE
STATE OF THE HORSE.

ASSES. BREEDS OF—COLOUR OF—LEG- AND SHOULDER-STRIPES—SHOULDER-STRIPES
SOMETIMES ABSENT, SOMETIMES FORKED.


    The history of the Horse is lost in antiquity. Remains of this
    animal in a domesticated condition have been found in the Swiss
    lake-dwellings, belonging to the Neolithic period.[1] At the
    present time the number of breeds is great, as may be seen by
    consulting any treatise on the Horse.[2] Looking only to the native
    ponies of Great Britain, those of the Shetland Isles, Wales, the
    New Forest, and Devonshire are distinguishable; and so it is,
    amongst other instances, with each separate island in the great
    Malay archipelago.[3] Some of the breeds present great differences
    in size, shape of ears, length of mane, proportions of the body,
    form of the withers and hind quarters, and especially in the head.
    Compare the race-horse, dray-horse, and a Shetland pony in size,
    configuration, and disposition; and see how much greater the
    difference is than between the seven or eight other living species
    of the genus Equus.

    Of individual variations not known to characterise particular
    breeds, and not great or injurious enough to be called
    monstrosities, I have not collected many cases. Mr. G. Brown, of
    the Cirencester Agricultural College, who has particularly attended
    to the dentition of our domestic animals, writes to me that he has
    “several times noticed eight permanent incisors instead of six in
    the jaw.” Male horses only should have canines, but they are
    occasionally found in the mare, though a small size.[4] The number
    of ribs on each side is properly eighteen, but Youatt[5] asserts
    that not unfrequently there are nineteen, the additional one being
    always the posterior rib. It is a remarkable fact that the ancient
    Indian horse is said in the Rig-Vêda to have only seventeen ribs;
    and M. Piétrement,[6] who has called attention to this subject,
    gives various reasons for placing full trust in this statement,
    more especially as during former times the Hindoos carefully
    counted the bones of animals. I have seen several notices of
    variations in the bones of the leg; thus Mr. Price[7] speaks of an
    additional bone in the hock, and of certain abnormal appearances
    between the tibia and astragalus, as quite common in Irish horses,
    and not due to disease. Horses have often been observed, according
    to M. Gaudry,[8] to possess a trapezium and a rudiment of a fifth
    metacarpal bone, so that “one sees appearing by monstrosity, in the
    foot of the horse, structures which normally exist in the foot of
    the Hipparion,”—an allied and extinct animal. In various countries
    horn-like projections have been observed on the frontal bones of
    the horse: in one case described by Mr. Percival they arose about
    two inches above the orbital processes, and were “very like those
    in a calf from five to six months old,” being from half to
    three-quarters of an inch in length.[9] Azara has described two
    cases in South America in which the projections were between three
    and four inches in length: other instances have occurred in Spain.

    That there has been much inherited variation in the horse cannot be
    doubted, when we reflect on the number of the breeds existing
    throughout the world or even within the same country, and when we
    know that they have largely increased in number since the earliest
    known records.[10] Even in so fleeting a character as colour,
    Hofacker[11] found that, out of 216 cases in which horses of the
    same colour were paired, only eleven pairs produced foals of a
    quite different colour. As Professor Low[12] has remarked, the
    English race-horse offers the best possible evidence of
    inheritance. The pedigree of a race-horse is of more value in
    judging of its probable success than its appearance: “King Herod”
    gained in prizes 201,505 pounds sterling, and begot 497 winners;
    “Eclipse” begot 334 winners.

    Whether the whole amount of difference between the various breeds
    has arisen under domestication is doubtful. From the fertility of
    the most distinct breeds[13] when crossed, naturalists have
    generally looked at all the breeds as having descended from a
    single species. Few will agree with Colonel H. Smith, who believes
    that they have descended from no less than five primitive and
    differently coloured stocks.[14] But as several species and
    varieties of the horse existed[15] during the later tertiary
    periods, and as Rutimeyer found differences in the size and form of
    the skull in the earliest known domesticated horses,[16] we ought
    not to feel sure that all our breeds are descended from a single
    species. The savages of North and South America easily reclaim the
    feral horses, so that there is no improbability in savages in
    various quarters of the world having domesticated more than one
    native species or natural race. M. Sanson[17] thinks that he has
    proved that two distinct species have been domesticated, one in the
    East, and one in North Africa; and that these differed in the
    number of their lumbar vertebra and in various other parts; but M.
    Sanson seems to believe that osteological characters are subject to
    very little variation, which is certainly a mistake. At present no
    aboriginal or truly wild horse is positively known to exist; for it
    is commonly believed that the wild horses of the East are escaped
    domestic animals.[18] If therefore our domestic breeds are
    descended from several species or natural races, all have become
    extinct in the wild state.

    With respect to the causes of the modifications which horses have
    undergone, the conditions of life seem to produce a considerable
    direct effect. Mr. D. Forbes, who has had excellent opportunities
    of comparing the horses of Spain with those of South America,
    informs me that the horses of Chile, which have lived under nearly
    the same conditions as their progenitors in Andalusia, remain
    unaltered, whilst the Pampas horses and the Puno horses are
    considerably modified. There can be no doubt that horses become
    greatly reduced in size and altered in appearance by living on
    mountains and islands; and this apparently is due to want of
    nutritious or varied food. Every one knows how small and rugged the
    ponies are on the Northern islands and on the mountains of Europe.
    Corsica and Sardinia have their native ponies; and there were,[19]
    or still are, on some islands on the coast of Virginia, ponies like
    those of the Shetland Islands, which are believed to have
    originated through exposure to unfavourable conditions. The Puno
    ponies, which inhabit the lofty regions of the Cordillera, are, as
    I hear from Mr. D. Forbes, strange little creatures, very unlike
    their Spanish progenitors. Further south, in the Falkland Islands,
    the offspring of the horses imported in 1764 have already so much
    deteriorated in size[20] and strength that they are unfitted for
    catching wild cattle with the lasso; so that fresh horses have to
    be brought for this purpose from La Plata at a great expense. The
    reduced size of the horses bred on both southern and northern
    islands, and on several mountain-chains, can hardly have been
    caused by the cold, as a similar reduction has occurred on the
    Virginian and Mediterranean islands. The horse can withstand
    intense cold, for wild troops live on the plains of Siberia under
    lat. 56°,[21] and aboriginally the horses must have inhabited
    countries annually covered with snow, for he long retains the
    instinct of scraping it away to get at the herbage beneath. The
    wild tarpans in the East have this instinct; and so it is, as I am
    informed by Admiral Sulivan, with the horses recently and formerly
    introduced into the Falkland Islands from La Plata, some of which
    have run wild; this latter fact is remarkable, as the progenitors
    of these horses could not have followed this instinct during many
    generations in La Plata. On the other hand, the wild cattle of the
    Falklands never scrape away the snow, and perish when the ground is
    long covered. In the northern parts of America the horses descended
    from those introduced by the Spanish conquerors of Mexico, have the
    same habit, as have the native bisons, but not so the cattle
    introduced from Europe.[22]

    The horse can flourish under intense heat as well as under intense
    cold, for he is known to come to the highest perfection, though not
    attaining a large size, in Arabia and northern Africa. Much
    humidity is apparently more injurious to the horse than heat or
    cold. In the Falkland Islands, horses suffer much from the
    dampness; and this circumstance may perhaps partly account for the
    singular fact that to the eastward of the Bay of Bengal,[23] over
    an enormous and humid area, in Ava, Pegu, Siam, the Malayan
    archipelago, the Loo Choo Islands, and a large part of China, no
    full-sized horse is found. When we advance as far eastward as
    Japan, the horse reacquires his full size.[24]

    With most of our domesticated animals, some breeds are kept on
    account of their curiosity or beauty; but the horse is valued
    almost solely for its utility. Hence semi-monstrous breeds are not
    preserved; and probably all the existing breeds have been slowly
    formed either by the direct action of the conditions of life, or
    through the selection of individual differences. No doubt
    semi-monstrous breeds might have been formed: thus Mr. Waterton
    records[25] the case of a mare which produced successively three
    foals without tails; so that a tailless race might have been formed
    like the tailless races of dogs and cats. A Russian breed of horses
    is said to have curled hair, and Azara[26] relates that in Paraguay
    horses are occasionally born, but are generally destroyed, with
    hair like that on the head of a negro; and this peculiarity is
    transmitted even to half-breeds: it is a curious case of
    correlation that such horses have short manes and tails, and their
    hoofs are of a peculiar shape like those of a mule.

    It is scarcely possible to doubt that the long-continued selection
    of qualities serviceable to man has been the chief agent in the
    formation of the several breeds of the horse. Look at a dray-horse,
    and see how well adapted he is to draw heavy weights, and how
    unlike in appearance to any allied wild animal. The English
    race-horse is known to be derived from the commingled blood of
    Arabs, Turks, and Barbs; but selection, which was carried on during
    very early times in England,[27] together with training, have made
    him a very different animal from his parent-stocks. As a writer in
    India, who evidently knows the pure Arab well, asks, who now,
    “looking at our present breed of race-horses, could have conceived
    that they were the result of the union of the Arab horse and
    African mare?” The improvement is so marked that in running for the
    Goodwood Cup the first descendants of Arabian, Turkish, and Persian
    horses, are allowed a discount of 18 pounds weight; and when both
    parents are of these countries a discount of 36 pounds.[28] It is
    notorious that the Arabs have long been as careful about the
    pedigree of their horses as we are, and this implies great and
    continued care in breeding. Seeing what has been done in England by
    careful breeding, can we doubt that the Arabs must likewise have
    produced during the course of centuries a marked effect on the
    qualities of their horses? But we may go much farther back in time,
    for in the Bible we hear of studs carefully kept for breeding, and
    of horses imported at high prices from various countries.[29] We
    may therefore conclude that, whether or not the various existing
    breeds of the horse have proceeded from one or more aboriginal
    stocks, yet that a great amount of change has resulted from the
    direct action of the conditions of life, and probably a still
    greater amount from the long-continued selection by man of slight
    individual differences.

    With several domesticated quadrupeds and birds, certain coloured
    marks are either strongly inherited or tend to reappear after
    having been lost for a long time. As this subject will hereafter be
    seen to be of importance, I will give a full account of the
    colouring of horses. All English breeds, however unlike in size and
    appearance, and several of those in India and the Malay
    archipelago, present a similar range and diversity of colour. The
    English race-horse, however, is said[30] never to be dun-coloured;
    but as dun and cream-coloured horses are considered by the Arabs as
    worthless, “and fit only for Jews to ride,”[31] these tints may
    have been removed by long-continued selection. Horses of every
    colour, and of such widely different kinds as dray-horses, cobs,
    and ponies, are all occasionally dappled,[32] in the same manner as
    is so conspicuous with grey horses. This fact does not throw any
    clear light on the colouring of the aboriginal horse, but is a case
    of analogous variation, for even asses are sometimes dappled, and I
    have seen, in the British Museum, a hybrid from the ass and zebra
    dappled on its hinder quarters. By the expression analogous
    variation (and it is one that I shall often have occasion to use) I
    mean a variation occurring in a species or variety which resembles
    a normal character in another and distinct species or variety.
    Analogous variations may arise, as will be explained in a future
    chapter, from two or more forms with a similar constitution having
    been exposed to similar conditions,—or from one of two forms having
    reacquired through reversion a character inherited by the other
    form from their common progenitor,—or from both forms having
    reverted to the same ancestral character. We shall immediately see
    that horses occasionally exhibit a tendency to become striped over
    a large part of their bodies; and as we know that in the varieties
    of the domestic cat and in several feline species stripes readily
    pass into spots and cloudy marks—even the cubs of the
    uniformly-coloured lion being spotted with dark marks on a lighter
    ground—we may suspect that the dappling of the horse, which has
    been noticed by some authors with surprise, is a modification or
    vestige of a tendency to become striped.

Illustration: Fig. 1.—Dun Devonshire Pony, with shoulder, spinal, and
leg stripes.

    This tendency in the horse to become striped is in several respects
    an interesting fact. Horses of all colours, of the most diverse
    breeds, in various parts of the world, often have a dark stripe
    extending along the spine, from the mane to the tail; but this is
    so common that I need enter into no particulars.[33] Occasionally
    horses are transversely barred on the legs, chiefly on the under
    side; and more rarely they have a distinct stripe on the shoulder,
    like that on the shoulder of the ass, or a broad dark patch
    representing a stripe. Before entering on any details I must
    premise that the term dun-coloured is vague, and includes three
    groups of colours, viz., that between cream-colour and
    reddish-brown, which graduates into light-bay or
    light-chestnut—this, I believe is often called fallow-dun;
    secondly, leaden or slate-colour or mouse-dun, which graduates into
    an ash-colour; and, lastly, dark-dun, between brown and black. In
    England I have examined a rather large, lightly-built, fallow-dun
    Devonshire pony (Figure 1), with a conspicuous stripe along the
    back, with light transverse stripes on the under sides of its front
    legs, and with four parallel stripes on each shoulder. Of these
    four stripes the posterior one was very minute and faint; the
    anterior one, on the other hand, was long and broad, but
    interrupted in the middle, and truncated at its lower extremity,
    with the anterior angle produced into a long tapering point. I
    mention this latter fact because the shoulder-stripe of the ass
    occasionally presents exactly the same appearance. I have had an
    outline and description sent to me of a small, purely-bred, light
    fallow-dun Welch pony, with a spinal stripe, a single transverse
    stripe on each leg, and three shoulder-stripes; the posterior
    stripe corresponding with that on the shoulder of the ass was the
    longest, whilst the two anterior parallel stripes, arising from the
    mane, decreased in length, in a reversed manner as compared with
    the shoulder-stripes on the above-described Devonshire pony. I have
    seen a bright fallow-dun cob, with its front legs transversely
    barred on the under sides in the most conspicuous manner; also a
    dark-leaden mouse-coloured pony with similar leg stripes, but much
    less conspicuous; also a bright fallow-dun colt, fully three-parts
    thoroughbred, with very plain transverse stripes on the legs; also
    a chestnut-dun cart-horse with a conspicuous spinal stripe, with
    distinct traces of shoulder-stripes, but none on the legs; I could
    add other cases. My son made a sketch for me of a large, heavy,
    Belgian cart-horse, of a fallow-dun, with a conspicuous spinal
    stripe, traces of leg-stripes, and with two parallel (three inches
    apart) stripes about seven or eight inches in length on both
    shoulders. I have seen another rather light cart-horse, of a dirty
    dark cream-colour, with striped legs, and on one shoulder a large
    ill-defined dark cloudy patch, and on the opposite shoulder two
    parallel faint stripes. All the cases yet mentioned are duns of
    various tints; but Mr. W. W. Edwards has seen a nearly thoroughbred
    chestnut horse which had the spinal stripe, and distinct bars on
    the legs; and I have seen two bay carriage-horses with black spinal
    stripes; one of these horses had on each shoulder a light
    shoulder-stripe, and the other had a broad back ill-defined stripe,
    running obliquely half-way down each shoulder; neither had
    leg-stripes.

    The most interesting case which I have met with occurred in a colt
    of my own breeding. A bay mare (descended from a dark-brown Flemish
    mare by a light grey Turcoman horse) was put to Hercules, a
    thoroughbred dark bay, whose sire (Kingston) and dam were both
    bays. The colt ultimately turned out brown; but when only a
    fortnight old it was a dirty bay, shaded with mouse-grey, and in
    parts with a yellowish tint: it had only a trace of the spinal
    stripe, with a few obscure transverse bars on the legs; but almost
    the whole body was marked with very narrow dark stripes, in most
    parts so obscure as to be visible only in certain lights, like the
    stripes which may be seen on black kittens. These stripes were
    distinct on the hind-quarters, where they diverged from the spine,
    and pointed a little forwards; many of them as they diverged became
    a little branched, exactly in the same manner as in some zebrine
    species. The stripes were plainest on the forehead between the
    ears, where they formed a set of pointed arches, one under the
    other, decreasing in size downwards towards the muzzle; exactly
    similar marks may be seen on the forehead of the quagga and
    Burchell’s zebra. When this foal was two or three months old all
    the stripes entirely disappeared. I have seen similar marks on the
    forehead of a fully grown, fallow-dun, cob-like horse, having a
    conspicuous spinal stripe, and with its front legs well barred.

    In Norway the colour of the native horse or pony is dun, varying
    from almost cream-colour to dark-mouse dun; and an animal is not
    considered purely bred unless it has the spinal and
    leg-stripes.[34] My son estimated that about a third of the ponies
    which he saw there had striped legs; he counted seven stripes on
    the fore-legs and two on the hind-legs of one pony; only a few of
    them exhibited traces of shoulder stripes; but I have heard of a
    cob imported from Norway which had the shoulder as well as the
    other stripes well developed. Colonel H. Smith[35] alludes to
    dun-horses with the spinal stripe in the Sierras of Spain; and the
    horses originally derived from Spain, in some parts of South
    America, are now duns. Sir W. Elliot informs me that he inspected a
    herd of 300 South American horses imported into Madras, and many of
    these had transverse stripes on the legs and short
    shoulder-stripes; the most strongly marked individual, of which a
    coloured drawing was sent me, was a mouse-dun, with the
    shoulder-stripes slightly forked.

    In the North-Western parts of India striped horses of more than one
    breed are apparently commoner than in any other part of the world;
    and I have received information respecting them from several
    officers, especially from Colonel Poole, Colonel Curtis, Major
    Campbell, Brigadier St. John, and others. The Kattywar horses are
    often fifteen or sixteen hands in height, and are well but lightly
    built. They are of all colours, but the several kinds of duns
    prevail; and these are so generally striped, that a horse without
    stripes is not considered pure. Colonel Poole believes that all the
    duns have the spinal stripe, the leg-stripes are generally present,
    and he thinks that about half the horses have the shoulder-stripe;
    this stripe is sometimes double or treble on both shoulders.
    Colonel Poole has often seen stripes on the cheeks and sides of the
    nose. He has seen stripes on the grey and bay Kattywars when first
    foaled, but they soon faded away. I have received other accounts of
    cream-coloured, bay, brown, and grey Kattywar horses being striped.
    Eastward of India, the Shan (north of Burmah) ponies, as I am
    informed by Mr. Blyth, have spinal, leg, and shoulder stripes. Sir
    W. Elliot informs me that he saw two bay Pegu ponies with
    leg-stripes. Burmese and Javanese ponies are frequently
    dun-coloured, and have the three kinds of stripes, “in the same
    degree as in England.”[36] Mr. Swinhoe informs me that he examined
    two light-dun ponies of two Chinese breeds, viz., those of Shanghai
    and Amoy; both had the spinal stripe, and the latter an indistinct
    shoulder-stripe.

    We thus see that in all parts of the world breeds of the horse as
    different as possible, when of a dun-colour (including under this
    term a wide range of tint from cream to dusty black), and rarely
    when almost white tinged with yellow, grey, bay, and chestnut, have
    the several above-specified stripes. Horses which are of a yellow
    colour with white mane and tail, and which are sometimes called
    duns, I have never seen with stripes.[37]

    From reasons which will be apparent in the chapter on Reversion, I
    have endeavoured, but with poor success, to discover whether duns,
    which are so much oftener striped than other coloured horses, are
    ever produced from the crossing of two horses, neither of which are
    duns. Most persons to whom I have applied believe that one parent
    must be dun; and it is generally asserted that, when this is the
    case, the dun-colour and the stripes are strongly inherited.[38]
    One case, however, has fallen under my own observation of a foal
    from a black mare by a bay horse, which when fully grown was a dark
    fallow-dun and had a narrow but plain spinal stripe. Hofacker[39]
    gives two instances of mouse-duns (Mausrapp) being produced from
    two parents of different colours and neither duns.

    The stripes of all kinds are generally plainer in the foal than in
    the adult horse, being commonly lost at the first shedding of the
    hair.[40] Colonel Poole believes that “the stripes in the Kattywar
    breed are plainest when the colt is first foaled; they then become
    less and less distinct till after the first coat is shed, when they
    come out as strongly as before; but certainly often fade away as
    the age of the horse increases.” Two other accounts confirm this
    fading of the stripes in old horses in India. One writer, on the
    other hand, states that colts are often born without stripes, but
    that they appear as the colt grows older. Three authorities affirm
    that in Norway the stripes are less plain in the foal than in the
    adult. In the case described by me of the young foal which was
    narrowly striped over nearly all its body, there was no doubt about
    the early and complete disappearance of the stripes. Mr. W. W.
    Edwards examined for me twenty-two foals of race-horses, and twelve
    had the spinal stripe more or less plain; this fact, and some other
    accounts which I have received, lead me to believe that the spinal
    stripe often disappears in the English race-horse when old. With
    natural species, the young often exhibit characters which disappear
    at maturity.

The stripes are variable in colour, but are always darker than the rest
of the body. They do not by any means always coexist on the different
parts of the body: the legs may be striped without any shoulder-stripe,
or the converse case, which is rarer, may occur; but I have never heard
of either shoulder or leg-stripes without the spinal stripe. The latter
is by far the commonest of all the stripes, as might have been
expected, as it characterises the other seven or eight species of the
genus. It is remarkable that so trifling a character as the
shoulder-stripe being double or triple should occur in such different
breeds as Welch and Devonshire ponies, the Shan pony, heavy
cart-horses, light South American horses, and the lanky Kattywar breed.
Colonel Hamilton Smith believes that one of his five supposed primitive
stocks was dun-coloured and striped; and that the stripes in all the
other breeds result from ancient crosses with this one primitive dun;
but it is extremely improbable that different breeds living in such
distant quarters of the world should all have been crossed with any one
aboriginally distinct stock. Nor have we any reason to believe that the
effects of a cross at a very remote period would be propagated for so
many generations as is implied on this view.

    With respect to the primitive colour of the horse having been dun,
    Colonel Hamilton Smith[41] has collected a large body of evidence
    showing that this tint was common in the East as far back as the
    time of Alexander, and that the wild horses of Western Asia and
    Eastern Europe now are, or recently were, of various shades of dun.
    It seems that not very long ago a wild breed of dun-coloured horses
    with a spinal stripe was preserved in the royal parks in Prussia. I
    hear from Hungary that the inhabitants of that country look at the
    duns with a spinal stripe as the aboriginal stock, and so it is in
    Norway. Dun-coloured ponies are not rare in the mountainous parts
    of Devonshire, Wales, and Scotland, where the aboriginal breed
    would have the best chance of being preserved. In South America in
    the time of Azara, when the horse had been feral for about 250
    years, 90 out of 100 horses were “bai-châtains,” and the remaining
    ten were “zains,” that is brown; not more than one in 2000 being
    black. In North America the feral horses show a strong tendency to
    become roans of various shades; but in certain parts, as I hear
    from Dr. Canfield, they are mostly duns and striped.[42]

In the following chapters on the Pigeon we shall see that a blue bird
is occasionally produced by pure breeds of various colours and that
when this occurs certain black marks invariably appear on the wings and
tail; so again, when variously coloured breeds are crossed, blue birds
with the same black marks are frequently produced. We shall further see
that these facts are explained by, and afford strong evidence in favour
of, the view that all the breeds are descended from the rock-pigeon, or
_ Columba livia,_ which is thus coloured and marked. But the appearance
of the stripes on the various breeds of the horse, when of a dun
colour, does not afford nearly such good evidence of their descent from
a single primitive stock as in the case of the pigeon: because no horse
certainly wild is known as a standard of comparison; because the
stripes when they appear are variable in character; because there is
far from sufficient evidence that the crossing of distinct breeds
produces stripes, and lastly, because all the species of the genus
Equus have the spinal stripe, and several species have shoulder and leg
stripes. Nevertheless the similarity in the most distinct breeds in
their general range of colour, in their dappling, and in the occasional
appearance, especially in duns, of leg-stripes and of double or triple
shoulder-stripes, taken together, indicate the probability of the
descent of all the existing races from a single, dun-coloured, more or
less striped, primitive stock, to which our horses occasionally revert.

THE ASS.

    Four species of Asses, besides three zebras, have been described by
    naturalists. There is now little doubt that our domesticated animal
    is descended from the _Equus tæniopus_ of Abyssinia.[43] The ass is
    sometimes advanced as an instance of an animal domesticated, as we
    know by the Old Testament, from an ancient period, which has varied
    only in a very slight degree. But this is by no means strictly
    true; for in Syria alone there are four breeds;[44] first, a light
    and graceful animal, with an agreeable gait, used by ladies;
    secondly, an Arab breed reserved exclusively for the saddle;
    thirdly, a stouter animal used for ploughing and various purposes;
    and lastly, the large Damascus breed, with a peculiarly long body
    and ears. In the South of France also there are several breeds, and
    one of extraordinary size, some individuals being as tall as
    full-sized horses. Although the ass in England is by no means
    uniform in appearance, distinct breeds have not been formed. This
    may probably be accounted for by the animal being kept chiefly by
    poor persons, who do not rear large numbers, nor carefully match
    and select the young. For, as we shall see in a future chapter, the
    ass can with ease be greatly improved in size and strength by
    careful selection, combined no doubt with good food; and we may
    infer that all its other characters would be equally amenable to
    selection. The small size of the ass in England and Northern Europe
    is apparently due far more to want of care in breeding than to
    cold; for in Western India, where the ass is used as a beast of
    burden by some of the lower castes, it is not much larger than a
    Newfoundland dog, “being generally not more than from twenty to
    thirty inches high.”[45]

    The ass varies greatly in colour; and its legs, especially the
    fore-legs, both in England and other countries—for instance, in
    China—are occasionally barred more plainly than those of
    dun-coloured horses. Thirteen or fourteen transverse stripes have
    been counted on both the fore and hind legs. With the horse the
    occasional appearance of leg-stripes was accounted for by reversion
    to a supposed parent-form, and in the case of the ass we may
    confidently believe in this explanation, as _E. tæniopus_ is known
    to be barred, though only in a slight degree, and not quite
    invariably. The stripes are believed to occur most frequently and
    to be plainest on the legs of the domestic ass during early
    youth,[46] as likewise occurs with the horse. The shoulder-stripe,
    which is so eminently characteristic of the species, is
    nevertheless variable in breadth, length, and manner of
    termination. I have measured one four times as broad as another,
    and some more than twice as long as others. In one light-grey ass
    the shoulder-stripe was only six inches in length, and as thin as a
    piece of string; and in another animal of the same colour there was
    only a dusky shade representing a stripe. I have heard of three
    white asses, not albinoes, with no trace of shoulder or spinal
    stripes;[47] and I have seen nine other asses with no
    shoulder-stripe, and some of them had no spinal stripe. Three of
    the nine were light-greys, one a dark-grey, another grey passing
    into reddish-roan, and the others were brown, two being tinted on
    parts of their bodies with a reddish or bay shade. If therefore
    grey and reddish-brown asses had been steadily selected and bred
    from, the shoulder stripe would probably have been lost almost as
    generally and completely as in the case of the horse.

    The shoulder stripe on the ass is sometimes double, and Mr. Blyth
    has seen even three or four parallel stripes.[48] I have observed
    in ten cases shoulder-stripes abruptly truncated at the lower end,
    with the anterior angle produced into a tapering point, precisely
    as in the above dun Devonshire pony. I have seen three cases of the
    terminal portion abruptly and angularly bent; and have seen and
    heard of four cases of a distinct though slight forking of the
    stripe. In Syria, Dr. Hooker and his party observed for me no less
    than five similar instances of the shoulder-stripe plainly
    bifurcating over the fore leg. In the common mule it likewise
    sometimes bifurcates. When I first noticed the forking and angular
    bending of the shoulder-stripe, I had seen enough of the stripes in
    the various equine species to feel convinced that even a character
    so unimportant as this had a distinct meaning, and was thus led to
    attend to the subject. I now find that in the _E. burchellii_ and
    _quagga,_ the stripe which corresponds with the shoulder-stripe of
    the ass, as well as some of the stripes on the neck, bifurcate, and
    that some of those near the shoulder have their extremities bent
    angularly backwards. The bifurcation and angular bending of the
    stripes on the shoulders apparently are connected with the nearly
    upright stripes on the sides of the body and neck changing their
    direction and becoming transverse on the legs. Finally, we see that
    the presence of shoulder, leg, and spinal stripes in the horse,—
    their occasional absence in the ass,—the occurrence of double and
    triple shoulder-stripes in both animals, and the similar manner in
    which these stripes terminate downwards,—are all cases of analogous
    variation in the horse and ass. These cases are probably not due to
    similar conditions acting on similar constitutions, but to a
    partial reversion in colour to the common progenitor of the genus.
    We shall hereafter return to this subject, and discuss it more
    fully.

REFERENCES

 [1] Rütimeyer ‘Fauna der Pfahlbauten,’ 1861, s. 122.

 [2] _See_ ‘Youatt on the Horse’: J. Lawrence on the Horse, 1829; W. C.
 L. Martin, ‘History of the Horse,’ 1845: Col. H. Smith, in ‘Nat.
 Library, Horses,’ 1841, vol. xii.: Prof. Veith, ‘Die naturgesch.
 Haussäugethiere,’ 1856.

 [3] Crawfurd, ‘Descript. Dict. of Indian Islands,’ 1856, p. 153.
 “There are many different breeds, every island having at least one
 peculiar to it.” Thus in Sumatra there are at least two breeds; in
 Achin and Batubara one; in Java several breeds; one in Bali, Lomboc,
 Sumbawa (one of the best breeds), Tambora, Bima, Gunung-api, Celebes,
 Sumba, and Philippines. Other breeds are specified by Zollinger in the
 ‘Journal of the Indian Archipelago,’ vol. v, p. 343, etc.

 [4] ‘The Horse,’ etc. by John Lawrence, 1829, p. 14.

 [5] ‘The Veterinary,’ London, vol. v, p. 543.

 [6] ‘Mémoire sur les chevaux à trente-quatre côtes,’ 1871.

 [7] Proc. Veterinary Assoc., in ‘The Veterinary,’ vol. xiii. p. 42.

 [8] ‘Bulletin de la Soc. Géolog.,’ tom. xxii., 1866, p. 22.

 [9] Mr. Percival of the Enniskillen Dragoons, in ‘The Veterinary,’
 vol. i. p. 224: _see_ Azara, ‘Des Quadrupèdes du Paraguay,’ tom. ii.
 p. 313. The French translator of Azara refers to other cases mentioned
 by Huzard as having occurred in Spain.

 [10] Godron, ‘De l’Espèce’ tom. i. p. 378.

 [11] ‘Ueber die Eigenschaften,’ etc., 1828, s. 10.

 [12] ‘Domesticated Animals of the British Islands,’ pp. 527, 532. In
 all the veterinary treatises and papers which I have read, the writers
 insist in the strongest terms on the inheritance by the horse of all
 good and bad tendencies and qualities. Perhaps the principle of
 inheritance is not really stronger in the horse than in any other
 animal; but, from its value, the tendency has been more carefully
 observed.

 [13] Andrew Knight crossed breeds so different in size as a dray-horse
 and Norwegian pony: _see_ A. Walker on ‘Intermarriage,’ 1838, p. 205.

 [14] ‘Nat. Library, Horses,’ vol. xii. p. 208.

 [15] Gervais, ‘Hist. Nat. Mamm.,’ tom. ii. p. 143. Owen, ‘British
 Fossil Mammals,’ p. 383.

 [16] ‘Kenntniss der fossilen Pferde,’ 1863, s. 131.

 [17] ‘Comptes rendus,’ 1866, p. 485, and ‘Journal de l’Anat. et de la
 Phys.,’ Mai 1868.

 [18] Mr. W. C. L. Martin, (‘The Horse,’ 1845, p. 34), in arguing
 against the belief that the wild Eastern horses are merely feral, has
 remarked on the improbability of man in ancient times having
 extirpated a species in a region where it can now exist in numbers.

 [19] ‘Transact. Maryland Academy,’ vol. i. part i. p. 28.

 [20] Mr. Mackinnon ‘The Falkland Islands,’ p. 25. The average height
 of the Falkland horses is said to be 14 hands 2 inches. _See_ also my
 ‘Journal of Researches.’

 [21] Pallas, ‘Act. Acad. St. Petersburgh,’ 1777, part ii. p. 265. With
 respect to the tarpans scraping away the snow _see_ Col. Hamilton
 Smith in ‘Nat. Lib.,’ vol. xii. p. 165.

 [22] Franklin’s ‘Narrative,’ vol. i. p. 87; note by Sir J. Richardson.

 [23] Mr. J. H. Moor, ‘Notices of the Indian Archipelago;’ Singapore,
 1837, p. 189. A pony from Java was sent (‘Athenæum,’ 1842, p. 718) to
 the Queen only 28 inches in height. For the Loo Choo Islands, _see_
 Beechey’s ‘Voyage,’ 4th. edit., vol. i. p. 499.

 [24] J. Crawford, ‘History of the Horse;’ ‘Journal of Royal United
 Service Institution,’ vol. iv.

 [25] ‘Essays on Natural History,’ 2nd series, p. 161.

 [26] ‘Quadrupédes du Paraguay,’ tom. ii. p. 333. Dr. Canfield informs
 me that a breed with curly hair was formed by selection at Los Angeles
 in North America.

 [27] See the evidence on this head in ‘Land and Water,’ May 2nd, 1868.

 [28] Prof. Low, ‘Domesticated Animals,’ p. 546. With respect to the
 writer in India _see_ ‘India Sporting Review,’ vol. ii. p. 181. As
 Lawrence has remarked (‘The Horse,’ p. 9), “perhaps no instance has
 ever occurred of a three-part bred horse (_i.e._ a horse, one of whose
 grandparents was of impure blood) saving his distance in running two
 miles with thoroughbred racers.” Some few instances are on record of
 seven-eights racers having been successful.

 [29] Prof. Gervais (in his ‘Hist. Nat. Mamm.,’ tom. ii. p. 144) has
 collected many facts on this head. For instance Solomon (Kings, B. i.
 ch. x. v. 28) bought horses in Egypt at a high price.

 [30] ‘The Field,’ July 13th, 1861, p. 42.

 [31] E. Vernon Harcourt, ‘Sporting in Algeria,’ p. 26.

 [32] I state this from my own observations made during several years
 on the colours of horses. I have seen cream-coloured, light-dun and
 mouse-dun horses dappled, which I mention because it has been stated
 (Martin, ‘History of the Horse,’ p. 134) that duns are never dappled.
 Martin (p. 205) refers to dappled asses. In the ‘Farrier’ (London,
 1828, pp. 453, 455) there are some good remarks on the dappling of
 horses; and likewise in Col. Hamilton Smith on ‘The Horse.’

 [33] Some details are given in ‘The Farrier,’ 1828, pp. 452, 455. One
 of the smallest ponies I ever saw, of the colour of a mouse, had a
 conspicuous spinal stripe. A small Indian chestnut pony had the same
 stripe, as had a remarkably heavy chestnut cart-horse. Race-horses
 often have the spinal stripe.

 [34] I have received information, through the kindness of the
 Consul-General, Mr. J. R. Crowe, from Prof. Boeck, Rasck, and Esmarck,
 on the colours of the Norwegian ponies. _See also_ ‘The Field,’ 1861,
 p. 431.

 [35] Col. Hamilton Smith, ‘Nat. Lib.,’ vol. xii. p. 275.

 [36] Mr. G. Clark, in ‘Annal and Mag. of Nat. History,’ 2nd series,
 vol. ii. 1848, p. 363. Mr. Wallace informs me that he saw in Java a
 dun and clay-coloured horse with spinal and leg stripes.

 [37] _See also_ on this point, ‘The Field,’ July 27th, 1861, p. 91.

 [38] ‘The Field,’ 1861, pp. 431, 493, 545.

 [39] ‘Ueber die Eigenschaften,’ etc., 1828, s. 13, 14.

 [40] Von Nathusius, ‘Vorträge über Viehzucht,’ 1872, 135.

 [41] ‘Nat. Library,’ vol. xii. (1841), pp. 109, 156 to 163, 280, 281.
 Cream-colour, passing into Isabella (_i.e._ the colour of the dirty
 linen of Queen Isabella), seems to have been common in ancient times.
 _See also_ Pallas’s account of the wild horses of the East, who speaks
 of dun and brown as the prevalent colours. In the Icelandic sagas,
 which were committed to writing in the twelfth century, dun-coloured
 horses with a black spinal stripe are mentioned; _see_ Dasent’s
 translation, vol. i. p. 169.

 [42] Azara, ‘Quadrupèdes du Paraguay,’ tom. ii. p. 307. In North
 America, Catlin (vol. ii. p. 57) describes the wild horses, believed
 to have descended from the Spanish horses of Mexico, as of all
 colours, black, grey, roan, and roan pied with sorrel. F. Michaux
 (‘Travels in North America,’ Eng. translat., p. 235) describes two
 wild horses from Mexico as roan. In the Falkland Islands, where the
 horse has been feral only between 60 and 70 years, I was told that
 roans and iron-greys were the prevalent colours. These several facts
 show that horses do not soon revert to any uniform colour.

 [43] Dr. Sclater, in ‘Proc. Zoolog. Soc.,’ 1862, p. 164. Dr. Hartmann
 says (‘Annalen der Landw.’ B. xliv. p. 222) that this animal in its
 wild state is not always striped across the legs.

 [44] W. C. Martin, ‘History of the Horse,’ 1845, p. 207.

 [45] Col. Sykes’ Cat. of Mammalia, ‘Proc. Zoolog. Soc.’ July 12th,
 1831. Williamson ‘Oriental Field Sports,’ vol. ii., quoted by Martin,
 p. 206.

 [46] Blyth, in ‘Charlesworth’s Mag. of Nat. Hist.,’ vol. iv., 1840, p.
 83. I have also been assured by a breeder that this is the case.

 [47] (One case is given by Martin, ‘The Horse,’ p. 205.

 [48] ‘Journal As. Soc. of Bengal,’ vol. xxviii. 1860, p. 231. Martin
 on the Horse, p. 205.




CHAPTER III. PIGS—CATTLE—SHEEP—GOATS

PIGS BELONG TO TWO DISTINCT TYPES, SUS SCROFA AND
INDICUS—TORFSCHWEIN—JAPAN PIGS—FERTILITY OF CROSSED PIGS—CHANGES IN THE
SKULL OF THE HIGHLY CULTIVATED RACES—CONVERGENCE OF
CHARACTER—GESTATION—SOLID-HOOFED SWINE—CURIOUS APPENDAGES TO THE
JAWS—DECREASE IN SIZE OF THE TUSKS—YOUNG PIGS LONGITUDINALLY
STRIPED—FERAL PIGS—CROSSED BREEDS.

CATTLE—ZEBU A DISTINCT SPECIES—EUROPEAN CATTLE PROBABLY DESCENDED FROM
THREE WILD FORMS—ALL THE RACES NOW FERTILE TOGETHER—BRITISH PARK
CATTLE—ON THE COLOUR OF THE ABORIGINAL SPECIES—CONSTITUTIONAL
DIFFERENCES—SOUTH AFRICAN RACES—SOUTH AMERICAN RACES—NIATA
CATTLE—ORIGIN OF THE VARIOUS RACES OF CATTLE.

SHEEP —REMARKABLE RACES OF—VARIATIONS ATTACHED TO THE MALE
SEX—ADAPTATIONS TO VARIOUS CONDITIONS—GESTATION OF—CHANGES IN THE
WOOL—SEMI-MONSTROUS BREEDS.

GOATS —REMARKABLE VARIATIONS OF.


    The breeds of the pig have recently been more closely studied,
    though much still remains to be done, than those of almost any
    other domesticated animal. This has been effected by Hermann von
    Nathusius in two admirable works, especially in the later one on
    the Skulls of the several races, and by Rütimeyer in his celebrated
    Fauna of the ancient Swiss lake-dwellings.[1] Nathusius has shown
    that all the known breeds may be divided into two great groups: one
    resembling in all important respects and no doubt descended from
    the common wild boar; so that this may be called the _Sus scrofa_
    group. The other group differs in several important and constant
    osteological characters; its wild parent-form is unknown; the name
    given to it by Nathusius, according to the law of priority, is _
    Sus indicus,_ of Pallas. This name must now be followed, though an
    unfortunate one, as the wild aboriginal does not inhabit India, and
    the best-known domesticated breeds have been imported from Siam and
    China.

    First for the _Sus scrofa_ breeds, or those resembling the common
    wild boar. These still exist, according to Nathusius
    (‘Schweineschädel’ s. 75), in various parts of central and northern
    Europe; formerly every kingdom,[2] and almost every province in
    Britain, possessed its own native breed; but these are now
    everywhere rapidly disappearing, being replaced by improved breeds
    crossed with the _S. indicus_ form. The skull in the breeds of the
    _ S. scrofa_ type resembles, in all important respects, that of the
    European wild boar; but it has become (‘Schweineschädel’ s. 63-68)
    higher and broader relatively to its length; and the hinder part is
    more upright. The differences, however, are all variable in degree.
    The breeds which thus resemble _S. scrofa_ in their essential skull
    characters differ conspicuously from each other in other respects,
    as in the length of the ears and legs, curvature of the ribs,
    colour, hairiness, size and proportions of the body.

    The wild _Sus scrofa_ has a wide range, namely, Europe, North
    Africa, as identified by osteological characters by Rütimeyer, and
    Hindostan, as similarly identified by Nathusius. But the wild boars
    inhabiting these several countries differ so much from each other
    in external characters, that they have been ranked by some
    naturalists as specifically distinct. Even within Hindostan these
    animals, according to Mr. Blyth, form very distinct races in the
    different districts; in the N. Western provinces, as I am informed
    by the Rev. R. Everest, the boar never exceeds 36 inches in height,
    whilst in Bengal one has been measured 44 inches in height. In
    Europe, Northern Africa, and Hindostan, domestic pigs have been
    known to cross with the wild native species;[3] and in Hindostan an
    accurate observer,[4] Sir Walter Elliot, after describing the
    differences between wild Indian and wild German boars, remarks that
    “the same differences are perceptible in the domesticated
    individuals of the two countries.” We may therefore conclude that
    the breeds of the _Sus scrofa_ type are descended from, or have
    been modified by crossing with, forms which may be ranked as
    geographical races, but which, according to some naturalists, ought
    to be ranked as distinct species.

Pigs of the _Sus indicus_ type are best known to Englishmen under the
form of the Chinese breed. The skull of _S. indicus,_ as described by
Nathusius, differs from that of _S. scrofa_ in several minor respects,
as in its greater breadth and in some details in the teeth; but chiefly
in the shortness of the lachrymal bones, in the greater width of the
fore part of the palate-bones, and in the divergence of the premolar
teeth. It deserves especial notice that these latter characters are not
gained, even in the least degree, by the domesticated forms of _S.
scrofa._ After reading the remarks and descriptions given by Nathusius,
it seems to me to be merely playing with words to doubt whether _S.
indicus_ ought to be ranked as a species; for the above-specified
differences are more strongly marked than any that can be pointed out
between, for instance, the fox and the wolf, or the ass and the horse.
As already stated, _S. indicus_ is not known in a wild state; but its
domesticated forms, according to Nathusius, come near to _S. vittatus_
of Java and some allied species. A pig found wild in the Aru islands
(‘Schweineschädel’ s. 169) is apparently identical with _S. indicus_;
but it is doubtful whether this is a truly native animal. The
domesticated breeds of China, Cochin-China, and Siam belong to this
type. The Roman or Neapolitan breed, the Andalusian, the Hungarian, and
the “Krause” swine of Nathusius, inhabiting south-eastern Europe and
Turkey, and having fine curly hair, and the small Swiss
“Bündtnerschwein” of Rütimeyer, all agree in their more important
skull-characters with _S. indicus,_ and, as is supposed, have all been
largely crossed with this form. Pigs of this type have existed during a
long period on the shores of the Mediterranean, for a figure
(‘Schweineschädel’ s. 142) closely resembling the existing Neapolitan
pig was found in the buried city of Herculaneum.

    Rütimeyer has made the remarkable discovery that there lived
    contemporaneously in Switzerland, during the Neolithic period, two
    domesticated forms, the _S. scrofa,_ and the _S. scrofa palustris_
    or Torfschwein. Rütimeyer perceived that the latter approached the
    Eastern breeds, and, according to Nathusius, it certainly belongs
    to the _S. indicus_ group; but Rütimeyer has subsequently shown
    that it differs in some well-marked characters. This author was
    formerly convinced that his Torfschwein existed as a wild animal
    during the first part of the Stone period, and was domesticated
    during a later part of the same period.[5] Nathusius, whilst he
    fully admits the curious fact first observed by Rütimeyer, that the
    bones of domesticated and wild animals can be distinguished by
    their different aspect, yet, from special difficulties in the case
    of the bones of the pig (‘Schweineschädel’ s. 147), is not
    convinced of the truth of the above conclusion; and Rütimeyer
    himself seems now to feel some doubt. Other naturalists have also
    argued strongly on the same side as Nathusius.[6]

    Several breeds, differing in the proportions of the body, in the
    length of the ears, in the nature of the hair, in colour, etc.,
    come under the _S. indicus_ type. Nor is this surprising,
    considering how ancient the domestication of this form has been
    both in Europe and in China. In this latter country the date is
    believed by an eminent Chinese scholar[7] to go back at least 4900
    years from the present time. This same scholar alludes to the
    existence of many local varieties of the pig in China; and at the
    present time the Chinese take extraordinary pains in feeding and
    tending their pigs, not even allowing them to walk from place to
    place.[8] Hence these pigs, as Nathusius has remarked,[9] display
    in an eminent degree the characters of a highly-cultivated race,
    and hence, no doubt, their high value in the improvement of our
    European breeds. Nathusius makes a remarkable statement
    (‘Schweineschädel’ s. 138), that the infusion of the 1/32nd, or
    even of the 1/64th, part of the blood of _S. indicus_ into a breed
    of _S. scrofa,_ is sufficient plainly to modify the skull of the
    latter species. This singular fact may perhaps be accounted for by
    several of the chief distinctive characters of _S. indicus,_ such
    as the shortness of the lachrymal bones, etc., being common to
    several species of the genus; for in crosses characters which are
    common to many species apparently tend to be prepotent over those
    appertaining to only a few species.

Illustration: Fig. 2.—Head of Japan or Masked Pig.

    The Japan pig (_S. pliciceps_ of Gray), which was formerly
    exhibited in the Zoological Gardens, has an extraordinary
    appearance from its short head, broad forehead and nose, great
    fleshy ears, and deeply furrowed skin. Figure 2 is copied from that
    given by Mr. Bartlett.[10] Not only is the face furrowed, but thick
    folds of skin, which are harder than the other parts, almost like
    the plates on the Indian rhinoceros, hang about the shoulders and
    rump. It is coloured black, with white feet, and breeds true. That
    it has long been domesticated there can be little doubt; and this
    might have been inferred even from the fact that its young are not
    longitudinally striped; for this is a character common to all the
    species included within the genus _Sus_ and the allied genera
    whilst in their natural state.[11] Dr. Gray[12] has described the
    skull of this animal, which he ranks not only as a distinct
    species, but places it in a distinct section of the genus.
    Nathusius, however, after his careful study of the whole group,
    states positively (‘Schweineschädel’ s. 153-158). that the skull in
    all essential characters closely resembles that of the short-eared
    Chinese breed of the _S. indicus_ type. Hence Nathusius considers
    the Japan pig as only a domesticated variety of _S. indicus_: if
    this really be the case, it is a wonderful instance of the amount
    of modification which can be effected under domestication.

    Formerly there existed in the central islands of the Pacific Ocean
    a singular breed of pigs. These are described by the Rev. D.
    Tyerman and G. Bennett[13] as of small size, hump-backed, with a
    disproportionately long head, with short ears turned backwards,
    with a bushy tail not more than two inches in length, placed as if
    it grew from the back. Within half a century after the introduction
    of European and Chinese pigs into these islands, the native breed,
    according to the above authors, became almost completely lost by
    being repeatedly crossed with them. Secluded islands, as might have
    been expected, seem favourable for the production or retention of
    peculiar breeds; thus, in the Orkney Islands, the hogs have been
    described as very small, with erect and sharp ears, and “with an
    appearance altogether different from the hogs brought from the
    south.”[14]

Seeing how different the Chinese pigs, belonging to the _Sus indicus_
type, are in their osteological characters and in external appearance
from the pigs of the _S. scrofa_ type, so that they must be considered
specifically distinct, it is a fact well deserving attention, that
Chinese and common pigs have been repeatedly crossed in various
manners, with unimpaired fertility. One great breeder who had used pure
Chinese pigs assured me that the fertility of the half-breeds _inter
se_ and of their recrossed progeny was actually increased; and this is
the general belief of agriculturists. Again, the Japan pig or _S.
pliciceps_ of Gray is so distinct in appearance from all common pigs,
that it stretches one’s belief to the utmost to admit that it is simply
a domestic variety; yet this breed has been found perfectly fertile
with the Berkshire breed; and Mr. Eyton informs me that he paired a
half-bred brother and sister and found them quite fertile together.

Illustration: Fig. 3—Head of Wild Boar, and of “Golden Days,” a pig of
the Yorkshire Large Breed

    The modification of the skull in the most highly cultivated races
    is wonderful. To appreciate the amount of change, Nathusius’ work,
    with its excellent figures, should be studied. The whole of the
    exterior in all its parts has been altered: the hinder surface,
    instead of sloping backwards, is directed forwards, entailing many
    changes in other parts; the front of the head is deeply concave;
    the orbits have a different shape; the auditory meatus has a
    different direction and shape; the incisors of the upper and lower
    jaws do not touch each other, and they stand in both jaws beyond
    the plane of the molars; the canines of the upper jaw stand in
    front of those of the lower jaw, and this is a remarkable anomaly:
    the articular surfaces of the occipital condyles are so greatly
    changed in shape, that, as Nathusius remarks (s. 133), no
    naturalist, seeing this important part of the skull by itself,
    would suppose that it belonged to the genus Sus. These and various
    other modifications, as Nathusius observes, can hardly be
    considered as monstrosities, for they are not injurious, and are
    strictly inherited. The whole head is much shortened; thus, whilst
    in common breeds its length to that of the body is as 1 to 6, in
    the “cultur-racen” the proportion is as 1 to 9, and even recently
    as 1 to 11.[15] The following woodcut[16] of the head of a wild
    boar and of a sow from a photograph of the Yorkshire Large Breed,
    may aid in showing how greatly the head in a highly cultivated race
    has been modified and shortened.

    Nathusius has well discussed the causes of the remarkable changes
    in the skull and shape of the body which the highly cultivated
    races have undergone. These modifications occur chiefly in the pure
    and crossed races of the _S. indicus_ type; but their commencement
    may be clearly detected in the slightly improved breeds of the _S.
    scrofa_ type.[17] Nathusius states positively (s. 99, 103), as the
    result of common experience and of his experiments, that rich and
    abundant food, given during youth, tends by some direct action to
    make the head broader and shorter; and that poor food works a
    contrary result. He lays much stress on the fact that all wild and
    semi-domesticated pigs, in ploughing up the ground with their
    muzzles, have, whilst young, to exert the powerful muscles fixed to
    the hinder part of the head. In highly cultivated races this habit
    is no longer followed, and consequently the back of the skull
    becomes modified in shape, entailing other changes in other parts.
    There can hardly be a doubt that so great a change in habits would
    affect the skull; but it seems rather doubtful how far this will
    account for the greatly reduced length of the skull and for its
    concave front. It is well known (Nathusius himself advancing many
    cases, s. 104) that there is a strong tendency in many domestic
    animals—in bull- and pug-dogs, in the niata cattle, in sheep, in
    Polish fowls, short-faced tumbler pigeons, and in one variety of
    the carp—for the bones of the face to become greatly shortened. In
    the case of the dog, as H. Müller has shown, this seems caused by
    an abnormal state of the primordial cartilage. We may, however,
    readily admit that abundant and rich food supplied during many
    generations would give an inherited tendency to increased size of
    body, and that, from disuse, the limbs would become finer and
    shorter.[18] We shall in a future chapter see also that the skull
    and limbs are apparently in some manner correlated, so that any
    change in the one tends to affect the other.

    Nathusius has remarked, and the observation is an interesting one,
    that the peculiar form of the skull and body in the most highly
    cultivated races is not characteristic of any one race, but is
    common to all when improved up to the same standard. Thus the
    large-bodied, long-eared, English breeds with a convex back, and
    the small-bodied, short-eared, Chinese breeds with a concave back,
    when bred to the same state of perfection, nearly resemble each
    other in the form of the head and body. This result, it appears, is
    partly due to similar causes of change acting on the several races,
    and partly to man breeding the pig for one sole purpose, namely,
    for the greatest amount of flesh and fat; so that selection has
    always tended towards one and the same end. With most domestic
    animals the result of selection has been divergence of character,
    here it has been convergence.[19]

    The nature of the food supplied during many generations has
    apparently affected the length of the intestines; for, according to
    Cuvier,[20] their length to that of the body in the wild boar is as
    9 to 1,—in the common domestic boar as 13·5 to 1,—and in the Siam
    breed as 16 to 1. In this latter breed the greater length may be
    due either to descent from a distinct species or to more ancient
    domestication. The number of mammæ vary, as does the period of
    gestation. The latest authority says[21] that “the period averages
    from 17 to 20 weeks,” but I think there must be some error in this
    statement: in M. Tessier’s observations on 25 sows it varied from
    109 to 123 days. The Rev. W. D. Fox has given me ten carefully
    recorded cases with well-bred pigs, in which the period varied from
    101 to 116 days. According to Nathusius the period is shortest in
    the races which come early to maturity; but the course of their
    development does not appear to be actually shortened, for the young
    animal is born, judging from the state of the skull, less fully
    developed, or in a more embryonic condition,[22] than in the case
    of common swine. In the highly cultivated and early matured races
    the teeth, also, are developed earlier.

    The difference in the number of the vertebræ and ribs in different
    kinds of pigs, as observed by Mr. Eyton,[23] and as given in the
    following table, has often been quoted. The African sow probably
    belongs to the _S. scrofa_ type; and Mr. Eyton informs me that,
    since the publication of this paper, cross-bred animals from the
    African and English races were found by Lord Hill to be perfectly
    fertile.


               English
          Long-legged
          Male.     African
          Female.     Chinese
          Male.     Wild Boar
          from Cuvier.     French
          Domestic
          Boar, from
          Cuvier. Dorsal vertebræ     15     13     15     14     14
          Lumbar       6       6       4       5       5 Dorsal and lumbar
          together     21     19     19     19     19 Sacral       5      
          5       4       4       4 Total number of
          vertebræ     26     24     23     23     23


    Some semi-monstrous breeds deserve notice. From the time of
    Aristotle to the present time solid-hoofed swine have occasionally
    been observed in various parts of the world. Although this
    peculiarity is strongly inherited, it is hardly probable that all
    the animals with solid hoofs have descended from the same parents;
    it is more probable that the same peculiarity has reappeared at
    various times and places. Dr. Struthers has lately described and
    figured[24] the structure of the feet; in both front and hind feet
    the distal phalanges of the two greater toes are represented by a
    single, great, hoof-bearing phalanx; and in the front feet, the
    middle phalanges are represented by a bone which is single towards
    the lower end, but bears two separate articulations towards the
    upper end. From other accounts it appears that an intermediate toe
    is likewise sometimes superadded.

Illustration: Old Irish Pig, with jaw-appendages.

    Another curious anomaly is offered by the appendages, described by
    M. Eudes-Deslongchamps as often characterizing the Normandy pigs.
    These appendages are always attached to the same spot, to the
    corners of the jaw; they are cylindrical, about three inches in
    length, covered with bristles, and with a pencil of bristles rising
    out of a sinus on one side: they have a cartilaginous centre, with
    two small longitudinal muscles they occur either symmetrically on
    both sides of the face or on one side alone. Richardson figures
    them on the gaunt old “Irish Greyhound pig;” and Nathusius states
    that they occasionally appear in all the long eared races, but are
    not strictly inherited, for they occur or fail in animals of the
    same litter.[25] As no wild pigs are known to have analogous
    appendages, we have at present no reason to suppose that their
    appearance is due to reversion; and if this be so, we are forced to
    admit that a somewhat complex, though apparently useless, structure
    may be suddenly developed without the aid of selection.

It is a remarkable fact that the boars of all domesticated breeds have
much shorter tusks than wild boars. Many facts show that with many
animals the state of the hair is much affected by exposure to, or
protection from, climate; and as we see that the state of the hair and
teeth are correlated in Turkish dogs (other analogous facts will be
hereafter given), may we not venture to surmise that the reduction of
the tusks in the domestic boar is related to his coat of bristles being
diminished from living under shelter? On the other hand, as we shall
immediately see, the tusks and bristles reappear with feral boars,
which are no longer protected from the weather. It is not surprising
that the tusks should be more affected than the other teeth; as parts
developed to serve as secondary sexual characters are always liable to
much variation.

    It is a well-known fact that the young of wild European and Indian
    pigs,[26] for the first six months, are longitudinally banded with
    light-coloured stripes. This character generally disappears under
    domestication. The Turkish domestic pigs, however, have striped
    young, as have those of Westphalia, “whatever may be their
    hue;”[27] whether these latter pigs belong to the same curly-haired
    race as the Turkish swine, I do not know. The pigs which have run
    wild in Jamaica and the semi-feral pigs of New Granada, both those
    which are black and those which are black with a white band across
    the stomach, often extending over the back, have resumed this
    aboriginal character and produce longitudinally-striped young. This
    is likewise the case, at least occasionally, with the neglected
    pigs in the Zambesi settlement on the coast of Africa.[28]

    The common belief that all domesticated animals, when they run
    wild, revert completely to the character of their parent-stock, is
    chiefly founded, as far as I can discover, on feral pigs. But even
    in this case the belief is not grounded on sufficient evidence; for
    the two main types, namely, _S. scrofa_ and _indicus,_ have not
    been distinguished. The young, as we have just seen, reacquire
    their longitudinal stripes, and the boars invariably reassume their
    tusks. They revert also in the general shape of their bodies, and
    in the length of their legs and muzzles, to the state of the wild
    animal, as might have been expected from the amount of exercise
    which they are compelled to take in search of food. In Jamaica the
    feral pigs do not acquire the full size of the European wild boar,
    “never attaining a greater height than 20 inches at the shoulder.”
    In various countries they reassume their original bristly covering,
    but in different degrees, dependent on the climate; thus, according
    to Roulin, the semi-feral pigs in the hot valleys of New Granada
    are very scantily clothed; whereas, on the Paramos, at the height
    of 7000 to 8000 feet, they acquire a thick covering of wool lying
    under the bristles, like that on the truly wild pigs of France.
    These pigs on the Paramos are small and stunted. The wild boar of
    India is said to have the bristles at the end of its tail arranged
    like the plumes of an arrow, whilst the European boar has a simple
    tuft; and it is a curious fact that many, but not all, of the feral
    pigs in Jamaica, derived from a Spanish stock, have a plumed
    tail.[29] With respect to colour, feral pigs generally revert to
    that of the wild boar; but in certain parts of S. America, as we
    have seen, some of the semi-feral pigs have a curious white band
    across their stomachs; and in certain other hot places the pigs are
    red, and this colour has likewise occasionally been observed in the
    feral pigs of Jamaica. From these several facts we see that with
    pigs when feral there is a strong tendency to revert to the wild
    type; but that this tendency is largely governed by the nature of
    the climate, amount of exercise, and other causes of change to
    which they have been subjected.

    The last point worth notice is that we have unusually good evidence
    of breeds of pigs now keeping perfectly true, which have been
    formed by the crossing of several distinct breeds. The Improved
    Essex pigs, for instance, breed very true; but there is no doubt
    that they largely owe their present excellent qualities to crosses
    originally made by Lord Western with the Neapolitan race, and to
    subsequent crosses with the Berkshire breed (this also having been
    improved by Neapolitan crosses), and likewise, probably, with the
    Sussex breed.[30] In breeds thus formed by complex crosses, the
    most careful and unremitting selection during many generations has
    been found to be indispensable. Chiefly in consequence of so much
    crossing, some well-known breeds have undergone rapid changes;
    thus, according to Nathusius,[31] the Berkshire breed of 1780 is
    quite different from that of 1810; and, since this latter period,
    at least two distinct forms have borne the same name.

CATTLE.

    Domestic cattle are certainly the descendants of more than one wild
    form, in the same manner as has been shown to be the case with our
    dogs and pigs. Naturalists have generally made two main divisions
    of cattle: the humped kinds inhabiting tropical countries, called
    in India Zebus, to which the specific name of _ Bos indicus_ has
    been given; and the common non-humped cattle, generally included
    under the name of _Bos taurus._ The humped cattle were
    domesticated, as may be seen on the Egyptian monuments, at least as
    early as the twelfth dynasty, that is 2100 B.C. They differ from
    common cattle in various osteological characters, even in a greater
    degree, according to Rütimeyer,[32] than do the fossil and
    prehistoric European species, namely, _Bos primigenius_ and _
    longifrons,_ from each other. They differ, also, as Mr. Blyth,[33]
    who has particularly attended to this subject, remarks, in general
    configuration, in the shape of their ears, in the point where the
    dewlap commences, in the typical curvature of their horns, in their
    manner of carrying their heads when at rest, in their ordinary
    variations of colour, especially in the frequent presence of
    “nilgau-like markings on their feet,” and “in the one being born
    with teeth protruding through the jaws, and the other not so.” They
    have different habits, and their voice is entirely different. The
    humped cattle in India “seldom seek shade, and never go into the
    water and there stand knee-deep, like the cattle of Europe.” They
    have run wild in parts of Oude and Rohilcund, and can maintain
    themselves in a region infested by tigers. They have given rise to
    many races differing greatly in size, in the presence of one or two
    humps, in length of horns, and other respects. Mr. Blyth sums up
    emphatically that the humped and humpless cattle must be considered
    as distinct species. When we consider the number of points in
    external structure and habits, independently of important
    osteological differences, in which they differ from each other; and
    that many of these points are not likely to have been affected by
    domestication, there can hardly be a doubt, notwithstanding the
    adverse opinion of some naturalists, that the humped and non-humped
    cattle must be ranked as specifically distinct.

    The European breeds of humpless cattle are numerous. Professor Low
    enumerates 19 British breeds, only a few of which are identical
    with those on the Continent. Even the small Channel islands of
    Guernsey, Jersey, and Alderney possess their own sub-breeds;[34]
    and these again differ from the cattle of the other British
    islands, such as Anglesea, and the western isles of Scotland.
    Desmarest, who paid attention to the subject, describes 15 French
    races, excluding sub-varieties and those imported from other
    countries. In other parts of Europe there are several distinct
    races, such as the pale-coloured Hungarian cattle, with their light
    and free step, and enormous horns sometimes measuring above five
    feet from tip to tip:[35] the Podolian cattle also are remarkable
    from the height of their fore-quarters. In the most recent work on
    Cattle,[36] engravings are given of fifty-five European breeds; it
    is, however, probable that several of these differ very little from
    each other, or are merely synonyms. It must not be supposed that
    numerous breeds of cattle exist only in long-civilised countries,
    for we shall presently see that several kinds are kept by the
    savages of Southern Africa.

    With respect to the parentage of the several European breeds, we
    already know much from Nilsson’s Memoir,[37] and more especially
    from Rütimeyer’s works and those of Boyd Dawkins. Two or three
    species or forms of Bos, closely allied to still living domestic
    races, have been found in the more recent tertiary deposits or
    amongst prehistoric remains in Europe. Following Rütimeyer, we
    have:—

    _Bos primigenius._This magnificent, well known species was
    domesticated in Switzerland during the Neolithic period; even at
    this early period it varied a little, having apparently been
    crossed with other races. Some of the larger races on the
    Continent, as the Friesland, etc., and the Pembroke race in
    England, closely resemble in essential structure _B. primigenius,_
    and no doubt are its descendants. This is likewise the opinion of
    Nilsson. _Bos primigenius_ existed as a wild animal in Cæsar’s
    time, and is now semi-wild, though much degenerated in size, in the
    park of Chillingham; for I am informed by Professor Rütimeyer, to
    whom Lord Tankerville sent a skull, that the Chillingham cattle are
    less altered from the true primigenius type than any other known
    breed.[38]

    _Bos trochoceros._ This form is not included in the three species
    above mentioned, for it is now considered by Rütimeyer to be the
    female of an early domesticated form of _B. primigenius,_ and as
    the progenitor of his _frontosus_ race. I may add that specific
    names have been given to four other fossil oxen, now believed to be
    identical with _B. primigenius._[39]

    _Bos longifrons_ (or _ brachyceros_) of Owen.—This very distinct
    species was of small size, and had a short body with fine legs.
    According to Boyd Dawkins[40] it was introduced as a domesticated
    animal into Britain at a very early period, and supplied food to
    the Roman legionaries.[41] Some remains have been found in Ireland
    in certain crannoges, of which the dates are believed to be from
    843-933 A.D.[42] It was also the commonest form in a domesticated
    condition in Switzerland during the earliest part of the Neolithic
    period. Professor Owen[43] thinks it probable that the Welsh and
    Highland cattle are descended from this form; as likewise is the
    case, according to Rütimeyer, with some of the existing Swiss
    breeds. These latter are of different shades of colour from
    light-grey to blackish-brown, with a lighter stripe along the
    spine, but they have no pure white marks. The cattle of North Wales
    and the Highlands, on the other hand, are generally black or
    dark-coloured.

    _Bos frontosus_ of Nilsson.—This species is allied to _B.
    longifrons,_ and, according to the high authority of Mr. Boyd
    Dawkins, is identical with it, but in the opinion of some judges is
    distinct. Both co-existed in Scania during the same late geological
    period,[44] and both have been found in the Irish crannoges.[45]
    Nilsson believes that his _B. frontosus_ may be the parent of the
    mountain cattle of Norway, which have a high protuberance on the
    skull between the base of the horns. As Professor Owen and others
    believe that the Scotch Highland cattle are descended from his _B.
    longifrons,_ it is worth notice that a capable judge[46] has
    remarked that he saw no cattle in Norway like the Highland breed,
    but that they more nearly resembled the Devonshire breed.

    On the whole we may conclude, more especially from the researches
    of Boyd Dawkins, that European cattle are descended from two
    species; and there is no improbability in this fact, for the genus
    Bos readily yields to domestication. Besides these two species and
    the zebu, the yak, the gayal, and the arni[47] (not to mention the
    buffalo or genus Bubalus) have been domesticated; making altogether
    six species of Bos. The zebu and the two European species are now
    extinct in a wild state. Although certain races of cattle were
    domesticated at a very ancient period in Europe, it does not follow
    that they were first domesticated here. Those who place much
    reliance on philology argue that they were imported from the
    East.[48] It is probable that they originally inhabited a temperate
    or cold climate, but not a land long covered with snow; for our
    cattle, as we have seen in the chapter on Horses, have not the
    instinct of scraping away the snow to get at the herbage beneath.
    No one could behold the magnificent wild bulls on the bleak
    Falkland Islands in the southern hemisphere, and doubt about the
    climate being admirably suited to them. Azara has remarked that in
    the temperate regions of La Plata the cows conceive when two years
    old, whilst in the much hotter country of Paraguay they do not
    conceive till three years old; “from which fact,” as he adds, “one
    may conclude that cattle do not succeed so well in warm
    countries.”[49]

    _Bos primigenius_ and _longifrons_ have been ranked by nearly all
    palæontologists as distinct species; and it would not be reasonable
    to take a different view simply because their domesticated
    descendants now intercross with the utmost freedom. All the
    European breeds have so often been crossed both intentionally and
    unintentionally, that, if any sterility had ensued from such
    unions, it would certainly have been detected. As zebus inhabit a
    distant and much hotter region, and as they differ in so many
    characters from our European cattle, I have taken pains to
    ascertain whether the two forms are fertile when crossed. The late
    Lord Powis imported some zebus and crossed them with common cattle
    in Shropshire; and I was assured by his steward that the cross-bred
    animals were perfectly fertile with both parent-stocks. Mr. Blyth
    informs me that in India hybrids, with various proportions of
    either blood, are quite fertile; and this can hardly fail to be
    known, for in some districts[50] the two species are allowed to
    breed freely together. Most of the cattle which were first
    introduced into Tasmania were humped, so that at one time thousands
    of crossed animals existed there; and Mr. B. O’Neile Wilson, M.A.,
    writes to me from Tasmania that he has never heard of any sterility
    having been observed. He himself formerly possessed a herd of such
    crossed cattle, and all were perfectly fertile; so much so, that he
    cannot remember even a single cow failing to calve. These several
    facts afford an important confirmation of the Pallasian doctrine
    that the descendants of species which when first domesticated would
    if crossed have been in all probability in some degree sterile,
    become perfectly fertile after a long course of domestication. In a
    future chapter we shall see that this doctrine throws some light on
    the difficult subject of Hybridism.

    I have alluded to the cattle in Chillingham Park, which, according
    to Rütimeyer, have been very little changed from the _Bos
    primigenius_ type. This park is so ancient that it is referred to
    in a record of the year 1220. The cattle in their instincts and
    habits are truly wild. They are white, with the inside of the ears
    reddish-brown, eyes rimmed with black, muzzles brown, hoofs black,
    and horns white tipped with black. Within a period of thirty-three
    years about a dozen calves were born with “brown and blue spots
    upon the cheeks or necks; but these, together with any defective
    animals, were always destroyed.” According to Bewick, about the
    year 1770 some calves appeared with black ears; but these were also
    destroyed by the keeper, and black ears have not since reappeared.
    The wild white cattle in the Duke of Hamilton’s park, where I have
    heard of the birth of a black calf, are said by Lord Tankerville to
    be inferior to those at Chillingham. The cattle kept until the year
    1780 by the Duke of Queensberry, but now extinct, had their ears,
    muzzle, and orbits of the eyes black. Those which have existed from
    time immemorial at Chartley, closely resemble the cattle at
    Chillingham, but are larger, “with some small difference in the
    colour of the ears.” “They frequently tend to become entirely
    black; and a singular superstition prevails in the vicinity that,
    when a black calf is born, some calamity impends over the noble
    house of Ferrers. All the black calves are destroyed.” The cattle
    at Burton Constable in Yorkshire, now extinct, had ears, muzzle,
    and the tip of the tail black. Those at Gisburne, also in
    Yorkshire, are said by Bewick to have been sometimes without dark
    muzzles, with the inside alone of the ears brown; and they are
    elsewhere said to have been low in stature and hornless.[51]

The several above-specified differences in the park-cattle, slight
though they be, are worth recording, as they show that animals living
nearly in a state of nature, and exposed to nearly uniform conditions,
if not allowed to roam freely and to cross with other herds, do not
keep as uniform as truly wild animals. For the preservation of a
uniform character, even within the same park, a certain degree of
selection—that is, the destruction of the dark-coloured calves—is
apparently necessary.

    Boyd Dawkins believes that the park-cattle are descended from
    anciently domesticated, and not truly wild animals; and from the
    occasional appearance of dark-coloured calves, it is improbable
    that the aboriginal _Bos primigenius_ was white. It is curious what
    a strong, though not invariable, tendency there is in wild or
    escaped cattle to become white with coloured ears, under widely
    different conditions of life. If the old writers Boethius and
    Leslie[52] can be trusted, the wild cattle of Scotland were white
    and furnished with a great mane; but the colour of their ears is
    not mentioned. In Wales,[53] during the tenth century, some of the
    cattle are described as being white with red ears. Four hundred
    cattle thus coloured were sent to King John; and an early record
    speaks of a hundred cattle with red ears having been demanded as a
    compensation for some offence, but, if the cattle were of a dark or
    black colour, 150 were to be presented. The black cattle of North
    Wales apparently belong, as we have seen, to the small _
    longifrons_ type: and as the alternative was offered of either 150
    dark cattle, or 100 white cattle with red ears, we may presume that
    the latter were the larger beasts, and probably belonged to the
    _primigenius_ type. Youatt has remarked that at the present day,
    whenever cattle of the shorthorn breed are white, the extremities
    of their ears are more or less tinged with red.

    The cattle which have run wild on the Pampas, in Texas, and in two
    parts of Africa, have become of a nearly uniform dark
    brownish-red.[54] On the Ladrone Islands, in the Pacific Ocean,
    immense herds of cattle, which were wild in the year 1741, are
    described as “milk-white, except their ears, which are generally
    black.”[55] The Falkland Islands, situated far south, with all the
    conditions of life as different as it is possible to conceive from
    those of the Ladrones, offer a more interesting case. Cattle have
    run wild there during eighty or ninety years; and in the southern
    districts the animals are mostly white, with their feet, or whole
    heads, or only their ears black; but my informant, Admiral
    Sulivan,[56] who long resided on these islands, does not believe
    that they are ever purely white. So that in these two archipelagos
    we see that the cattle tend to become white with coloured ears. In
    other parts of the Falkland Islands other colours prevail: near
    Port Pleasant brown is the common tint; round Mount Usborn, about
    half the animals in some of the herds were lead- or mouse-coloured,
    which elsewhere is an unusual tint. These latter cattle, though
    generally inhabiting high land, breed about a month earlier than
    the other cattle; and this circumstance would aid in keeping them
    distinct and in perpetuating a peculiar colour. It is worth
    recalling to mind that blue or lead-coloured marks have
    occasionally appeared on the white cattle of Chillingham. So
    plainly different were the colours of the wild herds in different
    parts of the Falkland Islands, that in hunting them, as Admiral
    Sulivan informs me, white spots in one district, and dark spots in
    another district, were always looked out for on the distant hills.
    In the intermediate districts, intermediate colours prevailed.
    Whatever the cause may be, this tendency in the wild cattle of the
    Falkland Islands, which are all descended from a few brought from
    La Plata, to break up into herds of three different colours, is an
    interesting fact.

Returning to the several British breeds, the conspicuous difference in
general appearance between Shorthorns, Longhorns (now rarely seen),
Herefords, Highland cattle, Alderneys, etc., must be familiar to every
one. A part of this difference may be attributed to descent from
primordially distinct species; but we may feel sure that there has been
a considerable amount of variation. Even during the Neolithic period,
the domestic cattle were to a certain extent variable. Within recent
times most of the breeds have been modified by careful and methodical
selection. How strongly the characters thus acquired are inherited, may
be inferred from the prices realised by the improved breeds; even at
the first sale of Colling’s Shorthorns, eleven bulls reached an average
of 214 pounds, and lately Shorthorn bulls have been sold for a thousand
guineas, and have been exported to all quarters of the world.

    Some constitutional differences may be here noticed. The Shorthorns
    arrive at maturity far earlier than the wilder breeds, such as
    those of Wales or the Highlands. This fact has been shown in an
    interesting manner by Mr. Simonds,[57] who has given a table of the
    average period of their dentition, which proves that there is a
    difference of no less than six months in the appearance of the
    permanent incisors. The period of gestation, from observations made
    by Tessier on 1131 cows, varies to the extent of eighty-one days;
    and what is more interesting, M. Lefour affirms “that the period of
    gestation is longer in the large German cattle than in the smaller
    breeds.”[58] With respect to the period of conception, it seems
    certain that Alderney and Zetland cows often become pregnant
    earlier than other breeds.[59] Lastly, as four fully developed
    mammæ is a generic character in the genus Bos,[60] it is worth
    notice that with our domestic cows the two rudimentary mammæ often
    become fairly well developed and yield milk.

    As numerous breeds are generally found only in long-civilised
    countries, it may be well to show that in some countries inhabited
    by barbarous races, who are frequently at war with each other, and
    therefore have little free communication, several distinct breeds
    of cattle now exist or formerly existed. At the Cape of Good Hope
    Leguat observed, in the year 1720, three kinds.[61] At the present
    day various travellers have noticed the differences in the breeds
    in Southern Africa. Sir Andrew Smith several years ago remarked to
    me that the cattle possessed by the different tribes of Caffres,
    though living near each other under the same latitude and in the
    same kind of country, yet differed, and he expressed much surprise
    at the fact. Mr. Andersson has described[62] the Damara, Bechuana,
    and Namaqua cattle; and he informs me in a letter that the cattle
    north of Lake Ngami are likewise different, as Mr. Galton has heard
    is also the case with the cattle of Benguela. The Namaqua cattle in
    size and shape nearly resemble European cattle, and have short
    stout horns and large hoofs. The Damara cattle are very peculiar,
    being big-boned, with slender legs, and small hard feet; their
    tails are adorned with a tuft of long bushy hair nearly touching
    the ground, and their horns are extraordinarily large. The Bechuana
    cattle have even larger horns, and there is now a skull in London
    with the two horns 8 ft. 8-1/4 in. long, as measured in a straight
    line from tip to tip, and no less than 13 ft. 5 in. as measured
    along their curvature! Mr. Andersson in his letter to me says that,
    though he will not venture to describe the differences between the
    breeds belonging to the many different sub-tribes, yet such
    certainly exist, as shown by the wonderful facility with which the
    natives discriminate them.

    That many breeds of cattle have originated through variation,
    independently of descent from distinct species, we may infer from
    what we see in South America, where the genus Bos was not endemic,
    and where the cattle which now exist in such vast numbers are the
    descendants of a few imported from Spain and Portugal. In Columbia,
    Roulin[63] describes two peculiar breeds, namely, _pelones,_ with
    extremely thin and fine hair, and _calongos,_ absolutely naked.
    According to Castelnau there are two races in Brazil, one like
    European cattle, the other different, with remarkable horns. In
    Paraguay, Azara describes a breed which certainly originated in S.
    America, called _chivos,_ “because they have straight vertical
    horns, conical, and very large at the base.” He likewise describes
    a dwarf race in Corrientes, with short legs and a body larger than
    usual. Cattle without horns, and others with reversed hair, have
    also originated in Paraguay.

    Another monstrous breed, called niatas or natas, of which I saw two
    small herds on the northern bank of the Plata, is so remarkable as
    to deserve a fuller description. This breed bears the same relation
    to other breeds, as bull or pug dogs do to other dogs, or as
    improved pigs, according to H. von Nathusius, do to common
    pigs.[64] Rütimeyer believes that these cattle belong to the
    primigenius type.[65] The forehead is very short and broad, with
    the nasal end of the skull, together with the whole plane of the
    upper molar-teeth, curved upwards. The lower jaw projects beyond
    the upper, and has a corresponding upward curvature. It is an
    interesting fact that an almost similar confirmation characterizes,
    as I am informed by Dr. Falconer, the extinct and gigantic
    Sivatherium of India, and is not known in any other ruminant. The
    upper lip is much drawn back, the nostrils are seated high up and
    are widely open, the eyes project outwards, and the horns are
    large. In walking the head is carried low, and the neck is short.
    The hind legs appear to be longer, compared with the front legs,
    than is usual. The exposed incisor teeth, the short head and
    upturned nostrils, give these cattle the most ludicrous,
    self-confident air of defiance. The skull which I presented to the
    College of Surgeons has been thus described by Professor Owen:[66]
    “It is remarkable from the stunted development of the nasals,
    premaxillaries, and fore-part of the lower jaw, which is unusually
    curved upwards to come into contact with the premaxillaries. The
    nasal bones are about one-third the ordinary length, but retain
    almost their normal breadth. The triangular vacuity is left between
    them, the frontal and lachrymal, which latter bone articulates with
    the premaxillary, and thus excludes the maxillary from any junction
    with the nasal.” So that even the connexion of some of the bones is
    changed. Other differences might be added: thus the plane of the
    condyles is somewhat modified, and the terminal edge of the
    premaxillaries forms an arch. In fact, on comparison with the skull
    of a common ox, scarcely a single bone presents the same exact
    shape, and the whole skull has a wonderfully different appearance.

The first brief published notice of this race was by Azara, between the
years 1783-96; but Don F. Muniz, of Luxan, who has kindly collected
information for me, states that about 1760 these cattle were kept as
curiosities near Buenos Ayres. Their origin is not positively known,
but they must have originated subsequently to the year 1552, when
cattle were first introduced. Senor Muniz informs me that the breed is
believed to have originated with the Indians southward of the Plata.
Even to this day those reared near the Plata show their less civilised
nature in being fiercer than common cattle, and in the cow, if visited
too often, easily deserting her first calf. The breed is very true, and
a niata bull and cow invariably produce niata calves. The breed has
already lasted at least a century. A niata bull crossed with a common
cow, and the reverse cross, yield offspring having an intermediate
character, but with the niata character strongly displayed. According
to Senor Muniz, there is the clearest evidence, contrary to the common
belief of agriculturists in analogous cases, that the niata cow when
crossed with a common bull transmits her peculiarities more strongly
than does the niata bull when crossed with a common cow. When the
pasture is tolerably long, these cattle feed as well as common cattle
with their tongue and palate; but during the great droughts, when so
many animals perish on the Pampas, the niata breed lies under a great
disadvantage, and would, if not attended to, become extinct; for the
common cattle, like horses, are able to keep alive by browsing with
their lips on the twigs of trees and on reeds: this the niatas cannot
so well do, as their lips do not join, and hence they are found to
perish before the common cattle. This strikes me as a good illustration
of how little we are able to judge from the ordinary habits of an
animal, on what circumstances, occurring only at long intervals of
time, its rarity or extinction may depend. It shows us, also, how
natural selection would have determined the rejection of the niata
modification had it arisen in a state of nature.

    Having described the semi-monstrous niata breed, I may allude to a
    white bull, said to have been brought from Africa, which was
    exhibited in London in 1829, and which has been well figured by Mr.
    Harvey.[67] It had a hump, and was furnished with a mane. The
    dewlap was peculiar, being divided between its fore-legs into
    parallel divisions. Its lateral hoofs were annually shed, and grew
    to the length of five or six inches. The eye was very peculiar,
    being remarkably prominent, and “resembled a cup and ball, thus
    enabling the animal to see on all sides with equal ease; the pupil
    was small and oval, or rather a parallelogram with the ends cut
    off, and lying transversely across the ball.” A new and strange
    breed might probably have been formed by careful breeding and
    selection from this animal.

    I have often speculated on the probable causes through which each
    separate district in Great Britain came to possess in former times
    its own peculiar breed of cattle; and the question is, perhaps,
    even more perplexing in the case of Southern Africa. We now know
    that the differences may be in part attributed to descent from
    distinct species; but this cause is far from sufficient. Have the
    slight differences in climate and in the nature of the pasture, in
    the different districts of Britain, directly induced corresponding
    differences in the cattle? We have seen that the semi-wild cattle
    in the several British parks are not identical in colouring or
    size, and that some degree of selection has been requisite to keep
    them true. It is almost certain that abundant food given during
    many generations directly affects the size of a breed.[68] That
    climate directly affects the thickness of the skin and the hair is
    likewise certain: thus Roulin asserts[69] that the hides of the
    feral cattle on the hot Llanos “are always much less heavy than
    those of the cattle raised on the high platform of Bogota; and that
    these hides yield in weight and in thickness of hair to those of
    the cattle which have run wild on the lofty Paramos.” The same
    difference has been observed in the hides of the cattle reared on
    the bleak Falkland Islands and on the temperate Pampas. Low has
    remarked[70] that the cattle which inhabit the more humid parts of
    Britain have longer hair and thicker skins than other British
    cattle. When we compare highly improved stall-fed cattle with the
    wilder breeds, or compare mountain and lowland breeds, we cannot
    doubt that an active life, leading to the free use of the limbs and
    lungs, affects the shape and proportions of the whole body. It is
    probable that some breeds, such as the semi-monstrous niata cattle,
    and some peculiarities, such as being hornless, etc., have appeared
    suddenly owing to what we may call in our ignorance spontaneous
    variation; but even in this case a rude kind of selection is
    necessary, and the animals thus characterised must be at least
    partially separated from others. This degree of care, however, has
    sometimes been taken even in little-civilised districts, where we
    should least have expected it, as in the case of the niata, chivo,
    and hornless cattle in S. America.

    That methodical selection has done wonders within a recent period
    in modifying our cattle, no one doubts. During the process of
    methodical selection it has occasionally happened that deviations
    of structure, more strongly pronounced than mere individual
    differences, yet by no means deserving to be called monstrosities,
    have been taken advantage of: thus the famous Longhorn Bull,
    Shakespeare, though of the pure Canley stock, scarcely inherited a
    single point of the long-horned breed, his horns excepted;[71] yet
    in the hands of Mr. Fowler, this bull greatly improved his race. We
    have also reason to believe that selection, carried on so far
    unconsciously that there was at no one time any distinct intention
    to improve or change the breed, has in the course of time modified
    most of our cattle; for by this process, aided by more abundant
    food, all the lowland British breeds have increased greatly in size
    and in early maturity since the reign of Henry VII.[72] It should
    never be forgotten that many animals have to be annually
    slaughtered; so that each owner must determine which shall be
    killed and which preserved for breeding. In every district, as
    Youatt has remarked, there is a prejudice in favour of the native
    breed; so that animals possessing qualities, whatever they may be,
    which are most valued in each district, will be oftenest preserved;
    and this unmethodical selection assuredly will in the long run
    affect the character of the whole breed. But it may be asked, can
    this rude kind of selection have been practised by barbarians such
    as those of southern Africa? In a future chapter on Selection we
    shall see that this has certainly occurred to some extent.
    Therefore, looking to the origin of the many breeds of cattle which
    formerly inhabited the several districts of Britain, I conclude
    that, although slight differences in the nature of the climate,
    food, etc., as well as changed habits of life, aided by correlation
    of growth, and the occasional appearance from unknown causes of
    considerable deviations of structure, have all probably played
    their parts; yet that the occasional preservation in each district
    of those individual animals which were most valued by each owner
    has perhaps been even more effective in the production of the
    several British breeds. As soon as two or more breeds were formed
    in any district, or when new breeds descended from distinct species
    were introduced, their crossing, especially if aided by some
    selection, will have multiplied the number and modified the
    characters of the older breeds.

SHEEP.

    I shall treat this subject briefly. Most authors look at our
    domestic sheep as descended from several distinct species. Mr.
    Blyth, who has carefully attended to the subject, believes that
    fourteen wild species now exist, but “that not one of them can be
    identified as the progenitor of any one of the interminable
    domestic races.” M. Gervais thinks that there are six species of
    Ovis,[73] but that our domestic sheep form a distinct genus, now
    completely extinct. A German naturalist[74] believes that our sheep
    descend from ten aboriginally distinct species, of which only one
    is still living in a wild state! Another ingenious observer,[75]
    though not a naturalist, with a bold defiance of everything known
    on geographical distribution, infers that the sheep of Great
    Britain alone are the descendants of eleven endemic British forms!
    Under such a hopeless state of doubt it would be useless for my
    purpose to give a detailed account of the several breeds; but a few
    remarks may be added.

    Sheep have been domesticated from a very ancient period.
    Rütimeyer[76] found in the Swiss lake-dwellings the remains of a
    small breed, with thin tall legs, and horns like those of a goat,
    thus differing somewhat from any kind now known. Almost every
    country has its own peculiar breed; and many countries have several
    breeds differing greatly from each other. One of the most strongly
    marked races is an Eastern one with a long tail, including,
    according to Pallas, twenty vertebræ, and so loaded with fat that
    it is sometimes placed on a truck, which is dragged about by the
    living animal. These sheep, though ranked by Fitzinger as a
    distinct aboriginal form, bear in their drooping ears the stamp of
    long domestication. This is likewise the case with those sheep
    which have two great masses of fat on the rump, with the tail in a
    rudimentary condition. The Angola variety of the long-tailed race
    has curious masses of fat on the back of the head and beneath the
    jaws.[77] Mr. Hodgson in an admirable paper[78] on the sheep of the
    Himalaya infers from the distribution of the several races, “that
    this caudal augmentation in most of its phases is an instance of
    degeneracy in these pre-eminently Alpine animals.” The horns
    present an endless diversity in character; being not rarely absent,
    especially in the female sex, or, on the other hand, amounting to
    four or even eight in number. The horns, when numerous, arise from
    a crest on the frontal bone, which is elevated in a peculiar
    manner. It is remarkable that multiplicity of horns “is generally
    accompanied by great length and coarseness of the fleece.”[79] This
    correlation, however, is far from being general; for instance, I am
    informed by Mr. D. Forbes, that the Spanish sheep in Chile
    resemble, in fleece and in all other characters, their parent
    merino-race, except that instead of a pair they generally bear four
    horns. The existence of a pair of mammæ is a generic character in
    the genus Ovis as well as in several allied forms; nevertheless, as
    Mr. Hodgson has remarked, “this character is not absolutely
    constant even among the true and proper sheep: for I have more than
    once met with Càgias (a sub-Himalayan domestic race) possessed of
    four teats.”[80] This case is the more remarkable as, when any part
    or organ is present in reduced number in comparison with the same
    part in allied groups, it usually is subject to little variation.
    The presence of interdigital pits has likewise been considered as a
    generic distinction in sheep; but Isidore Geoffroy[81] has shown
    that these pits or pouches are absent in some breeds.

    In sheep there is a strong tendency for characters, which have
    apparently been acquired under domestication, to become attached
    either exclusively to the male sex, or to be more highly developed
    in this than in the other sex. Thus in many breeds the horns are
    deficient in the ewe, though this likewise occurs occasionally with
    the female of the wild musmon. In the rams of the Wallachian breed,
    “the horns spring almost perpendicularly from the frontal bone, and
    then take a beautiful spiral form; in the ewes they protrude nearly
    at right angles from the head, and then become twisted in a
    singular manner.”[82] Mr. Hodgson states that the extraordinarily
    arched nose or chaffron, which is so highly developed in several
    foreign breeds, is characteristic of the ram alone, and apparently
    is the result of domestication.[83] I hear from Mr. Blyth that the
    accumulation of fat in the fat-tailed sheep of the plains of India
    is greater in the male than in the female; and Fitzinger[84]
    remarks that the mane in the African maned race is far more
    developed in the ram than in the ewe.

    Different races of sheep, like cattle, present constitutional
    differences. Thus the improved breeds arrive at maturity at an
    early age, as has been well shown by Mr. Simonds through their
    early average period of dentition. The several races have become
    adapted to different kinds of pasture and climate: for instance, no
    one can rear Leicester sheep on mountainous regions, where Cheviots
    flourish. As Youatt has remarked, “In all the different districts
    of Great Britain we find various breeds of sheep beautifully
    adapted to the locality which they occupy. No one knows their
    origin; they are indigenous to the soil, climate, pasturage, and
    the locality on which they graze; they seem to have been formed for
    it and by it.”[85] Marshall relates[86] that a flock of heavy
    Lincolnshire and light Norfolk sheep which had been bred together
    in a large sheep-walk, part of which was low, rich, and moist, and
    another part high and dry, with benty grass, when turned out,
    regularly separated from each other; the heavy sheep drawing off to
    the rich soil, and the lighter sheep to their own soil; so that
    “whilst there was plenty of grass the two breeds kept themselves as
    distinct as rooks and pigeons.” Numerous sheep from various parts
    of the world have been brought during a long course of years to the
    Zoological Gardens of London; but as Youatt, who attended the
    animals as a veterinary surgeon, remarks, “few or none die of the
    rot, but they are phthisical; not one of them from a torrid climate
    lasts out the second year, and when they die their lungs are
    tuberculated.”[87] There is very good evidence that English breeds
    of sheep will not succeed in France.[88] Even in certain parts of
    England it has been found impossible to keep certain breeds of
    sheep; thus on a farm on the banks of the Ouse, the Leicester sheep
    were so rapidly destroyed by pleuritis[89] that the owner could not
    keep them; the coarser-skinned sheep never being affected.

    The period of gestation was formerly thought to be of so
    unalterable a character, that a supposed difference of this kind
    between the wolf and the dog was esteemed a sure sign of specific
    distinction; but we have seen that the period is shorter in the
    improved breeds of the pig, and in the larger breeds of the ox,
    than in other breeds of these two animals. And now we know, on the
    excellent authority of Hermann von Nathusius,[90] that Merino and
    Southdown sheep, when both have long been kept under exactly the
    same conditions, differ in their average period of gestation, as is
    seen in the following Table:—

Merinos     150·3 days. Southdowns     144·2 days. Half-bred Merinos and
Southdowns     146·3 days. 3/4 blood of Southdown     145·5 days. 7/8
blood of Southdown     144·2 days.

In this graduated difference in cross-bred animals having different
proportions of Southdown blood, we see how strictly the two periods of
gestation have been transmitted. Nathusius remarks that, as Southdowns
grow with remarkable rapidity after birth, it is not surprising that
their foetal development should have been shortened. It is of course
possible that the difference in these two breeds may be due to their
descent from distinct parent-species; but as the early maturity of the
Southdowns has long been carefully attended to by breeders, the
difference is more probably the result of such attention. Lastly, the
fecundity of the several breeds differs much; some generally producing
twins or even triplets at a birth, of which fact the curious Shangai
sheep (with their truncated and rudimentary ears, and great Roman
noses), lately exhibited in the Zoological Gardens, offer a remarkable
instance.

    Sheep are perhaps more readily affected by the direct action of the
    conditions of life to which they have been exposed than almost any
    other domestic animal. According to Pallas, and more recently
    according to Erman, the fat-tailed Kirghisian sheep, when bred for
    a few generations in Russia, degenerate, and the mass of fat
    dwindles away, “the scanty and bitter herbage of the steppes seems
    so essential to their development.” Pallas makes an analogous
    statement with respect to one of the Crimean breeds. Burnes states
    that the Karakool breed, which produces a fine, curled, black, and
    valuable fleece, when removed from its own canton near Bokhara to
    Persia or to other quarters, loses its peculiar fleece.[91] In all
    such cases, however, it may be that a change of any kind in the
    conditions of life causes variability and consequent loss of
    character, and not that certain conditions are necessary for the
    development of certain characters.

    Great heat, however, seems to act directly on the fleece: several
    accounts have been published of the change which sheep imported
    from Europe undergo in the West Indies. Dr. Nicholson of Antigua
    informs me that, after the third generation, the wool disappears
    from the whole body, except over the loins; and the animal then
    appears like a goat with a dirty door-mat on its back. A similar
    change is said to take place on the west coast of Africa.[92] On
    the other hand, many wool-bearing sheep live on the hot plains of
    India. Roulin asserts that in the lower and heated valleys of the
    Cordillera, if the lambs are sheared as soon as the wool has grown
    to a certain thickness, all goes on afterwards as usual; but if not
    sheared, the wool detaches itself in flakes, and short shining hair
    like that on a goat is produced ever afterwards. This curious
    result seems merely to be an exaggerated tendency natural to the
    Merino breed, for as a great authority, namely, Lord Somerville,
    remarks, “the wool of our Merino sheep after shear-time is hard and
    coarse to such a degree as to render it almost impossible to
    suppose that the same animal could bear wool so opposite in
    quality, compared to that which has been clipped from it: as the
    cold weather advances, the fleeces recover their soft quality.” As
    in sheep of all breeds the fleece naturally consists of longer and
    coarser hair covering shorter and softer wool, the change which it
    often undergoes in hot climates is probably merely a case of
    unequal development; for even with those sheep which like goats are
    covered with hair, a small quantity of underlying wool may always
    be found.[93] In the wild mountain-sheep (_0vis montana_) of North
    America there is an analogous annual change of coat; “the wool
    begins to drop out in early spring, leaving in its place a coat of
    hair resembling that of the elk, a change of pelage quite different
    in character from the ordinary thickening of the coat or hair,
    common to all furred animals in winter,—for instance, in the horse,
    the cow, etc., which shed their winter coat in the spring.”[94]

A slight difference in climate or pasture sometimes slightly affects
the fleece, as has been observed even in different districts in
England, and is well shown by the great softness of the wool brought
from Southern Australia. But it should be observed, as Youatt
repeatedly insists, that the tendency to change may generally be
counteracted by careful selection. M. Lasterye, after discussing this
subject, sums up as follows: “The preservation of the Merino race in
its utmost purity at the Cape of Good Hope, in the marshes of Holland,
and under the rigorous climate of Sweden, furnishes an additional
support of this my unalterable principle, that fine-woolled sheep may
be kept wherever industrious men and intelligent breeders exist.”

    That methodical selection has effected great changes in several
    breeds of sheep no one who knows anything on the subject,
    entertains a doubt. The case of the Southdowns, as improved by
    Ellman, offers perhaps the most striking instance. Unconscious or
    occasional selection has likewise slowly produced a great effect,
    as we shall see in the chapters on Selection. That crossing has
    largely modified some breeds, no one who will study what has been
    written on this subject—for instance, Mr. Spooner’s paper—will
    dispute; but to produce uniformity in a crossed breed, careful
    selection and “rigorous weeding,” as this author expresses it, are
    indispensable.[95]

    In some few instances new breeds have suddenly originated; thus, in
    1791, a ram-lamb was born in Massachusetts, having short crooked
    legs and a long back, like a turnspit-dog. From this one lamb the
    _otter_ or _ancon_ semi-monstrous breed was raised; as these sheep
    could not leap over the fences, it was thought that they would be
    valuable; but they have been supplanted by merinos, and thus
    exterminated. The sheep are remarkable from transmitting their
    character so truly that Colonel Humphreys[96] never heard of “but
    one questionable case” of an ancon ram and ewe not producing ancon
    offspring. When they are crossed with other breeds the offspring,
    with rare exceptions, instead of being intermediate in character,
    perfectly resemble either parent; even one of twins has resembled
    one parent and the second the other. Lastly, “the ancons have been
    observed to keep together, separating themselves from the rest of
    the flock when put into enclosures with other sheep.”

A more interesting case has been recorded in the Report of the Juries
for the Great Exhibition (1851), namely, the production of a merino
ram-lamb on the Mauchamp farm, in 1828, which was remarkable for its
long, smooth, straight, and silky wool. By the year 1833 M. Graux had
raised rams enough to serve his whole flock, and after a few more years
he was able to sell stock of his new breed. So peculiar and valuable is
the wool, that it sells at 25 per cent above the best merino wool: even
the fleeces of half-bred animals are valuable, and are known in France
as the “Mauchamp-merino.” It is interesting, as showing how generally
any marked deviation of structure is accompanied by other deviations,
that the first ram and his immediate offspring were of small size, with
large heads, long necks, narrow chests, and long flanks; but these
blemishes were removed by judicious crosses and selection. The long
smooth wool was also correlated with smooth horns; and as horns and
hair are homologous structures, we can understand the meaning of this
correlation. If the Mauchamp and ancon breeds had originated a century
or two ago, we should have had no record of their birth; and many a
naturalist would no doubt have insisted, especially in the case of the
Mauchamp race, that they had each descended from, or been crossed with,
some unknown aboriginal form.

GOATS.

    From the recent researches of M. Brandt, most naturalists now
    believe that all our goats are descended from the _Capra ægagrus_
    of the mountains of Asia, possibly mingled with the allied Indian
    species _C. falconeri_ of India.[97] In Switzerland, during the
    neolithic period, the domestic goat was commoner than the sheep;
    and this very ancient race differed in no respect from that now
    common in Switzerland.[98] At the present time, the many races
    found in several parts of the world differ greatly from each other;
    nevertheless, as far as they have been tried,[99] they are all
    quite fertile when crossed. So numerous are the breeds, that Mr. G.
    Clark[100] has described eight distinct kinds imported into the one
    island of Mauritius. The ears of one kind were enormously
    developed, being, as measured by Mr. Clark, no less than 19 inches
    in length and 4-3/4 inches in breadth. As with cattle, the mammæ of
    those breeds which are regularly milked become greatly developed;
    and, as Mr. Clark remarks, “it is not rare to see their teats
    touching the ground.” The following cases are worth notice as
    presenting unusual points of variation. According to Godron,[101]
    the mammæ differ greatly in shape in different breeds, being
    elongated in the common goat, hemispherical in the Angora race, and
    bilobed and divergent in the goats of Syria and Nubia. According to
    this same author, the males of certain breeds have lost their usual
    offensive odour. In one of the Indian breeds the males and females
    have horns of widely-different shapes;[102] and in some breeds the
    females are destitute of horns.[103] M. Ramu of Nancy informs me
    that many of the goats there bear on the upper part of the throat a
    pair of hairy appendages, 70 mm. in length and about 10 mm. in
    diameter, which in external appearance resemble those above
    described on the jaws of pigs. The presence of inter-digital pits
    or glands on all four feet has been thought to characterise the
    genus Ovis, and their absence to be characteristic of the genus
    Capra; but Mr. Hodgson has found that they exist in the front feet
    of the majority of Himalayan goats.[104] Mr. Hodgson measured the
    intestines in two goats of the Dúgú race, and he found that the
    proportional length of the great and small intestines differed
    considerably. In one of these goats the cæcum was thirteen inches,
    and in the other no less than thirty-six inches in length!

REFERENCES

 [1] Hermann von Nathusius ‘Die Racen des Schweines,’ Berlin, 1860; and
 ‘Vorstudien für Geschichte,’ etc., ‘Schweineschädel,’ Berlin, 1864.
 Rütimeyer, ‘Die Fauna der Pfahlbauten,’ Basel, 1861.

 [2] Nathusius, ‘Die Racen des Schweines,’ Berlin, 1860. An excellent
 appendix is given with references to published and trustworthy
 drawings of the breeds of each country.

 [3] For Europe _see_ Bechstein, ‘Naturgesch. Deutschlands,’ 1801, B.
 i., s. 505. Several accounts have been published on the fertility of
 the offspring from wild and tame swine. _See_ Burdach’s ‘Physiology,’
 and Godron ‘De l’Espèce,’ tom. i. p. 370. For Africa, ‘Bull. de la
 Soc. d’Acclimat.’ tom. iv. p. 389. For India, _see_ Nathusius,
 ‘Schweineschädel,’ s. 148.

 [4] Sir W. Elliot, Catalogue of Mammalia, ‘Madras Journal of Lit. and
 Science,’ vol. x. p. 219.

 [5] ‘Pfahlbauten,’ s. 163 _et passim._

 [6] _See_ J. W. Schütz’ interesting essay, ‘Zur Kenntniss des
 Torfschweins,’ 1868. This author believes that the Torfschwein is
 descended from a distinct species, the _S. sennariensis_ of Central
 Africa.

 [7] Stan. Julien quoted by de Blainville, ‘Ostéographie,’ p. 163.

 [8] Richardson, ‘Pigs, their Origin,’ etc., p. 26.

 [9] ‘Die Racen des Schweines’ s. 47, 64.

 [10] ‘Proc. Zoolog. Soc.,’ 1861, p. 263.

 [11] Sclater, in ‘Proc. Zoolog. Soc.,’ Feb. 26, 1861.

 [12] ‘Proc. Zoolog. Soc.,’ 1862, p. 13. The skull has since been
 described much more fully by Professor Lucae in a very interesting
 essay, ‘Der Schädel des Maskenschweines,’ 1870. He confirms the
 conclusion of von Nathusius on the relationship of this kind of pig.

 [13] ‘Journal of Voyages and Travels from 1821 to 1829,’ vol. i. p.
 300.

 [14] Rev. G. Low ‘Fauna Orcadensis,’ p. 10. _See also_ Dr. Hibbert’s
 account of the pig of the Shetland Islands.

 [15] ‘Die Racen des Schweines’ s. 70.

 [16] These woodcuts are copied from engravings given in Mr. S.
 Sidney’s excellent edition of ‘The Pig,’ by Youatt, 1860. _ See_ pp.
 1, 16, 19.

 [17] ‘Schweineschädel’ s. 74, 135.

 [18] Nathusius, ‘Die Racen des Schweines,’ s. 71.

 [19] ‘Die Racen des Schweines,’ s. 47. ‘Schweineschädel’ s. 104.
 Compare, also, the figures of the old Irish and the improved Irish
 breeds in Richardson on ‘The Pig,’ 1847.

 [20] Quoted by Isid. Geoffroy, ‘Hist. Nat. Gén.,’ tom. iii. p. 441.

 [21] S. Sidney, ‘The Pig,’ p. 61.

 [22] ‘Schweineschädel,’ s. 2, 20.

 [23] ‘Proc. Zoolog. Soc.,’ 1837, p. 23. I have not given the caudal
 vertebræ, as Mr. Eyton says some might possibly have been lost. I have
 added together the dorsal and lumbar vertebræ, owing to Prof. Owen’s
 remarks (‘Journal Linn. Soc.,’ vol. ii. p. 28) on the difference
 between dorsal and lumbar vertebræ depending only on the development
 of the ribs. Nevertheless the difference in the number of the ribs in
 pigs deserves notice. M. Sanson gives the number of lumbar vertebræ in
 various pigs; ‘Comptes Rendus,’ lxiii. p. 843.

 [24] ‘Edinburgh New Philosoph. Journal,’ April, 1863. _See also_ De
 Blainville’s ‘Ostéographie,’ p. 128, for various authorities on this
 subject.

 [25] Eudes-Deslongchamps, ‘Mémoires de la Soc. Linn. de Normandie,’
 vol. vii., 1842, p. 41. Richardson, ‘Pigs, their Origin, etc.,’ 1847,
 p. 30. Nathusius, ‘Die Racen des Schweines,’ 1863, s. 54.

 [26] D. Johnson’s ‘Sketches of Indian Field Sports,’ p. 272. Mr.
 Crawfurd informs me that the same fact holds good with the wild pigs
 of the Malay peninsula.

 [27] For Turkish pigs _see_ Desmarest, ‘Mammalogie,’ 1820, p. 391. For
 those of Westphalia _see_ Richardson’s ‘Pigs, their Origin, etc.,’
 1847, p. 41.

 [28] With respect to the several foregoing and following statements on
 feral pigs, _see_ Roulin, in ‘Mém. présentés par divers Savans a
 l’Acad.,’ etc., Paris, tom. vi. 1835, p. 326. It should be observed
 that his account does not apply to truly feral pigs; but to pigs long
 introduced into the country and living in a half-wild state. For the
 truly feral pigs of Jamaica, _see_ Gosse’s ‘Sojourn in Jamaica,’ 1851,
 p. 386; and Col. Hamilton Smith, in ‘Nat. Library,’ vol. ix. p. 93.
 With respect to Africa _see_ Livingstone’s ‘Expedition to the
 Zambesi,’ 1865, p. 153. The most precise statement with respect to the
 tusks of the West Indian feral boars is by P. Labat (quoted by
 Roulin); but this author attributes the state of these pigs to descent
 from a domestic stock which he saw in Spain. Admiral Sulivan, R.N.,
 had ample opportunities of observing the wild pigs on Eagle Islet in
 the Falklands; and he informs me that they resembled wild boars with
 bristly ridged backs and large tusks. The pigs which have run wild in
 the province of Buenos Ayres (Rengger ‘Säugethiere,’ s. 331) have not
 reverted to the wild type. De Blainville (‘Ostéographie,’ p. 132)
 refers to two skulls of domestic pigs sent from Patagonia by Al.
 d’Orbigny, and he states that they have the occipital elevation of the
 wild European boar, but that the head altogether is “plus courte et
 plus ramassée.” He refers, also, to the skin of a feral pig from North
 America, and says “il ressemble tout à fait à un petit sanglier, mais
 il est presque tout noir, et peut-être un peu plus ramassé dans ses
 formes.”

 [29] Gosse’s ‘Jamaica,’ p. 386, with a quotation from Williamson’s
 ‘Oriental Field Sports.’ Also Col. Hamilton Smith, in ‘Naturalist
 Library,’ vol. ix. p. 94.

 [30] S. Sidney’s edition of ‘Youatt on the Pig,’ 1860, pp. 7, 26, 27,
 29, 30.

 [31] ‘Schweineschädel’ s. 140.

 [32] ‘Die Fauna der Pfahlbauten,’ 1861, s. 109, 149, 222. _See also_
 Geoffroy Saint-Hilaire in ‘Mém. du Mus. d’Hist. Nat.,’ tom. x. p. 172;
 and his son Isidore in ‘Hist. Nat. Gen.’ tom. iii. p. 69. Vasey, in
 his ‘Delineations of the Ox Tribe,’ 1851, p. 127, says the zebu has
 four, and common ox five, sacral vertebræ. Mr. Hodgson found the ribs
 either thirteen or fourteen in number; _see_ a note in ‘Indian Field,’
 1858, p. 62.

 [33] ‘The Indian Field,’ 1858, p. 74, where Mr. Blyth gives his
 authorities with respect to the feral humped cattle. Pickering, also,
 in his ‘Races of Man,’ 1850, p. 274, notices the peculiar grunt-like
 character of the voice of the humped cattle.

 [34] Mr. H. E. Marquand, in ‘The Times,’ June 23rd, 1856.

 [35] Vasey, ‘Delineations of the Ox-Tribe,’ p. 124. Brace’s ‘Hungary,’
 1851, p. 94. The Hungarian cattle descend, according to Rütimeyer
 ‘Zahmen Europ. Rindes,’ 1866, s. 13 from _Bos primigenius._

 [36] Moll and Gayot, ‘La Connaissance Gén. du Bœuf,’ Paris, 1860. Fig.
 82 is that of the Podolian breed.

 [37] A translation appeared in three parts in the ‘Annals and Mag. of
 Nat. Hist.,’ 2nd series, vol. iv., 1849.

 [38] _See also_ Rütimeyer’s ‘Beiträge pal. Gesch. der Wiederkäuer
 Basel,’ 1865, s. 54.

 [39] Pictet ‘Paléontologie,’ tom. i. p. 365 (2nd edit.). With respect
 to _B. trochoceros, see_ Rütimeyer ‘Zahmen Europ. Rindes,’ 1866, s.
 26.

 [40] W. Boyd Dawkins on the British Fossil Oxen, ‘Journal of the
 Geolog. Soc.,’ Aug. 1867, p. 182. Also ‘Proc. Phil. Soc. of
 Manchester,’ Nov. 14th, 1871, and ‘Cave Hunting,’ 1875, p. 27, 138.

 [41] ‘British Pleistocene Mammalia,’ by W. B. Dawkins and W. A.
 Sandford, 1866, p. 15.

 [42] W. R. Wilde, ‘An Essay on the Animal Remains, etc. Royal Irish
 Academy,’ 1860, p. 29. Also ‘Proc. of R. Irish Academy,’ 1858, p. 48.

 [43] ‘Lecture: Royal Institution of G. Britain,’ May 2nd, 1856, p. 4.
 ‘British Fossil Mammals,’ p. 513.

 [44] Nilsson, in ‘Annals and Mag. of Nat. Hist.,’ 1849, vol. iv. p.
 354.

 [45] _See_ W. R. Wilde, ut supra; and Mr. Blyth, in ‘Proc. Irish
 Academy,’ March 5th, 1864.

 [46] Laing’s ‘Tour in Norway,’ p. 110.

 [47] Isid. Geoffroy Saint-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. 96.

 [48] Idem, tom. iii. pp. 82, 91.

 [49] ‘Quadrupèdes du Paraguay,’ tom. ii. p. 360.

 [50] Walther ‘Das Rindvieh,’ 1817, s. 30.

 [51] I am much indebted to the present Earl of Tankerville for
 information about his wild cattle; and for the skull which was sent to
 Prof. Rütimeyer. The fullest account of the Chillingham cattle is
 given by Mr. Hindmarsh, together with a letter by the late Lord
 Tankerville, in ‘Annals and Mag. of Nat. Hist.,’ vol. ii., 1839, p.
 274. _See_ Bewick, ‘Quadrupeds,’ 2nd edit., 1791, p. 35, note. With
 respect to those of the Duke of Queensberry, _see_ Pennant’s ‘Tour in
 Scotland,’ p. 109. For those of Chartley, _see_ Low’s ‘Domesticated
 Animals of Britain,’ 1845, p. 238. For those of Gisburne, _see_ Bewick
 ‘Quadrupeds,’ and ‘Encyclop. of Rural Sports,’ p. 101.

 [52] Boethius was born in 1470; ‘Annals and Mag. of Nat. Hist.,’ vol.
 ii., 1839, p. 281; and vol. iv., 1849, p. 424.

 [53] n’Youatt on Cattle,’ 1834, p. 48: _See also_ p. 242, on
 short-horn cattle. Bell, in his ‘British Quadrupeds,’ p. 423, states
 that, after long attending to the subject, he has found that white
 cattle invariably have coloured ears.ote

 [54] Azara, ‘Quadrupèdes du Paraguay,’ tom. ii. p. 361. Azara quotes
 Buffon for the feral cattle of Africa. For Texas _ see_ ‘Times,’ Feb.
 18th, 1846.

 [55] Anson’s Voyage. _See_ Kerr and Porter’s ‘Collection,’ vol. xii.
 p. 103.

 [56] _See also_ Mr. Mackinnon’s pamphlet on the Falkland Islands, p.
 24.

 [57] ‘The Age of the Ox, Sheep, Pig,’ etc., by Prof. James Simonds,
 published by order of the Royal Agricult. Soc.

 [58] ‘Ann. Agricult. France,’ April, 1837, as quoted in ‘The
 Veterinary,’ vol. xii. p. 725. I quote Tessier’s observations from
 ‘Youatt on Cattle,’ p. 527.

 [59] ‘The Veterinary,’ vol. viii. p. 681 and vol. x. p. 268. Low’s
 ‘Domest. Animals, etc.’ p. 297.

 [60] Mr. Ogleby in ‘Proc. Zoolog. Soc.,’ 1836, p. 138, and 1840, p. 4.
 Quatrefages quotes Philippi (‘Revue des Cours Scientifiques,’ Feb. 12,
 1688, p. 657), that the cattle of Piacentino have thirteen dorsal
 vertebræ and ribs in the place of the ordinary number of twelve.

 [61] Leguat’s Voyage, quoted by Vasey in his ‘Delineations of the
 Ox-tribe,’ p. 132.

 [62] ‘Travels in South Africa,’ pp. 317, 336.

 [63] ‘Mem. de l’Institut présent. par divers Savans,’ tom. vi., 1835,
 p. 333. For Brazil, _see_ ‘Comptes Rendus,’ June 15, 1846. _See_ Azara
 ‘Quadrupèdes du Paraguay,’ tom. ii. pp. 359, 361.

 [64] ‘Schweineschädel,’ 1864, s. 104. Nathusius states that the form
 of skull characteristic in the niata cattle occasionally appears in
 European cattle; but he is mistaken, as we shall hereafter see, in
 supposing that these cattle do not form a distinct race. Prof. Wyman,
 of Cambridge, United States, informs me that the common cod-fish
 presents a similar monstrosity, called by the fishermen “bull-dog
 cod.” Prof. Wyman also concluded, after making numerous inquiries in
 La Plata, that the niata cattle transmit their peculiarities or form a
 race.

 [65] ‘Ueber Art des zahmen Europ. Rindes,’ 1866, s. 28.

 [66] ‘Descriptive Cat. of Ost. Collect. of College of Surgeons,’ 1853,
 p. 624. Vasey in his ‘Delineations of the Ox-tribe’ has given a figure
 of this skull; and I sent a photograph of it to Prof. Rütimeyer.

 [67] Loudon’s ‘Magazine of Nat. Hist.,’ vol. i. 1829, p. 113. Separate
 figures are given of the animal, its hoofs, eye, and dewlap.

 [68] Low, ‘Domesticated Animals of the British Isles,’ p. 264.

 [69] ‘Mém. de l’Institut présent. Par divers Savans,’ tom. vi., 1835,
 p. 332.

 [70] Idem, pp. 304, 368, etc.

 [71] ‘Youatt on Cattle,’ p. 193. A full account of this bull is taken
 from Marshall.

 [72] ‘Youatt on Cattle,’ p. 116. Lord Spencer has written on this same
 subject.

 [73] Blyth, on the genus Ovis, in ‘Annals and Mag. of Nat. History,’
 vol. vii., 1841, p. 261. With respect to the parentage of the breeds
 _see_ Mr. Blyth’s excellent articles in ‘Land and Water,’ 1867, pp.
 134, 156. Gervais, ‘Hist. Nat. des Mammifères,’ 1855, tom. ii. p. 191.

 [74] Dr. L. Fitzinger, ‘Ueber die Racen des Zahmen Schafes,’ 1860, s.
 86.

 [75] J. Anderson, ‘Recreations in Agriculture and Natural History,’
 vol. ii. p. 264.

 [76] ‘Pfahlbauten’ s. 127, 193.

 [77] ‘Youatt on Sheep,’ p. 120.

 [78] ‘Journal of the Asiatic Soc. of Bengal,’ vol.xvi. pp. 1007, 1016.

 [79] ‘Youatt on Sheep,’ pp. 142-169.

 [80] ‘Journal Asiat. Soc. of Bengal,’ vol. xvi., 1847, p. 1015.

 [81] ‘Hist. Nat. Gén.,’ tom. iii. p. 435.

 [82] ‘Youatt on Sheep,’ p. 138.

 [83] ‘Journal Asiat. Soc. of Bengal,’ vol. xvi., 1847, pp. 1015, 1016.

 [84] ‘Racen des Zahmen Schafes,’ s. 77.

 [85] ‘Rural Economy of Norfolk,’ vol. ii. p. 136.

 [86] ‘Youatt on Sheep,’ p. 312. On same subject, _see_ excellent
 remarks in ‘Gardener’s Chronicle,’ 1858, p. 868. For experiments in
 crossing Cheviot sheep with Leicesters _see_ Youatt, p. 325.

 [87] ‘Youatt on Sheep,’ note, p. 491.

 [88] M. Malingié-Nouel, ‘Journal R. Agricult. Soc.,’ vol. xiv. 1853,
 p. 214. Translated and therefore approved by a great authority, Mr.
 Pusey.

 [89] ‘The Veterinary,’ vol. x. p. 217.

 [90] A translation of his paper is given in ‘Bull. Soc. Imp.
 d’Acclimat.,’ tom. ix., 1862, p. 723.

 [91] Erman’s ‘Travels in Siberia,’ (Eng. trans.) vol. i. p. 228. For
 Pallas on the fat-tailed sheep I quote from Anderson’s account of the
 ‘Sheep of Russia,’ 1794, p. 34. With respect to the Crimean sheep
 _see_ Pallas’ ‘Travels’ (Eng. trans.) vol. ii. p. 454. For the
 Karakool sheep _see_ Burnes’ ‘Travels in Bokhara,’ vol. iii. p. 151.

 [92] _See_ Report of the Directors of the Sierra Leone Company, as
 quoted in White’s ‘Gradation of Man,’ p. 95. With respect to the
 change which sheep undergo in the West Indies _ see also_ Dr. Davy, in
 ‘Edin. New. Phil. Journal,’ Jan. 1852. For the statement made by
 Roulin, _see_ ‘Mém. de l’Institut présent. par divers Savans,’ tom.
 vi., 1835, p. 347.

 [93] ‘Youatt on Sheep,’ p. 69, where Lord Somerville is quoted. _See_
 p. 117 on the presence of wool under the hair. With respect to the
 fleeces of Australian sheep, p. 185. On selection counteracting any
 tendency to change, _see_ pp. 70, 117, 120, 168.

 [94] Audubon and Bachman, ‘The Quadrupeds of North America,’ 1846,
 vol. v. p. 365.

 [95] ‘Journal of R. Agricult. Soc. of England,’ vol. xx., part ii., W.
 C. Spooner on cross-Breeding.

 [96] ‘Philosoph. Transactions,’ London, 1813, p. 88.

 [97] Isidore Geoffroy St. Hilaire, ‘Hist. Nat. Générale,’ tom. iii. p.
 87. Mr. Blyth, (‘Land and Water,’ 1867, p. 37) has arrived at a
 similar conclusion, but he thinks that certain Eastern races may
 perhaps be in part descended from the Asiatic markhor.

 [98] Rütimeyer ‘Pfahlbauten,’ s. 127.

 [99] Godron ‘De l’Espèce,’ tom. i. p. 402.

 [100] ‘Annals and Mag. of Nat. History,’ vol ii. (2nd series), 1848,
 p. 363.

 [101] ‘De l’Espèce,’ tom. i. p. 406. Mr. Clark also refers to
 differences in the shape of the mammæ. Godron states that in the
 Nubian race the scrotum is divided into two lobes; and Mr. Clark gives
 a ludicrous proof of this fact, for he saw in the Mauritius a male
 goat of the Muscat breed purchased at a high price for a female in
 full milk. These differences in the scrotum are probably not due to
 descent from distinct species: for Mr. Clark states that this part
 varies much in form.

 [102] Mr. Clark, ‘Annals and Mag. of Nat. Hist.,’ vol. ii. (2nd
 series), 1848, p. 361.

 [103] Desmarest, ‘Encyclop. Méthod. Mammalogie,’ p. 480.

 [104] ‘Journal of Asiatic Soc. of Bengal,’ vol. xvi., 1847, pp. 1020,
 1025.




CHAPTER IV. DOMESTIC RABBITS.

DOMESTIC RABBITS DESCENDED FROM THE COMMON WILD RABBIT—ANCIENT
DOMESTICATION—ANCIENT SELECTION—LARGE LOP-EARED RABBITS—VARIOUS
BREEDS—FLUCTUATING CHARACTERS—ORIGIN OF THE HIMALAYAN BREED—CURIOUS
CASE OF INHERITANCE—FERAL RABBITS IN JAMAICA AND THE FALKLAND
ISLANDS—PORTO SANTO FERAL RABBITS—OSTEOLOGICAL CHARACTERS—SKULL—SKULL
OF HALF-LOP RABBITS—VARIATIONS IN THE SKULL ANALOGOUS TO DIFFERENCES IN
DIFFERENT SPECIES OF HARES—VERtebræ—STERNUM—SCAPULA—EFFECTS OF USE AND
DISUSE ON THE PROPORTIONS OF THE LIMBS AND BODY—CAPACITY OF THE SKULL
AND REDUCED SIZE OF THE BRAIN—SUMMARY ON THE MODIFICATIONS OF
DOMESTICATED RABBITS.


    All naturalists, with, as far as I know, a single exception,
    believe that the several domestic breeds of the rabbit are
    descended from the common wild species; I shall therefore describe
    them more carefully than in the previous cases. Professor
    Gervais[1] states “that the true wild rabbit is smaller than the
    domestic; its proportions are not absolutely the same; its tail is
    smaller; its ears are shorter and more thickly clothed with hair;
    and these characters, without speaking of colour, are so many
    indications opposed to the opinion which unites these animals under
    the same specific denomination.” Few naturalists will agree with
    this author that such slight differences are sufficient to separate
    as distinct species the wild and domestic rabbit. How extraordinary
    it would be, if close confinement, perfect tameness, unnatural
    food, and careful breeding, all prolonged during many generations,
    had not produced at least some effect! The tame rabbit has been
    domesticated from an ancient period. Confucius ranges rabbits among
    animals worthy to be sacrificed to the gods, and, as he prescribes
    their multiplication, they were probably at this early period
    domesticated in China. They are mentioned by several of the
    classical writers. In 1631 Gervaise Markham writes, “You shall not,
    as in other cattell, looke to their shape, but to their richnesse,
    onely elect your buckes, the largest and goodliest conies you can
    get; and for the richnesse of the skin, that is accounted the
    richest which hath the equallest mixture of blacke and white haire
    together, yet the blacke rather shadowing the white; the furre
    should be thicke, deepe, smooth, and shining; ... they are of body
    much fatter and larger, and, when another skin is worth two or
    three pence, they are worth two shillings.” From this full
    description we see that silver-grey rabbits existed in England at
    this period; and what is far more important, we see that the
    breeding or selection of rabbits was then carefully attended to.
    Aldrovandi, in 1637, describes, on the authority of several old
    writers (as Scaliger, in 1557), rabbits of various colours, some
    “like a hare,” and he adds that P. Valerianus (who died a very old
    man in 1558) saw at Verona rabbits four times bigger than ours.[2]

    From the fact of the rabbit having been domesticated at an ancient
    period, we must look to the northern hemisphere of the Old World,
    and to the warmer temperate regions alone, for the aboriginal
    parent-form; for the rabbit cannot live without protection in
    countries as cold as Sweden, and, though it has run wild in the
    tropical island of Jamaica, it has never greatly multiplied there.
    It now exists, and has long existed, in the warmer temperate parts
    of Europe, for fossil remains have been found in several
    countries.[3] The domestic rabbit readily becomes feral in these
    same countries, and when variously coloured kinds are turned out
    they generally revert to the ordinary grey colour.[4] Wild rabbits,
    if taken young, can be domesticated, though the process is
    generally very troublesome.[5] The various domestic races are often
    crossed, and are believed to be quite fertile together, and a
    perfect gradation can be shown to exist from the largest domestic
    kinds, having enormously developed ears, to the common wild kind.
    The parent-form must have been a burrowing animal, a habit not
    common, as far as I can discover, to any other species in the large
    genus Lepus. Only one wild species is known with certainty to exist
    in Europe; but the rabbit (if it be a true rabbit) from Mount
    Sinai, and likewise that from Algeria, present slight differences;
    and these forms have been considered by some authors as
    specifically distinct.[6] But such slight differences would aid us
    little in explaining the more considerable differences
    characteristic of the several domestic races. If the latter are the
    descendants of two or more closely allied species, these, with the
    exception of the common rabbit, have been exterminated in a wild
    state; and this is very improbable, seeing with what pertinacity
    this animal holds its ground. From these several reasons we may
    infer with safety that all the domestic breeds are the descendants
    of the common wild species. But from what we hear of the marvellous
    success in France in rearing hybrids between the hare and
    rabbit,[7] it is possible, though not probable, from the great
    difficulty in making the first cross, that some of the larger
    races, which are coloured like the hare, may have been modified by
    crosses with this animal. Nevertheless, the chief differences in
    the skeletons of the several domestic breeds cannot, as we shall
    presently see, have been derived from a cross with the hare.

    There are many breeds which transmit their characters more or less
    truly. Every one has seen the enormous lop-eared rabbits exhibited
    at our shows; various allied sub-breeds are reared on the
    Continent, such as the so-called Andalusian, which is said to have
    a large head with a round forehead, and to attain a greater size
    than any other kind; another large Paris breed is named the
    Rouennais, and has a square head; the so-called Patagonian rabbit
    has remarkably short ears and a large round head. Although I have
    not seen all these breeds, I feel some doubt about there being any
    marked difference in the shape of their skulls.[8] English
    lop-eared rabbits often weigh 8 pounds or 10 pounds, and one has
    been exhibited weighing 18 pounds; whereas a full-sized wild rabbit
    weighs only about 3-1/4 pounds. The head or skull in all the large
    lop-eared rabbits examined by me is much longer relatively to its
    breadth than in the wild rabbit. Many of them have loose transverse
    folds of skin or dewlaps beneath the throat, which can be pulled
    out so as to reach nearly to the ends of the jaws. Their ears are
    prodigiously developed, and hang down on each side of their faces.
    A rabbit was exhibited in 1867 with its two ears, measured from the
    tip of one to the tip of the other, 22 inches in length, and each
    ear 5-3/8 inches in breadth. In 1869 one was exhibited with ears,
    measured in the same manner, 23-1/8 in length and 5-1/2 in breadth;
    “thus exceeding any rabbit ever exhibited at a prize show.” In a
    common wild rabbit I found that the length of two ears, from tip to
    tip, was 7-5/8 inches, and the breadth only 1-7/8 inch. The weight
    of body in the larger rabbits, and the development of their ears,
    are the qualities which win prizes, and have been carefully
    selected.

    The hare-coloured, or, as it is sometimes called, the Belgian
    rabbit, differs in nothing except colour from the other large
    breeds; but Mr. J. Young, of Southampton, a great breeder of this
    kind, informs me that the females, in all the specimens examined by
    him, had only six mammæ and this certainly was the case with two
    females which came into my possession. Mr. B. P. Brent, however,
    assures me that the number is variable with other domestic rabbits.
    The common wild rabbit always has ten mammæ. The Angora rabbit is
    remarkable from the length and fineness of its fur, which even on
    the soles of the feet is of considerable length. This breed is the
    only one which differs in its mental qualities, for it is said to
    be much more sociable than other rabbits, and the male shows no
    wish to destroy its young.[9] Two live rabbits were brought to me
    from Moscow, of about the size of the wild species, but with long
    soft fur, different from that of the Angora. These Moscow rabbits
    had pink eyes and were snow-white, excepting the ears, two spots
    near the nose, the upper and under surface of the tail, and the
    hinder tarsi, which were blackish-brown. In short, they were
    coloured nearly like the so-called Himalayan rabbits, presently to
    be described, and differed from them only in the character of their
    fur. There are two other breeds which come true to colour, but
    differ in no other respect, namely silver-greys and chinchillas.
    Lastly, the Nicard or Dutch rabbit may be mentioned, which varies
    in colour, and is remarkable from its small size, some specimens
    weighing only 1-1/4 pounds; rabbits of this breed make excellent
    nurses for other and more delicate kinds.[10]

Illustration: Fig. 5—Half-lop Rabbit.

    Certain characters are remarkably fluctuating, or are very feebly
    transmitted by domestic rabbits: thus, one breeder tells me that
    with the smaller kinds he has hardly ever raised a whole litter of
    the same colour: with the large lop-eared breeds “it is
    impossible,” says a great judge,[11] “to breed true to colour, but
    by judicious crossing a great deal may be done towards it. The
    fancier should know how his does are bred, that is, the colour of
    their parents.” Nevertheless, certain colours, as we shall
    presently see, are transmitted truly. The dewlap is not strictly
    inherited. Lop-eared rabbits, with their ears hanging down flat on
    each side of the face, do not transmit this character at all truly.
    Mr. Delamer remarks that, “with fancy rabbits, when both the
    parents are perfectly formed, have model ears, and are handsomely
    marked, their progeny do not invariably turn out the same.” When
    one parent, or even both, are oar-laps, that is, have their ears
    sticking out at right angles, or when one parent or both are
    half-lops, that is, have only one ear dependent, there is nearly as
    good a chance of the progeny having both ears full-lop, as if both
    parents had been thus characterised. But I am informed, if both
    parents have upright ears, there is hardly a chance of a full-lop.
    In some half-lops the ear that hangs down is broader and longer
    than the upright ear;[12] so that we have the unusual case of a
    want of symmetry on the two sides. This difference in the position
    and size of the two ears probably indicates that the lopping
    results from the great length and weight of the ear, favoured no
    doubt by the weakness of the muscles consequent on disuse.
    Anderson[13] mentions a breed having only a single ear; and
    Professor Gervais another breed destitute of ears.

    We come now to the Himalayan breed, which is sometimes called
    Chinese, Polish, or Russian. These pretty rabbits are white, or
    occasionally yellow, excepting their ears, nose, feet, and the
    upper side of the tail, which are all brownish-black; but as they
    have red eyes, they may be considered as albinoes. I have received
    several accounts of their breeding perfectly true. From their
    symmetrical marks, they were at first ranked as specifically
    distinct, and were provisionally named _L. nigripes._[14] Some good
    observers thought that they could detect a difference in their
    habits, and stoutly maintained that they formed a new species. The
    origin of this breed is so curious, both in itself and as throwing
    some light on the complex laws of inheritance that it is worth
    giving in detail. But it is first necessary briefly to describe two
    other breeds: silver-greys or silver-sprigs generally have black
    heads and legs, and their fine grey fur is interspersed with
    numerous black and white long hairs. They breed perfectly true, and
    have long been kept in warrens. When they escape and cross with
    common rabbits, the product, as I hear from Mr. Wyrley Birch, of
    Wretham Hall, is not a mixture of the two colours, but about half
    take after the one parent, and the other half after the other
    parent. Secondly, chinchillas or tame silver-greys (I will use the
    former name) have short, paler, mouse or slate-coloured fur,
    interspersed with long, blackish, slate-coloured, and white
    hairs.[15] These rabbits breed perfectly true. A writer stated in
    1857[16] that he had produced Himalayan rabbits in the following
    manner. He had a breed of chinchillas which had been crossed with
    the common black rabbit, and their offspring were either blacks or
    chinchillas. These latter were again crossed with other chinchillas
    (which had also been crossed with silver-greys), and from this
    complicated cross Himalayan rabbits were raised. From these and
    other similar statements, Mr. Bartlett[17] was led to make a
    careful trial in the Zoological Gardens, and he found that by
    simply crossing silver-greys with chinchillas he could always
    produce some few Himalayans; and the latter, notwithstanding their
    sudden origin, if kept separate, bred perfectly true. But I have
    recently been assured the pure silver-greys of any sub-breed
    occasionally produce Himalayans.

    The Himalayans, when first born, are quite white, and are then true
    albinoes; but in the course of a few months they gradually assume
    their dark ears, nose, feet, and tail. Occasionally, however, as I
    am informed by Mr. W. A. Wooler and the Rev. W. D. Fox, the young
    are born of a very pale grey colour, and specimens of such fur were
    sent me by the former gentleman. The grey tint, however, disappears
    as the animal comes to maturity. So that with these Himalayans
    there is a tendency, strictly confined to early youth, to revert to
    the colour of the adult silver-grey parent-stock. Silver-greys and
    chinchillas, on the other hand, present a remarkable contrast with
    the Himalayans in their colour whilst quite young, for they are
    born perfectly black, but soon assume their characteristic grey or
    silver tints. The same thing occurs with grey horses, which, as
    long as they are foals, are generally of a nearly black colour, but
    soon become grey, and get whiter and whiter as they grow older.
    Hence the usual rule is that Himalayans are born white and
    afterwards become in certain parts of their bodies dark-coloured;
    whilst silver-greys are born black and afterwards become sprinkled
    with white. Exceptions, however, and of a directly opposite nature,
    occasionally occur in both cases. For young silver-greys are
    sometimes born in warrens, as I hear from Mr. W. Birch, of a
    cream-colour, but these young animals ultimately become black. The
    Himalayans, on the other hand, sometimes produce, as is stated by
    an experienced amateur,[18] a single black young one in a litter;
    and this, before two months elapse, becomes perfectly white.

To sum up the whole curious case: wild silver-greys may be considered
as black rabbits which become grey at an early period of life. When
they are crossed with common rabbits, the offspring are said not to
have blended colours, but to take after either parent; and in this
respect they resemble black and albino varieties of most quadrupeds,
which often transmit their colours in this same manner. When they are
crossed with chinchillas, that is, with a paler sub-variety, the young
are at first pure albinoes, but soon become dark-coloured in certain
parts of their bodies, and are then called Himalayans. The young
Himalayans, however, are sometimes at first either pale grey or
completely black, in either case changing after a time to white. In a
future chapter I shall advance a large body of facts showing that, when
two varieties are crossed both of which differ in colour from their
parent-stock, there is a strong tendency in the young to revert to the
aboriginal colour; and what is very remarkable, this reversion
occasionally supervenes, not before birth, but during the growth of the
animal. Hence, if it could be shown that silver-greys and chinchillas
were the offspring of a cross between a black and albino variety with
the colours intimately blended—a supposition in itself not improbable,
and supported by the circumstance of silver-greys in warrens sometimes
producing creamy-white young, which ultimately become black—then all
the above given paradoxical facts on the changes of colour in
silver-greys and in their descendants the Himalayans would come under
the law of reversion, supervening at different periods of growth and in
different degrees, either to the original black or to the original
albino parent-variety.

    It is, also, remarkable that Himalayans, though produced so
    suddenly; breed true. But as, whilst young, they are albinoes, the
    case falls under a very general rule; albinism being well known to
    be strongly inherited, for instance with white mice and many other
    quadrupeds, and even white flowers. But why, it may be asked, do
    the ears, tail, nose, and feet, and no other part of the body,
    revert to a black colour? This apparently depends on a law, which
    generally holds good, namely, that characters common to many
    species of a genus—and this, in fact, implies long inheritance from
    the ancient progenitor of the genus—are found to resist variation,
    or to reappear if lost, more persistently than the characters which
    are confined to the separate species. Now, in the genus Lepus, a
    large majority of the species have their ears and the upper surface
    of the tail tinted black; but the persistence of these marks is
    best seen in those species which in winter become white: thus, in
    Scotland the _L. variabilis_[19] in its winter dress has a shade of
    colour on its nose, and the tips of its ears are black: in the _L.
    tibetanus_ the ears are black, the upper surface of the tail
    greyish-black, and the soles of the feet brown: in _L. glacialis_
    the winter fur is pure white, except the soles of the feet and the
    points of the ears. Even in the variously-coloured fancy rabbits we
    may often observe a tendency in these same parts to be more darkly
    tinted than the rest of the body. Thus the several coloured marks
    on the Himalayan rabbits, as they grow old, are rendered
    intelligible. I may add a nearly analogous case: fancy rabbits very
    often have a white star on their foreheads; and the common English
    hare, whilst young, generally has, as I have myself observed, a
    similar white star on its forehead.

    When variously coloured rabbits are set free in Europe, and are
    thus placed under their natural conditions, they generally revert
    to the aboriginal grey colour; this may be in part due to the
    tendency in all crossed animals, as lately observed, to revert to
    their primordial state. But this tendency does not always prevail;
    thus silver-grey rabbits are kept in warrens, and remain true
    though living almost in a state of nature; but a warren must not be
    stocked with both silver-greys and common rabbits; otherwise “in a
    few years there will be none but common greys surviving.”[20] When
    rabbits run wild in foreign countries under new conditions of life,
    they by no means always revert to their aboriginal colour. In
    Jamaica the feral rabbits are described as having been
    “slate-coloured, deeply tinted with sprinklings of white on the
    neck, on the shoulders, and on the back; softening off to
    blue-white under the breast and belly.”[21] But in this tropical
    island the conditions were not favourable to their increase, and
    they never spread widely, and are now extinct, as I hear from Mr.
    R. Hill, owing to a great fire which occurred in the woods. Rabbits
    during many years have run wild in the Falkland Islands; they are
    abundant in certain parts, but do not spread extensively. Most of
    them are of the common grey colour; a few, as I am informed by
    Admiral Sulivan, are hare-coloured, and many are black, often with
    nearly symmetrical white marks on their faces. Hence, M. Lesson
    described the black variety as a distinct species, under the name
    of _Lepus magellanicus,_ but this, as I have elsewhere shown, is an
    error.[22] Within recent times the sealers have stocked some of the
    small outlying islets in the Falkland group with rabbits; and on
    Pebble Islet, as I hear from Admiral Sulivan, a large proportion
    are hare-coloured, whereas on Rabbit Islet a large proportion are
    of a bluish colour, which is not elsewhere seen. How the rabbits
    were coloured which were turned out of these islets is not known.

    The rabbits which have become feral on the island of Porto Santo,
    near Madeira, deserve a fuller account. In 1418 or 1419, J.
    Gonzales Zarco[23] happened to have a female rabbit on board which
    had produced young during the voyage, and he turned them all out on
    the island. These animals soon increased so rapidly, that they
    became a nuisance, and actually caused the abandonment of the
    settlement. Thirty-seven years subsequently, Cada Mosto describes
    them as innumerable; nor is this surprising, as the island was not
    inhabited by any beast of prey or by any terrestrial mammal. We do
    not know the character of the mother-rabbit; but it was probably
    the common domesticated kind. The Spanish peninsula, whence Zarco
    sailed, is known to have abounded with the common wild species at
    the most remote historical period; and as these rabbits were taken
    on board for food, it is improbable that they should have been of
    any peculiar breed. That the breed was well domesticated is shown
    by the doe having littered during the voyage. Mr. Wollaston, at my
    request, brought home two of these feral rabbits in spirits of
    wine; and, subsequently, Mr. W. Haywood sent to me three more
    specimens in brine, and two alive. These seven specimens, though
    caught at different periods, closely resembled each other. They
    were full grown, as shown by the state of their bones. Although the
    conditions of life in Porto Santo are evidently highly favourable
    to rabbits, as proved by their extraordinarily rapid increase, yet
    they differ conspicuously in their small size from the wild English
    rabbit. Four English rabbits, measured from the incisors to the
    anus, varied between 17 and 17-3/4 inches in length; whilst two of
    the Porto Santo rabbits were only 14-1/2 and 15 inches in length.
    But the decrease in size is best shown by weight; four wild English
    rabbits averaged 3 pounds 5 ounces, whilst one of the Porto Santo
    rabbits, which had lived for four years in the Zoological Gardens,
    but had become thin, weighed only 1 pound 9 ounces. A fairer test
    is afforded by the comparison of the well-cleaned limb-bones of a
    Porto Santo rabbit killed on the island with the same bones of a
    wild English rabbit of average size, and they differed in the
    proportion of rather less than five to nine. So that the Porto
    Santo rabbits have decreased nearly three inches in length, and
    almost half in weight of body.[24] The head has not decreased in
    length proportionally with the body; and the capacity of the brain
    case is, as we shall hereafter see, singularly variable. I prepared
    four skulls, and these resembled each other more closely than do
    generally the skulls of wild English rabbits; but the only
    difference in structure which they presented was that the
    supra-orbital processes of the frontal bones were narrower.

In colour the Porto Santo rabbit differs considerably from the common
rabbit; the upper surface is redder, and is rarely interspersed with
any black or black-tipped hairs. The throat and certain parts of the
under surface, instead of being pure white, are generally pale grey or
leaden colour. But the most remarkable difference is in the ears and
tail; I have examined many fresh English rabbits, and the large
collection of skins in the British Museum from various countries, and
all have the upper surface of the tail and the tips of the ears clothed
with blackish-grey fur; and this is given in most works as one of the
specific characters of the rabbit. Now in the seven Porto Santo rabbits
the upper surface of the tail was reddish-brown, and the tips of the
ears had no trace of the black edging. But here we meet with a singular
circumstance: in June, 1861 I examined two of these rabbits recently
sent to the Zoological Gardens, and their tails and ears were coloured
as just described; but when one of their dead bodies was sent to me in
February, 1865, the ears were plainly edged, and the upper surface of
the tail was covered with blackish-grey fur, and the whole body was
much less red; so that under the English climate this individual rabbit
had recovered the proper colour of its fur in rather less than four
years!

The two little Porto Santo rabbits, whilst alive in the Zoological
Gardens, had a remarkably different appearance from the common kind.
They were extraordinarily wild and active, so that many persons
exclaimed on seeing them that they were more like large rats than
rabbits. They were nocturnal to an unusual degree in their habits, and
their wildness was never in the least subdued; so that the
superintendent, Mr. Bartlett, assured me that he had never had a wilder
animal under his charge. This is a singular fact, considering that they
are descended from a domesticated breed. I was so much surprised at it,
that I requested Mr. Haywood to make inquiries on the spot, whether
they were much hunted by the inhabitants, or persecuted by hawks, or
cats, or other animals; but this is not the case, and no cause can be
assigned for their wildness. They live both on the central, higher
rocky land and near the sea-cliffs, and, from being exceedingly shy and
timid, seldom appear in the lower and cultivated districts. They are
said to produce from four to six young at a birth, and their breeding
season is in July and August. Lastly, and this is a highly remarkable
fact, Mr. Bartlett could never succeed in getting these two rabbits,
which were both males, to associate or breed with the females of
several breeds which were repeatedly placed with them.

If the history of these Porto Santo rabbits had not been known, most
naturalists, on observing their much reduced size, their colour,
reddish above and grey beneath, their tails and ears not tipped with
black, would have ranked them as a distinct species. They would have
been strongly confirmed in this view by seeing them alive in the
Zoological Gardens, and hearing that they refused to couple with other
rabbits. Yet this rabbit, which there can be little doubt would thus
have been ranked as a distinct species, as certainly originated since
the year 1420. Finally, from the three cases of the rabbits which have
run wild in Porto Santo, Jamaica, and the Falkland Islands, we see that
these animals do not, under new conditions of life, revert to or retain
their aboriginal character, as is so generally asserted to be the case
by most authors.

_Osteological Characters._

When we remember, on the one hand, how frequently it is stated that
important parts of the structure never vary; and, on the other hand, on
what small differences in the skeleton fossil species have often been
founded, the variability of the skull and of some other bones in the
domesticated rabbit well deserves attention. It must not be supposed
that the more important differences immediately to be described
strictly characterise any one breed; all that can be said is, that they
are generally present in certain breeds. We should bear in mind that
selection has not been applied to fix any character in the skeleton,
and that the animals have not had to support themselves under uniform
habits of life. We cannot account for most of the differences in the
skeleton; but we shall see that the increased size of the body, due to
careful nurture and continued selection, has affected the head in a
particular manner. Even the elongation and lopping of the ears have
influenced in a small degree the form of the whole skull. The want of
exercise has apparently modified the proportional length of the limbs
in comparison with that of the body.

As a standard of comparison, I prepared skeletons of two wild rabbits
from Kent, one from the Shetland Islands, and one from Antrim in
Ireland. As all the bones in these four specimens from such distant
localities closely resembled each other, presenting scarcely any
appreciable difference, it may be concluded that the bones of the wild
rabbit are generally uniform in character.

_Skull._—I have carefully examined skulls of ten large lop-eared
rabbits, and of five common domestic rabbits, which latter differ from
the lop-eared only in not having such large bodies or ears, yet both
larger than in the wild rabbit. First for the ten lop-eared rabbits: in
all these the skull is remarkably elongated in comparison with its
breadth. In a wild rabbit the length was 3·15 inches, in a large fancy
rabbit 4·3; whilst the breadth of the cranium enclosing the brain was
in both almost exactly the same. Even by taking as the standard of
comparison the widest part of the zygomatic arch, the skulls of the
lop-eared are proportionally to their breadth three-quarters of an inch
too long. The depth of the head has increased almost in the same
proportion with the length; it is the breadth alone which has not
increased. The parietal and occipital bones enclosing the brain are
less arched, both in a longitudinal and transverse line, than in the
wild rabbit, so that the shape of the cranium is somewhat different.
The surface is rougher, less cleanly sculptured, and the lines of
sutures are more prominent.

Although the skulls of the large lop-eared rabbits in comparison with
those of the wild rabbit are much elongated relatively to their
breadth, yet, relatively to the size of body, they are far from
elongated. The lop-eared rabbits which I examined were, though not fat,
more than twice as heavy as the wild specimens; but the skull was very
far from being twice as long. Even if we take the fairer standard of
the length of body, from the nose to the anus, the skull is not on an
average as long as it ought to be by a third of an inch. In the small
feral Porto Santo rabbit, on the other hand, the head relatively to the
length of body is about a quarter of an inch too long.

This elongation of the skull relatively to its breadth, I find a
universal character, not only with the large lop-eared rabbits, but in
all the artificial breeds; as is well seen in the skull of the Angora.
I was at first much surprised at the fact, and could not imagine why
domestication could produce this uniform result; but the explanation
seems to lie in the circumstance that during a number of generations
the artificial races have been closely confined, and have had little
occasion to exert either their senses, or intellect, or voluntary
muscles; consequently the brain, as we shall presently more fully see,
has not increased relatively with the size of body. As the brain has
not increased, the bony case enclosing it has not increased, and this
has evidently affected through correlation the breadth of the entire
skull from end to end.

Illustration: Fig. 6—Skull of Wild Rabbit. Fig. 7—Skull of large
Lop-eared Rabbit.

Illustration: Fig. 8—Part of Zygomatic Arch.

    In all the skulls of the large lop-eared rabbits, the supra-orbital
    plates or processes of the frontal bones are much broader than in
    the wild rabbit, and they generally project more upwards. In the
    zygomatic arch the posterior or projecting point of the malar-bone
    is broader and blunter; and in the specimen, fig. 8, it is so in a
    remarkable degree. This point approaches nearer to the auditory
    meatus than in the wild rabbit, as may be best seen in fig. 8; but
    this circumstance mainly depends on the changed direction of the
    meatus. The inter-parietal bone (see fig. 9) differs much in shape
    in the several skulls; generally it is more oval, that is more
    extended in the line of the longitudinal axis of the skull, than in
    the wild rabbit. The posterior margin of “the square raised
    platform”[25] of the occiput, instead of being truncated, or
    projecting slightly as in the wild rabbit, is in most lop-eared
    rabbits pointed, as in fig. 9, C. The paramastoids relatively to
    the size of the skull are generally much thicker than in the wild
    rabbit.

Illustration: Fig. 9—Posterior end of skull of Rabbits.

Illustration: Fig. 10—Occipital Foramen of Rabbits.

The occipital foramen (fig. 10) presents some remarkable differences:
in the wild rabbit, the lower edge between the condyles is considerably
and almost angularly hollowed out, and the upper edge is deeply and
squarely notched; hence the longitudinal axis exceeds the transverse
axis. In the skulls of the lop-eared rabbits the transverse axis
exceeds the longitudinal; for in none of these skulls was the lower
edge between the condyles so deeply hollowed out; in five of them there
was no upper square notch, in three there was a trace of the notch, and
in two alone it was well developed. These differences in the shape of
the foramen are remarkable, considering that it gives passage to so
important a structure as the spinal marrow, though apparently the
outline of the latter is not affected by the shape of the passage.

In all the skulls of the large lop-eared rabbits, the bony auditory
meatus is conspicuously larger than in the wild rabbit. In a skull 4·3
inches in length, and which barely exceeded in breadth the skull of a
wild rabbit (which was 3·15 inches in length), the longer diameter of
the meatus was exactly twice as great. The orifice is more compressed,
and its margin on the side nearest the skull stands up higher than the
outer side. The whole meatus is directed more forwards. As in breeding
lop-eared rabbits the length of the ears, and their consequent lopping
and lying flat on the face, are the chief points of excellence, there
can hardly be a doubt that the great change in the size, form, and
direction of the bony meatus, relatively to this same part in the wild
rabbit, is due to the continued selection of individuals having larger
and larger ears. The influence of the external ear on the bony meatus
is well shown in the skulls (I have examined three) of half-lops (see
fig. 5), in which one ear stands upright, and the other and longer ear
hangs down; for in these skulls there was a plain difference in the
form and direction of the bony meatus on the two sides. But it is a
much more interesting fact, that the changed direction and increased
size of the bony meatus have slightly affected on the same side the
structure of the whole skull. I here give a drawing (fig. 11) of the
skull of a half-lop; and it may be observed that the suture between the
parietal and frontal bones does not run strictly at right angles to the
longitudinal axis of the skull; the left frontal bone projects beyond
the right one; both the posterior and anterior margins of the left
zygomatic arch on the side of the lopping ear stand a little in advance
of the corresponding bones on the opposite side. Even the lower jaw is
affected, and the condyles are not quite symmetrical, that on the left
standing a little in advance of that on the right. This seems to me a
remarkable case of correlation of growth. Who would have surmised that
by keeping an animal during many generations under confinement, and so
leading to the disuse of the muscles of the ears, and by continually
selecting individuals with the longest and largest ears, he would thus
indirectly have affected almost every suture in the skull and the form
of the lower jaw!

Illustration: Fig. 11—Skull of Half-lop Rabbit.

In the large lop-eared rabbits the only difference in the lower jaw, in
comparison with that of the wild rabbit, is that the posterior margin
of the ascending ramus is broader and more inflected. The teeth in
neither jaw present any difference, except that the small incisors,
beneath the large ones, are proportionately a little longer. The molar
teeth have increased in size proportionately with the increased width
of the skull, measured across the zygomatic arch, and not
proportionally with its increased length. The inner line of the sockets
of the molar teeth in the upper jaw of the wild rabbit forms a
perfectly straight line; but in some of the largest skulls of the
lop-eared this line was plainly bowed inwards. In one specimen there
was an additional molar tooth on each side of the upper jaw, between
the molars and premolars; but these two teeth did not correspond in
size; and as no rodent has seven molars, this is merely a monstrosity,
though a curious one.

The five other skulls of common domestic rabbits, some of which
approach in size the above-described largest skulls, whilst the others
exceed but little those of the wild rabbit, are only worth notice as
presenting a perfect gradation in all the above-specified differences
between the skulls of the largest lop-eared and wild rabbits. In all,
however, the supra-orbital plates are rather larger, and in all the
auditory meatus is larger, in conformity with the increased size of the
external ears, than in the wild rabbit. The lower notch in the
occipital foramen in some was not so deep as in the wild rabbit, but in
all five skulls the upper notch was well developed.

The skull of the _Angora_ rabbit, like the latter five skulls, is
intermediate in general proportions, and in most other characters,
between those of the largest lop-eared and wild rabbits. It presents
only one singular character: though considerably longer than the skull
of the wild rabbit, the breadth measured within the posterior
supra-orbital fissures is nearly a third less than in the wild. The
skulls of the _silver-grey,_ and _chinchilla_ and _Himalayan_ rabbits
are more elongated than in the wild, with broader supra-orbital plates,
but differ little in any other respect, excepting that the upper and
lower notches of the occipital foramen are not so deep or so well
developed. The skull of the _Moscow rabbit_ scarcely differs at all
from that of the wild rabbit. In the Porto Santo feral rabbits the
supra-orbital plates are generally narrower and more pointed than in
our wild rabbits.

As some of the largest lop-eared rabbits of which I prepared skeletons
were coloured almost like hares, and as these latter animals and
rabbits have, as it is affirmed, been recently crossed in France, it
might be thought that some of the above-described characters had been
derived from a cross at a remote period with the hare. Consequently I
examined skulls of the hare, but no light could thus be thrown on the
peculiarities of the skulls of the larger rabbits. It is, however, an
interesting fact, as illustrating the law that varieties of one species
often assume the characters of other species of the same genus, that I
found, on comparing the skulls of ten species of hares in the British
Museum, that they differed from each other chiefly in the very same
points in which domestic rabbits vary,—namely, in general proportions,
in the form and size of the supra-orbital plates, in the form of the
free end of the malar bone, and in the line of suture separating the
occipital and frontal bones. Moreover two eminently variable characters
in the domestic rabbit, namely, the outline of the occipital foramen
and the shape of the “raised platform” of the occiput, were likewise
variable in two instances in the same species of hare.

_Vertebræ._—The number is uniform in all the skeletons which I have
examined, with two exceptions, namely, in one of the small feral Porto
Santo rabbits and in one of the largest lop-eared kinds; both of these
had as usual seven cervical, twelve dorsal with ribs, but, instead of
seven lumbar, both had eight lumbar vertebræ. This is remarkable, as
Gervais gives seven as the number for the whole genus Lepus. The caudal
vertebræ apparently differ by two or three, but I did not attend to
them, and they are difficult to count with certainty.

Illustration: Fig. 12—Atlas Vertebræ of Rabbits.

In the first cervical vertebra, or atlas, the anterior margin of the
neural arch varies a little in wild specimens, being either nearly
smooth, or furnished with a small supra-median atlantoid process; I
have figured a specimen with the largest process (_a_) which I have
seen; but it will be observed how inferior this is in size and
different in shape to that in a large lop-eared rabbit. In the latter,
the infra-median process (_b_) is also proportionally much thicker and
longer. The alæ are a little squarer in outline.

Illustration: Fig. 13—Third Cervical Vertebræ, of natural size, of—A.
Wild Rabbit; B. Hare-coloured, large, Lop-eared Rabbit.

_Third cervical vertebra._—In the wild rabbit (fig. 13, A _a_) this
vertebra, viewed on the inferior surface, has a transverse process,
which is directed obliquely backwards, and consists of a single pointed
bar; in the fourth vertebra this process is slightly forked in the
middle. In the large lop-eared rabbits this process (B _ a_) is forked
in the third vertebra, as in the fourth of the wild rabbit. But the
third cervical vertebræ of the wild and lop-eared (A _b,_ B _b_)
rabbits differ more conspicuously when their anterior articular
surfaces are compared; for the extremities of the antero-dorsal
processes in the wild rabbit are simply rounded, whilst in the
lop-eared they are trifid, with a deep central pit. The canal for the
spinal marrow in the lop-eared (B _b_) is more elongated in a
transverse direction than in the wild rabbit; and the passages for the
arteries are of a slightly different shape. These several differences
in this vertebra seem to me well deserving attention.

_First dorsal vertebra._—Its neural spine varies in length in the wild
rabbit; being sometimes very short, but generally more than half as
long as that of the second dorsal; but I have seen it in two large
lop-eared rabbits three-fourths of the length of that of the second
dorsal vertebra.

Illustration: Fig. 14—Dorsal Vertebræ, from sixth to tenth inclusive,
of natural size, viewed laterally. A. Wild Rabbit. B. Large,
Hare-coloured, so-called Spanish Rabbit.

    _Ninth and tenth dorsal vertebræ._—In the wild rabbit the neural
    spine of the ninth vertebra is just perceptibly thicker than that
    of the eighth; and the neural spine of the tenth is plainly thicker
    and shorter than those of all the anterior vertebræ. In the large
    lop-eared rabbits the neural spines of the tenth, ninth, and eighth
    vertebræ, and even in a slight degree that of the seventh, are very
    much thicker, and of somewhat different shape, in comparison with
    those of the wild rabbit. So that this part of the vertebral column
    differs considerably in appearance from the same part in the wild
    rabbit, and closely resembles in an interesting manner these same
    vertebræ in some species of hares. In the Angora, Chinchilla, and
    Himalayan rabbits, the neural spines of the eighth and ninth
    vertebræ are in a slight degree thicker than in the wild. On the
    other hand, in one of the feral Porto Santo rabbits, which in most
    of its characters deviates from the common wild rabbit, in a
    direction exactly opposite to that assumed by the large lop-eared
    rabbits, the neural spines of the ninth and tenth vertebræ were not
    at all larger than those of the several anterior vertebra. In this
    same Porto Santo specimen there was no trace in the ninth vertebra
    of the anterior lateral processes (see fig. 14), which are plainly
    developed in all British wild rabbits, and still more plainly
    developed in the large lop-eared rabbits. In a half-wild rabbit
    from Sandon Park,[26] a haemal spine was moderately well developed
    on the under side of the twelfth dorsal vertebra, and I have seen
    this in no other specimen.

_Lumbar vertebræ._—I have stated that in two cases there were eight
instead of seven lumbar vertebræ. The third lumbar vertebræ in one
skeleton of a wild British rabbit, and in one of the Porto Santo feral
rabbits, had a haemal spine; whilst in four skeletons of large
lop-eared rabbits, and in the Himalayan rabbit, this same vertebra had
a well developed hæmal spine.

Illustration: Fig. 15—Terminal bone of Sternum of Rabbits.

_Pelvis._—In four wild specimens this bone was almost absolutely
identical in shape; but in several domesticated breeds shades of
differences could be distinguished. In the large lop-eared rabbits, the
whole upper part of the ilium is straighter, or less splayed outwards,
than in the wild rabbit; and the tuberosity on the inner lip of the
anterior and upper part of the ilium is proportionally more prominent.

_Sternum._—The posterior end of the posterior sternal bone in the wild
rabbit (fig. 15, A) is thin and slightly enlarged; in some of the large
lop-eared rabbits (B) it is much more enlarged towards the extremity;
whilst in other specimens (C) it keeps nearly of the same breadth from
end to end, but is much thicker at the extremity.

Illustration: Fig. 16—Acromion of Scapula, of natural size. A. Wild
Rabbit. B, C, D, Large, Lop-eared Rabbits.

_Scapula._—The acromion sends out a rectangular bar, ending in an
oblique knob, which latter in the wild rabbit (fig. 16, A) varies a
little in shape and size, as does the apex of the acromion in
sharpness, and the part just below the rectangular bar in breadth. But
the variations in these respects in the wild rabbit are very slight:
whilst in the large lop-eared rabbits they are considerable. Thus in
some specimens (B) the oblique terminal knob is developed into a short
bar, forming an obtuse angle with the rectangular bar. In another
specimen (C) these two unequal bars form nearly a straight line. The
apex of the acromion varies much in breadth and sharpness, as may be
seen by comparing figures B, C, and D.

_Limbs._—In these I could detect no variation; but the bones of the
feet were too troublesome to compare with much care.

I have now described all the differences in the skeletons which I have
observed. It is impossible not to be struck with the high degree of
variability or plasticity of many of the bones. We see how erroneous
the often-repeated statement is, that only the crests of the bones
which give attachment to muscles vary in shape, and that only parts of
slight importance become modified under domestication. No one will say,
for instance, that the occipital foramen, or the atlas, or the third
cervical vertebra is a part of slight importance. If the several
vertebræ of the wild and lop-eared rabbits, of which figures have been
given, had been found fossil, palæontologists would have declared
without hesitation that they had belonged to distinct species.

_The effects of the use and disuse of parts._—In the large lop-eared
rabbits the relative proportional length of the bones of the same leg,
and of the front and hind legs compared with each other, have remained
nearly the same as in the wild rabbit; but in weight, the bones of the
hind legs apparently have not increased in due proportion with the
front legs. The weight of the whole body in the large rabbits examined
by me was from twice to twice and a half as great as that of the wild
rabbit; and the weight of the bones of the front and hind limbs taken
together (excluding the feet, on account of the difficulty of cleaning
so many small bones) has increased in the large lop-eared rabbits in
nearly the same proportion; consequently in due proportion to the
weight of body which they have to support. If we take the length of the
body as the standard of comparison, the limbs of the large rabbits have
not increased in length in due proportion by one inch and a half.
Again, if we take as the standard of comparison the length of the
skull, which, as we have before seen, has not increased in length in
due proportion to the length of body, the limbs will be found to be,
proportionally with those of the wild rabbit, from half to
three-quarters of an inch too short. Hence, whatever standard of
comparison be taken, the limb-bones of the large lop-eared rabbits have
not increased in length, though they have in weight, in full proportion
to the other parts of the frame; and this, I presume, may be accounted
for by the inactive life which during many generations they have spent.
Nor has the scapula increased in length in due proportion to the
increased length of the body.

    The capacity of the osseous case of the brain is a more interesting
    point, to which I was led to attend by finding, as previously
    stated, that with all domesticated rabbits the length of the skull
    relatively to its breadth has greatly increased in comparison with
    that of the wild rabbits. If we had possessed a large number of
    domesticated rabbits of nearly the same size with the wild rabbits,
    it would have been a simple task to have measured and compared the
    capacities of their skulls. But this is not the case: almost all
    the domestic breeds have larger bodies than wild rabbits, and the
    lop-eared kinds are more than double their weight. As a small
    animal has to exert its senses, intellect, and instincts equally
    with a large animal, we ought not by any means to expect an animal
    twice or thrice as large as another to have a brain of double or
    treble the size.[27] Now, after weighing the bodies of four wild
    rabbits, and of four large but not fattened lop-eared rabbits, I
    find that on an average the wild are to the lop-eared in weight as
    1 to 2·17; in average length of body as 1 to 1·41; whilst in
    capacity of skull they are as 1 to 1·15. Hence we see that the
    capacity of the skull, and consequently the size of the brain, has
    increased but little, relatively to the increased size of the body;
    and this fact explains the narrowness of the skull relatively to
    its length in all domestic rabbits.

            I     II     III     IV Name of Breed
        WILD AND SEMI-WILD RABBITS.     Length of
        Skull.     Length of
        Body from
        Incisors
        to Anus.     Weight
        of whole
        Body.     Capacity
        of Skull
        measured
        by Small
        Shot. inches     inches     lbs  ozs     grains 1     Wild Rabbit,
        Kent     3·15     17·4     3    5       972 2     Wild Rabbit,
        Shetland Islands     3·15     —     —       979 3     Wild Rabbit,
        Ireland     3·15     —     —       992 4     Domestic rabbit, run
        wild, Sandon     3·15     18·5     —       997 5     Wild, common
        variety, small specimen, Kent     2·96     17·0     2  14       875
        6     Wild, fawn-coloured variety,
        Scotland     3·10     —     —       918 7     Silver-grey, small
        specimen, Thetford warren     2·95     15·5     2  11       938
        8     Feral rabbit, Porto Santo     2·83     —     —       893
        9     Feral rabbit, Porto Santo     2·85     —     —       756
        10     Feral Rabbit, Porto Santo     2·95     —     —       835
        Average of the three Porto Santo rabbits     2·88     —     —      
        828
      DOMESTIC RABBITS. 11     Himalayan     3·50     20·5     —       963
      12     Moscow     3·25     17·0     3    8       803
      13     Angora     3·50     19·5     3    1       697
      14     Chinchilla     3·65     22·0     —       995 15     Large
      lop-eared     4·10     24·5     7    0     1065 16     Large
      lop-eared     4·10     25·0     7  13     1153 17     Large
      lop-eared     4·07     —     —     1037 18     Large
      lop-eared     4·10     25·0     7    4     1208 19     Large
      lop-eared     4·30     —     —     1232 20     Large
      lop-eared     4·25     —     —     1124 21     Large
      hare-coloured     3·86     24·0     6  14     1131 22     Average of
      above seven large lop-eared rabbits     4·11       24·62     7   
      4     1136
23     Hare (_L. timidus_) English specimen     3·61     —     7   
0     1315 24     Hare (_L. timidus_) German specimen     3·82     —     7  
 0     1415


            V     VI     VII Name of Breed

        WILD AND SEMI-WILD RABBITS.     Capacity
        calculated
        according to
        Length of Skull
        relatively
        to that of
        No. 1.     Difference
        between
        actual and
        calculated
        capacities
        of Skulls.     Showing how much
        per cent. the Brain,
        by calculation
        according to the
        length of the Skull
        is too light or too
        heavy, relatively
        to the Brain of the
        Wild Rabbit No. 1. grains     grains 1     Wild Rabbit,
        Kent     —     — 2     Wild Rabbit, Shetland
        Islands     —     —     2 per cent. too heavy
        in comparison with No. 1 3     Wild Rabbit, Ireland     —     —
        4     Domestic rabbit, run wild, Sandon 5     Wild, common
        variety, small specimen, Kent       913       38     4 per cent.
        too light. 6     Wild, fawn-coloured variety, Scotland      
        950       32     3 per cent. too light. 7     Silver-grey, small
        specimen, Thetford warren       910       28     3 per cent. too
        heavy. 8     Feral rabbit, Porto Santo       873       20     2 per
        cent. too heavy. 9     Feral rabbit, Porto Santo      
        879     123     16 per cent. too light. 10     Feral Rabbit, Porto
        Santo       910       75     9 per cent. too light. Average of the
        three Porto Santo rabbits       888       60     7 per cent. too
        light.
      DOMESTIC RABBITS. 11     Himalayan     1080     117     12 per cent.
      too light. 12     Moscow     1002     199     24 per cent. too light.
      13     Angora     1080     383     54 per cent. too light.
      14     Chinchilla     1126     131     13 per cent. too light.
      15     Large lop-eared     1265     200     18 per cent. too light.
      16     Large lop-eared     1265     112     9 per cent. too light.
      17     Large lop-eared     1255     218     21 per cent. too light.
      18     Large lop-eared     1265       57     4 per cent. too light.
      19     Large lop-eared     1326       94     7 per cent. too light.
      20     Large lop-eared     1311     187     16 per cent. too light.
      21     Large hare-coloured     1191       60     5 per cent. too
      light. 22     Average of above seven large lop-eared
      rabbits     1268     132     11 per cent. too light.

In the upper half of Table 3 I have given the measurements of the skull
of ten wild rabbits; and in the lower half, of eleven thoroughly
domesticated kinds. As these rabbits differ so greatly in size, it is
necessary to have some standard by which to compare the capacities of
their skulls. I have selected the length of skull as the best standard,
for in the larger rabbits it has not, as already stated, increased in
length so much as the body; but as the skull, like every other part,
varies in length, neither it nor any other part affords a perfect
standard.

In the first column of figures the extreme length of the skull is given
in inches and decimals. I am aware that these measurements pretend to
greater accuracy than is possible; but I have found it the least
trouble to record the exact length which the compass gave. The second
and third columns give the length and weight of body, whenever these
observations were made. The fourth column gives the capacity of the
skull by the weight of small shot with which the skulls were filled;
but it is not pretended that these weights are accurate within a few
grains. In the fifth column the capacity is given which the skull ought
to have had by calculation, according to the length of skull, in
comparison with that of the wild rabbit No. 1; in the sixth column the
difference between the actual and calculated capacities, and in the
seventh the percentage of increase or decrease, are given. For
instance, as the wild rabbit No. 5 has a shorter and lighter body than
the wild rabbit No. 1, we might have expected that its skull would have
had less capacity; the actual capacity, as expressed by the weight of
shot, is 875 grains, which is 97 grains less than that of the first
rabbit. But comparing these two rabbits by the length of their skulls,
we see that in No. 1 the skull is 3·15 inches in length, and in No. 5
2·96 inches in length; according to this ratio, the brain of No. 5
ought to have had a capacity of 913 grains of shot, which is above the
actual capacity, but only by 38 grains. Or, to put the case in another
way (as in column vii), the brain of this small rabbit, No. 5, for
every 100 grains of weight is only 4 grains too light,—that is, it
ought, according to the standard rabbit No. 1, to have been 4 per cent
heavier. I have taken the rabbit No. 1 as the standard of comparison
because, of the skulls having a full average length, this has the least
capacity; so that it is the least favourable to the result which I wish
to show, namely, that the brain in all long-domesticated rabbits has
decreased in size, either actually, or relatively to the length of the
head and body, in comparison with the brain of the wild rabbit. Had I
taken the Irish rabbit, No. 3, as the standard, the following results
would have been somewhat more striking.

Turning to Table 3: the first four wild rabbits have skulls of the same
length, and these differ but little in capacity. The Sandon rabbit (No.
4) is interesting, as, though now wild, it is known to be descended
from a domesticated breed, as is still shown by its peculiar colouring
and longer body; nevertheless the skull has recovered its normal length
and full capacity. The next three rabbits are wild, but of small size,
and they all have skulls with slightly lessened capacities. The three
Porto Santo feral rabbits (Nos. 8 to 10) offer a perplexing case; their
bodies are greatly reduced in size, as in a lesser degree are their
skulls in length and in actual capacity, in comparison with the skulls
of wild English rabbits. But when we compare the capacities of the
skull in the three Porto Santo rabbits, we observe a surprising
difference, which does not stand in any relation to the slight
difference in the length of their skulls, nor, as I believe, to any
difference in the size of their bodies; but I neglected weighing
separately their bodies. I can hardly suppose that the medullary matter
of the brain in these three rabbits, living under similar conditions,
can differ as much as is indicated by the proportional difference of
capacity in their skulls; nor do I know whether it is possible that one
brain may contain considerably more fluid than another. Hence I can
throw no light on this case.

    Looking to the lower half of Table 3, which gives the measurements
    of domesticated rabbits, we see that in all the capacity of the
    skull is less, but in very various degrees, than might have been
    anticipated according to the length of their skulls, relatively to
    that of the wild rabbit No. 1. In line 22 the average measurements
    of seven large lop-eared rabbits are given. Now the question
    arises, has the average capacity of the skull in these seven large
    rabbits increased as much as might have been expected from the
    greatly increased size of body. We may endeavour to answer this
    question in two ways: in the upper half of the Table we have
    measurements of the skulls of six small wild rabbits (Nos. 5 to
    10), and we find that on an average the skulls are ·18 of an inch
    shorter, and in capacity 91 grains less, than the average length
    and capacity of the three first wild rabbits on the list. The seven
    large lop-eared rabbits, on an average, have skulls 4·11 inches in
    length, and 1136 grains in capacity; so that these skulls have
    increased in length more than five times as much as the skulls of
    the six small wild rabbits have decreased in length; hence we might
    have expected that the skulls of the large lop-eared rabbits would
    have increased in capacity five times as much as the skulls of the
    six small rabbits have decreased in capacity; and this would have
    given an average increased capacity of 455 grains, whilst the real
    average increase is only 155 grains. Again, the large lop-eared
    rabbits have bodies of nearly the same weight and size as the
    common hare, but their heads are longer; consequently, if the
    lop-eared rabbits had been wild, it might have been expected that
    their skulls would have had nearly the same capacity as that of the
    skull of the hare. But this is far from being the case; for the
    average capacity of the two hare-skulls (Nos. 23, 24) is so much
    larger than the average capacity of the seven lop-eared skulls,
    that the latter would have to be increased 21 per cent to come up
    to the standard of the hare.[28]

I have previously remarked that, if we had possessed many domestic
rabbits of the same average size with the wild rabbit, it would have
been easy to compare the capacity of their skulls. Now the Himalayan,
Moscow, and Angora rabbits (Nos. 11, 12, 13 of Table 3) are only a
little larger in body and have skulls only a little longer, than the
wild animal, and we see that the actual capacity of their skulls is
less than in the wild animal, and considerably less by calculation
(column 7), according to the difference in the length of their skulls.
The narrowness of the brain-case in these three rabbits could be
plainly seen and proved by external measurement. The Chinchilla rabbit
(No. 14) is a considerably larger animal than the wild rabbit, yet the
capacity of its skull only slightly exceeds that of the wild rabbit.
The Angora rabbit, No. 13, offers the most remarkable case; this animal
in its pure white colour and length of silky fur bears the stamp of
long domesticity. It has a considerably longer head and body than the
wild rabbit, but the actual capacity of its skull is less than that of
even the little wild Porto Santo rabbits. By the standard of the length
of skull the capacity (see column 7) is only half of what it ought to
have been! I kept this individual animal alive, and it was not
unhealthy nor idiotic. This case of the Angora rabbit so much surprised
me, that I repeated all the measurements and found them correct. I have
also compared the capacity of the skull of the Angora with that of the
wild rabbit by other standards, namely, by the length and weight of the
body, and by the weight of the limb-bones; but by all these standards
the brain appears to be much too small, though in a less degree when
the standard of the limb-bones was used; and this latter circumstance
may probably be accounted for by the limbs of this anciently
domesticated breed having become much reduced in weight, from its
long-continued inactive life. Hence I infer that in the Angora breed,
which is said to differ from other breeds in being quieter and more
social, the capacity of the skull has really undergone a remarkable
amount of reduction.

From the several facts above given,—namely, firstly, that the actual
capacity of the skull in the Himalayan, Moscow, and Angora breeds, is
less than in the wild rabbit, though they are in all their dimensions
rather larger animals; secondly, that the capacity of the skull of the
large lop-eared rabbits has not been increased in nearly the same ratio
as the capacity of the skull of the smaller wild rabbits has been
decreased; and thirdly, that the capacity of the skull in these same
large lop-eared rabbits is very inferior to that of the hare, an animal
of nearly the same size,—I conclude, notwithstanding the remarkable
differences in capacity in the skulls of the small Porto Santo rabbits,
and likewise in the large lop-eared kinds, that in all
long-domesticated rabbits the brain has either by no means increased in
due proportion with the increased length of the head and increased size
of the body, or that it has actually decreased in size, relatively to
what would have occurred had these animals lived in a state of nature.
When we remember that rabbits, from having been domesticated and
closely confined during many generations, cannot have exerted their
intellect, instincts, senses, and voluntary movements, either in
escaping from various dangers or in searching for food, we may conclude
that their brains will have been feebly exercised, and consequently
have suffered in development. We thus see that the most important and
complicated organ in the whole organisation is subject to the law of
decrease in size from disuse.

Finally, let us sum up the more important modifications which domestic
rabbits have undergone, together with their causes as far as we can
obscurely see them. By the supply of abundant and nutritious food,
together with little exercise, and by the continued selection of the
heaviest individuals, the weight of the larger breeds has been more
than doubled. The bones of the limbs taken together have increased in
weight, in due proportion with the increased weight of body, but the
hind legs have increased less than the front legs; but in length they
have not increased in due proportion, and this may have been caused by
the want of proper exercise. With the increased size of the body the
third cervical has assumed characters proper to the fourth cervical
vertebra; and the eighth and ninth dorsal vertebræ have similarly
assumed characters proper to the tenth and posterior vertebræ. The
skull in the larger breeds has increased in length, but not in due
proportion with the increased length of body; the brain has not duly
increased in dimensions, or has even actually decreased, and
consequently the bony case for the brain has remained narrow, and by
correlation has affected the bones of the face and the entire length of
the skull. The skull has thus acquired its characteristic narrowness.
From unknown causes the supra-orbital process of the frontal bones and
the free end of the malar bones have increased in breadth; and in the
larger breeds the occipital foramen is generally much less deeply
notched than in wild rabbits. Certain parts of the scapula and the
terminal sternal bones have become highly variable in shape. The ears
have been increased enormously in length and breadth through continued
selection; their weight, conjoined probably with the disuse of their
muscles, has caused them to lop downwards; and this has affected the
position and form of the bony auditory meatus; and this again, by
correlation, the position in a slight degree of almost every bone in
the upper part of the skull, and even the position of the condyles of
the lower jaw.

REFERENCES

 [1] M. P. Gervais, ‘Hist. Nat. des Mammifères,’ 1854, tom. i., p. 288.

 [2] U. Aldrovandi ‘De Quadrupedibus digitatis,’ 1637, p. 383. For
 Confucius and G. Markham _see_ a writer who has studied the subject in
 ‘Cottage Gardener,’ Jan. 22, 1861, p. 250.

 [3] Owen, ‘British Fossil Mammals,’ p. 212.

 [4] Bechstein, ‘Naturgesch. Deutschlands,’ 1801, B. i. p. 1133. I have
 received similar accounts with respect to England and Scotland.

 [5] ‘Pigeons and Rabbits,’ by E. S. Delamer, 1854, p. 133. Sir J.
 Sebright (‘Observations on Instinct,’ 1836, p. 10.) speaks most
 strongly on the difficulty. But this difficulty is not invariable, as
 I have received two accounts of perfect success in taming and breeding
 from the wild rabbit. _See also_ Dr. P. Broca in ‘Journal de la
 Physiologie,’ tom. ii. p. 368.

 [6] Gervais, ‘Hist. Nat. des Mammifères,’ tom. i. p. 292.

 [7] _See_ Dr. P. Broca’s interesting memoir on this subject in
 Brown-Séquard’s ‘Journ. de. Phys.,’ vol. ii. p. 367.

 [8] The skulls of these breeds are briefly described in the ‘Journal
 of Horticulture,’ May 7, 1861, p. 108.

 [9] ‘Journal of Horticulture,’ 1861, p. 380.

 [10] ‘Journal of Horticulture,’ May 28, 1861, p. 169.

 [11] ‘Journal of Horticulture,’ 1861, p. 327. With respect to the ears
 _see_ Delamer on ‘Pigeons and Rabbits,’ 1854, p. 141; also ‘Poultry
 Chronicle,’ vol. ii. p. 499, and ditto for 1854, p. 586.

 [12] Delamer, ‘Pigeons and Rabbits,’ p. 136. _See also_ ‘Journal of
 Horticulture,’ 1861, p. 375.

 [13] ‘An Account of the different Kinds of Sheep in the Russian
 Dominions,’ 1794, p. 39.

 [14] ‘Proc. Zoolog. Soc.,’ June 23, 1857, p. 159.

 [15] ‘Journal of Horticulture,’ April 9, 1861, p. 35.

 [16] ‘Cottage Gardener,’ 1857, p. 141.

 [17] Mr. Bartlett, in ‘Proc. Zoolog Soc.,’ 1861, p. 40.

 [18] ‘Phenomenon in Himalayan Rabbits,’ in ‘Journal of Horticulture,’
 Jan. 27, 1865, p. 102.

 [19] G. R. Waterhouse, ‘Natural History of Mammalia: Rodents,’ 1846,
 pp. 52, 60, 105.

 [20] Delamer on ‘Pigeons and Rabbits,’ p. 114.

 [21] Gosse’s ‘Sojourn in Jamaica,’ 1851, p. 441, as described by an
 excellent observer, Mr. R. Hill. This is the only known case in which
 rabbits have become feral in a hot country. They can be kept, however,
 at Loanda (_see_ Livingstone’s ‘Travels,’ p. 407). In parts of India,
 as I am informed by Mr. Blyth, they breed well.

 [22] Darwin’s ‘Journal of Researches,’ p. 193; and ‘Zoology of the
 Voyage of the Beagle: Mammalia,’ p. 92.

 [23] Kerr’s ‘Collection of Voyages,’ vol. ii. p. 177: p. 205 for Cada
 Mosto. According to a work published in Lisbon in 1717 entitled
 ‘Historia Insulana,’ written by a Jesuit, the rabbits were turned out
 in 1420. Some authors believe that the island was discovered in 1413.

 [24] Something of the same kind has occurred on the island of Lipari,
 where, according to Spallanzani (‘Voyage dans les deux Siciles,’
 quoted by Godron, ‘De l’Espèce,’ p. 364), a countryman turned out some
 rabbits which multiplied prodigiously, but, says Spallanzani, “les
 lapins de l’ile de Lipari sont plus petits que ceux qu’on élève en
 domesticité.”

 [25] Waterhouse, ‘Nat. Hist. Mammalia,’ vol. ii. p. 36.

 [26] These rabbits have run wild for a considerable time in Sandon
 Park, and in other places in Staffordshire and Shropshire. They
 originated, as I have been informed by the gamekeeper, from
 variously-coloured domestic rabbits which had been turned out. They
 vary in colour; but many are symmetrically coloured, being white with
 a streak along the spine, and with the ears and certain marks about
 the head of a blackish-grey tint. They have rather longer bodies than
 common rabbits.

 [27] _See_ Prof. Owen’s remarks on this subject in his paper on the
 ‘Zoological Significance of the Brain, etc., of Man, etc.,’ read
 before Brit. Association 1862: with respect to Birds, _see_ ‘Proc.
 Zoolog. Soc.,’ Jan. 11, 1848, p. 8.

 [28] This standard is apparently considerably too low, for Dr. Crisp
 (‘Proc. Zoolog. Soc.,’ 1861, p. 86) gives 210 grains as the actual
 weight of the brain of a hare which weighed 7 pounds, and 125 grains
 as the weight of the brain of a rabbit which weighed 3 pounds 5
 ounces, that is, the same weight as the rabbit No. 1 in my list. Now
 the contents of the skull of rabbit No. 1 in shot is in my table 972
 grains; and according to Dr. Crisp’s ratio of 125 to 210, the skull of
 the hare ought to have contained 1632 grains of shot, instead of only
 (in the largest hare in my table) 1455 grains.




CHAPTER V. DOMESTIC PIGEONS.

ENUMERATION AND DESCRIPTION OF THE SEVERAL BREEDS—INDIVIDUAL
VARIABILITY—VARIATIONS OF A REMARKABLE NATURE—OSTEOLOGICAL CHARACTERS:
SKULL, LOWER JAW, NUMBER OF vertebræ—CORRELATION OF GROWTH: TONGUE WITH
BEAK; EYELIDS AND NOSTRILS WITH WATTLED SKIN—NUMBER OF WING-FEATHERS,
AND LENGTH OF WING—COLOUR AND DOWN—WEBBED AND FEATHERED FEET—ON THE
EFFECTS OF DISUSE—LENGTH OF FEET IN CORRELATION WITH LENGTH OF
BEAK—LENGTH OF STERNUM, SCAPULA, AND FURCULUM—LENGTH OF WINGS—SUMMARY
ON THE POINTS OF DIFFERENCE IN THE SEVERAL BREEDS.


I have been led to study domestic pigeons with particular care, because
the evidence that all the domestic races are descended from one known
source is far clearer than with any other anciently domesticated
animal. Secondly, because many treatises in several languages, some of
them old, have been written on the pigeon, so that we are enabled to
trace the history of several breeds. And lastly, because, from causes
which we can partly understand, the amount of variation has been
extraordinarily great. The details will often be tediously minute; but
no one who really wants to understand the progress of change in
domestic animals, and especially no one who has kept pigeons and has
marked the great difference between the breeds and the trueness with
which most of them propagate their kind, will doubt that this
minuteness is worth while. Notwithstanding the clear evidence that all
the breeds are the descendants of a single species, I could not
persuade myself until some years had passed that the whole amount of
difference between them, had arisen since man first domesticated the
wild rock-pigeon.

    I have kept alive all the most distinct breeds, which I could
    procure in England or from the Continent; and have prepared
    skeletons of all. I have received skins from Persia, and a large
    number from India and other quarters of the world.[1] Since my
    admission into two of the London pigeon-clubs, I have received the
    kindest assistance from many of the most eminent amateurs.[2]

    The races of the Pigeon which can be distinguished, and which breed
    true, are very numerous. MM. Boitard and Corbié[3] describe in
    detail 122 kinds; and I could add several European kinds not known
    to them. In India, judging from the skins sent me, there are many
    breeds unknown here; and Sir W. Elliot informs me that a collection
    imported by an Indian merchant into Madras from Cairo and
    Constantinople included several kinds unknown in India. I have no
    doubt that there exist considerably above 150 kinds which breed
    true and have been separately named. But of these the far greater
    number differ from each other only in unimportant characters. Such
    differences will be here entirely passed over, and I shall confine
    myself to the more important points of structure. That many
    important differences exist we shall presently see. I have looked
    through the magnificent collection of the Columbidæ in the British
    Museum, and, with the exception of a few forms (such as the
    Didunculus, Calænas, Goura, etc.), I do not hesitate to affirm that
    some domestic races of the rock-pigeon differ fully as much from
    each other in external characters as do the most distinct natural
    genera. We may look in vain through the 288 known species[4] for a
    beak so small and conical as that of the short-faced tumbler; for
    one so broad and short as that of the barb; for one so long,
    straight, and narrow, with its enormous wattles, as that of the
    English carrier; for an expanded upraised tail like that of the
    fantail; or for an œsophagus like that of the pouter. I do not for
    a moment pretend that the domestic races differ from each other in
    their whole organisation as much as the more distinct natural
    genera. I refer only to external characters, on which, however, it
    must be confessed that most genera of birds have been founded.
    When, in a future chapter, we discuss the principle of selection as
    followed by man, we shall clearly see why the differences between
    the domestic races are almost always confined to external, or at
    least to externally visible, characters.

Owing to the amount and gradations of difference between the several
breeds, I have found it indispensable in the following classification
to rank them under Groups, Races, and Sub-races; to which varieties and
sub-varieties, all strictly inheriting their proper characters, must
often be added. Even with the individuals of the same sub-variety, when
long kept by different fanciers, different strains can sometimes be
recognised. There can be no doubt that, if well-characterised forms of
the several races had been found wild, all would have been ranked as
distinct species, and several of them would certainly have been placed
by ornithologists in distinct genera. A good classification of the
various domestic breeds is extremely difficult, owing to the manner in
which many of the forms graduate into each other; but it is curious how
exactly the same difficulties are encountered, and the same rules have
to be followed, as in the classification of any natural but difficult
group of organic beings. An “artificial classification” might be
followed which would present fewer difficulties than a “natural
classification;” but then it would interrupt many plain affinities.
Extreme forms can readily be defined; but intermediate and troublesome
forms often destroy our definitions. Forms which may be called
“aberrant” must sometimes be included within groups to which they do
not accurately belong. Characters of all kinds must be used; but as
with birds in a state of nature, those afforded by the beak are the
best and most readily appreciated. It is not possible to weigh the
importance of all the characters which have to be used so as to make
the groups and sub-groups of equal value. Lastly, a group may contain
only one race, and another and less distinctly defined group may
contain several races and sub-races, and in this case it is difficult,
as in the classification of natural species, to avoid placing too high
a value on the number of forms which a group may contain.

    In my measurements I have never trusted to the eye; and when
    speaking of a part being large or small, I always refer to the wild
    rock-pigeon (_Columba livia_) as the standard of comparison. The
    measurements are given in decimals of an inch.[5]

Illustration: Fig. 17—The Rock-Pigeon, or Columba livia.[6] The
parent-form of all domesticated pigeons.

_COLUMBA LIVIA_ or ROCK-PIGEON.

Illustration:

Illustration:

I will now give a brief description of all the principal breeds. The
diagram above may aid the reader in learning their names and seeing
their affinities. The rock-pigeon, or _ Columba livia_ (including under
this name two or three closely-allied sub-species or geographical
races, hereafter to be described), may be confidently viewed, as we
shall see in the next chapter, as the common parent-form. The names in
italics on the right-hand side of the page show us the most distinct
breeds, or those which have undergone the greatest amount of
modification. The lengths of the dotted lines rudely represent the
degree of distinctness of each breed from the parent-stock, and the
names placed under each other in the columns show the more or less
closely connecting links. The distances of the dotted lines from each
other approximately represent the amount of difference between the
several breeds.

Illustration: Fig. 18—English Pouter.

GROUP I.

This group includes a single race, that of the Pouters. If the most
strongly marked sub-race be taken, namely, the Improved English Pouter,
this is perhaps the most distinct of all domesticated pigeons.

      Race I. Pouter Pigeons.
      (Kropftauben, German. Grosses-gorges, or Boulans, French.)

_Œsophagus of great size, barely separated from the crop, often
inflated. Body and legs elongated. Beak of moderate dimensions._

_Sub-race I._—The improved English Pouter, when its crop is fully
inflated, presents a truly astonishing appearance. The habit of
slightly inflating the crop is common to all domestic pigeons, but is
carried to an extreme in the Pouter. The crop does not differ, except
in size, from that of other pigeons; but is less plainly separated by
an oblique constriction from the œsophagus. The diameter of the upper
part of the œsophagus is immense, even close up to the head. The beak
in one bird which I possessed was almost completely buried when the
œsophagus was fully expanded. The males, especially when excited, pout
more than the females, and they glory in exercising this power. If a
bird will not, to use the technical expression, “play,” the fancier, as
I have witnessed, by taking the beak into his mouth, blows him up like
a balloon; and the bird, then puffed up with wind and pride, struts
about, retaining his magnificent size as long as he can. Pouters often
take flight with their crops inflated. After one of my birds had
swallowed a good meal of peas and water, as he flew up in order to
disgorge them and feed his nearly fledged young, I heard the peas
rattling in his inflated crop as if in a bladder. When flying, they
often strike the backs of their wings together, and thus make a
clapping noise.

Pouters stand remarkably upright, and their bodies are thin and
elongated. In connexion with this form of body, the ribs are generally
broader and the vertebræ more numerous than in other breeds. From their
manner of standing their legs appear longer than they really are,
though, in proportion with those of _C. livia_, the legs and feet are
actually longer. The wings appear much elongated, but by measurement,
in relation to the length of body, this is not the case. The beak
likewise appears longer, but it is in fact a little shorter (about ·03
of an inch), proportionally with the size of the body, and relatively
to the beak of the rock-pigeon. The Pouter, though not bulky, is a
large bird; I measured one which was 34½ inches from tip to tip of
wing, and 19 inches from tip of beak to end of tail. In a wild
rock-pigeon from the Shetland Islands the same measurements gave only
28¼ and 14¾. There are many sub-varieties of the Pouter of different
colours, but these I pass over.

    _Sub-race II. Dutch Pouter._—This seems to be the parent-form of
    our improved English Pouters. I kept a pair, but I suspect that
    they were not pure birds. They are smaller than English pouters,
    and less well developed in all their characters. Neumeister[7] says
    that the wings are crossed over the tail, and do not reach to its
    extremity.

    _Sub-race III. The Lille Pouter._—I know this breed only from
    description.[8] It approaches in general form the Dutch Pouter, but
    the inflated œsophagus assumes a spherical form, as if the pigeon
    had swallowed a large orange, which had stuck close under the beak.
    This inflated ball is represented as rising to a level with the
    crown of the head. The middle toe alone is feathered. A variety of
    this sub-race, called the claquant, is described by MM. Boitard and
    Corbié; it pouts but little, and is characterised by the habit of
    violently hitting its wings together over its back,—a habit which
    the English Pouter has in a slight degree.

_Sub-race IV. Common German Pouter._—I know this bird only from the
figures and description given by the accurate Neumeister, one of the
few writers on pigeons who, as I have found, may always be trusted.
This sub-race seems considerably different. The upper part of the
œsophagus is much less distended. The bird stands less upright. The
feet are not feathered, and the legs and beak are shorter. In these
respects there is an approach in form to the common rock-pigeon. The
tail-feathers are very long, yet the tips of the closed wings extend
beyond the end of the tail; and the length of the wings, from tip to
tip, and of the body, is greater than in the English Pouter.

Illustration: Fig. 19—English Carrier.

GROUP II.

This group includes three Races, namely, Carriers, Runts, and Barbs,
which are manifestly allied to each other. Indeed, certain carriers and
runts pass into each other by such insensible gradations that an
arbitrary line has to be drawn between them. Carriers also graduate
through foreign breeds into the rock-pigeon. Yet, if well-characterised
Carriers and Barbs (see figs 19 and 20) had existed as wild species, no
ornithologist would have placed them in the same genus with each other
or with the rock-pigeon. This group may, as a general rule, be
recognised by the beak being long, with the skin over the nostrils
swollen and often carunculated or wattled, and with that round the eyes
bare and likewise carunculated. The mouth is very wide, and the feet
are large. Nevertheless the Barb, which must be classed in this same
group, has a very short beak, and some runts have very little bare skin
round their eyes.

Race II.—Carriers.
      (Türkische Tauben; pigeons turcs, dragons.)

_Beak elongated, narrow, pointed; eyes surrounded by much naked,
generally carunculated, skin; neck and body elongated._

_Sub-race I. The English Carrier._—This is a fine bird, of large size,
close feathered, generally dark-coloured, with an elongated neck. The
beak is attenuated and of wonderful length: in one specimen it was 1·4
inch in length from the feathered base to the tip; therefore nearly
twice as long as that of the rock-pigeon, which measured only ·77.
Whenever I compare proportionally any part in the carrier and
rock-pigeon, I take the length of the body from the base of the beak to
the end of the tail as the standard of comparison; and according to
this standard, the beak in one Carrier was nearly half an inch longer
than in the rock-pigeon. The upper mandible is often slightly arched.
The tongue is very long. The development of the carunculated skin or
wattle round the eyes, over the nostrils, and on the lower mandible, is
prodigious. The eyelids, measured longitudinally, were in some
specimens exactly twice as long as in the rock-pigeon. The external
orifice or furrow of the nostrils was also twice as long. The open
mouth in its widest part was in one case ·75 of an inch in width,
whereas in the rock-pigeon it is only about ·4 of an inch. This great
width of mouth is shown in the skeleton by the reflexed edges of the
ramus of the lower jaw. The head is flat on the summit and narrow
between the orbits. The feet are large and coarse; the length, as
measured from end of hind toe to end of middle toe (without the claws),
was in two specimens 2·6 inches; and this, proportionally with the
rock-pigeon, is an excess of nearly a quarter of an inch. One very fine
Carrier measured 31½ inches from tip to tip of wing. Birds of this
sub-race are too valuable to be flown as carriers.

_Sub-race II. Dragons; Persian Carriers._—The English Dragon differs
from the improved English Carrier in being smaller in all its
dimensions, and in having less wattle round the eyes and over the
nostrils, and none on the lower mandible. Sir W. Elliot sent me from
Madras a Bagdad Carrier (sometimes called khandesi), the name of which
shows its Persian origin: it would be considered here a very poor
Dragon; the body was of the size of the rock-pigeon, with the beak a
little longer, namely, 1 inch from the tip to the feathered base. The
skin round the eyes was only slightly wattled, whilst that over the
nostrils was fairly wattled. The Hon. C. Murray, also, sent me two
Carriers direct from Persia; these had nearly the same character as the
Madras bird, being about as large as the rock-pigeon, but the beak in
one specimen was as much as 1·15 in length; the skin over the nostrils
was only moderately, and that round the eyes scarcely at all wattled.

    _Sub-race III. Bagadotten-Tauben of Neumeister_ (Pavdotten-or
    Hocker-Tauben).—I owe to the kindness of Mr. Baily, jun., a dead
    specimen of this singular breed imported from Germany. It is
    certainly allied to the Runts; nevertheless, from its close
    affinity with Carriers, it will be convenient here to describe it.
    The beak is long, and is hooked or bowed downwards in a highly
    remarkable manner, as will be seen in fig. 24-D when I treat of the
    skeleton. The eyes are surrounded by a wide space of bright red
    skin, which, as well as that over the nostrils, is moderately
    wattled. The breast-bone is remarkably protuberant, being abruptly
    bowed outwards. The feet and tarsi are of great length, larger than
    in first-rate English Carriers. The whole bird is of large size,
    but in proportion to the size of the body the feathers of the wing
    and tail are short; a wild rock-pigeon, of considerably less size,
    had tail-feathers 4·6 inches in length, whereas in the large
    Bagadotten these feathers were scarcely over 4·1 inches in length.
    Riedel[9] remarks that it is a very silent bird.

    _Sub-race IV. Bussorah Carrier._—Two specimens were sent me by Sir
    W. Elliot from Madras, one in spirits and the other skinned. The
    name shows its Persian origin. It is much valued in India, and is
    considered as a distinct breed from the Bagdad Carrier, which forms
    my second sub-race. At first I suspected that these two sub-races
    might have been recently formed by crosses with other breeds,
    though the estimation in which they are held renders this
    improbable; but in a Persian treatise,[10] believed to have been
    written about 100 years ago, the Bagdad and Bussorah breeds are
    described as distinct. The Bussorah Carrier is of about the same
    size as the wild rock-pigeon. The shape of the beak, with some
    little carunculated skin over the nostrils,— the much elongated
    eyelids,—the broad mouth measured internally,—the narrow head,—the
    feet proportionally a little longer than in the rock-pigeon,—and
    the general appearance, all show that this bird is an undoubted
    Carrier; yet in one specimen the beak was of exactly the same
    length as in the rock-pigeon. In the other specimen the beak (as
    well as the opening of the nostrils) was only a very little longer,
    viz., by ·08 of an inch. Although there was a considerable space of
    bare and slightly carunculated skin round the eyes, that over the
    nostrils was only in a slight degree rugose. Sir W. Elliot informs
    me that in the living bird the eye seems remarkably large and
    prominent, and the same fact is noticed in the Persian treatise;
    but the bony orbit is barely larger than that in the rock-pigeon.

Amongst the several breeds sent to me from Madras by Sir W. Elliot
there is a pair of the _Kali Par_, black birds with the beak slightly
elongated, with the skin over the nostrils rather full, and with a
little naked skin round the eyes. This breed seems more closely allied
to the Carrier than to any other breed, being nearly intermediate
between the Bussorah Carrier and the rock-pigeon.

The names applied in different parts of Europe and in India to the
several kinds of Carriers all point to Persia or the surrounding
countries as the source of this Race. And it deserves especial notice
that, even if we neglect the Kali Par as of doubtful origin, we get a
series broken by very small steps, from the rock-pigeon, through the
Bussorah, which sometimes has a beak not at all longer than that of the
rock-pigeon and with the naked skin round the eyes and over the
nostrils very slightly swollen and carunculated, through the Bagdad
sub-race and Dragons, to our improved English Carriers, which present
so marvellous a difference from the rock-pigeon or _Columba livia._

      Race III.—Runts.
      (Scanderoons: die Florentiner Tauben and Hinkeltauben of
      Neumeister; pigeon bagadais, pigeon romain.)

_Beak long, massive; body of great size._

Inextricable confusion reigns in the classification, affinities, and
naming of Runts. Several characters which are generally pretty constant
in other pigeons, such as the length of the wings, tail, legs, and
neck, and the amount of naked skin round the eyes, are excessively
variable in Runts. When the naked skin over the nostrils and round the
eyes is considerably developed and wattled, and when the size of body
is not very great, Runts graduate in so insensible a manner into
Carriers, that the distinction is quite arbitrary. This fact is
likewise shown by the names given to them in different parts of Europe.
Nevertheless, taking the most distinct forms, at least five sub-races
(some of them including well-marked varieties) can be distinguished,
which differ in such important points of structure, that they would be
considered as good species in a state of nature.

_Sub-race I. Scanderoon of English Writers_ (die Florentiner and
Hinkeltauben of Neumeister).—Birds of this sub-race, of which I kept
one alive and have since seen two others, differ from the Bagadotten of
Neumeister only in not having the beak nearly so much curved downwards,
and in the naked skin round the eyes and over the nostrils being hardly
at all wattled. Nevertheless I have felt myself compelled to place the
Bagadotten in Race II., or that of the Carriers, and the present bird
in Race III., or that of the Runts. The Scanderoon has a very short,
narrow, and elevated tail; wings extremely short, so that the first
primary feathers were not longer than those of a small tumbler pigeon!
Neck long, much bowed; breast-bone prominent. Beak long, being 1·15
inch from tip to feathered base; vertically thick; slightly curved
downwards. The skin over the nostrils swollen, not wattled; naked skin
round the eyes, broad, slightly carunculated. Legs long; feet very
large. Skin of neck bright red, often showing a naked medial line, with
a naked red patch at the distal end of the radius of the wing. My bird,
as measured from the base of the beak to the root of the tail, was
fully 2 inches longer than the rock-pigeon; yet the tail itself was
only 4 inches in length, whereas in the rock-pigeon, which is a much
smaller bird, the tail is 4-5/8 inches in length.

The Hinkel-or Florentiner Taube of Neumeister (Table 13 fig. 1) agrees
with the above description in all the specified characters (for the
beak is not mentioned), except that Neumeister expressly says that the
neck is short, whereas in my Scanderoon it was remarkably long and
bowed; so that the Hinkel forms a well-marked variety.

_Sub-race II. Pigeon cygne and Pigeon bagadais of Boitard and Corbié_
(Scanderoon of French writers).—I kept two of these birds alive,
imported from France. They differed from the first sub-race or true
Scanderoon in the much greater length of the wing and tail, in the beak
not being so long, and in the skin about the head being more
carunculated. The skin of the neck is red; but the naked patches on the
wings are absent. One of my birds measured 38½ inches from tip to tip
of wing. By taking the length of the body as the standard of
comparison, the two wings were no less than 5 inches longer than those
of the rock-pigeon! The tail was 6¼ inches in length, and therefore 2¼
inches longer than that of the Scanderoon,—a bird of nearly the same
size. The beak is longer, thicker, and broader than in the rock-pigeon,
proportionally with the size of body. The eyelids, nostrils, and
internal gape of mouth are all proportionally very large, as in
Carriers. The foot, from the end of the middle to end of hind toe, was
actually 2·85 inches in length, which is an excess of ·32 of an inch
over the foot of the rock-pigeon, proportionally to the relative size
of the two birds.

    _Sub-race III. Spanish and Roman Runts._—I am not sure that I am
    right in placing these Runts in a distinct sub-race; yet, if we
    take well-characterised birds, there can be no doubt of the
    propriety of the separation. They are heavy, massive birds, with
    shorter necks, legs, and beaks than in the foregoing races. The
    skin over the nostrils is swollen, but not carunculated; the naked
    skin round the eyes is not very wide, and only slightly
    carunculated; and I have seen a fine so-called Spanish Runt with
    hardly any naked skin round the eyes. Of the two varieties to be
    seen in England, one, which is the rarer, has very long wings and
    tail, and agrees pretty closely with the last sub-race; the other,
    with shorter wings and tail, is apparently the _Pigeon romain
    ordinaire_ of Boitard and Corbié. These Runts are apt to tremble
    like Fantails. They are bad flyers. A few years ago Mr.
    Gulliver[11] exhibited a Runt which weighed 1 pound 14 ounces; and,
    as I am informed by Mr. Tegetmeier, two Runts from the south of
    France were lately exhibited at the Crystal Palace, each of which
    weighed 2 pounds 2½ ounces. A very fine rock-pigeon from the
    Shetland Islands weighed only 14½ ounces.

_Sub-race IV. Tronfo of Aldrovandi_ (Leghorn Runt?).—In Aldrovandi’s
work published in 1600 there is a coarse woodcut of a great Italian
pigeon, with an elevated tail, short legs, massive body, and with the
beak short and thick. I had imagined that this latter character so
abnormal in the group, was merely a false representation from bad
drawing; but Moore, in his work published in 1735, says that he
possessed a Leghorn Runt of which “the beak was very short for so large
a bird.” In other respects Moore’s bird resembled the first sub-race or
Scanderoon, for it had a long bowed neck, long legs, short beak, and
elevated tail, and not much wattle about the head. So that Aldrovandi’s
and Moore’s birds must have formed distinct varieties, both of which
seem to be now extinct in Europe. Sir W. Elliot, however, informs me
that he has seen in Madras a short-beaked Runt imported from Cairo.

_Sub-race V. Murassa (adorned Pigeon) of Madras._—Skins of these
handsome chequered birds were sent me from Madras by Sir W. Elliot.
They are rather larger than the largest rock-pigeon, with longer and
more massive beaks. The skin over the nostrils is rather full and very
slightly carunculated, and they have some naked skin round the eyes;
feet large. This breed is intermediate between the rock-pigeon and a
very poor variety of Runt or Carrier.

From these several descriptions we see that with Runts, as with
Carriers, we have a fine gradation from the rock-pigeon (with the
Tronfo diverging as a distinct branch) to our largest and most massive
Runts. But the chain of affinities, and many points of resemblance,
between Runts and carriers, make me believe that these two races have
not descended by independent lines from the rock-pigeon, but from some
common parent, as represented in the Table, which had already acquired
a moderately long beak with slightly swollen skin over the nostrils,
and with some slightly carunculated naked skin round the eyes.

Illustration: Fig. 20—English Barb.

      Race IV.—Barbs.
      (Indische Tauben; pigeons polonais.)

_Beak short, broad, deep; naked skin round the eyes, broad and
carunculated; skin over nostrils slightly swollen._

Misled by the extraordinary shortness and form of the beak, I did not
at first perceive the near affinity of this Race to that of Carriers
until the fact was pointed out to me by Mr. Brent. Subsequently, after
examining the Bussorah Carrier, I saw that no very great amount of
modification would be requisite to convert it into a Barb. This view of
the affinity of Barbs to Carriers is supported by the analogical
difference between the short and long-beaked Runts; and still more
strongly by the fact, that, young Barbs and Dragons, within 24 hours
after being hatched, resemble each other much more closely than do
young pigeons of other and equally distinct breeds. At this early age,
the length of beak, the swollen skin over the rather open nostrils, the
gape of the mouth, and the size of the feet, are the same in both;
although these parts afterwards become widely different. We thus see
that embryology (as the comparison of very young animals may perhaps be
called) comes into play in the classification of domestic varieties, as
with species in a state of nature.

Fanciers, with some truth, compare the head and beak of the Barb to
that of a bullfinch. The Barb, if found in a state of nature would
certainly have been placed in a new genus formed for its reception. The
body is a little larger than that of the rock-pigeon, but the beak is
more than ·2 of an inch shorter; although shorter, it is both
vertically and horizontally thicker. From the outward flexure of the
rami of the lower jaw, the mouth internally is very broad, in the
proportion of ·6 to ·4 to that of the rock-pigeon. The whole head is
broad. The skin over the nostril is swollen, but not carunculated,
except slightly in first-rate birds when old; whilst the naked skin
round the eye is broad and much carunculated. It is sometimes so much
developed, that a bird belonging to Mr. Harrison Weir could hardly see
to pick up food from the ground. The eyelids in one specimen were
nearly twice as long as those of the rock-pigeon. The feet are coarse
and strong, but proportionally rather shorter than in the rock-pigeon.
The plumage is generally dark and uniform. Barbs, in short, may be
called short-beaked Carriers, bearing the same relation to Carriers
that the Tronfo of Aldrovandi does to the common Runt.

GROUP III.

This group is artificial, and includes a heterogeneous collection of
distinct forms. It may be defined by the beak, in well-characterised
specimens of the several races, being shorter than in the rock-pigeon,
and by the skin round the eyes not being much developed.

Illustration: Fig. 21—English Fantail.

Race V.—Fantails.

_Sub-race I. European Fantails_ (Pfauentauben; trembleurs).

_Tail expanded, directed upwards, formed of many feathers; oil-gland
aborted; body and beak rather short._

    The normal number of tail-feathers in the genus Columba is 12; but
    Fantails have from only 12 (as has been asserted) up to, according
    to MM. Boitard and Corbié, 42. I have counted in one of my own
    birds 33, and at Calcutta Mr. Blyth[12] has counted in an
    _imperfect_ tail 34 feathers. In Madras, as I am informed by Sir W.
    Elliot, 32 is the standard number; but in England number is much
    less valued than the position and expansion of the tail. The
    feathers are arranged in an irregular double row; their permanent
    fanlike expansion and their upward direction are more remarkable
    characters than their increased number. The tail is capable of the
    same movements as in other pigeons, and can be depressed so as to
    sweep the ground. It arises from a more expanded basis than in
    other pigeons; and in three skeletons there were one or two extra
    coccygeal vertebræ. I have examined many specimens of various
    colours from different countries, and there was no trace of the
    oil-gland; this is a curious case of abortion.[13] The neck is thin
    and bowed backwards. The breast is broad and protuberant. The feet
    are small. The carriage of the bird is very different from that of
    other pigeons; in good birds the head touches the tail-feathers,
    which consequently often become crumpled. They habitually tremble
    much: and their necks have an extraordinary, apparently convulsive,
    backward and forward movement. Good birds walk in a singular
    manner, as if their small feet were stiff. Owing to their large
    tails, they fly badly on a windy day. The dark-coloured varieties
    are generally larger than white Fantails.

    Although between the best and common Fantails, now existing in
    England, there is a vast difference in the position and size of the
    tail, in the carriage of the head and neck, in the convulsive
    movements of the neck, in the manner of walking, and in the breadth
    of the breast, the differences so graduate away, that it is
    impossible to make more than one sub-race. Moore, however, an
    excellent old authority[14] says, that in 1735 there were two sorts
    of broad-tailed shakers (_i.e._ Fantails), “one having a neck much
    longer and more slender than the other;” and I am informed by Mr.
    B. P. Brent, that there is an existing German Fantail with a
    thicker and shorter beak.

_Sub-race II. Java Fantail._—Mr. Swinhoe sent me from Amoy, in China,
the skin of a Fantail belonging to a breed known to have been imported
from Java. It was coloured in a peculiar manner, unlike any European
Fantail; and, for a Fantail, had a remarkably short beak. Although a
good bird of the kind, it had only 14 tail-feathers; but Mr. Swinhoe
has counted in other birds of this breed from 18 to 24 tail-feathers.
From a rough sketch sent to me, it is evident that the tail is not so
much expanded or so much upraised as in even second-rate European
Fantails. The bird shakes its neck like our Fantails. It had a
well-developed oil-gland. Fantails were known in India, as We shall
hereafter see, before the year 1600; and we may suspect that in the
Java Fantail we see the breed in its earlier and less improved
condition.

Illustration: Fig. 22—African Owl.

Race VI.—Turbit and Owl.
      (Möventauben; pigeons à cravate.)

_Feathers divergent along the front of the neck and breast; beak very
short, vertically rather thick; œsophagus somewhat enlarged._

Turbits and Owls differ from each other slightly in the shape of the
head; the former have a crest, and the beak is differently curved; but
they may be here conveniently grouped together. These pretty birds,
some of which are very small, can be recognised at once by the feathers
irregularly diverging, like a frill, along the front of the neck, in
the same manner, but in a less degree, as along the back of the neck in
the Jacobin. They have the remarkable habit of continually and
momentarily inflating the upper part of the œsophagus, which causes a
movement in the frill. When the œsophagus of a dead bird is inflated,
it is seen to be larger than in other breeds, and not so distinctly
separated from the crop. The Pouter inflates both its true crop and
œsophagus; the Turbit inflates in a much less degree the œsophagus
alone. The beak of the Turbit is very short, being ·28 of an inch
shorter than that of the rock-pigeon, proportionally with the size of
their bodies; and in some owls brought by Mr. E. Vernon Harcourt from
Tunis, it was even shorter. The beak is vertically thicker, and perhaps
a little broader, in proportion to that of the rock-pigeon.

      Race VII.—Tumblers.
      (Tümmler, or Burzeltauben; culbutants.)

_During flight, tumble backwards; body generally small; beak generally
short, sometimes excessively short and conical._

This race may be divided into four sub-races, namely, Persian, Lotan,
Common, and short-faced Tumblers. These sub-races include many
varieties which breed true. I have examined eight skeletons of various
kinds of Tumblers: excepting in one imperfect and doubtful specimen,
the ribs are only seven in number, whereas the rock-pigeon has eight
ribs.

_Sub-race I. Persian Tumblers._—I received a pair direct from Persia,
from the Hon. C. Murray. They are rather smaller birds than the wild
rock-pigeon, about the size of the common dovecot pigeon, white and
mottled, slightly feathered on the feet, with the beak just perceptibly
shorter than in the rock-pigeon. H.M. Consul, Mr. Keith Abbott, informs
me that the difference in the length of beak is so slight, that only
practised Persian fanciers can distinguish these Tumblers from the
common pigeon of the country. He informs me that they fly in flocks
high up in the air and tumble well. Some of them occasionally appear to
become giddy and tumble to the ground, in which respect they resemble
some of our Tumblers.

    _Sub-race II. Lotan, or Lowtun: Indian Ground Tumblers._—These
    birds present one of the most remarkable inherited habits or
    instincts ever recorded. The specimens sent to me from Madras by
    Sir W. Elliot are white, slightly feathered on the feet, with the
    feathers on the head reversed; and they are rather smaller than the
    rock or dovecot pigeon. The beak is proportionally only slightly
    shorter and rather thinner than in the rock-pigeon. These birds
    when gently shaken and placed on the ground immediately begin
    tumbling head over heels, and they continue thus to tumble until
    taken up and soothed,—the ceremony being generally to blow in their
    faces, as in recovering a person from a state of hypnotism or
    mesmerism. It is asserted that they will continue to roll over till
    they die, if not taken up. There is abundant evidence with respect
    to these remarkable peculiarities; but what makes the case the more
    worthy of attention is, that the habit has been inherited since
    before the year 1600, for the breed is distinctly described in the
    ‘Ayeen Akbery.’[15] Mr. Evans kept a pair in London, imported by
    Captain Vigne; and he assures me that he has seen them tumble in
    the air, as well as in the manner above described on the ground.
    Sir W. Elliot, however, writes to me from Madras, that he is
    informed that they tumble exclusively on the ground, or at a very
    small height above it. He also mentions birds of another
    sub-variety, called the Kalmi Lotan, which begin to roll over if
    only touched on the neck with a rod or wand.

    _Sub-race III. Common English Tumblers._—These birds have exactly
    the same habits as the Persian Tumbler, but tumble better. The
    English bird is rather smaller than the Persian, and the beak is
    plainly shorter. Compared with the rock-pigeon, and proportionally
    with the size of body, the beak is from ·15 to nearly ·2 of an inch
    shorter, but it is not thinner. There are several varieties of the
    common Tumbler, namely, Baldheads, Beards, and Dutch Rollers. I
    have kept the latter alive; they have differently shaped heads,
    longer necks, and are feather-footed. They tumble to an
    extraordinary degree; as Mr. Brent remarks,[16] “Every few seconds
    over they go; one, two, or three summersaults at a time. Here and
    there a bird gives a very quick and rapid spin, revolving like a
    wheel, though they sometimes lose their balance, and make a rather
    ungraceful fall, in which they occasionally hurt themselves by
    striking some object.” From Madras I have received several
    specimens of the common Tumbler of India, differing slightly from
    each other in the length of their beaks. Mr. Brent sent me a dead
    specimen of a “House-tumbler,”[17] which is a Scotch variety, not
    differing in general appearance and form of beak from the common
    Tumbler. Mr. Brent states that these birds generally begin to
    tumble “almost as soon as they can well fly; at three months old
    they tumble well, but still fly strong; at five or six months they
    tumble excessively; and in the second year they mostly give up
    flying, on account of their tumbling so much and so close to the
    ground. Some fly round with the flock, throwing a clean summersault
    every few yards, till they are obliged to settle from giddiness and
    exhaustion. These are called Air Tumblers, and they commonly throw
    from twenty to thirty summersaults in a minute, each clear and
    clean. I have one red cock that I have on two or three occasions
    timed by my watch, and counted forty summersaults in the minute.
    Others tumble differently. At first they throw a single
    summersault, then it is double, till it becomes a continuous roll,
    which puts an end to flying, for if they fly a few yards over they
    go, and roll till they reach the ground. Thus I had one kill
    herself, and another broke his leg. Many of them turn over only a
    few inches from the ground, and will tumble two or three times in
    flying across their loft. These are called House-tumblers, from
    tumbling in the house. The act of tumbling seems to be one over
    which they have no control, an involuntary movement which they seem
    to try to prevent. I have seen a bird sometimes in his struggles
    fly a yard or two straight upwards, the impulse forcing him
    backwards while he struggles to go forwards. If suddenly startled,
    or in a strange place, they seem less able to fly than if quiet in
    their accustomed loft.” These House-tumblers differ from the Lotan
    or Ground Tumbler of India, in not requiring to be shaken in order
    to begin tumbling. The breed has probably been formed merely by
    selecting the best common Tumblers, though it is possible that they
    may have been crossed at some former period with Lotans.

Illustration: Fig. 23—Short-faced English Tumbler.

    _Sub-race IV. Short-faced Tumblers._—These are marvellous birds,
    and are the glory and pride of many fanciers. In their extremely
    short, sharp, and conical beaks, with the skin over the nostrils
    but little developed, they almost depart from the type of the
    Columbidæ. Their heads are nearly globular and upright in front, so
    that some fanciers say[18] “the head should resemble a cherry with
    a barleycorn stuck in it.” These are the smallest kind of pigeons.
    Mr. Esquilant possessed a blue Baldhead, two years old, which when
    alive weighed, before feeding-time, only 6 ounces 5 drs.; two
    others, each weighed 7 ounces. We have seen that a wild rock-pigeon
    weighed 14 ounces 2 drs., and a Runt 34 ounces 4 drs. Short-faced
    Tumblers have a remarkably erect carriage, with prominent breasts,
    drooping wings, and very small feet. The length of the beak from
    the tip to the feathered base was in one good bird only ·4 of an
    inch; in a wild rock-pigeon it was exactly double this length. As
    these Tumblers have shorter bodies than the wild rock-pigeon, they
    ought of course to have shorter beaks; but proportionally with the
    size of the body, the beak is ·28 of an inch too short. So, again,
    the feet of this bird were actually ·45 shorter, and proportionally
    ·21 of an inch shorter, than the feet of the rock-pigeon. The
    middle toe has only twelve or thirteen, instead of fourteen or
    fifteen scutellæ. The primary wing-feathers are not rarely nine
    instead of ten in number. The improved short-faced Tumblers have
    almost lost the power of tumbling; but there are several authentic
    accounts of their occasionally tumbling. There are several
    sub-varieties, such as Bald-heads, Beards, Mottles, and Almonds;
    the latter are remarkable from not acquiring their
    perfectly-coloured plumage until they have moulted three or four
    times. There is good reason to believe that most of these
    sub-varieties, some of which breed truly, have arisen since the
    publication of Moore’s treatise in 1735.[19]

Finally, in regard to the whole group of Tumblers, it is impossible to
conceive a more perfect gradation than I have now lying before me, from
the rock-pigeon, through Persian, Lotan, and common Tumblers, up to the
marvellous short-faced birds; which latter, no ornithologist, judging
from mere external structure, would place in the same genus with the
rock-pigeon. The differences between the successive steps in this
series are not greater than those which may be observed between common
dovecot-pigeons (_C. livia_) brought from different countries.

      Race VIII.—Indian Frill-back.

_Beak very short; feathers reversed._

A specimen of this bird, in spirits, was sent to me from Madras by Sir
W. Elliot. It is wholly different from the Frill-back often exhibited
in England. It is a smallish bird, about the size of the common
Tumbler, but has a beak in all its proportions like our short-faced
Tumblers. The beak, measured from the tip to the feathered base, was
only ·46 of an inch in length. The feathers over the whole body are
reversed or curl backwards. Had this bird occurred in Europe, I should
have thought it only a monstrous variety of our improved Tumbler: but
as short-faced Tumblers are not known in India, I think it must rank as
a distinct breed. Probably this is the breed seen by Hasselquist in
1757 at Cairo, and said to have been imported from India.

      Race IX.—Jacobin.
      (Zopf-or Perrückentaube; nonnain.)

_Feathers of the neck forming a hood; wings and tail long; beak
moderately short._

    This pigeon can at once be recognised by its hood, almost enclosing
    the head and meeting in front of the neck. The hood seems to be
    merely an exaggeration of the crest of reversed feathers on the
    back of the head, which is common to many sub-varieties, and which
    in the Latztaube[20] is in a nearly intermediate state between a
    hood and a crest. The feathers of the hood are elongated. Both the
    wings and tail are likewise much elongated; thus the folded wing of
    the Jacobin, though a somewhat smaller bird, is fully 1¼ inch
    longer than in the rock-pigeon. Taking the length of the body
    without the tail as the standard of comparison, the folded wing,
    proportionally with the wings of the rock-pigeon, is 2¼ inches too
    long, and the two wings, from tip to tip, 5¼ inches too long. In
    disposition this bird is singularly quiet, seldom flying or moving
    about, as Bechstein and Riedel have likewise remarked in
    Germany.[21] The latter author also notices the length of the wings
    and tail. The beak is nearly ·2 of an inch shorter in proportion to
    the size of the body than in the rock-pigeon; but the internal gape
    of the mouth is considerably wider.

GROUP IV.

The birds of this group may be characterised by their resemblance in
all important points of structure, especially in the beak, to the
rock-pigeon. The Trumpeter forms the only well-marked race. Of the
numerous other sub-races and varieties I shall specify only a few of
the most distinct, which I have myself seen and kept alive.

      Race X.—Trumpeter.
      (Trommeltaube; pigeon tambour, glouglou.)

_A tuft of feathers at the base of the beak curling forward; feet much
feathered; voice very peculiar; size exceeding that of the
rock-pigeon._

This is a well-marked breed, with a peculiar voice, wholly unlike that
of any other pigeon. The coo is rapidly repeated, and is continued for
several minutes; hence their name of Trumpeters. They are also
characterised by a tuft of elongated feathers, which curls forward over
the base of the beak, and which is possessed by no other breed. Their
feet are so heavily feathered, that they almost appear like little
wings. They are larger birds than the rock-pigeon, but their beak is of
very nearly the same proportional size. Their feet are rather small.
This breed was perfectly characterised in Moore’s time, in 1735. Mr.
Brent says that two varieties exist, which differ in size.

      Race XI.—Scarcely differing in structure from the wild _Columba
      livia._

_Sub-race I. Laughers.—Size less than the Rock-pigeon; voice very
peculiar._—As this bird agrees in nearly all its proportions with the
rock-pigeon, though of smaller size, I should not have thought it
worthy of mention, had it not been for its peculiar voice—a character
supposed seldom to vary with birds. Although the voice of the Laugher
is very different from that of the Trumpeter, yet one of my Trumpeters
used to utter a single note like that of the Laugher. I have kept two
varieties of Laughers, which differed only in one variety being
turn-crowned; the smooth-headed kind, for which I am indebted to the
kindness of Mr. Brent, besides its peculiar note, used to coo in a
singular and pleasing manner, which, independently, struck both Mr.
Brent and myself as resembling that of the turtle-dove. Both varieties
come from Arabia. This breed was known by Moore in 1735. A pigeon which
seems to say Yak-roo is mentioned in 1600 in the ‘Ayeen Akbery’ and is
probably the same breed. Sir W. Elliot has also sent me from Madras a
pigeon called Yahui, said to have come from Mecca, which does not
differ in appearance from the Laugher; it has “a deep melancholy voice,
like Yahu, often repeated.” Yahu, yahu, means Oh God, oh God; and
Sayzid Mohammed Musari, in the treatise written about 100 years ago,
says that these birds “are not flown, because they repeat the name of
the most high God.” Mr. Keith Abbott, however, informs me that the
common pigeon is called Yahoo in Persia.

_Sub-race II. Common Frill-back_ (die Strupptaube).—_Beak rather longer
than in the rock-pigeon; feathers reversed._—This is a considerably
larger bird than the rock-pigeon, and with the beak, proportionally
with the size of body, a little (viz. by ·04 of an inch) longer. The
feathers, especially on the wing-coverts, have their points curled
upwards or back-wards.

_Sub-race III. Nuns_ (Pigeons coquilles).—These elegant birds are
smaller than the rock-pigeon. The beak is actually 1·7, and
proportionally with the size of the body ·1 of an inch shorter than in
the rock-pigeons, although of the same thickness. In young birds the
scutellæ on the tarsi and toes are generally of a leaden-black colour;
and this is a remarkable character (though observed in a lesser degree
in some other breeds), as the colour of the legs in the adult state is
subject to very little variation in any breed. I have on two or three
occasions counted thirteen or fourteen feathers in the tail; this
likewise occurs in the barely distinct breed called Helmets. Nuns are
symmetrically coloured, with the head, primary wing-feathers, tail, and
tail-coverts of the same colour, namely, black or red, and with the
rest of the body white. This breed has retained the same character
since Aldrovandi wrote in 1600. I have received from Madras almost
similarly coloured birds.

    _Sub-race IV. Spots_ (die Blasstauben; pigeons heurtés).—These
    birds are a very little larger than the rock-pigeon, with the beak
    a trace smaller in all its dimensions, and with the feet decidedly
    smaller. They are symmetrically coloured, with a spot on the
    forehead, with the tail and tail-coverts of the same colour, the
    rest of the body being white. This breed existed in 1676;[22] and
    in 1735 Moore remarks that they breed truly, as is the case at the
    present day.

_Sub-race V. Swallows._—These birds, as measured from tip to tip of
wing, or from the end of the beak to the end of the tail, exceed in
size the rock-pigeon; but their bodies are much less bulky; their feet
and legs are likewise smaller. The beak is of about the same length,
but rather slighter. Altogether their general appearance is
considerably different from that of the rock-pigeon. Their heads and
wings are of the same colour, the rest of the body being white. Their
flight is said to be peculiar. This seems to be a modern breed, which,
however, originated before the year 1795 in Germany, for it is
described by Bechstein.

    Besides the several breeds now described, three or four other very
    distinct kinds existed lately, or perhaps still exist, in Germany
    and France. Firstly, the Karmeliten, or carme pigeon, which I have
    not seen; it is described as of small size, with very short legs,
    and with an extremely short beak. Secondly, the Finnikin, which is
    now extinct in England. It had, according to Moore’s[23] treatise,
    published in 1735, a tuft of feathers on the hinder part of the
    head, which ran down its back not unlike a horse’s mane. “When it
    is salacious it rises over the hen and turns round three or four
    times, flapping its wings, then reverses and turns as many times
    the other way.” The Turner, on the other hand, when it “plays to
    the female, turns only one way.” Whether these extraordinary
    statements may be trusted I know not; but the inheritance of any
    habit may be believed, after what we have seen with respect to the
    Ground-tumbler of India. MM. Boitard and Corbié describe a
    pigeon[24] which has the singular habit of sailing for a
    considerable time through the air, without flapping its wings, like
    a bird of prey. The confusion is inextricable, from the time of
    Aldrovandi in 1600 to the present day, in the accounts published of
    the Draijers, Smiters, Finnikins, Turners, Claquers, etc., which
    are all remarkable from their manner of flight. Mr. Brent informs
    me that he has seen one of these breeds in Germany with its
    wing-feathers injured from having been so often struck together but
    he did not see it flying. An old stuffed specimen of a Finnikin in
    the British Museum presents no well-marked character. Thirdly, a
    singular pigeon with a forked tail is mentioned in some treatises;
    and as Bechstein[25] briefly describes and figures this bird, with
    a tail “having completely the structure of that of the
    house-swallow,” it must once have existed, for Bechstein was far
    too good a naturalist to have confounded any distinct species with
    the domestic pigeon. Lastly, an extraordinary pigeon imported from
    Belgium has lately been exhibited at the Philoperisteron Society in
    London,[26] which “conjoins the colour of an archangel with the
    head of an owl or barb, its most striking peculiarity being the
    extraordinary length of the tail and wing-feathers, the latter
    crossing beyond the tail, and giving to the bird the appearance of
    a gigantic swift (Cypselus), or long-winged hawk.” Mr. Tegetmeier
    informs me that this bird weighed only 10 ounces, but in length was
    15½ inches from tip to beak to end of tail, and 32½ inches from tip
    to tip of wing; now the wild rock-pigeon weighs 14½ ounces, and
    measures from tip to beak to end of tail 15 inches, and from tip to
    tip of wing only 26¾ inches.

I have now described all the domestic pigeons known to me, and have
added a few others on reliable authority. I have classed them under
four Groups, in order to mark their affinities and degrees of
difference; but the third group is artificial. The kinds examined by me
form eleven races, which include several sub-races; and even these
latter present differences that would certainly have been thought of
specific value if observed in a state of nature. The sub-races likewise
include many strictly inherited varieties; so that altogether there
must exist, as previously remarked, above 150 kinds which can be
distinguished, though generally by characters of extremely slight
importance. Many of the genera of the Columbidæ, admitted by
ornithologists, do not differ in any great degree from each other;
taking this into consideration, there can be no doubt that several of
the most strongly characterised domestic forms, if found wild, would
have been placed in at least five new genera. Thus a new genus would
have been formed for the reception of the improved English Pouter: a
second genus for Carriers and Runts; and this would have been a wide or
comprehensive genus, for it would have admitted common Spanish Runts
without any wattle, short-beaked Runts like the Tronfo, and the
improved English Carrier: a third genus would have been formed for the
Barb: a fourth for the Fantail: and lastly, a fifth for the short
beaked, not-wattled pigeons, such as Turbits and short-faced Tumblers.
The remaining domestic forms might have been included, in the same
genus with the wild rock-pigeon.

_Individual Variability; variations of a remarkable nature._

The differences which we have as yet considered are characteristic of
distinct breeds; but there are other differences, either confined to
individual birds, or often observed in certain breeds but not
characteristic of them. These individual differences are of importance,
as they might in most cases be secured and accumulated by man’s power
of selection and thus an existing breed might be greatly modified or a
new one formed. Fanciers notice and select only those slight
differences which are externally visible; but the whole organisation is
so tied together by correlation of growth, that a change in one part is
frequently accompanied by other changes. For our purpose, modifications
of all kinds are equally important, and if affecting a part which does
not commonly vary, are of more importance than a modification in some
conspicuous part. At the present day any visible deviation of character
in a well-established breed is rejected as a blemish; but it by no
means follows that at an early period, before well-marked breeds had
been formed, such deviations would have been rejected; on the contrary,
they would have been eagerly preserved as presenting a novelty, and
would then have been slowly augmented, as we shall hereafter more
clearly see, by the process of unconscious selection.

    I have made numerous measurements of the various parts of the body
    in the several breeds, and have hardly ever found them quite the
    same in birds of the same breed,—the differences being greater than
    we commonly meet with in wild species within the same district. To
    begin with the primary feathers of the wing and tail; but I must
    first mention, as some readers may not be aware of the fact, that
    the number of the primary wing and tail-feathers in wild birds is
    generally constant, and characterises, not only whole genera, but
    even whole families. When the tail-feathers are unusually numerous,
    as for instance in the swan, they are apt to be variable in number;
    but this does not apply to the several species and genera of the
    Columbidæ, which never (as far as I can hear) have less than twelve
    or more than sixteen tail-feathers; and these numbers characterise,
    with rare exception, whole sub-families.[27] The wild rock-pigeon
    has twelve tail-feathers. With Fantails, as we have seen, the
    number varies from fourteen to forty-two. In two young birds in the
    same nest I counted twenty-two and twenty-seven feathers. Pouters
    are very liable to have additional tail-feathers, and I have seen
    on several occasions fourteen or fifteen in my own birds. Mr. Bult
    had a specimen, examined by Mr. Yarrell, with seventeen
    tail-feathers. I had a Nun with thirteen, and another with fourteen
    tail-feathers; and in a Helmet, a breed barely distinguishable from
    the Nun, I have counted fifteen, and have heard of other such
    instances. On the other hand, Mr. Brent possessed a Dragon, which
    during its whole life never had more than ten tail-feathers; and
    one of my Dragons, descended from Mr. Brent’s, had only eleven. I
    have seen a Bald-head Tumbler with only ten; and Mr. Brent had an
    Air-Tumbler with the same number, but another with fourteen
    tail-feathers. Two of these latter Tumblers, bred by Mr. Brent,
    were remarkable,—one from having the two central tail-feathers a
    little divergent, and the other from having the two outer feathers
    longer by three-eighths of an inch than the others; so that in both
    cases the tail exhibited a tendency, but in different ways, to
    become forked. And this shows us how a swallow-tailed breed, like
    that described by Bechstein, might have been formed by careful
    selection.

With respect to the primary wing-feathers, the number in the Columbidæ,
as far as I can find out, is always nine or ten. In the rock-pigeon it
is ten; but I have seen no less than eight short-faced Tumblers with
only nine primaries, and the occurrence of this number has been noticed
by fanciers, owing to ten primaries of a white colour being one of the
points in Short-faced Bald-head-Tumblers. Mr. Brent, however, had an
Air-Tumbler (not short-faced) which had in both wings eleven primaries.
Mr. Corker, the eminent breeder of prize Carriers, assures me that some
of his birds had eleven primaries in both wings. I have seen eleven in
one wing in two Pouters. I have been assured by three fanciers that
they have seen twelve in Scanderoons; but as Neumeister asserts that in
the allied Florence Runt the middle flight-feather is often double, the
number twelve may have been caused by two of the ten primaries having
each two shafts to a single feather. The secondary wing-feathers are
difficult to count, but the number seems to vary from twelve to
fifteen. The length of the wing and tail relatively to the body, and of
the wings to the tail, certainly varies; I have especially noticed this
in Jacobins. In Mr. Bult’s magnificent collection of Pouters, the wings
and tail varied greatly in length; and were sometimes so much elongated
that the birds could hardly play upright. In the relative length of the
few first primaries I have observed only a slight degree of
variability. Mr. Brent informs me that he has observed the shape of the
first feather to vary very slightly. But the variation in these latter
points is extremely slight compared with the differences which may be
observed in the natural species of the Columbidæ.

In the beak I have seen very considerable differences in birds of the
same breed, as in carefully bred Jacobins and Trumpeters. In Carriers
there is often a conspicuous difference in the degree of attenuation
and curvature of the beak. So it is indeed in many breeds: thus I had
two strains of black Barbs, which evidently differed in the curvature
of the upper mandible. In width of mouth I have found a great
difference in two Swallows. In Fantails of first-rate merit I have seen
some birds with much longer and thinner necks than in others. Other
analogous facts could be given. We have seen that the oil-gland is
aborted in all Fantails (with the exception of the sub-race from Java),
and, I may add, so hereditary is this tendency to abortion, that some,
although not all, of the mongrels which I reared from the Fantail and
Pouter had no oil-gland; in one Swallow out of many which I have
examined, and in two Nuns, there was no oil-gland.

    The number of the scutellæ on the toes often varies in the same
    breed, and sometimes even differs on the two feet of the same
    individual; the Shetland rock-pigeon has fifteen on the middle, and
    six on the hinder toe; whereas I have seen a Runt with sixteen on
    the middle and eight on the hind toe; and a short-faced Tumbler
    with only twelve and five on these same toes. The rock-pigeon has
    no sensible amount of skin between its toes; but I possessed a Spot
    and a Nun with the skin extending for a space of a quarter of an
    inch from the fork, between the two _ inner_ toes. On the other
    hand, as will hereafter be more fully shown, pigeons with feathered
    feet very generally have the bases of their _outer_ toes connected
    by skin. I had a red Tumbler, which had a coo unlike that of its
    fellows, approaching in tone to that of the Laugher: this bird had
    the habit, to a degree which I never saw equalled in any other
    pigeon, of often walking with its wings raised and arched in an
    elegant-manner. I need say nothing on the great variability, in
    almost every breed, in size of body, in colour, in the feathering
    of the feet, and in the feathers on the back of the head being
    reversed. But I may mention a remarkable Tumbler[28] exhibited at
    the Crystal Palace, which had an irregular crest of feathers on its
    head, somewhat like the tuft on the head of the Polish fowl. Mr.
    Bult reared a hen Jacobin with the feathers on the thigh so long as
    to reach the ground, and a cock having, but in a lesser degree, the
    same peculiarity: from these two birds he bred others similarly
    characterised, which were exhibited at the Philoperisteron Soc. I
    bred a mongrel pigeon which had fibrous feathers, and the wing and
    tail-feathers so short and imperfect that the bird could not fly
    even a foot in height.

    There are many singular and inherited peculiarities in the plumage
    of pigeons: thus Almond-Tumblers do not acquire their perfect
    mottled feathers until they have moulted three or four times: the
    Kite Tumbler is at first brindled black and red with a barred
    appearance, but when “it throws its nest feathers it becomes almost
    black, generally with a bluish tail, and a reddish colour on the
    inner webs of the primary wing-feathers.”[29] Neumeister describes
    a breed of a black colour with white bars on the wing and a white
    crescent-shaped mark on the breast; these marks are generally
    rusty-red before the first moult, but after the third or fourth
    moult they undergo a change; the wing-feathers and the crown of the
    head likewise then become white or grey.[30]

    It is an important fact, and I believe there is hardly an exception
    to the rule, that the especial characters for which each breed is
    valued are eminently variable: thus, in the Fantail, the number and
    direction of the tail-feathers, the carriage of the body, and the
    degree of trembling are all highly variable points; in Pouters, the
    degree to which they pout, and the shape of their inflated crops;
    in the Carrier, the length, narrowness, and curvature of the beak,
    and the amount of wattle; in Short-faced Tumblers, the shortness of
    the beak, the prominence of the forehead, and general carriage,[31]
    and in the Almond-Tumbler the colour of the plumage; in common
    Tumblers, the manner of tumbling; in the Barb, the breadth and
    shortness of the beak and the amount of eye-wattle; in Runts, the
    size of body; in Turbits the frill; and lastly in Trumpeters, the
    cooing, as well as the size of the tuft of feathers over the
    nostrils. These, which are the distinctive and selected characters
    of the several breeds, are all eminently variable.

    There is another interesting fact with respect to the characters of
    the several breeds, namely, that they are often most strongly
    displayed in the male bird. In Carriers, when the males and females
    are exhibited in separate pens, the wattle is plainly seen to be
    much more developed in the males, though I have seen a hen Carrier
    belonging to Mr. Haynes heavily wattled. Mr. Tegetmeier informs me
    that, in twenty Barbs in Mr. P. H. Jones’s possession, the males
    had generally the largest eye-wattles; Mr. Esquilant also believes
    in this rule, but Mr. H. Weir, a first-rate judge, entertains some
    doubt on the subject. Male Pouters distend their crops to a much
    greater size than do the females; I have, however, seen a hen in
    the possession of Mr. Evans which pouted excellently; but this is
    an unusual circumstance. Mr. Harrison Weir, a successful breeder of
    prize Fantails, informs me that his male birds often have a greater
    number of tail-feathers than the females. Mr. Eaton asserts[32]
    that if a cock and hen Tumbler were of equal merit, the hen would
    be worth double the money; and as pigeons always pair, so that an
    equal number of both sexes is necessary for reproduction, this
    seems to show that high merit is rarer in the female than in the
    male. In the development of the frill in Turbits, of the hood in
    Jacobins, of the tuft in Trumpeters, of tumbling in Tumblers, there
    is no difference between the males and females. I may here add a
    rather different case, namely, the existence in France[33] of a
    wine-coloured variety of the Pouter, in which the male is generally
    chequered with black, whilst the female is never so chequered. Dr.
    Chapuis also remarks[34] that in certain light-coloured pigeons the
    males have their feathers striated with black, and these striæ
    increase in size at each moult, so that the male ultimately becomes
    spotted with black. With Carriers, the wattle, both on the beak and
    round the eyes, and with Barbs that round the eyes, goes on
    increasing with age. This augmentation of character with advancing
    age, and more especially the difference between the males and
    females in the above-mentioned several respects, are remarkable
    facts, for there is no sensible difference at any age between the
    two sexes in the aboriginal rock-pigeon; and not often any strongly
    marked difference throughout the family of the Columbidæ.[35]

_Osteological Characters._

In the skeletons of the various breeds there is much variability; and
though certain differences occur frequently, and others rarely, in
certain breeds, yet none can be said to be absolutely characteristic of
any breed. Considering that strongly-marked domestic races have been
formed chiefly by man’s selection, we ought not to expect to find great
and constant differences in the skeleton; for fanciers neither see, nor
do they care for, modifications of structure in the internal framework.
Nor ought we to expect changes in the skeletons from changed habits of
life; as every facility is given to the most distinct breeds to follow
the same habits, and the much modified races are never allowed to
wander abroad and procure their own food in various ways. Moreover, I
find, on comparing the skeletons of _Columba livia, oenas, palumbus,_
and _turtur_, which are ranked by all systematists in two or three
distinct though allied genera, that the differences are extremely
slight, certainly less than between the skeletons of some of the most
distinct domestic breeds. How far the skeleton of the wild rock-pigeon
is constant I have had no means of judging, as I have examined only
two.

Illustration: Fig. 24—Skulls of Pigeons, viewed laterally.

_Skull._—The individual bones, especially those at the base, do not
differ in shape. But the whole skull, in its proportions, outline, and
relative direction of the bones, differs greatly in some of the breeds,
as may be seen by comparing the figures of (A) the wild rock-pigeon,
(B) the Short-faced Tumbler, (C) the English Carrier, and (D) the
Bagadotten Carrier (of Neumeister), all drawn of the natural size and
viewed laterally. In the Carrier, besides the elongation of the bones
of the face, the space between the orbits is proportionally a little
narrower than in the rock-pigeon. In the Bagadotten the upper mandible
is remarkably arched, and the premaxillary bones are proportionally
broader. In the Short-faced Tumbler the skull is more globular: all the
bones of the face are much shortened, and the front of the skull and
descending nasal bones are almost perpendicular: the maxillo-jugal arch
and premaxillary bones form an almost straight line; the space between
the prominent edges of the eye-orbits is depressed. In the Barb the
premaxillary bones are much shortened, and their anterior portion is
thicker than in the rock-pigeon, as is the lower part of the nasal
bone. In two Nuns the ascending branches of the premaxillaries, near
their tips, were somewhat attenuated, and in these birds, as well as in
some others, for instance in the Spot, the occipital crest over the
foramen was considerably more prominent than in the rock-pigeon.

Illustration: Fig. 25—Lower jaws, seen from above.

Illustration: Fig. 26—Skull of Runt.

Illustration: Fig. 27—Lateral view of jaws.

In the lower jaw, the articular surface is proportionably smaller in
many breeds than in the rock-pigeon; and the vertical diameter, more
especially of the outer part of the articular surface, is considerably
shorter. May not this be accounted for by the lessened use of the jaws,
owing to nutritious food having been given during a long period to all
highly improved pigeons? In Runts, Carriers, and Barbs (and in a lesser
degree in several breeds), the whole side of the jaw near the articular
end is bent inwards in a highly remarkable manner; and the superior
margin of the ramus, beyond the middle, is reflexed in an equally
remarkable manner, as may be seen in fig. 25, in comparison with the
jaw of the rock-pigeon. This reflection of the upper margin of the
lower jaw is plainly connected with the singularly wide gape of the
mouth, as has been described in Runts, Carriers, and Barbs. The
reflection is well shown in fig. 26 of the head of a Runt seen from
above; here a wide open space may be observed on each side, between the
edges of the lower jaw and of the premaxillary bones. In the
rock-pigeon, and in several domestic breeds, the edges of the lower jaw
on each side come close up to the premaxillary bones, so that no open
space is left. The degree of downward curvature of the distal half of
the lower jaw also differs to an extraordinary degree in some breeds,
as may be seen in the drawings (fig. 27 A) of the rock-pigeon, (B) of
the Short-faced Tumbler, and (C) of the Bagadotten Carrier of
Neumeister. In some Runts the symphysis of the lower jaw is remarkably
solid. No one would readily have believed that jaws differing in the
several above-specified points so greatly could have belonged to the
same species.

    _Vertebræ._—All the breeds have twelve cervical vertebræ.[36] But
    in a Bussorah Carrier from India the twelfth vertebra carried a
    small rib, a quarter of an inch in length, with a perfect double
    articulation.

The _dorsal vertebræ_ are always eight. In the rock-pigeon all eight
bear ribs; the eighth rib being very thin, and the seventh having no
process. In Pouters all the ribs are extremely broad, eight bear ribs;
the eighth rib being very thin and the seventh having no process. In
Pouters all the ribs are extremely broad, and, in three out of four
skeletons examined by me, the eighth rib was twice or even thrice as
broad as in the rock-pigeon; and the seventh pair had distinct
processes. In many breeds there are only seven ribs, as in seven out of
eight skeletons of various Tumblers, and in several skeletons of
Fantails, Turbits and Nuns.>

In all these breeds the seventh pair was very small, and was destitute
of processes, in which respect it differed from the same rib in the
rock-pigeon. In one Tumbler, and in the Bussorah Carrier, even the
sixth pair had no process. The hypapophysis of the second dorsal
vertebra varies much in development; being sometimes (as in several,
but not all Tumblers) nearly as prominent as that of the third dorsal
vertebra; and the two hypapophyses together tend to form an ossified
arch. The development of the arch, formed by the hypapophyses of the
third and fourth dorsal vertebræ, also varies considerably, as does the
size of the hypapophysis of the fifth vertebra.

The rock-pigeon has twelve sacral vertebræ; but these vary in number,
relative size, and distinctness, in the different breeds. In Pouters,
with their elongated bodies, there are thirteen or even fourteen, and,
as we shall immediately see, an additional number of caudal vertebræ.
In Runts and Carriers there is generally the proper number, namely
twelve; but in one Runt, and in the Bussorah Carrier, there were only
eleven. In Tumblers there are either eleven, or twelve, or thirteen
sacral vertebræ.

The _caudal vertebræ_ are seven in number in the rock-pigeon. In
Fantails, which have their tails so largely developed, there are eight
or nine, and apparently in one case ten, and they are a little longer
than in the rock-pigeon, and their shape varies considerably. Pouters,
also, have eight or nine caudal vertebræ. I have seen eight in a Nun
and Jacobin. Tumblers, though such small birds, always have the normal
number seven; as have Carriers, with one exception, in which there were
only six.

The following table will serve as a summary, and will show the most
remarkable deviations in the number of the vertebra and ribs which I
have observed:—

                 Rock Pigeon.     Pouter, from Mr. Bult.     Tumbler,
                 Dutch Roller.     Bussorah Carrier. Cervical
                 Vertebræ     12     12     12     12
          The 12th bore a small rib. Dorsal Vertebræ       8       8      
          8       8 Dorsal Ribs       8
          The 6th pair with processes, the 7th pair without a
          process.       8
          The 6th and 7th pair with processes.       7
          The 6th and 7th pair without processes.       7
          The 6th and 7th pair without processes. Sacral
          Vertebræ     12     14     11     11 Caudal Vertebræ       7     8
          or 9       7       7 Total Vertebræ     39     42 or
          43     38     38

The _pelvis_ differs very little in any breed. The anterior margin of
the ilium, however, is sometimes a little more equally rounded on both
sides than in the rock-pigeon. The ischium is also frequently rather
more elongated. The obturator-notch is sometimes, as in many Tumblers,
less developed than in the rock-pigeon. The ridges on the ilium are
very prominent in most Runts.

Illustration: Fig. 28—Scapulæ of Pigeons.

Illustration: Fig. 29—Furcula of Pigeons.

In the bones of the extremities I could detect no difference, except in
their proportional lengths; for instance, the metatarsus in a Pouter
was 1·65 inch, and in a Short-faced Tumbler only ·95 in length; and
this is a greater difference than would naturally follow from their
differently-sized bodies; but long legs in the Pouter, and small feet
in the Tumbler, are selected points. In some Pouters the _scapula_ is
rather straighter, and in some Tumblers it is straighter, with the apex
less elongated, than in the rock-pigeon: in fig. 28, the scapula of the
rock-pigeon (A), and of a short-faced Tumbler (B), are given. The
processes at the summit of the _coracoid,_ which receive the
extremities of the furculum, form a more perfect cavity in some
Tumblers than in the rock-pigeon: in Pouters these processes are larger
and differently shaped, and the exterior angle of the extremity of the
coracoid, which is articulated to the sternum, is squarer.

The two arms of the _furculum_ in Pouters diverge less, proportionally
to their length, than in the rock-pigeon; and the symphysis is more
solid and pointed. In Fantails the degree of divergence of the two arms
varies in a remarkable manner. In fig. 29, B and C represent the
furcula of two Fantails; and it will be seen that the divergence in B
is rather less even than in the furculum of the short-faced,
small-sized Tumbler (A), whereas the divergence in C equals that in a
rock-pigeon, or in the Pouter (D), though the latter is a much larger
bird. The extremities of the furculum, where articulated to the
coracoids, vary considerably in outline.

In the _sternum_ the differences in form are slight, except in the size
and outline of the perforations, which, both in the larger and lesser
sized breeds, are sometimes small. These perforations, also, are
sometimes either nearly circular, or elongated as is often the case
with Carriers. The posterior perforations occasionally are not
complete, being left open posteriorly. The marginal apophyses forming
the anterior perforations vary greatly in development. The degree of
convexity of the posterior part of the sternum differs much, being
sometimes almost perfectly flat. The manubrium is rather more prominent
in some individuals than in others, and the pore immediately under it
varies greatly in size.

_Correlation of Growth._—By this term I mean that the whole
organisation is so connected, that when one part varies, other parts
vary; but which of two correlated variations ought to be looked at as
the cause and which as the effect, or whether both result from some
common cause, we can seldom or never tell. The point of interest for us
is that, when fanciers, by the continued selection of slight
variations, have largely modified one part, they often unintentionally
produce other modifications. For instance, the beak is readily acted on
by selection, and, with its increased or diminished length, the tongue
increases or diminishes, but not in due proportion; for, in a Barb and
Short-faced Tumbler, both of which have very short beaks, the tongue,
taking the rock-pigeon as the standard of comparison, was
proportionally not shortened enough, whilst in two Carriers and in a
Runt the tongue, proportionally with the beak, was not lengthened
enough, thus, in a first-rate English Carrier, in which the beak from
the tip to the feathered base was exactly thrice as long as in a
first-rate Short-faced Tumbler, the tongue was only a little more than
twice as long. But the tongue varies in length independently of the
beak: thus in a Carrier with a beak 1·2 inch in length, the tongue was
·67 in length: whilst in a Runt which equalled the Carrier in length of
body and in stretch of wings from tip to tip, the beak was ·92 whilst
the tongue was ·73 of an inch in length, so that the tongue was
actually longer than in the carrier with its long beak. The tongue of
the Runt was also very broad at the root. Of two Runts, one had its
beak longer by ·23 of an inch, whilst its tongue was shorter by ·14
than in the other.

With the increased or diminished length of the beak the length of the
slit forming the external orifice of the nostrils varies, but not in
due proportion, for, taking the rock-pigeon as the standard, the
orifice in a Short-faced Tumbler was not shortened in due proportion
with its very short beak. On the other hand (and this could not have
been anticipated), the orifice in three English Carriers, in the
Bagadotten Carrier, and in a Runt (_pigeon cygne_), was longer by above
the tenth of an inch than would follow from the length of the beak
proportionally with that of the rock-pigeon. In one Carrier the orifice
of the nostrils was thrice as long as in the rock-pigeon, though in
body and length of beak this bird was not nearly double the size of the
rock-pigeon. This greatly increased length of the orifice of the
nostrils seems to stand partly in correlation with the enlargement of
the wattled skin on the upper mandible and over the nostrils; and this
is a character which is selected by fanciers. So again, the broad,
naked, and wattled skin round the eyes of Carriers and Barbs is a
selected character; and in obvious correlation with this, the eyelids,
measured longitudinally, are proportionally more than double the length
of those of the rock-pigeon.

The great difference (see fig. 27) in the curvature of the lower jaw in
the rock-pigeon, the Tumbler, and Bagadotten Carrier, stands in obvious
relation to the curvature of the upper jaw, and more especially to the
angle formed by the maxillo-jugal arch with the premaxillary bones. But
in Carriers, Runts, and Barbs the singular reflexion of the upper
margin of the middle part of the lower jaw (see fig. 25) is not
strictly correlated with the width or divergence (as may be clearly
seen in fig. 26) of the premaxillary bones, but with the breadth of the
horny and soft parts of the upper mandible, which are always overlapped
by the edges of the lower mandible.

In Pouters, the elongation of the body is a selected character, and the
ribs, as we have seen, have generally become very broad, with the
seventh pair furnished with processes; the sacral and caudal vertebræ
have been augmented in number; the sternum has likewise increased in
length (but not in the depth of the crest) by ·4 of an inch more than
would follow from the greater bulk of the body in comparison with that
of the rock-pigeon. In Fantails, the length and number of the caudal
vertebræ have increased. Hence, during the gradual progress of
variation and selection, the internal bony framework and the external
shape of the body have been, to a certain extent, modified in a
correlated manner.

    Although the wings and tail often vary in length independently of
    each other, it is scarcely possible to doubt that they generally
    tend to become elongated or shortened in correlation. This is well
    seen in Jacobins, and still more plainly in Runts, some varieties
    of which have their wings and tail of great length, whilst others
    have both very short. With Jacobins, the remarkable length of the
    tail and wing-feathers is not a character which is intentionally
    selected by fanciers; but fanciers have been trying for centuries,
    at least since the year 1600, to increase the length of the
    reversed feathers on the neck, so that the hood may more completely
    enclose the head; and it may be suspected that the increased length
    of the wing and tail-feathers stand in correlation with the
    increased length of the neck-feathers. Short-faced Tumblers have
    short wings in nearly due proportion with the reduced size of their
    bodies; but it is remarkable, seeing that the number of the primary
    wing-feathers is a constant character in most birds, that these
    Tumblers generally have only nine instead of ten primaries. I have
    myself observed this in eight birds; and the Original Columbarian
    Society[37] reduced the standard for Bald-head Tumblers from ten to
    nine white flight-feathers, thinking it unfair that a bird which
    had only nine feathers should be disqualified for a prize because
    it had not ten _white_ flight-feathers. On the other hand, in
    Carriers and Runts, which have large bodies and long wings, eleven
    primary feathers have occasionally been observed.

Mr. Tegetmeier has informed me of a curious and inexplicable case of
correlation, namely, that young pigeons of all breeds which when mature
become white, yellow, silver (_i.e.,_ extremely pale blue), or
dun-coloured, are born almost naked; whereas pigeons of other colours
are born well-clothed with down. Mr. Esquilant, however, has observed
that young dun Carriers are not so bare as young dun Barbs and
Tumblers. Mr. Tegetmeier has seen two young birds in the same nest,
produced from differently coloured parents, which differed greatly in
the degree to which they were at first clothed with down.

I have observed another case of correlation which at first sight
appears quite inexplicable, but on which, as we shall see in a future
chapter, some light can be thrown by the law of homologous parts
varying in the same manner. The case is, that, when the feet are much
feathered, the roots of the feathers are connected by a web of skin,
and apparently in correlation with this the two outer toes become
connected for a considerable space by skin. I have observed this in
very many specimens of Pouters, Trumpeters, Swallows, Roller-tumblers
(likewise observed in this breed by Mr. Brent), and in a lesser degree
in other feather-footed pigeons.

The feet of the smaller and larger breeds are of course much smaller or
larger than those of the rock-pigeon; but the scutellæ or scales
covering the toes and tarsi have not only decreased or increased in
size, but likewise in number. To give a single instance, I have counted
eight scutellæ on the hind toe of a Runt, and only five on that of a
Short-faced Tumbler. With birds in a state of nature the number of the
scutellæ on the feet is usually a constant character. The length of the
feet and the length of the beak apparently stand in correlation; but as
disuse apparently has affected the size of the feet, this case may come
under the following discussion.

_On the Effects of Disuse._—In the following discussion on the relative
proportions of the feet, sternum, furculum, scapulæ, and wings, I may
premise, in order to give some confidence to the reader, that all my
measurements were made in the same manner, and that they were made
without the least intention of applying them to the following purpose.

Table I.
      _Pigeons with their beaks generally shorter than that of the
      Rock-pigeon, proportionally to the size of their bodies._

Name of Breed.     Actual
          length
          of Feet     Difference between
          actual and calculated
          length of feet, in
          proportion to length of
          feet and size of body
          in the Rock-pigeon. Wild rock-pigeon (mean
          measurement)     2·02     Too short
           by     Too long
          by Short-faced Tumbler, blad-head     1·57     0·11     —
          Short-faced Tumbler, almond     1·60     0·16     — Tumbler, red
          magpie     1·75     0·19     — Tumbler, red common (by standard
          to end of tail)     1·85     0·07     — Tumbler, common
          bald-head     1·85     0·18     — Tumbler,
          roller     1·80     0·06     — Turbit     1·75     0·17     —
          Turbit     1·80     0·01     — Turbit     1·84     0·15     —
          Jacobin     1·90     0·02     — Trumpeter,
          white     2·02     0·06     — Trumpeter,
          mottled     1·95     0·18     — Fantail (by standard to end of
          tail)     1·85     0·15     — Fantail (by standard to end of
          tail)     1·95     0·15     — Fantail crested va. (by standard
          to end of tail)     1·95     0·0       0·0 Indian Frill-back (by
          standard to end of tail)     1·80     0·19     — English
          Frill-back     2·10     0·03     — Nun     1·82     0·02     —
          Laugher     1·65     0·16     — Barb     2·00     0·03     —
          Barb     2·00     —     0·03 Spot     1·90     0·02     —
          Spot     1·90     0·07     — Swallow, red     1·85     0·18     —
          Swallow, blue     2·00     —     0·03
          Pouter     2·42     —     0·11 Pouter,
          German     2·30     —     0·09 Bussorah
          Carrier     2·17     —     0·09 Number of
          specimens     28     22     5

I measured most of the birds which came into my possession, from the
feathered _base_ of the beak (the length of beak itself being so
variable) to the end of the tail, and to the oil-gland, but
unfortunately (except in a few cases) not to the root of the tail; I
measured each bird from the extreme tip to tip of wing; and the length
of the terminal folded part of the wing, from the extremity of the
primaries to the joint of the radius. I measured the feet without the
claws, from the end of the middle toe to the end of the hind toe; and
the tarsus and middle toe together. I have taken in every case the mean
measurement of two wild rock-pigeons from the Shetland Islands, as the
standard of comparison. The following table shows the actual length of
the feet in each bird; and the difference between the length which the
feet ought to have had according to the size of body of each, in
comparison with the size of body and length of feet of the rock-pigeon,
calculated (with a few specified exceptions) by the standard of the
length of the body from the base of the beak to the oil-gland. I have
preferred this standard, owing to the variability of the length of
tail. But I have made similar calculations, taking as the standard the
length from tip to tip of wing, and likewise in most cases from the
base of the beak to the end of the tail; and the result has always been
closely similar. To give an example: the first bird in the table, being
a Short-faced Tumbler, is much smaller than the rock-pigeon, and would
naturally have shorter feet; but it is found on calculation to have
feet too short by ·11 of an inch, in comparison with the feet of the
rock-pigeon, relatively to the size of the body in these two birds, as
measured from the base of beak to the oil-gland. So again, when this
same Tumbler and the rock-pigeon were compared by the length of their
wings, or by the extreme length of their bodies, the feet of the
Tumbler were likewise found to be too short in very nearly the same
proportion. I am well aware that the measurements pretend to greater
accuracy than is possible, but it was less trouble to write down the
actual measurements given by the compasses in each case than an
approximation.

Table II.
      _Pigeons with their beaks longer than that of the Rock-pigeon,
      proportionally to the size of their bodies._

Name of Breed.     Actual
          length
          of
          Feet     Difference between
          actual and calculated
          length of feet, in
          proportion to length of
          feet and size of body
          in the Rock-pigeon. Wild rock-pigeon (mean
          measurement)     2·02     Too short
           by     Too long
          by Short-faced Tumbler, bald-head     1·57     0·11     —
          Carrier     2·60     —     0·31 Carrier     2·60     —     0·25
          Carrier     2·40     —     0·21 Carrier
          Dragon     2·25     —     0·06 Bagadotten
          Carrier     2·80     —     0·56 Scanderoon,
          white     2·80     —     0·37 Scanderoon, Pigeon
          cygne     2·85     —     0·29 Runt     2·75     —     0·27 Number
          of specimens     8     —     8

In these two tables (Tables I and II) we see in the first column the
actual length of the feet in thirty-six birds belonging to various
breeds, and in the two other columns we see by how much the feet are
too short or too long, according to the size of bird, in comparison
with the rock-pigeon. In the first table twenty-two specimens have
their feet too short, on an average by a little above the tenth of an
inch (viz. ·107); and five specimens have their feet on an average a
very little too long, namely, by ·07 of an inch. But some of these
latter cases can be explained; for instance, with Pouters the legs and
feet are selected for length, and thus any natural tendency to a
diminution in the length of the feet will have been counteracted. In
the Swallow and Barb, when the calculation was made on any standard of
comparison besides the one used (viz. length of body from base of beak
to oil-gland), the feet were found to be too small.

    In the second table we have eight birds, with their beaks much
    longer than in the rock-pigeon, both actually and proportionally
    with the size of body, and their feet are in an equally marked
    manner longer, namely, in proportion, on an average by ·29 of an
    inch. I should here state that in Table I there are a few partial
    exceptions to the beak being proportionally shorter than in the
    rock-pigeon: thus the beak of the English Frill-back is just
    perceptibly longer, and that of the Bussorah Carrier of the same
    length or slightly longer, than in the rock-pigeon. The beaks of
    Spots, Swallows, and Laughers are only a very little shorter, or of
    the same proportional length, but slenderer. Nevertheless, these
    two tables, taken conjointly, indicate pretty plainly some kind of
    correlation between the length of the beak and the size of the
    feet. Breeders of cattle and horses believe that there is an
    analogous connection between the length of the limbs and head; they
    assert that a race-horse with the head of a dray-horse, or a
    grey-hound with the head of a bulldog, would be a monstrous
    production. As fancy pigeons are generally kept in small aviaries,
    and are abundantly supplied with food, they must walk about much
    less than the wild rock-pigeon; and it may be admitted as highly
    probable that the reduction in the size of the feet in the
    twenty-two birds in the first table has been caused by disuse,[38]
    and that this reduction has acted by correlation on the beaks of
    the great majority of the birds in Table I. When, on the other
    hand, the beak has been much elongated by the continued selection
    of successive slight increments of length, the feet by correlation
    have likewise become much elongated in comparison with those of the
    wild rock-pigeon, notwithstanding their lessened use.

As I had taken measures from the end of the middle toe to the heel of
the tarsus in the rock-pigeon and in the above thirty-six birds, I have
made calculations analogous with those above given, and the result is
the same— namely, that in the short-beaked breeds, with equally few
exceptions as in the former case, the middle toe conjointly with the
tarsus has decreased in length; whereas in the long-beaked breeds it
has increased in length, though not quite so uniformly as in the former
case, for the leg, in some varieties of the Runt varies much in length.

As fancy pigeons are generally confined in aviaries of moderate size,
and as even when not confined they do not search for their own food,
they must during many generations have used their wings incomparably
less than the wild rock-pigeon. Hence it seemed to me probable that all
the parts of the skeleton subservient to flight would be found to be
reduced in size. With respect to the sternum, I have carefully measured
its extreme length in twelve birds of different breeds, and in two wild
rock-pigeons from the Shetland Islands. For the proportional comparison
I have tried three standards of measurement, with all twelve birds
namely, the length from the base of the beak to the oil-gland, to the
end of the tail, and from the extreme tip to tip of wings. The result
has been in each case nearly the same, the sternum being invariably
found to be shorter than in the wild rock-pigeon. I will give only a
single table, as calculated by the standard from the base of the beak
to the oil-gland; for the result in this case is nearly the mean
between the results obtained by the two other standards.

_Length of Sternum._

Name of Breed     Actual
          Length.
          Inches     Too
          short by Wild Rock-pigeon     2·55     — Wild
          Rock-pigeon     2·55     — Pied Scanderoon     2·80     0·60
          Bagadotten Carrier     2·80     0·17 Dragon     2·45     0·41
          Carrier     2·75     0·35 Short-faced Tumbler     2·05     0·28
          Barb     2·35     0·34 Nun     2·27     0·15 German
          Pouter     2·36     0·54 Jacobin     2·33     0·22 English
          Frill-back     2·40     0·43 Swallow     2·45     0·17

This table shows that in these twelve breeds the sternum is of an
average one-third of an inch (exactly ·332) shorter than in the
rock-pigeon, proportionally with the size of their bodies; so that the
sternum has been reduced by between one-seventh and one-eighth of its
entire length; and this is a considerable reduction.

I have also measured in twenty-one birds, including the above dozen,
the prominence of the crest of the sternum relatively to its length,
independently of the size of the body. In two of the twenty-one birds
the crest was prominent in the same relative degree as in the
rock-pigeon; in seven it was more prominent; but in five out of these
seven, namely, in a Fantail, two Scanderoons, and two English Carriers,
this greater prominence may to a certain extent be explained, as a
prominent breast is admired and selected by fanciers; in the remaining
twelve birds the prominence was less. Hence it follows that the crest
exhibits a slight, though uncertain, tendency to be reduced in
prominence in a greater degree than does the length of the sternum
relatively to the size of body, in comparison with the rock-pigeon.

I have measured the length of the scapula in nine different large and
small-sized breeds, and in all the scapula is proportionally shorter
(taking the same standard as before) than in the wild rock-pigeon. The
reduction in length on an average is very nearly one-fifth of an inch,
or about one-ninth of the length of the scapula in the rock-pigeon.

The arms of the furcula in all the specimens which I compared, diverged
less, proportionally with the size of body, than in the rock-pigeon;
and the whole furculum was proportionally shorter. Thus in a Runt,
which measured from tip to tip of wings 38½ inches, the furculum was
only a very little longer (with the arms hardly more divergent) than in
a rock-pigeon which measured from tip to tip 26½ inches. In a Barb,
which in all its measurements was a little larger than the same
rock-pigeon, the furculum was a quarter of an inch shorter. In a
Pouter, the furculum had not been lengthened proportionally with the
increased length of the body. In a Short-faced Tumbler, which measured
from tip to tip of wings 24 inches, therefore only 2½ inches less than
the rock-pigeon, the furculum was barely two-thirds of the length of
that of the rock-pigeon.

    We thus clearly see that the sternum, scapula, and furculum are all
    reduced in proportional length; but when we turn to the wings we
    find what at first appears a wholly different and unexpected
    result. I may here remark that I have not picked out specimens, but
    have used every measurement made by me. Taking the length from the
    base of beak to the end of the tail as the standard of comparison,
    I find that, out of thirty-five birds of various breeds,
    twenty-five have wings of greater, and ten have them of less
    proportional length, than in the rock-pigeon. But from the
    frequently correlated length of the tail and wing-feathers, it is
    better to take as the standard of comparison the length from the
    base of the beak to the oil-gland; and by this standard, out of
    twenty-six of the same birds which had been thus measured,
    twenty-one had wings too long, and only five had them too short. In
    the twenty-one birds the wings exceeded in length those of the
    rock-pigeon, on an average, by 1-1/3 inch; whilst in the five birds
    they were less in length by only ·8 of an inch. As I was much
    surprised that the wings of closely confined birds should thus so
    frequently have been increased in length, it occurred to me that it
    might be solely due to the greater length of the wing-feathers; for
    this certainly is the case with the Jacobin, which has wings of
    unusual length. As in almost every case I had measured the folded
    wings, I subtracted the length of this terminal part from that of
    the expanded wings, and thus I obtained, with a moderate degree of
    accuracy, the length of the wings from the ends of the two radii,
    answering from wrist to wrist in our arms. The wings, thus measured
    in the same twenty-five birds, now gave a widely different result;
    for they were proportionally with those of the rock-pigeon too
    short in seventeen birds, and in only eight too long. Of these
    eight birds, five were long-beaked,[39] and this fact perhaps
    indicates that there is some correlation of the length of the beak
    with the length of the bones of the wings, in the same manner as
    with that of the feet and tarsi. The shortening of the humerus and
    radius in the seventeen birds may probably be attributed to disuse,
    as in the case of the scapula and furculum to which the wing-bones
    are attached;—the lengthening of the wing-feathers, and
    consequently the expansion of the wings from tip to tip, being, on
    the other hand, as completely independent of use and disuse as is
    the growth of the hair or wool on our long-haired dogs or
    long-woolled sheep.

To sum up: we may confidently admit that the length of the sternum, and
frequently the prominence of its crest, the length of the scapula and
furculum, have all been reduced in size in comparison with the same
parts in the rock-pigeon. And I presume that this may be attributed to
disuse or lessened exercise. The wings, as measured from the ends of
the radii, have likewise been generally reduced in length; but, owing
to the increased growth of the wing-feathers, the wings, from tip to
tip, are commonly longer than in the rock-pigeon. The feet, as well as
the tarsi conjointly with the middle toe, have likewise in most cases
become reduced; and this it is probable has been caused by their
lessened use; but the existence of some sort of correlation between the
feet and beak is shown more plainly than the effects of disuse. We have
also some faint indication of a similar correlation between the main
bones of the wing and the beak.

_Summary on the Points of Difference between the several Domestic
Races, and between the individual Birds._—The beak, together with the
bones of the face, differ remarkably in length, breadth, shape, and
curvature. The skull differs in shape, and greatly in the angle formed
by the union of the pre-maxillary, nasal, and maxillo-jugal bones. The
curvature of the lower jaw and the reflection of its upper margin, as
well as the gape of the mouth, differ in a highly remarkable manner.
The tongue varies much in length, both independently and in correlation
with the length of the beak. The development of the naked, wattled skin
over the nostrils and round the eyes varies in an extreme degree. The
eyelids and the external orifices of the nostrils vary in length, and
are to a certain extent correlated with the degree of development of
the wattle. The size and form of the œsophagus and crop, and their
capacity for inflation, differ immensely. The length of the neck
varies. With the varying shape of the body, the breadth and number of
the ribs, the presence of processes, the number of the sacral vertebræ,
and the length of the sternum, all vary. The number and size of the
coccygeal vertebræ vary, apparently in correlation with the increased
size of the tail. The size and shape of the perforations in the
sternum, and the size and divergence of the arms of the furculum,
differ. The oil-gland varies in development, and is sometimes quite
aborted. The direction and length of certain feathers have been much
modified, as in the hood of the Jacobin and the frill of the Turbit.
The wing and tail-feathers generally vary in length together, but
sometimes independently of each other and of the size of the body. The
number and position of the tail-feather vary to an unparalleled degree.
The primary and secondary wing-feathers occasionally vary in number,
apparently in correlation with the length of the wing. The length of
the leg and the size of the feet, and, in connection with the latter,
the number of the scutellæ, all vary. A web of skin sometimes connects
the bases of the two inner toes, and almost invariably the two outer
toes when the feet are feathered.

    The size of the body differs greatly: a Runt has been known to
    weigh more than five times as much as a Short-faced Tumbler. The
    eggs differ in size and shape. According to Parmentier,[40] some
    races use much straw in building their nests, and others use
    little; but I cannot hear of any recent corroboration of this
    statement. The length of time required for hatching the eggs is
    uniform in all the breeds. The period at which the characteristic
    plumage of some breeds is acquired, and at which certain changes of
    colour supervene, differs. The degree to which the young birds are
    clothed with down when first hatched is different, and is
    correlated in a singular manner with the colour of the plumage. The
    manner of flight, and certain inherited movements, such as clapping
    the wings, tumbling either in the air or on the ground, and the
    manner of courting the female, present the most singular
    differences. In disposition the several races differ. Some races
    are very silent; others coo in a highly peculiar manner.

    Although many different races have kept true in character during
    several centuries, as we shall hereafter more fully see, yet there
    is far more individual variability in the most constant breeds than
    in birds in a state of nature. There is hardly any exception to the
    rule that those characters vary most which are now most valued and
    attended to by fanciers, and which consequently are now being
    improved by continued selection. This is indirectly admitted by
    fanciers when they complain that it is much more difficult to breed
    high fancy pigeons up to the proper standard of excellence than the
    so-called toy pigeons, which differ from each other merely in
    colour; for particular colours when once acquired are not liable to
    continued improvement or augmentation. Some characters become
    attached, from quite unknown causes, more strongly to the male than
    to the female sex; so that we have in certain races, a tendency
    towards the appearance of secondary sexual characters,[41] of which
    the aboriginal rock-pigeon displays not a trace.

REFERENCES

 [1] The Hon. C. Murray has sent me some very valuable specimens from
 Persia; and H.M. Consul, Mr. Keith Abbott, has given me information on
 the pigeons of the same country. I am deeply indebted to Sir Walter
 Elliot for an immense collection of skins from Madras, with much
 information regarding them. Mr. Blyth has freely communicated to me
 his stores of knowledge on this and all other related subjects. The
 Rajah Sir James Brooke sent me specimens from Borneo, as has H.M.
 Consul, Mr. Swinhoe, from Amoy in China, and Dr. Daniell from the west
 coast of Africa.

 [2] Mr. B. P. Brent, well known for his various contributions to
 poultry literature, has aided me in every way during several years: so
 has Mr. Tegetmeier, with unwearied kindness. This latter gentleman,
 who is well known for his works on poultry, and who has largely bred
 pigeons, has looked over this and the following chapters. Mr. Bult
 formerly showed me his unrivalled collection of Pouters, and gave me
 specimens. I had access to Mr. Wicking’s collection, which contained a
 greater assortment of kinds than could anywhere else be seen; and he
 has always aided me with specimens and information given in the freest
 manner. Mr. Haynes and Mr. Corker have given me specimens of their
 magnificent Carriers. To Mr. Harrison Weir I am likewise indebted. Nor
 must I by any means pass over the assistance received from Mr. J. M.
 Eaton, Mr. Baker, Mr. Evans, and Mr. J. Baily, jun., of
 Mount-street—to the latter gentleman I have been indebted for some
 valuable specimens. To all these gentlemen I beg permission to return
 my sincere and cordial thanks.

 [3] ‘Les Pigeons de Volière et de Colombier’ Paris 1824. During
 forty-five years the sole occupation of M. Corbié was the care of the
 pigeons belonging to the Duchess of Berry. Bonizzi has described a
 large number of coloured varieties in Italy: ‘Le variazioni dei
 colombi Domestici,’ Padova, 1873.

 [4] ‘Coup d’Oeil sur l’Ordre des Pigeons’ par Prince C. L. Bonaparte,
 Paris, 1855. This author makes 288 species, ranked under 85 genera.

 [5] As I so often refer to the size of the _C. livia,_ or rock-pigeon,
 it may be convenient to give the mean between the measurements of two
 wild birds, kindly sent me by Dr. Edmondstone from the Shetland
 Islands.

      Inches From feathered base of beak to end of tail:     14·25 From
      feathered base of beak to oil-gland:     9·50 From tip of beak to
      end of tail:     15·02 Of tail-feathers:     4·62 From tip to tip of
      wing:     26·75 Of folded wing:     9·25 Beak: Length from tip of
      beak to feathered base:     ·77 Thickness, measured vertically at
      distal end of nostrils:     ·23 Breadth, measured at same
      place:     ·16 Feet: From end of middle toe (without claw) to
      distal end of tibia:     2·77 From end of middle toe to end of hind
      toe (without claws):     2·02 Weight: 14-1/4 ounces.

 [6] This drawing was made from a dead bird. The six following figures
 were drawn with great care by Mr. Luke Wells from living birds
 selected by Mr. Tegetmeier. It may be confidently asserted that the
 characters of the six breeds which have been figured are not in the
 least exaggerated.

 [7] ‘Das Ganze der Taubenzucht:’ Weimar, 1837, pl. 11 and 12.

 [8] Boitard and Corbié, ‘Les Pigeons,’ etc., p. 177, pl. 6.

 [9] ‘Die Taubenzucht,’ Ulm, 1824, s. 42.

 [10] This treatise was written by Sayzid Mohammed Musari, who died in
 1770: I owe to the great kindness of Sir W. Elliot a translation of
 this curious treatise.

 [11] ‘Poultry Chronicle,’ vol. 2, p. 573.

 [12] ‘Annals and Mag. of Nat. History,’ vol. xix, 1847, p. 105.

 [13] This gland occurs in most birds; but Nitzsch (in his
 ‘Pterylographie,’ 1840, p. 55) states that it is absent in two species
 of Columba, in several species of Psittacus, in some species of Otis,
 and in most or all birds of the Ostrich family. It can hardly be an
 accidental coincidence that the two species of Columba, which are
 destitute of an oil-gland, have an unusual number of tail-feathers,
 namely 16, and in this respect resemble Fantails.

 [14] _See_ the two excellent editions published by Mr. J. M. Eaton in
 1852 and 1858, entitled ‘A Treatise on Fancy Pigeons.’

 [15] English translation, by F. Gladwin, 4th edition, vol. i. The
 habit of the Lotan is also described in the Persian treatise before
 alluded to, published about 100 years ago: at this date the Lotans
 were generally white and crested as at present. Mr. Blyth describes
 these birds in ‘Annals and Mag. of Nat. Hist.,’ vol. xiv., 1847, p.
 104; he says that they “may be seen at any of the Calcutta
 bird-dealers.”

 [16] ‘Journal of Horticulture,’ Oct. 22, 1861, p. 76.

 [17] _See_ the account of the House-tumblers kept at Glasgow, in the
 ‘Cottage Gardener,’ 1858, p. 285. Also Mr. Brent’s paper, ‘Journal of
 Horticulture,’ 1861, p. 76.

 [18] J. M. Eaton, ‘Treatise on Pigeons,’ 1852, p. 9.

 [19] J. M. Eaton, ‘Treatise,’ edit. 1858, p. 76.

 [20] Neumeister, ‘Taubenzucht,’ tab. 4. fig. i.

 [21] Riedel, ‘Die Taubenzucht,’ 1824, s. 26. Bechstein,
 ‘Naturgeschichte Deutschlands,’ Band iv. s. 36, 1795.

 [22] Willughby’s ‘Ornithology,’ edited by Ray.

 [23] J. M. Eaton’s edition (1858) of Moore, p. 98.

 [24] Pigeon pattu plongeur. ‘Les Pigeons,’ etc., p. 165.

 [25] ‘Naturgeschichte Deutschlands,’ Band iv. s. 47.

 [26] Mr. W. B. Tegetmeier, ‘Journal of Horticulture,’ Jan. 20, 1863,
 p. 58.

 [27] ‘Coup-d’œil sur L’Ordre des Pigeons,’ par C. L. Bonaparte
 (‘Comptes Rendus’), 1854-55. Mr. Blyth, in ‘Annals of Nat. Hist.,’
 vol. xix., 1847, p. 41, mentions, as a very singular fact, “that of
 the two species of Ectopistes, which are nearly allied to each other,
 one should have fourteen tail-feathers, while the other, the passenger
 pigeon of North America, should possess but the usual number—twelve.”

 [28] Described and figured in the ‘Poultry Chronicle,’ vol. iii.,
 1855, p. 82.

 [29] ‘The Pigeon Book,’ by Mr. B. P. Brent, 1859, p. 41.

 [30] ‘Die staarhälsige Taube. Das Ganze, etc.,’ s. 21, tab. i. fig. 4.

 [31] ‘A Treatise on the Almond-Tumbler,’ by J. M. Eaton, 1852, p. 8,
 _et passim._

 [32] ‘A Treatise, etc.,’ p. 10.

 [33] Boitard and Corbié ‘Les Pigeons,’ etc., 1824, p. 173.

 [34] ‘Le Pigeon Voyageur Belge,’ 1865, p. 87. I have given in my
 ‘Descent of Man’ (6th edit. p. 466) some curious cases, on the
 authority of Mr. Tegetmeier, of silver-coloured (_i.e._ very pale
 blue) birds being generally females, and of the ease with which a race
 thus characterised could be produced. Bonizzi (_see_ ‘Variazioni dei
 Columbi domestici:’ Padova, 1873) states that certain coloured spots
 are often different in the two sexes, and the certain tints are
 commoner in females than in male pigeons.

 [35] Prof. A. Newton (‘Proc. Zoolog. Soc.,’ 1865, p. 716) remarks that
 he knows no species which present any remarkable sexual distinction;
 but Mr. Wallace informs me, that in the sub-family of the Treronidæ
 the sexes often differ considerably in colour. _See also_ on sexual
 differences in the Columbidæ, Gould, ‘Handbook to the Birds of
 Australia,’ vol. ii., pp. 109-149.

 [36] I am not sure that I have designated the different kinds of
 vertebræ correctly: but I observe that different anatomists follow in
 this respect different rules, and, as I use the same terms in the
 comparison of all the skeletons, this, I hope, will not signify.

 [37] J. M. Eaton’s ‘Treatise,’ edit. 1858, p. 78.

 [38] In an analogous, but converse, manner, certain natural groups of
 the Columbidæ, from being more terrestrial in their habits than other
 allied groups, have larger feet. _See_ Prince Bonaparte’s ‘Coup d’œil
 sur l’Ordre des Pigeons.’

 [39] It perhaps deserves notice that besides these five birds two of
 the eight were Barbs, which, as I have shown, must be classed in the
 same group with the long-beaked Carriers and Runts. Barbs may properly
 be called short-beaked Carriers. It would, therefore, appear as if,
 during the reduction of their beaks, their wings had retained a little
 of that excess of length which is characteristic of their nearest
 relations and progenitors.

 [40] Temminck, ‘Hist. Nat. Gén. des Pigeons et des Gallinacés,’ tom.
 i., 1813, p. 170.

 [41] This term was used by John Hunter for such differences in
 structure between the males and females, as are not directly connected
 with the act of reproduction, as the tail of the peacock, the horns of
 deer, etc.




CHAPTER VI. PIGEONS—_continued._

ON THE ABORIGINAL PARENT-STOCK OF THE SEVERAL DOMESTIC RACES—HABITS OF
LIFE—WILD RACES OF THE ROCK-PIGEON—Dovecot-PIGEONS—PROOFS OF THE
DESCENT OF THE SEVERAL RACES FROM COLUMBA LIVIA—FERTILITY OF THE RACES
WHEN CROSSED—REVERSION TO THE PLUMAGE OF THE WILD
ROCK-PIGEON—CIRCUMSTANCES FAVOURABLE TO THE FORMATION OF THE
RACES—ANTIQUITY AND HISTORY OF THE PRINCIPAL RACES—MANNER OF THEIR
FORMATION—SELECTION—UNCONSCIOUS SELECTION—CARE TAKEN BY FANCIERS IN
SELECTING THEIR BIRDS—SLIGHTLY DIFFERENT STRAINS GRADUALLY CHANGE INTO
WELL-MARKED BREEDS—EXTINCTION OF INTERMEDIATE FORMS—CERTAIN BREEDS
REMAIN PERMANENT, WHILST OTHERS CHANGE—SUMMARY.


The differences described in the last chapter between the eleven chief
domestic races and between individual birds of the same race, would be
of little significance, if they had not all descended from a single
wild stock. The question of their origin is therefore of fundamental
importance, and must be discussed at considerable length. No one will
think this superfluous who considers the great amount of difference
between the races, who knows how ancient many of them are, and how
truly they breed at the present day. Fanciers almost unanimously
believe that the different races are descended from several wild
stocks, whereas most naturalists believe that all are descended from
the Columba livia or rock-pigeon.

    Temminck[1] has well observed, and Mr. Gould has made the same
    remark to me, that the aboriginal parent must have been a species
    which roosted and built its nest on rocks; and I may add that it
    must have been a social bird. For all the domestic races are highly
    social, and none are known to build or habitually to roost on
    trees. The awkward manner in which some pigeons, kept by me in a
    summer-house near an old walnut-tree, occasionally alighted on the
    barer branches, was evident.[2] Nevertheless, Mr. R. Scot Skirving
    informs me that he often saw crowds of pigeons in Upper Egypt
    settling on low trees, but not on palms, in preference to alighting
    on the mud hovels of the natives. In India Mr. Blyth[3] has been
    assured that the wild _C. livia,_ var. _intermedia,_ sometimes
    roosts in trees. I may here give a curious instance of compulsion
    leading to changed habits: the banks of the Nile above lat. 28° 30′
    are perpendicular for a long distance, so that when the river is
    full the pigeons cannot alight on the shore to drink, and Mr.
    Skirving repeatedly saw whole flocks settle on the water, and drink
    whilst they floated down the stream. These flocks seen from a
    distance resembled flocks of gulls on the surface of the sea.

    If any domestic race had descended from a species which was not
    social, or which built its nest and roosted in trees,[4] the sharp
    eyes of fanciers would assuredly have detected some vestige of so
    different an aboriginal habit. For we have reason to believe that
    aboriginal habits are long retained under domestication. Thus with
    the common ass we see signs of its original desert life in its
    strong dislike to cross the smallest stream of water, and in its
    pleasure in rolling in the dust. The same strong dislike to cross a
    stream is common to the camel, which has been domesticated from a
    very ancient period. Young pigs, though so tame, sometimes squat
    when frightened, and thus try to conceal themselves even on an open
    and bare place. Young turkeys, and occasionally even young fowls,
    when the hen gives the danger-cry, run away and try to hide
    themselves, like young partridges or pheasants, in order that their
    mother may take flight, of which she has lost the power. The
    musk-duck (_Cairina moschata_) in its native country often perches
    and roosts on trees,[5] and our domesticated musk-ducks, though
    such sluggish birds, “are fond of perching on the tops of barns,
    walls, etc., and, if allowed to spend the night in the hen-house,
    the female will generally go to roost by the side of the hens, but
    the drake is too heavy to mount thither with ease.”[6] We know that
    the dog, however well and regularly fed, often buries, like the
    fox, any superfluous food; and we see him turning round and round
    on a carpet, as if to trample down grass to form a bed; we see him
    on bare pavements scratching backwards as if to throw earth over
    his excrement, although, as I believe, this is never effected even
    where there is earth. In the delight with which lambs and kids
    crowd together and frisk on the smallest hillock, we see a vestige
    of their former alpine habits.

We have therefore good reason to believe that all the domestic races of
the pigeon are descended either from some one or from several species
which both roosted and built their nests on rocks, and were social in
disposition. As only five or six wild species have these habits, and
make any near approach in structure to the domesticated pigeon, I will
enumerate them.

    Firstly, the _Columba leuconota_ resembles certain domestic
    varieties in its plumage, with the one marked and never-failing
    difference of a white band which crosses the tail at some distance
    from the extremity. This species, moreover, inhabits the Himalaya,
    close to the limit of perpetual snow; and therefore, as Mr. Blyth
    has remarked, is not likely to have been the parent of our domestic
    breeds, which thrive in the hottest countries. Secondly, the _C.
    rupestris,_ of Central Asia, which is intermediate[7] between the
    _C. leuconota_ and _livia_; but has nearly the same coloured tail
    as the former species. Thirdly, the _ Columba littoralis_ builds
    and roosts, according to Temminck, on rocks in the Malayan
    archipelago; it is white, excepting parts of the wing and the tip
    of the tail, which are black; its legs are livid-coloured, and this
    is a character not observed in any adult domestic pigeon; but I
    need not have mentioned this species or the closely-allied _C.
    luctuosa,_ as they in fact belong to the genus Carpophaga.
    Fourthly, _Columba guinea,_ which ranges from Guinea[8] to the Cape
    of Good Hope, and roosts either on trees or rocks, according to the
    nature of the country. This species belongs to the genus
    Strictoenas of Reichenbach, but is closely allied to Columba; it is
    to some extent coloured like certain domestic races, and has been
    said to be domesticated in Abyssinia; but Mr. Mansfield Parkyns,
    who collected the birds of that country and knows the species,
    informs me that this is a mistake. Moreover, the _C. guinea_ is
    characterised by the feathers of the neck having peculiar notched
    tips,—a character not observed in any domestic race. Fifthly, the _
    Columba œnas_ of Europe, which roosts on trees, and builds its nest
    in holes, either in trees or the ground; this species, as far as
    external characters go, might be the parent of several domestic
    races; but, though it crosses readily with the true rock-pigeon,
    the offspring, as we shall presently see, are sterile hybrids, and
    of such sterility there is not a trace when the domestic races are
    intercrossed. It should also be observed that if we were to admit,
    against all probability, that any of the foregoing five or six
    species were the parents of some of our domestic pigeons, not the
    least light would be thrown on the chief differences between the
    eleven most strongly-marked races.

    We now come to the best known rock-pigeon, the _Columba livia,_
    which is often designated in Europe pre-eminently as the
    Rock-pigeon, and which naturalists believe to be the parent of all
    the domesticated breeds. This bird agrees in every essential
    character with the breeds which have been only slightly modified.
    It differs from all other species in being of a slaty-blue colour,
    with two black bars on the wings, and with the croup (or loins)
    white. Occasionally birds are seen in Faroe and the Hebrides with
    the black bars replaced by two or three black spots; this form has
    been named by Brehm[9] _C. amaliæ,_ but this species has not been
    admitted as distinct by other ornithologists. Graba[10] even found
    a difference in the bars on the right and left wings of the same
    bird in Faroe. Another and rather more distinct form is either
    truly wild or has become feral on the cliffs of England and was
    doubtfully named by Mr. Blyth[11] as _C. affinis,_ but is now no
    longer considered by him as a distinct species. _C. affinis_ is
    rather smaller than the rock-pigeon of the Scottish islands, and
    has a very different appearance owing to the wing-coverts being
    chequered with black, with similar marks often extending over the
    back. The chequering consists of a large black spot on the two
    sides, but chiefly on the outer side, of each feather. The
    wing-bars in the true rock-pigeon and in the chequered variety are,
    in fact, due to similar though larger spots symmetrically crossing
    the secondary wing-feather and the larger coverts. Hence the
    chequering arises merely from an extension of these marks to other
    parts of the plumage. Chequered birds are not confined to the
    coasts of England; for they were found by Graba at Faroe; and W.
    Thompson[12] says that at Islay fully half the wild rock-pigeons
    were chequered. Colonel King, of Hythe, stocked his dovecot with
    young wild birds which he himself procured from nests at the Orkney
    Islands; and several specimens, kindly sent to me by him, were all
    plainly chequered. As we thus see that chequered birds occur
    mingled with the true rock-pigeon at three distinct sites, namely,
    Faroe, the Orkney Islands, and Islay, no importance can be attached
    to this natural variation in the plumage.

    Prince C. L. Bonaparte,[13] a great divider of species, enumerates,
    with a mark of interrogation, as distinct from _C. livia,_ the _C.
    turricola_ of Italy, the _C. rupestris_ of Daouria, and the _C.
    schimperi_ of Abyssinia; but these birds differ from _C. livia_ in
    characters of the most trifling value. In the British Museum there
    is a chequered pigeon, probably the _C. schimperi_ of Bonaparte,
    from Abyssinia. To these may be added the _C. gymnocyclus_ of G. R.
    Gray from W. Africa, which is slightly more distinct, and has
    rather more naked skin round the eyes than the rock-pigeon; but
    from information given me by Dr. Daniell, it is doubtful whether
    this is a wild bird, for dovecot-pigeons (which I have examined)
    are kept on the coast of Guinea.

    The wild rock-pigeon of India (_C. intermedia_ of Strickland) has
    been more generally accepted as a distinct species. It differs
    chiefly in the croup being blue instead of snow-white; but as Mr.
    Blyth informs me, the tint varies, being sometimes albescent. When
    this form is domesticated chequered birds appear, just as occurs in
    Europe with the truly wild _C. livia._ Moreover we shall
    immediately have proof that the blue and white croup is a highly
    variable character; and Bechstein[14] asserts that with
    dovecot-pigeons in Germany this is the most variable of all the
    characters of the plumage. Hence it may be concluded that _C.
    intermedia_ cannot be ranked as specifically distinct from _C.
    livia._

In Madeira there is a rock-pigeon which a few ornithologists have
suspected to be distinct from _C. livia._ I have examined numerous
specimens collected by Mr. E. V. Harcourt and Mr. Mason. They are
rather smaller than the rock- pigeon from the Shetland Islands, and
their beaks are plainly thinner, but the thickness of the beak varied
in the several specimens. In plumage there is remarkable diversity;
some specimens are identical in every feather (I speak after actual
comparison) with the rock-pigeon of the Shetland Islands; others are
chequered, like _C. affinis_ from the cliffs of England, but generally
to a greater degree, being almost black over the whole back; others are
identical with the so-called _C. intermedia_ of India in the degree of
blueness of the croup; whilst others have this part very pale or very
dark blue, and are likewise chequered. So much variability raises a
strong suspicion that these birds are domestic pigeons which have
become feral.

    From these facts it can hardly be doubted that _C. livia, affinis,
    intermedia,_ and the forms marked with an interrogation by
    Bonaparte ought all to be included under a single species. But it
    is quite immaterial whether or not they are thus ranked, and
    whether some one of these forms or all are the progenitors of the
    various domestic kinds, as far as any light can thus be thrown on
    the differences between the more strongly-marked races. That common
    dovecot-pigeons, which are kept in various parts of the world, are
    descended from one or from several of the above-mentioned wild
    varieties of _C. livia,_ no one who compares them will doubt. But
    before making a few remarks on dovecot-pigeons, it should be stated
    that the wild rock-pigeon has been found easy to tame in several
    countries. We have seen that Colonel King at Hythe stocked his
    dovecot more than twenty years ago with young wild birds taken at
    the Orkney Islands, and since then they have greatly multiplied.
    The accurate Macgillivray[15] asserts that he completely tamed a
    wild rock-pigeon in the Hebrides; and several accounts are on
    records of these pigeons having bred in dovecots in the Shetland
    Islands. In India, as Captain Hutton informs me, the wild
    rock-pigeon is easily tamed, and breeds readily with the domestic
    kind; and Mr. Blyth[16] asserts that wild birds come frequently to
    the dovecots and mingle freely with their inhabitants. In the
    ancient ‘Ayeen Akbery’ it is written that, if a few wild pigeons be
    taken, “they are speedily joined by a thousand others of their
    kind.”

    Dovecot-pigeons are those which are kept in dovecots in a semi-
    domesticated state; for no special care is taken of them, and they
    procure their own food, except during the severest weather. In
    England, and, judging from MM. Boitard and Corbié’s work, in
    France, the common dovecot- pigeon exactly resembles the chequered
    variety of _C. livia;_ but I have seen dovecots brought from
    Yorkshire without any trace of chequering, like the wild
    rock-pigeon of the Shetland Islands. The chequered dovecots from
    the Orkney Islands, after having been domesticated by Colonel King
    for more than twenty years, differed slightly from each other in
    the darkness of their plumage and in the thickness of their beaks;
    the thinnest beak being rather thicker than the thickest one in the
    Madeira birds. In Germany, according to Bechstein, the common
    dovecot-pigeon is not chequered. In India they often become
    chequered, and sometimes pied with white; the croup also, as I am
    informed by Mr. Blyth, becomes nearly white. I have received from
    Sir. J. Brooke some dovecot-pigeons, which originally came from the
    S. Natunas Islands in the Malay Archipelago, and which had been
    crossed with the Singapore dovecots: they were small and the
    darkest variety was extremely like the dark chequered variety with
    a blue croup from Madeira; but the beak was not so thin, though
    decidedly thinner than in the rock- pigeon from the Shetland
    Islands. A dovecot-pigeon sent to me by Mr. Swinhoe from Foochow,
    in China, was likewise rather small, but differed in no other
    respect. I have also received through the kindness of Dr. Daniell,
    four living dovecot-pigeons from Sierra Leone,[17] these were fully
    as large as the Shetland rock-pigeon, with even bulkier bodies. In
    plumage some of them were identical with the Shetland rock pigeon,
    but with the metallic tints apparently rather more brilliant;
    others had a blue croup, and resembled the chequered variety of _C.
    intermedia_ of India; and some were so much chequered as to be
    nearly black. In these four birds the beak differed slightly in
    length, but in all it was decidedly shorter, more massive, and
    stronger than in the wild rock-pigeon from the Shetland Islands, or
    in the English dovecot. When the beaks of these African pigeons
    were compared with the thinnest beaks of the wild Madeira
    specimens, the contrast was great; the former being fully one-third
    thicker in a vertical direction than the latter; so that any one at
    first would have felt inclined to rank these birds as specifically
    distinct; yet so perfectly graduated a series could be formed
    between the above-mentioned varieties, that it was obviously
    impossible to separate them.

To sum up: the wild _Columba livia,_ including under this name _C.
affinis, intermedia,_ and the other still more closely-affined
geographical races, has a vast range from the southern coast of Norway
and the Faroe Islands to the shores of the Mediterranean, to Madeira
and the Canary Islands, to Abyssinia, India, and Japan. It varies
greatly in plumage, being in many places chequered with black, and
having either a white or blue croup or loins; it varies also slightly
in the size of the beak and body. Dovecot-pigeons, which no one
disputes are descended from one or more of the above wild forms,
present a similar but greater range of variation in plumage, in the
size of body, and in the length and thickness of the beak. There seems
to be some relation between the croup being blue or white, and the
temperature of the country inhabited by both wild and dovecot pigeons;
for nearly all the dovecot-pigeons in the northern parts of Europe have
a white croup, like that of the wild European rock-pigeon; and nearly
all the dovecot-pigeons of India have a blue croup like that of the
wild _C. intermedia_ of India. As in various countries the wild
rock-pigeon has been found easy to tame, it seems extremely probable
that the dovecot-pigeons throughout the world are the descendants of at
least two and perhaps more wild stocks; but these, as we have just
seen, cannot be ranked as specifically distinct.

With respect to the variation of _C. livia,_ we may without fear of
contradiction go one step further. Those pigeon-fanciers who believe
that all the chief races, such as Carriers, Pouters, Fantails, etc.,
are descended from distinct aboriginal stocks, yet admit that the
so-called toy-pigeons, which differ from the rock-pigeon in little
except colour, are descended from this bird. By toy-pigeons are meant
such birds as Spots, Nuns, Helmets, Swallows, Priests, Monks,
Porcelains, Swabians, Archangels, Breasts, Shields, and others in
Europe, and many others in India. It would indeed be as puerile to
suppose that all these birds are descended from so many distinct wild
stocks as to suppose this to be the case with the many varieties of the
gooseberry, heartsease, or dahlia. Yet these kinds all breed true, and
many of them include sub-varieties which likewise transmit their
character truly. They differ greatly from each other and from the
rock-pigeon in plumage, slightly in size and proportions of body, in
size of feet, and in the length and thickness of their beaks. They
differ from each other in these respects more than do dovecot-pigeons.
Although we may safely admit that dovecot-pigeons, which vary slightly,
and that toy- pigeons, which vary in a greater degree in accordance
with their more highly-domesticated condition, are descended from _C.
livia,_ including under this name the above-enumerated wild
geographical races; yet the question becomes far more difficult when we
consider the eleven principal races, most of which have been profoundly
modified. It can, however, be shown, by indirect evidence of a
perfectly conclusive nature, that these principal races are not
descended from so many wild stocks; and if this be once admitted, few
will dispute that they are the descendants of _C. livia,_ which agrees
with them so closely in habits and in most characters, which varies in
a state of nature, and which has certainly undergone a considerable
amount of variation, as in the toy-pigeons. We shall moreover presently
see how eminently favourable circumstances have been for a great amount
of modification in the more carefully tended breeds.

The reasons for concluding that the several principal races are not
descended from so many aboriginal and unknown stocks may be grouped
under the following six heads:—

_Firstly._—If the eleven chief races have not arisen from the variation
of some one species, together with its geographical races, they must be
descended from several extremely distinct aboriginal species; for no
amount of crossing between only six or seven wild forms could produce
races so distinct as Pouters, Carriers, Runts, Fantails, Turbits,
Short-faced Tumblers, Jacobins, and Trumpeters. How could crossing
produce, for instance, a Pouter or a Fantail, unless the two supposed
aboriginal parents possessed the remarkable characters of these breeds?
I am aware that some naturalists, following Pallas, believe that
crossing gives a strong tendency to variation, independently of the
characters inherited from either parent. They believe that it would be
easier to raise a Pouter or Fantail pigeon from crossing two distinct
species, neither of which possessed the characters of these races, than
from any single species. I can find few facts in support of this
doctrine, and believe in it only to a limited degree; but in a future
chapter I shall have to recur to this subject. For our present purpose
the point is not material. The question which concerns us is, whether
or not many new and important characters have arisen since man first
domesticated the pigeon. On the ordinary view, variability is due to
changed conditions of life; on the Pallasian doctrine, variability, or
the appearance of new characters, is due to some mysterious effect from
the crossing of two species, neither of which possesses the characters
in question. In some few instances it is possible that well-marked
races may have been formed by crossing; for instance, a Barb might
perhaps be formed by a cross between a long-beaked Carrier, having
large eye-wattles, and some short-beaked pigeon. That many races have
been in some degree modified by crossing, and that certain varieties
which are distinguished only by peculiar tints have arisen from crosses
between differently-coloured varieties, is almost certain. On the
doctrine, therefore, that the chief races owe their differences to
their descent from distinct species, we must admit that at least eight
or nine, or more probably a dozen species, all having the same habit of
breeding and roosting on rocks and living in society, either now exist
somewhere, or formerly existed, but have become extinct as wild birds.
Considering how carefully wild pigeons have been collected throughout
the world, and what conspicuous birds they are, especially when
frequenting rocks, it is extremely improbable that eight or nine
species, which were long ago domesticated and therefore must have
inhabited some anciently known country, should still exist in the wild
state and be unknown to ornithologists.

The hypothesis that such species formerly existed, but have become
extinct, is in some slight degree more probable. But the extinction of
so many species within the historical period is a bold hypothesis,
seeing how little influence man has had in exterminating the common
rock-pigeon, which agrees in all its habits of life with the domestic
races. The _C. livia_ now exists and flourishes on the small northern
islands of Faroe, on many islands off the coast of Scotland, on
Sardinia, and the shores of the Mediterranean, and in the centre of
India. Fanciers have sometimes imagined that the several supposed
parent-species were originally confined to small islands, and thus
might readily have been exterminated; but the facts just given do not
favour the probability of their extinction, even on small islands. Nor
is it probable, from what is known of the distribution of birds, that
the islands near Europe should have been inhabited by peculiar species
of pigeons; and if we assume that distant oceanic islands were the
homes of the supposed parent-species, we must remember that ancient
voyages were tediously slow, and that ships were then ill-provided with
fresh food, so that it would not have been easy to bring home living
birds. I have said ancient voyages, for nearly all the races of the
pigeon were known before the year 1600, so that the supposed wild
species must have been captured and domesticated before that date.

_Secondly._—The doctrine that the chief domestic races are descended
from several aboriginal species, implies that several species were
formerly so thoroughly domesticated as to breed readily when confined.
Although it is easy to tame most wild birds, experience shows us that
it is difficult to get them to breed freely under confinement; although
it must be owned that this is less difficult with pigeons than with
most other birds. During the last two or three hundred years, many
birds have been kept in aviaries, but hardly one has been added to our
list of thoroughly reclaimed species: yet on the above doctrine we must
admit that in ancient times nearly a dozen kinds of pigeons, now
unknown in the wild state, were thoroughly domesticated.

    _Thirdly._—Most of our domesticated animals have run wild in
    various parts of the world; but birds, owing apparently to their
    partial loss of the power of flight, less often than quadrupeds.
    Nevertheless I have met with accounts showing that the common fowl
    has become feral in South America and perhaps in West Africa, and
    on several islands: the turkey was at one time almost feral on the
    banks of the Parana; and the Guinea-fowl has become perfectly wild
    at Ascension and in Jamaica. In this latter island the peacock,
    also, “has become a maroon bird.” The common duck wanders from its
    home and becomes almost wild in Norfolk. Hybrids between the common
    and musk-duck which have become wild have been shot in North
    America, Belgium, and near the Caspian Sea. The goose is said to
    have run wild in La Plata. The common dovecot-pigeon has become
    wild at Juan Fernandez, Norfolk Island, Ascension, probably at
    Madeira, on the shores of Scotland, and, as is asserted, on the
    banks of the Hudson in North America.[18] But how different is the
    case, when we turn to the eleven chief domestic races of the
    pigeon, which are supposed by some authors to be descended from so
    many distinct species! no one has ever pretended that any one of
    these races has been found wild in any quarter of the world; yet
    they have been transported to all countries, and some of them must
    have been carried back to their native homes. On the view that all
    the races are the product of variation, we can understand why they
    have not become feral, for the great amount of modification which
    they have undergone shows how long and how thoroughly they have
    been domesticated; and this would unfit them for a wild life.

_Fourthly._—If it be assumed that the characteristic differences
between the various domestic races are due to descent from several
aboriginal species, we must conclude that man chose for domestication
in ancient times, either intentionally or by chance, a most abnormal
set of pigeons; for that species resembling such birds as Pouters,
Fantails, Carriers, Barbs, Short-faced Tumblers, Turbits, etc., would
be in the highest degree abnormal, as compared with all the existing
members of the great pigeon family, cannot be doubted. Thus we should
have to believe that man not only formerly succeeded in thoroughly
domesticating several highly abnormal species, but that these same
species have since all become extinct, or are at least now unknown.
This double accident is so extremely improbable that the assumed
existence of so many abnormal species would require to be supported by
the strongest evidence. On the other hand, if all the races are
descended from _C. livia,_ we can understand, as will hereafter be more
fully explained, how any slight deviation in structure which first
appeared would continually be augmented by the preservation of the most
strongly marked individuals; and as the power of selection would be
applied according to man’s fancy, and not for the bird’s own good, the
accumulated amount of deviation would certainly be of an abnormal
nature in comparison with the structure of pigeons living in a state of
nature.

I have already alluded to the remarkable fact that the characteristic
differences between the chief domestic races are eminently variable; we
see this plainly in the great difference in the number of the
tail-feathers in the Fantail, in the development of the crop in
Pouters, in the length of the beak in Tumblers, in the state of the
wattle in Carriers, etc. If these characters are the result of
successive variations added together by selection, we can understand
why they should be so variable: for these are the very parts which have
varied since the domestication of the pigeon, and therefore would be
likely still to vary; these variations moreover have been recently, and
are still being accumulated by man’s selection; therefore they have not
as yet become firmly fixed.

    _Fifthly._—All the domestic races pair readily together, and, what
    is equally important, their mongrel offspring are perfectly
    fertile. To ascertain this fact I made many experiments, which are
    given in the note below; and recently Mr. Tegetmeier has made
    similar experiments with the same result.[19] The accurate
    Neumeister asserts that when dovecots are crossed with pigeons of
    any other breed, the mongrels are extremely fertile and hardy.[20]
    MM. Boitard and Corbié[21] affirm, after their great experience,
    that the more distinct the breeds are which are crossed, the more
    productive are their mongrel offspring. I admit that the doctrine
    first broached by Pallas is highly probable, if not actually
    proved, namely, that closely allied species, which in a state of
    nature or when first captured would have been in some degree
    sterile if crossed, lose this sterility after a long course of
    domestication; yet when we consider the great difference between
    such races as Pouters, Carriers, Runts, Fantails, Turbits, Tumblers
    etc., the fact of their perfect, or even increased, fertility when
    intercrossed in the most complicated manner becomes a strong
    argument in favour of their having all descended from a single
    species. This argument is rendered much stronger when we hear (I
    append in a note[22] all the cases which I have collected) that
    hardly a single well-ascertained instance is known of hybrids
    between two true species of pigeons being fertile, _inter se,_ or
    even when crossed with one of their pure parents.

_Sixthly._—Excluding certain important characteristic differences, the
chief races agree most closely both with each other and with _C. livia_
in all other respects. As previously observed, all are eminently
sociable; all dislike to perch or roost, and refuse to build in trees;
all lay two eggs, and this is not a universal rule with the Columbidæ;
all, as far as I can hear, require the same time for hatching their
eggs; all can endure the same great range of climate; all prefer the
same food, and are passionately fond of salt; all exhibit (with the
asserted exception of the Finnikin and Turner which do not differ much
in any other character) the same peculiar gestures when courting the
females; and all (with the exception of Trumpeters and Laughers, which
likewise do not differ much in any other character) coo in the same
peculiar manner, unlike the voice of any other wild pigeon. All the
coloured breeds display the same peculiar metallic tints on the breast,
a character far from general with pigeons. Each race presents nearly
the same range of variation in colour; and in most of the races we have
the same singular correlation between the development of down in the
young and the future colour of plumage. All have the proportional
length of their toes, and of their primary wing-feathers, nearly the
same,—characters which are apt to differ in the several members of the
Columbidæ. In those races which present some remarkable deviation of
structure, such as in the tail of Fantails, crop of Pouters, beak of
Carriers and Tumblers, etc., the other parts remain nearly unaltered.
Now every naturalist will admit that it would be scarcely possible to
pick out a dozen natural species in any family which should agree
closely in habits and in general structure, and yet should differ
greatly in a few characters alone. This fact is explicable through the
doctrine of natural selection; for each successive modification of
structure in each natural species is preserved, solely because it is of
service; and such modifications when largely accumulated imply a great
change in the habits of life, and this will almost certainly lead to
other changes of structure throughout the whole organisation. On the
other hand, if the several races of the pigeon have been produced by
man through selection and variation, we can readily understand how it
is that they should still all resemble each other in habits and in
those many characters which man has not cared to modify, whilst they
differ to so prodigious a degree in those parts which have struck his
eye or pleased his fancy.

    Besides the points above enumerated, in which all the domestic
    races resemble _C. livia_ and each other, there is one which
    deserves special notice. The wild rock-pigeon is of a slaty-blue
    colour; the wings are crossed by two bars; the croup varies in
    colour, being generally white in the pigeon of Europe, and blue in
    that of India; the tail has a black bar close to the end, and the
    outer webs of the outer tail-feathers are edged with white, except
    near the tips. These combined characters are not found in any wild
    pigeon besides _C. livia._ I have looked carefully through the
    great collections of pigeons in the British Museum, and I find that
    a dark bar at the end of the tail is common; that the white edging
    to the outer tail-feathers is not rare; but that the white croup is
    extremely rare, and the two black bars on the wings occur in no
    other pigeon, excepting the alpine _C. leuconota_ and _C.
    rupestris_ of Asia. Now if we turn to the domestic races, it is
    highly remarkable, as an eminent fancier, Mr. Wicking, observed to
    me, that, whenever a blue bird appears in any race, the wings
    almost invariably show the double black bars.[23] The primary
    wing-feathers may be white or black, and the whole body may be of
    any colour, but if the wing-coverts are blue, the two black bars
    are sure to appear. I have myself seen, or acquired trustworthy
    evidence, as given below,[24] of blue birds with black bars on the
    wing, with the croup either white or very pale or dark blue, with
    the tail having a terminal black bar, and with the outer feathers
    externally edged with white or very pale coloured, in the following
    races, which, as I carefully observed in each case, appeared to be
    perfectly true: namely, in Pouters, Fantails, Tumblers, Jacobins,
    Turbits, Barbs, Carriers, Runts of three distinct varieties,
    Trumpeters, Swallows, and in many other toy-pigeons, which as being
    closely allied to _C. livia,_ are not worth enumerating. Thus we
    see that, in purely-bred races of every kind known in Europe, blue
    birds occasionally appear having all the marks which characterise
    _C. livia,_ and which concur in no other wild species. Mr. Blyth,
    also, has made the same observation with respect to the various
    domestic races known in India.

    Certain variations in the plumage are equally common in the wild
    _C. livia,_ in dovecot-pigeons, and in all the most highly modified
    races. Thus, in all, the croup varies from white to blue, being
    most frequently white in Europe, and very generally blue in
    India.[25] We have seen that the wild _C. livia_ in Europe, and
    dovecots in all parts of the world, often have the upper
    wing-coverts chequered with black; and all the most distinct races,
    when blue, are occasionally chequered in precisely the same manner.
    Thus I have seen Pouters, Fantails, Carriers, Turbits, Tumblers
    (Indian and English), Swallows, Bald-pates, and other toy-pigeons
    blue and chequered; and Mr. Esquilant has seen a chequered Runt. I
    bred from two pure blue Tumblers a chequered bird.

    The facts hitherto given refer to the occasional appearance in pure
    races of blue birds with black wing-bars, and likewise of blue and
    chequered birds; but it will now be seen that when two birds
    belonging to distinct races are crossed, neither of which have, nor
    probably have had during many generations, a trace of blue in their
    plumage, or a trace of wing-bars and the other characteristic
    marks, they very frequently produce mongrel offspring of a blue
    colour, sometimes chequered, with black wing-bars, etc.; or if not
    of a blue colour, yet with the several characteristic marks more or
    less plainly developed. I was led to investigate this subject from
    MM. Boitard and Corbié[26] having asserted that from crosses
    between certain breeds it is rare to get anything but bisets or
    dovecot pigeons, which, as we know, are blue birds with the usual
    characteristic marks. We shall hereafter see that this subject
    possesses, independently of our present object, considerable
    interest, so that I will give the results of my own trials in full.
    I selected for experiment races which, when pure, very seldom
    produce birds of a blue colour, or have bars on their wings and
    tail.

The Nun is white, with the head, tail, and primary wing-feathers black;
it is a breed which was established as long ago as the year 1600. I
crossed a male Nun with a female red common Tumbler, which latter
variety generally breeds true. Thus neither parent had a trace of blue
in the plumage, or of bars on the wing and tail. I should premise that
common Tumblers are rarely blue in England. From the above cross I
reared several young: one was red over the whole back, but with the
tail as blue as that of the rock-pigeon; the terminal bar, however, was
absent, but the outer feathers were edged with white: a second and
third nearly resembled the first, but the tail in both presented a
trace of the bar at the end: a fourth was brownish, and the wings
showed a trace of the double bar: a fifth was pale blue over the whole
breast, back, croup, and tail, but the neck and primary wing-feathers
were reddish; the wings presented two distinct bars of a red colour;
the tail was not barred, but the outer feathers were edged with white.
I crossed this last curiously coloured bird with a black mongrel of
complicated descent, namely, from a black Barb, a Spot, and
Almond-tumbler, so that the two young birds produced from this cross
included the blood of five varieties, none of which had a trace of blue
or of wing and tail-bars: one of the two young birds was
brownish-black, with black wing-bars; the other was reddish-dun, with
reddish wing-bars, paler than the rest of the body, with the croup pale
blue, the tail bluish with a trace of the terminal bar.

    Mr. Eaton[27] matched two Short-faced Tumblers, namely, a splash
    cock and kite hen (neither of which are blue or barred), and from
    the first nest he got a perfect blue bird, and from the second a
    silver or pale blue bird, both of which, in accordance with all
    analogy, no doubt presented the usual characteristic marks.

    I crossed two male black Barbs with two female red Spots. These
    latter have the whole body and wings white, with a spot on the
    forehead, the tail and tail-coverts red; the race existed at least
    as long ago as 1676, and now breeds perfectly true, as was known to
    be the case in the year 1735.[28] Barbs are uniformly-coloured
    birds, with rarely even a trace of bars on the wing or tail; they
    are known to breed very true. The mongrels thus raised were black
    or nearly black, or dark or pale brown, sometimes slightly piebald
    with white: of these birds no less than six presented double
    wing-bars; in two the bars were conspicuous and quite black; in
    seven some white feathers appeared on the croup; and in two or
    three there was a trace of the terminal bar to the tail, but in
    none were the outer tail-feathers edged with white.

I crossed black Barbs (of two excellent strains) with purely-bred,
snow-white Fantails. The mongrels were generally quite black, with a
few of the primary wing and tail feathers white: others were dark
reddish-brown, and others snow-white: none had a trace of wing-bars or
of the white croup. I then paired together two of these mongrels,
namely, a brown and black bird, and their offspring displayed
wing-bars, faint, but of a darker brown than the rest of body. In a
second brood from the same parents a brown bird was produced, with
several white feathers confined to the croup.

    I crossed a male dun Dragon belonging to a family which had been
    dun- coloured without wing-bars during several generations, with a
    uniform red Barb (bred from two black Barbs); and the offspring
    presented decided but faint traces of wing-bars. I crossed a
    uniform red male Runt with a White trumpeter; and the offspring had
    a slaty-blue tail with a bar at the end, and with the outer
    feathers edged with white. I also crossed a female black and white
    chequered Trumpeter (of a different strain from the last) with a
    male Almond-tumbler, neither of which exhibited a trace of blue, or
    of the white croup, or of the bar at end of tail: nor is it
    probable that the progenitors of these two birds had for many
    generations exhibited any of these characters, for I have never
    even heard of a blue Trumpeter in this country, and my
    Almond-tumbler was purely bred; yet the tail of this mongrel was
    bluish, with a broad black bar at the end, and the croup was
    perfectly white. It may be observed in several of these cases, that
    the tail first shows a tendency to become by reversion blue; and
    this fact of the persistency of colour in the tail and
    tail-coverts[29] will surprise no one who has attended to the
    crossing of pigeons.

The last case which I will give is the most curious. I paired a mongrel
female Barb-fantail with a mongrel male Barb-spot; neither of which
mongrels had the least blue about them. Let it be remembered that blue
Barbs are excessively rare; that Spots, as has been already stated,
were perfectly characterised in the year 1676, and breed perfectly
true; this likewise is the case with white Fantails, so much so that I
have never heard of white Fantails throwing any other colour.
Nevertheless the offspring from the above two mongrels was of exactly
the same blue tint as that of the wild rock-pigeon from the Shetland
Islands over the whole back and wings; the double black wing-bars were
equally conspicuous; the tail was exactly alike in all its characters,
and the croup was pure white; the head, however, was tinted with a
shade of red, evidently derived from the Spot, and was of a paler blue
than in the rock-pigeon, as was the stomach. So that two black Barbs, a
red Spot, and a white Fantail, as the four purely-bred grandparents,
produced a bird exhibiting the general blue colour, together with every
characteristic mark, the wild _Columba livia._

With respect to crossed breeds frequently producing blue birds
chequered with black, and resembling in all respects both the
dovecot-pigeon and the chequered wild variety of the rock-pigeon, the
statement before referred to by MM. Boitard and Corbié would almost
suffice; but I will give three instances of the appearance of such
birds from crosses in which one alone of the parents or
great-grandparents was blue, but not chequered. I crossed a male blue
Turbit with a snow-white Trumpeter, and the following year with a dark,
leaden-brown, Short-faced Tumbler; the offspring from the first cross
were as perfectly chequered as any dovecot-pigeon; and from the second,
so much so as to be nearly as black as the most darkly chequered
rock-pigeon from Madeira. Another bird, whose great-grandparents were a
white Trumpeter, a white Fantail, a white Red-spot, a red Runt, and a
blue Pouter, was slaty-blue and chequered exactly like a
dovecot-pigeon. I may here add a remark made to me by Mr. Wicking, who
has had more experience than any other person in England in breeding
pigeons of various colours: namely, that when a blue, or a blue and
chequered bird, having black wing- bars, once appears in any race and
is allowed to breed, these characters are so strongly transmitted that
it is extremely difficult to eradicate them.

What, then, are we to conclude from this tendency in all the chief
domestic races, both when purely bred and more especially when
intercrossed, to produce offspring of a blue colour, with the same
characteristic marks, varying in the same manner, as in _Columbia
livia_? If we admit that these races are all descended from _C. livia,_
no breeder will doubt that the occasional appearance of blue birds thus
characterised is accounted for on the well-known principle of “throwing
back” or reversion. Why crossing should give so strong a tendency to
reversion, we do not with certainty know; but abundant evidence of this
fact will be given in the following chapters. It is probable that I
might have bred even for a century pure black Barbs, Spots, Nuns, white
Fantails, Trumpeters, etc., without obtaining a single blue or barred
bird; yet by crossing these breeds I reared in the first and second
generation, during the course of only three or four years, a
considerable number of young birds, more or less plainly coloured blue,
and with most of the characteristic marks. When black and white, or
black and red birds, are crossed, it would appear that a slight
tendency exists in both parents to produce blue offspring, and that
this, when combined, overpowers the separate tendency in either parent
to produce black, or white, or red offspring.

If we reject the belief that all the races of the pigeon are the
modified descendants of _C. livia,_ and suppose that they are descended
from several aboriginal stocks, then we must choose between the three
following assumptions: firstly, that at least eight or nine species
formerly existed which were aboriginally coloured in various ways, but
have since varied in exactly the same manner so as to assume the
colouring of _C. livia_; but this assumption throws not the least light
on the appearance of such colours and marks when the races are crossed.
Or secondly, we may assume that the aboriginal species were all
coloured blue, and had the wing-bars and other characteristic marks of
_C. livia,_—a supposition which is highly improbable, as besides this
one species no existing member of the Columbidæ presents these combined
characters; and it would not be possible to find any other instance of
several species identical in plumage, yet as different in important
points of structure as are Pouters, Fantails, Carriers, Tumblers, etc.
Or lastly, we may assume that all the races, whether descended from _C.
livia_ or from several aboriginal species, although they have been bred
with so much care and are so highly valued by fanciers, have all been
crossed within a dozen or score of generations with _C. livia,_ and
have thus acquired their tendency to produce blue birds with the
several characteristic marks. I have said that it must be assumed that
each race has been crossed with _C. livia_ within a dozen, or, at the
utmost, within a score of generations; for there is no reason to
believe that crossed offspring ever revert to one of their ancestors
when removed by a greater number of generations. In a breed which has
been crossed only once, the tendency to reversion will naturally become
less and less in the succeeding generations, as in each there will be
less and less of the blood of the foreign breed; but when there has
been no cross with a distinct breed, and there is a tendency in both
parents to revert to some long-lost character, this tendency, for all
that we can see to the contrary, may be transmitted undiminished for an
indefinite number of generations. These two distinct cases of reversion
are often confounded together by those who have written on inheritance.

Considering, on the one hand, the improbability of the three
assumptions which have just been discussed, and, on the other hand, how
simply the facts are explained on the principle of reversion, we may
conclude that the occasional appearance in all the races, both when
purely bred and more especially when crossed, of blue birds, sometimes
chequered, with double wing-bars, with white or blue croups, with a bar
at the end of the tail, and with the outer tail-feathers edged with
white, affords an argument of the greatest weight in favour of the view
that all are descended from _Columba livia,_ including under this name
the three or four wild varieties or sub-species before enumerated.

To sum up the six foregoing arguments, which are opposed to the belief
that the chief domestic races are the descendants of at least eight or
nine or perhaps a dozen species; for the crossing of any less number
would not yield the characteristic differences between the several
races. _ Firstly,_ the improbability that so many species should still
exist somewhere, but be unknown to ornithologists, or that they should
have become within the historical period extinct, although man has had
so little influence in exterminating the wild _C. livia. Secondly,_ the
improbability of man in former times having thoroughly domesticated and
rendered fertile under confinement so many species. _Thirdly,_ these
supposed species having nowhere become feral. _Fourthly,_ the
extraordinary fact that man should, intentionally or by chance, have
chosen for domestication several species, extremely abnormal in
character; and furthermore, the points of structure which render these
supposed species so abnormal being now highly variable. _Fifthly,_ the
fact of all the races, though differing in many important points of
structure, producing perfectly fertile mongrels; whilst all the hybrids
which have been produced between even closely allied species in the
pigeon-family are sterile. _Sixthly,_ the remarkable statements just
given on the tendency in all the races, both when purely bred and when
crossed, to revert in numerous minute details of colouring to the
character of the wild rock-pigeon, and to vary in a similar manner. To
these arguments may be added the extreme improbability that a number of
species formerly existed, which differed greatly from each other in
some few points, but which resembled each other as closely as do the
domestic races in other points of structure, in voice, and in all their
habits of life. When these several facts and arguments are fairly taken
into consideration, it would require an overwhelming amount of evidence
to make us admit that the chief domestic races are descended from
several aboriginal stocks; and of such evidence there is absolutely
none.

The belief that the chief domestic races are descended from several
wild stocks no doubt has arisen from the apparent improbability of such
great modifications of structure having been effected since man first
domesticated the rock-pigeon. Nor am I surprised at any degree of
hesitation in admitting their common parentage: formerly, when I went
into my aviaries and watched such birds as Pouters, Carriers, Barbs,
Fantails, and Short-faced Tumblers, etc., I could not persuade myself
that all had descended from the same wild stock, and that man had
consequently in one sense created these remarkable modifications.
Therefore I have argued the question of their origin at great, and, as
some will think, superfluous length.

    Finally, in favour of the belief that all the races are descended
    from a single stock, we have in _Columba livia_ a still existing
    and widely distributed species, which can be and has been
    domesticated in various countries. This species agrees in most
    points of structure and in all its habits of life, as well as
    occasionally in every detail of plumage, with the several domestic
    races. It breeds freely with them, and produces fertile offspring.
    It varies in a state of nature,[30] and still more so when
    semi-domesticated, as shown by comparing the Sierra Leone pigeons
    with those of India, or with those which apparently have run wild
    in Madeira. It has undergone a still greater amount of variation in
    the case of the numerous toy-pigeons, which no one supposes to be
    descended from distinct species; yet some of these toy-pigeons have
    transmitted their character truly for centuries. Why, then, should
    we hesitate to believe in that greater amount of variation which is
    necessary for the production of the eleven chief races? It should
    be borne in mind that in two of the most strongly-marked races,
    namely, Carriers and Short-faced Tumblers, the extreme forms can be
    connected with the parent-species by graduated differences not
    greater than those which may be observed between the
    dovecot-pigeons inhabiting different countries, or between the
    various kinds of toy-pigeons,—gradations which must certainly be
    attributed to variation.

    That circumstances have been eminently favourable for the
    modification of the pigeon through variation and selection will now
    be shown. The earliest record, as has been pointed out to me by
    Professor Lepsius, of pigeons in a domesticated condition, occurs
    in the fifth Egyptian dynasty, about 3000 B.C.;[31] but Mr. Birch,
    of the British Museum, informs me that the pigeon appears in a bill
    of fare in the previous dynasty. Domestic pigeons are mentioned in
    Genesis, Leviticus, and Isaiah.[32] In the time of the Romans, as
    we hear from Pliny,[33] immense prices were given for pigeons;
    “nay, they are come to this pass, that they can reckon up their
    pedigree and race.” In India, about the year 1600, pigeons were
    much valued by Akbar Khan: 20,000 birds were carried about with the
    court, and the merchants brought valuable collections. “The monarch
    of Iran and Turan sent him some very rare breeds. His Majesty,”
    says the courtly historian, “by crossing the breeds, which method
    was never practised before, has improved them astonishingly.”[34]
    Akber Khan possessed seventeen distinct kinds, eight of which were
    valuable for beauty alone. At about this same period of 1600 the
    Dutch, according to Aldrovandi, were as eager about pigeons as the
    Romans had formerly been. The breeds which were kept during the
    fifteenth century in Europe and in India apparently differed from
    each other. Tavernier, in his Travels in 1677, speaks, as does
    Chardin in 1735, of the vast number of pigeon-houses in Persia; and
    the former remarks that, as Christians were not permitted to keep
    pigeons, some of the vulgar actually turned Mahometans for this
    sole purpose. The Emperor of Morocco had his favourite keeper of
    pigeons, as is mentioned in Moore’s treatise, published 1737. In
    England, from the time of Willughby in 1678 to the present day, as
    well as in Germany and in France, numerous treatises have been
    published on the pigeon. In India, about a hundred years ago, a
    Persian treatise was written; and the writer thought it no light
    affair, for he begins with a solemn invocation, “in the name of
    God, the gracious and merciful.” Many large towns, in Europe and
    the United States, now have their societies of devoted
    pigeon-fanciers: at present there are three such societies in
    London. In India, as I hear from Mr. Blyth, the inhabitants of
    Delhi and of some other great cities are eager fanciers. Mr. Layard
    informs me that most of the known breeds are kept in Ceylon. In
    China, according to Mr. Swinhoe of Amoy, and Dr. Lockhart of
    Shangai, Carriers, Fantails, Tumblers, and other varieties are
    reared with care, especially by the bonzes or priests. The Chinese
    fasten a kind of whistle to the tail-feathers of their pigeons, and
    as the flock wheels through the air they produce a sweet sound. In
    Egypt the late Abbas Pacha was a great fancier of Fantails. Many
    pigeons are kept at Cairo and Constantinople, and these have lately
    been imported by native merchants, as I hear from Sir W. Elliot,
    into Southern India, and sold at high prices.

    The foregoing statements show in how many countries, and during how
    long a period, many men have been passionately devoted to the
    breeding of pigeons. Hear how an enthusiastic fancier at the
    present day writes: “If it were possible for noblemen and gentlemen
    to know the amazing amount of solace and pleasure derived from
    Almond Tumblers, when they begin to understand their properties, I
    should think that scarce any nobleman or gentleman would be without
    their aviaries of Almond Tumblers.”[35] The pleasure thus taken is
    of paramount importance, as it leads amateurs carefully to note and
    preserve each slight deviation of structure which strikes their
    fancy. Pigeons are often closely confined during their whole lives;
    they do not partake of their naturally varied diet; they have often
    been transported from one climate to another; and all these changes
    in their conditions of life would be likely to cause variability.
    Pigeons have been domesticated for nearly 5000 years, and have been
    kept in many places, so that the numbers reared under domestication
    must have been enormous: and this is another circumstance of high
    importance, for it obviously favours the chance of rare
    modifications of structure occasionally appearing. Slight
    variations of all kinds would almost certainly be observed, and, if
    valued, would, owing to the following circumstances, be preserved
    and propagated with unusual facility. Pigeons, differently from any
    other domesticated animal, can easily be mated for life, and,
    though kept with other pigeons, rarely prove unfaithful to each
    other. Even when the male does break his marriage-vow, he does not
    permanently desert his mate. I have bred in the same aviaries many
    pigeons of different kinds, and never reared a single bird of an
    impure strain. Hence a fancier can with the greatest ease select
    and match his birds. He will also see the good results of his care;
    for pigeons breed with extraordinary rapidity. He may freely reject
    inferior birds, as they serve at an early age as excellent food.

      _History of the principal Races of the Pigeon._[36]

Before discussing the means and steps by which the chief races have
been formed, it will be advisable to give some historical details, for
more is known of the history of the pigeon, little though this is, than
of any other domesticated animal. Some of the cases are interesting as
proving how long domestic varieties may be propagated with exactly the
same or nearly the same characters; and other cases are still more
interesting as showing how slowly but steadily races have been greatly
modified during successive generations. In the last chapter I stated
that Trumpeters and Laughers, both so remarkable for their voices, seem
to have been perfectly characterised in 1735; and Laughers were
apparently known in India before the year 1600. Spots in 1676, and Nuns
in the time of Aldrovandi, before 1600, were coloured exactly as they
now are. Common Tumblers and Ground Tumblers displayed in India, before
the year 1600, the same extraordinary peculiarities of flight as at the
present day, for they are well described in the ‘Ayeen Akbery.’ These
breeds may all have existed for a much longer period; we know only that
they were perfectly characterised at the dates above given. The _
average_ length of life of the domestic pigeon is probably about five
or six years; if so, some of these races have retained their character
perfectly for at least forty or fifty generations.

    _Pouters._—These birds, as far as a very short description serves
    for comparison, appear to have been well characterised in
    Aldrovandi’s time,[37] before the year 1600. Length of body and
    length of leg are at the present time the two chief points of
    excellence. In 1735 Moore said (see Mr. J. M. Eaton’s edition)—and
    Moore was a first-rate fancier—that he once saw a bird with a body
    20 inches in length, “though 17 or 18 inches is reckoned a very
    good length;” and he has seen the legs very nearly 7 inches in
    length, yet a leg 6½ or 6¾ long “must be allowed to be a very good
    one.” Mr. Bult, the most successful breeder of Pouters in the
    world, informs me that at present (1858) the standard length of the
    body is not less than 18 inches; but he has measured one bird 19
    inches in length, and has heard of 20 and 22 inches, but doubts the
    truth of these latter statements. The standard length of the leg is
    now 7 inches, but Mr. Bult has recently measured two of his own
    birds with legs 7½ long. So that in the 123 years which have
    elapsed since 1735 there has been hardly any increase in the
    standard length of the body; 17 or 18 inches was formerly reckoned
    a very good length, and now 18 inches is the minimum standard; but
    the length of leg seems to have increased, as Moore never saw one
    quite 7 inches long; now the standard is 7, and two of Mr. Bult’s
    birds measured 7½ inches in length. The extremely slight
    improvement in Pouters, except in the length of the leg, during the
    last 123 years, may be partly accounted for by the neglect which
    they suffered, as I am informed by Mr. Bult, until within the last
    20 or 30 years. About 1765[38] there was a change of fashion,
    stouter and more feathered legs being preferred to thin and nearly
    naked legs.

    _Fantails._—The first notice of the existence of this breed is in
    India, before the year 1600, as given in the ‘Ayeen Akbery;’[39] at
    this date, judging from Aldrovandi, the breed was unknown in
    Europe. In 1677 Willughby speaks of a Fantail with 26
    tail-feathers; in 1735 Moore saw one with 36 feathers; and in 1824
    MM. Boitard and Corbié assert that in France birds can easily be
    found with 42 tail-feathers. In England, the number of the
    tail-feathers is not at present so much regarded as their upward
    direction and expansion. The general carriage of the bird is
    likewise now much valued. The old descriptions do not suffice to
    show whether in these latter respects there has been much
    improvement: but if Fantails with their heads and tails touching
    had formerly existed, as at the present time, the fact would almost
    certainly have been noticed. The Fantails which are now found in
    India probably show the state of the race, as far as carriage is
    concerned, at the date of their introduction into Europe; and some,
    said to have been brought from Calcutta, which I kept alive, were
    in a marked manner inferior to our exhibition birds. The Java
    Fantail shows the same difference in carriage; and although Mr.
    Swinhoe has counted 18 and 24 tail-feathers in his birds, a
    first-rate specimen sent to me had only 14 tail-feathers.

_Jacobins._—This breed existed before 1600, but the hood, judging from
the figure given by Aldrovandi, did not enclose the head nearly so
perfectly as at present: nor was the head then white; nor were the
wings and tail so long, but this last character might have been
overlooked by the rude artist. In Moore’s time, in 1735, the Jacobin
was considered the smallest kind of pigeon, and the bill is said to be
very short. Hence either the Jacobin, or the other kinds with which it
was then compared, must since that time have been considerably
modified; for Moore’s description (and it must be remembered that he
was a first-rate judge) is clearly not applicable, as far as size of
body and length of beak are concerned, to our present Jacobins. In
1795, judging from Bechstein, the breed had assumed its present
character.

_Turbits._—It has generally been supposed by the older writers on
pigeons, that the Turbit is the Cortbeck of Aldrovandi; but if this be
the case, it is an extraordinary fact that the characteristic frill
should not have been noticed. The beak, moreover, of the Cortbeck is
described as closely resembling that of the Jacobin, which shows a
change in the one or the other race. The Turbit, with its
characteristic frill, and bearing its present name, is described by
Willughby in 1677; and the bill is said to be like that of the
bullfinch,—a good comparison, but now more strictly applicable to the
beak of the Barb. The sub-breed called the Owl was well known in
Moore’s time, in 1735.

    _Tumblers._—Common Tumblers, as well as Ground Tumblers, perfect as
    far as tumbling is concerned, existed in India before the year
    1600; and at this period diversified modes of flight, such as
    flying at night, the ascent to a great height, and manner of
    descent, seem to have been much attended to in India, as at the
    present time. Belon[40] in 1555 saw in Paphlagonia what he
    describes as “a very new thing, viz. pigeons which flew so high in
    the air that they were lost to view, but returned to their
    pigeon-house without separating.” This manner of flight is
    characteristic of our present Tumblers, but it is clear that Belon
    would have mentioned the act of tumbling if the pigeons described
    by him had tumbled. Tumblers were not known in Europe in 1600, as
    they are not mentioned by Aldrovandi, who discusses the flight of
    pigeons. They are briefly alluded to by Willughby, in 1687, as
    small pigeons “which show like footballs in the air.” The
    short-faced race did not exist at this period, as Willughby could
    not have overlooked birds so remarkable for their small size and
    short beaks. We can even trace some of the steps by which this race
    has been produced. Moore in 1735 enumerates correctly the chief
    points of excellence, but does not give any description of the
    several sub-breeds; and from this fact Mr. Eaton infers[41] that
    the Short-faced Tumbler had not then come to full perfection. Moore
    even speaks of the Jacobin as being the smallest pigeon. Thirty
    years afterwards, in 1765, in the Treatise dedicated to Mayor,
    short-faced Almond Tumblers are fully described, but the author, an
    excellent fancier, expressly states in his Preface (p. xiv.) that,
    “from great care and expense in breeding them, they have arrived to
    so great perfection and are so different from what they were 20 or
    30 years past, that an old fancier would have condemned them for no
    other reason than because they are not like what used to be thought
    good when he was in the fancy before.” Hence it would appear that
    there was a rather sudden change in the character of the
    short-faced Tumbler at about this period; and there is reason to
    suspect that a dwarfed and half-monstrous bird, the parent-form of
    the several short-faced sub-breeds, then appeared. I suspect this
    because short-faced Tumblers are born with their beaks (ascertained
    by careful measurement) as short, proportionally with the size of
    their bodies, as in the adult bird; and in this respect they differ
    greatly from all other breeds, which slowly acquire during growth
    their various characteristic qualities.

    Since the year 1765 there has been some change in one of the chief
    characters of the short-faced Tumbler, namely, in the length of the
    beak. Fanciers measure the “head and beak” from the tip of the beak
    to the front corner of the eyeball. About the year 1765 a “head and
    beak” was considered good,[42] which, measured in the usual manner,
    was 7/8 of an inch in length; now it ought not to exceed 5/8 of an
    inch; “it is however possible,” as Mr. Eaton candidly
    confesses,“for a bird to be considered as pleasant or neat even at
    6/8 of an inch, but exceeding that length it must be looked upon as
    unworthy of attention.” Mr. Eaton states that he has never seen in
    the course of his life more than two or three birds with the “head
    and beak” not exceeding half an inch in length; “still I believe in
    the course of a few years that the head and beak will be shortened,
    and that half-inch birds will not be considered so great a
    curiosity as at the present time.” That Mr. Eaton’s opinion
    deserves attention cannot be doubted, considering his success in
    winning prizes at our exhibitions. Finally in regard to the Tumbler
    it may be concluded from the facts above given that it was
    originally introduced into Europe, probably first into England,
    from the East; and that it then resembled our common English
    Tumbler, or more probably the Persian or Indian Tumbler, with a
    beak only just perceptibly shorter than that of the common
    dovecot-pigeon. With respect to the short-faced Tumbler, which is
    not known to exist in the East, there can hardly be a doubt that
    the whole wonderful change in the size of the head, beak, body and
    feet, and in general carriage, has been produced during the last
    two centuries by continued selection, aided probably by the birth
    of a semi- monstrous bird somewhere about the year 1750.

_Runts._—Of their history little can be said. In the time of Pliny the
pigeons of Campania were the largest known; and from this fact alone
some authors assert that they were Runts. In Aldrovandi’s time, in
1600, two sub-breeds existed; but one of them, the short-beaked, is now
extinct in Europe.

_Barbs._—Notwithstanding statements to the contrary, it seems to me
impossible to recognise the Barb in Aldrovandi’s description and
figures; four breeds, however, existed in the year 1600 which evidently
were allied both to Barbs and Carriers. To show how difficult it is to
recognise some of the breeds described by Aldrovandi I will give the
different opinions in regard to the above four kinds, named by him _C.
indica, cretensis, gutturosa,_ and _persica._ Willughby thought that
the _Columba indica_ was a Turbit, but the eminent fancier Mr. Brent
believes that it was an inferior Barb: _C. cretensis,_ with a short
beak and a swelling on the upper mandible, cannot be recognised: _C._
(falsely called) _gutturosa,_ which from its _rostrum, breve, crassum,
et tuberosum_ seems to me to come nearest to the Barb, Mr. Brent
believes to be a Carrier; and lastly, the _C. persica et turcica,_ Mr.
Brent thinks, and I quite concur with him, was a short-beaked Carrier
with very little wattle. In 1687 the Barb was known in England, and
Willughby describes the beak as like that of the Turbit; but it is not
credible that his Barbs should have had a beak like that of our present
birds, for so accurate an observer could not have overlooked its great
breadth.

    _English Carrier._—We may look in vain in Aldrovandi’s work for any
    bird resembling our prize Carriers; the _C. persica et turcica_ of
    this author comes the nearest, but is said to have had a short
    thick beak; therefore it must have approached in character a Barb,
    and have differed greatly from our Carriers. In Willughby’s time,
    in 1677, we can clearly recognise the Carrier, yet he adds, “the
    bill is not short, but of a moderate length;” a description which
    no one would apply to our present Carriers, so conspicuous for the
    extraordinary length of their beaks. The old names given in Europe
    to the Carrier, and the several names now in use in India, indicate
    that Carriers originally came from Persia; and Willughby’s
    description would perfectly apply to the Bussorah Carrier as it now
    exists in Madras. In later times we can partially trace the
    progress of change in our English Carriers: Moore, in 1735, says
    “an inch and a half is reckoned a long beak, though there are very
    good Carriers that are found not to exceed an inch and a quarter.”
    These birds must have resembled or perhaps been a little superior
    to the Carriers, previously described, now found in Persia. In
    England at the present day “there are,” as Mr. Eaton[43] states,
    “beaks that would measure (from edge of eye to tip of beak) one
    inch and three-quarters, and some few even two inches in length.”

From these historical details we see that nearly all the chief domestic
races existed before the year 1600. Some remarkable only for colour
appear to have been identical with our present breeds, some were nearly
the same, some considerably different, and some have since become
extinct. Several breeds, such as Finnikins and Turners, the
swallow-tailed pigeon of Bechstein and the Carmelite, seem to have
originated and to have disappeared within this same period. Any one now
visiting a well-stocked English aviary would certainly pick out as the
most distinct kinds, the massive Runt, the Carrier with its wonderfully
elongated beak and great wattles, the Barb with its short broad beak
and eye-wattles, the short-faced Tumbler with its small conical beak,
the Pouter with its great crop, long legs and body, the Fantail with
its upraised, widely-expanded, well-feathered tail, the Turbit with its
frill and short blunt beak, and the Jacobin with his hood. Now, if this
same person could have viewed the pigeons kept before 1600 by Akber
Khan in India and by Aldrovandi in Europe, he would have seen the
Jacobin with a less perfect hood; the Turbit apparently without its
frill; the Pouter with shorter legs, and in every way less
remarkable—that is, if Aldrovandi’s Pouter resembled the old German
kind; the Fantail would have been far less singular in appearance, and
would have had much fewer feathers in its tail; he would have seen
excellent flying Tumblers, but he would in vain have looked for the
marvellous short-faced breeds; he would have seen birds allied to
Barbs, but it is extremely doubtful whether he would have met with our
actual Barbs; and lastly, he would have found Carriers with beaks and
wattle incomparably less developed than in our English Carriers. He
might have classed most of the breeds in the same groups as at present;
but the differences between the groups were then far less strongly
pronounced than at present. In short, the several breeds had at this
early period not diverged in so great a degree as now from their
aboriginal common parent, the wild rock-pigeon.

      _Manner of Formation of the chief Races._

We will now consider more closely the probable steps by which the chief
races have been formed. As long as pigeons are kept semi-domesticated
in dovecots in their native country, without any care in selecting and
matching them, they are liable to little more variation than the wild
_C. livia,_ namely, in the wings becoming chequered with black, in the
croup being blue or white, and in the size of the body. When, however,
dovecot-pigeons are transported into diversified countries, such as
Sierra Leone, the Malay archipelago, and Madeira, they are exposed to
new conditions of life; and apparently in consequence vary in a
somewhat greater degree. When closely confined, either for the pleasure
of watching them, or to prevent their straying, they must be exposed,
even in their native climate, to considerably different conditions; for
they cannot obtain their natural diversity of food; and, what is
probably more important, they are abundantly fed, whilst debarred from
taking much exercise. Under these circumstances we might expect to
find, from the analogy of all other domesticated animals, a greater
amount of individual variability than with the wild pigeon; and this is
the case. The want of exercise apparently tends to reduce the size of
the feet and organs of flight; and then, from the law of correlation of
growth, the beak apparently becomes affected. From what we now see
occasionally taking place in our aviaries, we may conclude that sudden
variations or sports, such as the appearance of a crest of feathers on
the head, of feathered feet, of a new shade of colour, of an additional
feather in the tail or wing, would occur at rare intervals during the
many centuries which have elapsed since the pigeon was first
domesticated. At the present day such “sports” are generally rejected
as blemishes; and there is so much mystery in the breeding of pigeons
that, if a valuable sport did occur, its history would often be
concealed. Before the last hundred and fifty years, there is hardly a
chance of the history of any such sport having been recorded. But it by
no means follows from this that such sports in former times, when the
pigeon had undergone much less variation, would have been rejected. We
are profoundly ignorant of the cause of each sudden and apparently
spontaneous variation, as well as of the infinitely numerous shades of
difference between the birds of the same family. But in a future
chapter we shall see that all such variations appear to be the indirect
result of changes of some kind in the conditions of life.

Hence, after a long course of domestication, we might expect to see in
the pigeon much individual variability, and occasional sudden
variations, as well as slight modifications from the lessened use of
certain parts, together with the effects of correlation of growth. But
without selection all this would produce only a trifling or no result;
for without such aid differences of all kinds would, from the two
following causes, soon disappear. In a healthy and vigorous lot of
pigeons many more young birds are killed for food or die than are
reared to maturity; so that an individual having any peculiar
character, if not selected, would run a good chance of being destroyed;
and if not destroyed, the peculiarity in question would generally be
obliterated by free intercrossing. It might, however, occasionally
happen that the same variation repeatedly occurred, owing to the action
of peculiar and uniform conditions of life, and in this case it would
prevail independently of selection. But when selection is brought into
play all is changed; for this is the foundation-stone in the formation
of new races; and with the pigeon, circumstances, as we have already
seen, are eminently favourable for selection. When a bird presenting
some conspicuous variation has been preserved, and its offspring have
been selected, carefully matched, and again propagated, and so onwards
during successive generations, the principle is so obvious that nothing
more need be said about it. This may be called _methodical selection,_
for the breeder has a distinct object in view, namely, to preserve some
character which has actually appeared; or to create some improvement
already pictured in his mind.

Another form of selection has hardly been noticed by those authors who
have discussed this subject, but is even more important. This form may
be called _unconscious selection,_ for the breeder selects his birds
unconsciously, unintentionally, and without method, yet he surely
though slowly produces a great result. I refer to the effects which
follow from each fancier at first procuring and afterwards rearing as
good birds as he can, according to his skill, and according to the
standard of excellence at each successive period. He does not wish
permanently to modify the breed; he does not look to the distant
future, or speculate on the final result of the slow accumulation
during many generations of successive slight changes; he is content if
he possesses a good stock, and more than content if he can beat his
rivals. The fancier in the time of Aldrovandi, when in the year 1600 he
admired his own Jacobins, Pouters, or Carriers, never reflected what
their descendants in the year 1860 would become: he would have been
astonished could he have seen our Jacobins, our improved English
Carriers, and our Pouters; he would probably have denied that they were
the descendants of his own once-admired stock, and he would perhaps not
have valued them, for no other reason, as was written in 1765, “than
because they were not like what used to be thought good when he was in
the fancy.” No one will attribute the lengthened beak of the Carrier,
the shortened beak of the Short-faced Tumbler, the lengthened leg of
the Pouter, the more perfectly enclosed hood of the Jacobin,
etc.—changes effected since the time of Aldrovandi, or even since a
much later period,—to the direct and immediate action of the conditions
of life. For these several races have been modified in various and even
in directly opposite ways, though kept under the same climate and
treated in all respects in as nearly uniform a manner as possible. Each
slight change in the length or shortness of the beak, in the length of
leg, etc., has no doubt been indirectly and remotely caused by some
change in the conditions to which the bird has been subjected, but we
must attribute the final result, as is manifest in those cases of which
we have any historical record, to the continued selection and
accumulation of many slight successive variations.

    The action of unconscious selection, as far as pigeons are
    concerned, depends on a universal principle in human nature,
    namely, on our rivalry, and desire to outdo our neighbours. We see
    this in every fleeting fashion, even in our dress, and it leads the
    fancier to endeavour to exaggerate every peculiarity in his breeds.
    A great authority on pigeons,[44] says, “Fanciers do not and will
    not admire a medium standard, that is, half and half, which is
    neither here nor there, but admire extremes.” After remarking that
    the fancier of Short-faced Beard Tumblers wishes for a very short
    beak, and that the fancier of Long-faced Beard Tumblers wishes for
    a very long beak, he says, with respect to one of intermediate
    length, “Don’t deceive yourself. Do you suppose for a moment the
    short or the long-faced fancier would accept such a bird as a gift?
    Certainly not; the short-faced fancier could see no beauty in it;
    the long-faced fancier would swear there was no use in it, etc.” In
    these comical passages, written seriously, we see the principle
    which has ever guided fanciers, and has led to such great
    modifications in all the domestic races which are valued solely for
    their beauty or curiosity.

Fashions in pigeon-breeding endure for long periods; we cannot change
the structure of a bird as quickly as we can the fashion of our dress.
In the time of Aldrovandi, no doubt the more the pouter inflated his
crop, the more he was valued. Nevertheless, fashions do to a certain
extent change; first one point of structure and then another is
attended to; or different breeds are admired at different times and in
different countries. As the author just quoted remarks, “the fancy ebbs
and flows; a thorough fancier now-a-days never stoops to breed
toy-birds;” yet these very “toys” are now most carefully bred in
Germany. Breeds which at the present time are highly valued in India
are considered worthless in England. No doubt, when breeds are
neglected, they degenerate; still we may believe that, as long as they
are kept under the same conditions of life, characters once gained will
be partially retained for a long time, and may form the starting-point
for a future course of selection.

Let it not be objected to this view of the action of unconscious
selection that fanciers would not observe or care for extremely slight
differences. Those alone who have associated with fanciers can be
thoroughly aware of their accurate powers of discrimination acquired by
long practice, and of the care and labour which they bestow on their
birds. I have known a fancier deliberately study his birds day after
day to settle which to match together and which to reject. Observe how
difficult the subject appears to one of the most eminent and
experienced fanciers. Mr. Eaton, the winner of many prizes, says, “I
would here particularly guard you against keeping too great a variety
of pigeons, otherwise you will know a little about all the kinds, but
nothing about one as it ought to be known.” “It is possible there may
be a few fanciers that have a good general knowledge of the several
fancy pigeons, but there are many who labour under the delusion of
supposing they know what they do not.” Speaking exclusively of one sub-
variety of one race, namely, the short-faced almond tumbler, and after
saying that some fanciers sacrifice every property to obtain a good
head and beak, and that other fanciers sacrifice everything for
plumage, he remarks: “Some young fanciers who are over covetous go in
for all the five properties at once, and they have their reward by
getting nothing.” In India, as I hear from Mr. Blyth, pigeons are
likewise selected and matched with the greatest care. We must not judge
of the slight divergences from existing varieties which would have been
valued in ancient days, by those which are now valued after the
formation of so many races, each with its own standard of perfection,
kept uniform by our numerous Exhibitions. The ambition of the most
energetic fancier may be fully satisfied by the difficulty of excelling
other fanciers in the breeds already established, without trying to
form a new one.

    A difficulty with respect to the power of selection will perhaps
    already have occurred to the reader, namely, what could have led
    fanciers first to attempt to make such singular breeds as Pouters,
    Fantails, Carriers, etc.? But it is this very difficulty which the
    principle of unconscious selection removes. Undoubtedly no fancier
    ever did intentionally make such an attempt. All that we need
    suppose is that a variation occurred sufficiently marked to catch
    the discriminating eye of some ancient fancier, and then
    unconscious selection carried on for many generations, that is, the
    wish of succeeding fanciers to excel their rivals, would do the
    rest. In the case of the Fantail we may suppose that the first
    progenitor of the breed had a tail only slightly erected, as may
    now be seen in certain Runts,[45] with some increase in the number
    of the tail-feathers, as now occasionally occurs with Nuns. In the
    case of the Pouter we may suppose that some bird inflated its crop
    a little more than other pigeons, as is now the case in a slight
    degree with the œesophagus of the Turbit. We do not know the origin
    of the common Tumbler, but we may suppose that a bird was born with
    some affection of the brain, leading it to make somersaults in the
    air;[46] and before the year 1600 pigeons remarkable for their
    diversified manner of flight were much valued in India, and by the
    order of the Emperor Akber Khan were sedulously trained and
    carefully matched.

In the foregoing cases we have supposed that a sudden variation,
conspicuous enough to catch a fancier’s eye, first appeared; but even
this degree of abruptness in the process of variation is not necessary
for the formation of a new breed. When the same kind of pigeon has been
kept pure, and has been bred during a long period by two or more
fanciers, slight differences in the strain can often be recognised.
Thus I have seen first- rate Jacobins in one man’s possession which
certainly differed slightly in several characters from those kept by
another. I possessed some excellent Barbs descended from a pair which
had won a prize, and another lot descended from a stock formerly kept
by that famous fancier Sir John Sebright, and these plainly differed in
the form of the beak; but the differences were so slight that they
could hardly be given by words. Again, the common English and Dutch
Tumbler differ in a somewhat greater degree, both in length of beak and
shape of head. What first caused these slight differences cannot be
explained any more than why one man has a long nose and another a short
one. In the strains long kept distinct by different fanciers, such
differences are so common that they cannot be accounted for by the
accident of the birds first chosen for breeding having been originally
as different as they now are. The explanation no doubt lies in
selection of a slightly different nature having been applied in each
case; for no two fanciers have exactly the same taste, and consequently
no two, in choosing and carefully matching their birds, prefer or
select exactly the same. As each man naturally admires his own birds,
he goes on continually exaggerating by selection whatever slight
peculiarities they may possess. This will more especially happen with
fanciers living in different countries, who do not compare their stocks
or aim at a common standard of perfection. Thus, when a mere strain has
once been formed, unconscious selection steadily tends to augment the
amount of difference, and thus converts the strain into a sub-breed and
this ultimately into a well-marked breed or race.

The principle of correlation of growth should never be lost sight of.
Most pigeons have small feet, apparently caused by their lessened use,
and from correlation, as it would appear, their beaks have likewise
become reduced in length. The beak is a conspicuous organ, and, as soon
as it had thus become perceptibly shortened, fanciers would almost
certainly strive to reduce it still more by the continued selection of
birds with the shortest beaks; whilst at the same time other fanciers,
as we know has actually been the case, would in other sub-breeds,
strive to increase its length. With the increased length of the beak,
the tongue becomes greatly lengthened, as do the eyelids with the
increased development of the eye-wattles; with the reduced or increased
size of the feet, the number of the scutellæ vary; with the length of
the wing, the number of the primary wing-feathers differ; and with the
increased length of the body in the pouter the number of the sacral
vertebræ is augmented. These important and correlated differences of
structure do not invariably characterise any breed; but if they had
been attended to and selected with as much care as the more conspicuous
external differences, there can hardly be a doubt that they would have
been rendered constant. Fanciers could assuredly have made a race of
Tumblers with nine instead of ten primary wing-feathers, seeing how
often the number nine appears without any wish on their part, and
indeed in the case of the white-winged varieties in opposition to their
wish. In a similar manner, if the vertebræ had been visible and had
been attended to by fanciers, assuredly an additional number might
easily have been fixed in the Pouter. If these latter characters had
once been rendered constant, we should never have suspected that they
had at first been highly variable, or that they had arisen from
correlation, in the one case with the shortness of the wings, and in
the other case with the length of the body.

In order to understand how the chief domestic races have become
distinctly separated from each other, it is important to bear in mind,
that fanciers constantly try to breed from the best birds, and
consequently that those which are inferior in the requisite qualities
are in each generation neglected; so that after a time the less
improved parent-stocks and many subsequently formed intermediate grades
become extinct. This has occurred in the case of the Pouter, Turbit,
and Trumpeter, for these highly improved breeds are now left without
any links closely connecting them either with each other or with the
aboriginal rock-pigeon. In other countries, indeed, where the same care
has not been applied, or where the same fashion has not prevailed, the
earlier forms may long remain unaltered, or altered only in a slight
degree, and we are thus sometimes enabled to recover the connecting
links. This is the case in Persia and India with the Tumbler and
Carrier, which there differ but slightly from the rock-pigeon in the
proportions of their beaks. So again in Java, the Fantail sometimes has
only fourteen caudal feathers, and the tail is much less elevated and
expanded than in our improved birds; so that the Java bird forms a link
between a first-rate Fantail and the rock-pigeon.

Occasionally a breed may be retained for some particular quality in a
nearly unaltered condition in the same country, together with highly
modified off-shoots or sub-breeds, which are valued for some distinct
property. We see this exemplified in England, where the common Tumbler,
which is valued only for its flight, does not differ much from its
parent-form, the Eastern Tumbler; whereas the Short-faced Tumbler has
been prodigiously modified, from being valued, not for its flight, but
for other qualities. But the common-flying Tumbler of Europe has
already begun to branch out into slightly different sub-breeds, such as
the common English Tumbler, the Dutch Roller, the Glasgow
House-tumbler, and the Long-faced Beard Tumbler, etc.; and in the
course of centuries, unless fashions greatly change, these sub-breeds
will diverge through the slow and insensible process of unconscious
selection, and become modified, in a greater and greater degree. After
a time the perfectly graduated links which now connect all these
sub-breeds together, will be lost, for there would be no object and
much difficulty in retaining such a host of intermediate sub-varieties.

The principle of divergence, together with the extinction of the many
previously existing intermediate forms, is so important for
understanding the origin of domestic races, as well as of species in a
state of nature, that I will enlarge a little more on this subject. Our
third main group includes Carriers, Barbs, and Runts, which are plainly
related to one another, yet wonderfully distinct in several important
characters. According to the view given in the last chapter, these
three races have probably descended from an unknown race having an
intermediate character, and this race from the rock-pigeon. Their
characteristic differences are believed to be due to different breeders
having at an early period admired different points of structure; and
then, on the acknowledged principle of admiring extremes, having gone
on breeding, without any thought of the future, as good birds as they
could,—Carrier-fanciers preferring long beaks with much
wattle,—Barb-fanciers preferring short thick beaks with much
eye-wattle,—and Runt-fanciers not caring about the beak or wattle, but
only for the size and weight of the body. This process would have led
to the neglect and final extinction of the earlier, inferior, and
intermediate birds; and thus it has come to pass, that in Europe these
three races are now so extraordinarily distinct from each other. But in
the East, whence they were originally brought, the fashion has been
different, and we there see breeds which connect the highly modified
English Carrier with the rock-pigeon, and others which to a certain
extent connect Carriers and Runts. Looking back to the time of
Aldrovandi, we find that there existed in Europe, before the year 1600,
four breeds which were closely allied to Carriers and Barbs, but which
competent authorities cannot now identify with our present Barbs and
Carriers; nor can Aldrovandi’s Runts be identified with our present
Runts. These four breeds certainly did not differ from each other
nearly so much as do our existing English Carriers, Barbs, and Runts.
All this is exactly what might have been anticipated. If we could
collect all the pigeons which have ever lived, from before the time of
the Romans to the present day, we should be able to group them in
several lines, diverging from the parent rock-pigeon. Each line would
consist of almost insensible steps, occasionally broken by some
slightly greater variation or sport, and each would culminate in one of
our present highly modified forms. Of the many former connecting links,
some would be found to have become absolutely extinct without having
left any issue, whilst others, though extinct, would be recognised as
the progenitors of the existing races.

I have heard it remarked as a strange circumstance that we occasionally
hear of the local or complete extinction of domestic races, whilst we
hear nothing of their origin. How, it has been asked, can these losses
be compensated, and more than compensated, for we know that with almost
all domesticated animals the races have largely increased in number
since the time of the Romans? But on the view here given, we can
understand this apparent contradiction. The extinction of a race within
historical times is an event likely to be noticed; but its gradual and
scarcely sensible modification through unconscious selection, and its
subsequent divergence, either in the same or more commonly in distant
countries, into two or more strains, and their gradual conversion into
sub-breeds, and these into well- marked breeds are events which would
rarely be noticed. The death of a tree, that has attained gigantic
dimensions, is recorded; the slow growth of smaller trees and their
increase in number excite no attention.

In accordance with the belief in the great power of selection, and of
the little direct power of changed conditions of life, except in
causing general variability or plasticity of organisation, it is not
surprising that dovecot-pigeons have remained unaltered from time
immemorial; and that some toy-pigeons, which differ in little else
besides colour from the dovecot-pigeon, have retained the same
character for several centuries. For when one of these toy-pigeons had
once become beautifully and symmetrically coloured,—when, for instance,
a Spot had been produced with the crown of its head, its tail, and
tail-coverts of a uniform colour, the rest of the body being
snow-white,—no alteration or improvement would be desired. On the other
hand, it is not surprising that during this same interval of time our
highly-bred pigeons have undergone an astonishing amount of change; for
in regard to them there is no defined limit to the wish of the fancier,
and there is no known limit to the variability of their characters.
What is there to stop the fancier desiring to give to his Carrier a
longer and longer beak, or to his Tumbler a shorter and shorter beak?
nor has the extreme limit of variability in the beak, if there be any
such limit, as yet been reached. Notwithstanding the great improvement
effected within recent times in the Short-faced Almond Tumbler, Mr.
Eaton remarks, “the field is still as open for fresh competitors as it
was one hundred years ago;” but this is perhaps an exaggerated
assertion, for the young of all highly-improved fancy birds are
extremely liable to disease and death.

I have heard it objected that the formation of the several domestic
races of the pigeon throws no light on the origin of the wild species
of the Columbidæ, because their differences are not of the same nature.
The domestic races, for instance do not differ, or differ hardly at
all, in the relative lengths and shape of the primary wing-feathers, in
the relative length of the hind toe, or in habits of life, as in
roosting and building in trees. But the above objection shows how
completely the principle of selection has been misunderstood. It is not
likely that characters selected by the caprice of man should resemble
differences preserved under natural conditions either from being of
direct service to each species, or from standing in correlation with
other modified and serviceable structures. Until man selects birds
differing in the relative length of the wing-feathers or toes, etc., no
sensible change in these parts should be expected. Nor could man do
anything unless these parts happened to vary under domestication: I do
not positively assert that this is the case, although I have seen
traces of such variability in the wing-feathers, and certainly in the
tail-feathers. It would be a strange fact if the relative length of the
hind toe should never vary, seeing how variable the foot is both in
size and in the number of the scutellæ. With respect to the domestic
races not roosting or building in trees, it is obvious that fanciers
would never attend to or select such changes in habits; but we have
seen that the pigeons in Egypt, which do not for some reason like
settling on the low mud hovels of the natives, are led, apparently by
compulsion, to perch in crowds on the trees. We may even affirm that,
if our domestic races had become greatly modified in any of the above
specified respects, and it could be shown that fanciers had never
attended to such points, or that they did not stand in correlation with
other selected characters, the fact, on the principles advocated in
this chapter, would have offered a serious difficulty.

Let us briefly sum up the last two chapters on the pigeon. We may
conclude with confidence that all the domestic races, notwithstanding
their great amount of difference, are descended from the _Columba
livia,_ including under this name certain wild races. But the
differences between the latter throw no light whatever on the
characters which distinguish the domestic races. In each breed or
sub-breed the individual birds are more variable than birds in a state
of nature; and occasionally they vary in a sudden and strongly-marked
manner. This plasticity of organisation apparently results from changed
conditions of life. Disuse has reduced certain parts of the body.
Correlation of growth so ties the organisation together, that when one
part varies other parts vary at the same time. When several breeds have
once been formed, their intercrossing aids the progress of
modification, and has even produced new sub-breeds. But as, in the
construction of a building, mere stones or bricks are of little avail
without the builder’s art, so, in the production of new races,
selection has been the presiding power. Fanciers can act by selection
on excessively slight individual differences, as well as on those
greater differences which are called sports. Selection is followed
methodically when the fancier tries to improve and modify a breed
according to a prefixed standard of excellence; or he acts
unmethodically and unconsciously, by merely trying to rear as good
birds as he can, without any wish or intention to alter the breed. The
progress of selection almost inevitably leads to the neglect and
ultimate extinction of the earlier and less improved forms, as well as
of many intermediate links in each long line of descent. Thus it has
come to pass that most of our present races are so marvellously
distinct from each other, and from the aboriginal rock-pigeon.

REFERENCES

 [1] Temminck ‘Hist. Nat. Gén. des Pigeons,’ etc., tom. i. p. 191.

 [2] I have heard through Sir C. Lyell from Miss Buckley, that some
 half-bred Carriers kept during many years near London regularly
 settled by day on some adjoining trees, and, after being disturbed in
 their loft by their young being taken, roosted on them at night.

 [3] ‘Annals and Mag. of Nat. Hist.,’ 2nd ser., vol. xx., 1857, p. 509;
 and in a late volume of the Journal of the Asiatic Society.

 [4] In works written on the pigeon by fanciers I have sometimes
 observed the mistaken belief expressed that the species which
 naturalists called ground-pigeons (in contradistinction to arboreal
 pigeons) do not perch and build on trees. In these same works by
 fanciers wild species resembling the chief domestic races are often
 said to exist in various parts of the world; but such species are
 quite unknown to naturalists.

 [5] Sir R. Schomburgk in ‘Journal R. Geograph. Soc.,’ vol. xiii.,
 1844, p. 32.

 [6] Rev. E. S. Dixon ‘Ornamental Poultry,’ 1848, pp. 63, 66.

 [7] ‘Proc. Zoolog. Soc.,’ 1859, p. 400.

 [8] Temminck, ‘Hist. Nat. Gén. des Pigeons,’ tom. i.; also ‘Les
 Pigeons’ par Mme. Knip and Temminck. Bonaparte, however, in his ‘Coup-
 d’œil’ believes that two closely allied species are confounded
 together under this name. The _C. leucocephala_ of the West Indies is
 stated by Temminck to be a rock-pigeon; but I am informed by Mr. Gosse
 that this is an error.

 [9] ‘Handbuch der Naturgesch. Vögel Deutschlands.’

 [10] ‘Tagebuch, Reise nach Färo,’ 1830, s. 62.

 [11] ‘Annals and Mag. of Nat. Hist.,’ vol. xix., 1847, p. 102. This
 excellent paper on pigeons is well worth consulting.

 [12] ‘Natural History of Ireland,’ Birds, vol. ii. (1850), p. 11. For
 Graba _see_ previous reference.

 [13] ‘Coup-d’œil sur l’Ordre des Pigeons,’ ‘Comptes Rendus,’ 1854-55.

 [14] ‘Naturgeschichte. Deutschlands,’ Band. iv. 1795, s. 14.

 [15] ‘History of British Birds,’ vol. i. pp. 275-284. Mr. Andrew
 Duncan tamed a rock-pigeon in the Shetland Islands. Mr. James Barclay,
 and Mr. Smith of Uyea Sound, both say that the wild rock-pigeon can be
 easily tamed; and the former gentleman asserts that the tamed birds
 breed four times a year. Dr. Lawrence Edmondstone informs me that a
 wild rock-pigeon came and settled in his dovecot in Balta Sound in the
 Shetland Islands, and bred with his pigeons; he has also given me
 other instances of the wild rock-pigeon having been taken young and
 breeding in captivity.

 [16] ‘Annals and Mag. of Nat. History,’ vol. xix. 1847, p. 103, and
 vol. for 1857, p. 512.

 [17] Domestic pigeons of the common kind are mentioned as being pretty
 numerous in John Barbut’s ‘Description of the Coast of Guinea’ (p.
 215), published in 1746; they are said, in accordance with the name
 which they bear, to have been imported.

 [18] With respect to feral pigeons—for Juan Fernandez, _ see_ Bertero
 in ‘Annal. des Sc. Nat.,’ tom. xxi. p. 351. For Norfolk Islands, _see_
 Rev. E. S. Dixon in the ‘Dovecote,’ 1851, p. 14, on the authority of
 Mr. Gould. For Ascension I rely on MS. information given me by Mr.
 Layard. For the banks of the Hudson, _see_ Blyth in ‘Annals of Nat.
 Hist.,’ vol. xx., 1857, p. 511. For Scotland, _see_ Macgillivray,
 ‘British Birds,’ vol. i. p. 275; also Thompson’s ‘Nat. Hist. of
 Ireland, Birds,’ vol. ii. p. 11. For ducks, _see_ Rev. E. S. Dixon,
 ‘Ornamental Poultry,’ 1847, p. 122. For the feral hybrids of the
 common and musk-ducks, _see_ Audubon’s ‘American Ornithology,’ and
 Selys-Longchamp’s ‘Hybrides dans la Famille des Anatides.’ For the
 goose, Isidore Geoffroy St.-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. p.
 498. For guinea-fowls, _see_ Gosse’s ‘Naturalist’s Sojourn in
 Jamaica,’ p. 124; and his ‘Birds of Jamaica,’ for fuller particulars.
 I saw the wild guinea-fowl in Ascension. For the peacock, _see_ ‘A
 Week at Port Royal,’ by a competent authority, Mr. R. Hill, p. 42. For
 the turkey I rely on oral information; I ascertained that they were
 not Curassows. With respect to fowls I will give the references in the
 next chapter.

 [19] I have drawn out a long table of the various crosses made by
 fanciers between the several domestic breeds but I do not think it
 worth while publishing. I have myself made for this special purpose
 many crosses, and all were perfectly fertile. I have united in one
 bird five of the most distinct races, and with patience I might
 undoubtedly have thus united all. The case of five distinct breeds
 being blended together with unimpaired fertility is important, because
 Gärtner has shown that it is a very general, though not, as he
 thought, universal rule, that complex crosses between several species
 are excessively sterile. I have met with only two or three cases of
 reported sterility in the offspring of certain races when crossed.
 Pistor (‘Das Ganze der Feldtaubenzucht,’ 1831, s. 15) asserts that the
 mongrels from Barbs and Fantails are sterile: I have proved this to be
 erroneous, not only by crossing those hybrids with several other
 hybrids of the same parentage, but by the more severe test of pairing
 brother and sister hybrids _inter se,_ and they were _perfectly_
 fertile. Temminck has stated (‘Hist. Nat. Gén. des Pigeons,’ tom. i.
 p. 197) that the Turbit or Owl will not cross readily with other
 breeds: but my Turbits crossed, when left free with Almond Tumblers
 and with Trumpeters; the same thing has occurred (Rev. E. S. Dixon,
 ‘The Dovecote,’ p. 107) between Turbits and Dovecots and Nuns. I have
 crossed Turbits with Barbs, as has M. Boitard (p. 34), who says the
 hybrids were very fertile. Hybrids from a Turbit and Fantail have been
 known to breed _inter se_ (Riedel, ‘Taubenzucht,’ s. 25, and
 Bechstein, ‘Naturgesch. Deutsch.,’ B. iv. s. 44. Turbits (Riedel, s.
 26) have been crossed with Pouters and with Jacobins, and with a
 hybrid Jacobin-trumpeter (Riedel, s. 27). The latter author has,
 however, made some vague statements (s. 22) on the sterility of
 Turbits when crossed with certain other crossed breeds. But I have
 little doubt that the Rev. E. S. Dixon’s explanation of such
 statements is correct, viz. that individual birds both with Turbits
 and other breeds are occasionally sterile.

 [20] ‘Das Ganze der Taubenzucht,’ s. 18.

 [21] ‘Les Pigeons,’ etc., p. 35.

 [22] Domestic pigeons pair readily with the allied _C. œnas_
 (Bechstein, ‘Naturgesch. Deutschlands,’ B. iv. s. 3); and Mr. Brent
 has made the same cross several times in England, but the young were
 very apt to die at about ten days old; one hybrid which he reared
 (from _C. œnas_ and a male Antwerp Carrier) paired with a Dragon, but
 never laid eggs. Bechstein further states (s. 26) that the domestic
 pigeon will cross with _C. palumbus, Turtur risoria,_ and _T.
 vulgaris,_ but nothing is said of the fertility of the hybrids, and
 this would have been mentioned had the fact been ascertained. In the
 Zoological Gardens (MS. report to me from Mr. James Hunt) a male
 hybrid from _Turtur vulgaris_ and a domestic pigeon “paired with
 several different species of pigeons and doves, but none of the eggs
 were good.” Hybrids from _C. œnas_ and _gymnophthalmos_ were sterile.
 In Loudon’s ‘Mag. of Nat. Hist.,’ vol. vii. 1834, p. 154, it is said
 that a male hybrid (from _Turtur vulgaris_ male, and the
 cream-coloured _T. risoria_ female) paired during two years with a
 female _T. risoria,_ and the latter laid many eggs, but all were
 sterile. MM. Boitard and Corbié (‘Les Pigeons,’ p. 235) state that the
 hybrids from these two turtle-doves are invariably sterile both _inter
 se_ and with either pure parent. The experiment was tried by M. Corbié
 “avec une espèce d’obstination;” and likewise by M. Mauduyt, and by M.
 Vieillot. Temminck also found the hybrids from these two species quite
 barren. Therefore, when Bechstein (‘Naturgesch. Deutschlands Vögel,’
 B. iv. s. 101) asserts that the hybrids from these two turtle-doves
 propagate _inter se_ equally well with pure species, and when a writer
 in the ‘Field’ newspaper (in a letter dated Nov. 10th, 1858) makes a
 similar assertion, it would appear that there must be some mistake;
 though what the mistake is I know not, as Bechstein at least must have
 known the white _variety_ of _T. risoria_: it would be an unparalleled
 fact if the same two species sometimes produced _extremely_ fertile,
 and sometimes _extremely_ barren, offspring. In the MS. report from
 the Zoological Gardens it is said that hybrids from _Turtur vulgaris_
 and _ suratensis,_ and from _T. vulgaris_ and _Ectopistes
 migratorius,_ were sterile. Two of the latter male hybrids paired with
 their pure parents, viz. _Turtur vulgaris_ and the Ectopistes, and
 likewise with _T. risoria_ and with _ Columba œnas,_ and many eggs
 were produced, but all were barren. At Paris, hybrids have been raised
 (Isid. Geoffrey Saint-Hilaire, ‘Hist. Nat. Générale,’ tom. iii. p.
 180) from _Turtur auritus_ with _T. cambayensis_ and with _T.
 suratensis_; but nothing is said of their fertility. At the Zoological
 Gardens of London the _Goura coronata_ and _victoriæ_ produced a
 hybrid which paired with the pure _G. coronata,_ and laid several
 eggs, but these proved barren. In 1860 _Columba gymnophthalmos_ and
 _maculosa_ produced hybrids in these same gardens.

 [23] There is one exception to the rule, namely, in a sub-variety of
 the Swallow of German origin, which is figured by Neumeister, and was
 shown to me by Mr. Wicking. This bird is blue, but has not the black
 wing-bars; for our object, however, in tracing the descent of the
 chief races, this exception signifies the less as the Swallow
 approaches closely in structure to _C. livia._ In many sub-varieties
 the black bars are replaced by bars of various colours. The figures
 given by Neumeister are sufficient to show that, if the wings alone
 are blue, the black wing-bars appear.

 [24] I have observed blue birds with all the above-mentioned marks in
 the following races, which seemed to be perfectly pure, and were shown
 at various exhibitions. Pouters, with the double black wing-bars, with
 white croup, dark bar to end of tail, and white edging to outer
 tail-feathers. Turbits, with all these same characters. Fantails with
 the same; but the croup in some was bluish or pure blue. Mr. Wicking
 bred blue Fantails from two black birds. Carriers (including the
 Bagadotten of Neumeister) with all the marks: two birds which I
 examined had white, and two had blue croups; the white edging to the
 outer tail-feathers was not present in all. Mr. Corker, a great
 breeder, assures me that, if black carriers are matched for many
 successive generations, the offspring become first ash-coloured, and
 then blue with black wing-bars. Runts of the elongated breed had the
 same marks, but the croup was pale blue; the outer tail-feathers had
 white edges. Neumeister figures the great Florence Runt of a blue
 colour with black bars. Jacobins are very rarely blue, but I have
 received authentic accounts of at least two instances of the blue
 variety with black bars having appeared in England; blue Jacobins were
 bred by Mr. Brent from two black birds. I have seen common Tumblers,
 both Indian and English, and Short-faced Tumblers, of a blue colour,
 with black wing-bars, with the black bar at the end of the tail, and
 with the outer tail-feathers edged with white; the croup in all was
 blue, or extremely pale blue, never absolutely white. Blue Barbs and
 Trumpeters seem to be excessively rare; but Neumeister, who may be
 implicitly trusted, figures blue varieties of both, with black
 wing-bars. Mr. Brent informs me that he has seen a blue Barb; and Mr.
 H. Weir, as I am informed by Mr. Tegetmeier, once bred a silver (which
 means very pale blue) Barb from two yellow birds.

 [25] Mr. Blyth informs me that all the domestic races in India have
 the croup blue; but this is not invariable, for I possess a very pale
 blue Simmali pigeon with the croup perfectly white, sent to me by Sir
 W. Elliot from Madras. A slaty-blue and chequered Nakshi pigeon has
 some white feathers on the croup alone. In some other Indian pigeons
 there were a few white feathers confined to the croup, and I have
 noticed the same fact in a carrier from Persia. The Java Fantail
 (imported into Amoy, and thence sent me) has a perfectly white croup.

 [26] ‘Les Pigeons,’ etc., p. 37.

 [27] ‘Treatise on Pigeons,’ 1858, p. 145.

 [28] J. Moore’s ‘Columbarium,’ 1735; in J. M. Eaton’s edition, 1852,
 p. 71.

 [29] I could give numerous examples; two will suffice. A mongrel,
 whose four grandparents were a white Turbit, white Trumpeter, white
 Fantail, and blue Pouter, was white all over, except a very few
 feathers about the head and on the wings, but the whole tail and
 tail-coverts were dark bluish-grey. Another mongrel whose four
 grandparents were a red Runt, white Trumpeter, white Fantail, and the
 same blue Pouter, was pure white all over, except the tail and upper
 tail-coverts, which were pale fawn, and except the faintest trace of
 double wing-bars of the same pale fawn tint.

 [30] It deserves notice, as bearing on the general subject of
 variation, that not only _C. livia_ presents several wild forms,
 regarded by some naturalists as species and by others as sub-species
 or as mere varieties, but that the species of several allied genera
 are in the same predicament. This is the case, as Mr. Blyth has
 remarked to me, with Treron, Palumbus, and Turtur.

 [31] ‘Denkmäler,’ Abth. ii. Bl. 70.

 [32] ‘The ‘Dovecote,’ by the Rev. E. S. Dixon, 1851, pp. 11-13.
 Adolphe Pictet (in his ‘Les Origines Indo-Européennes,’ 1859, p. 399)
 states that there are in the ancient Sanscrit language between 25 and
 30 names for the pigeon, and other 15 or 16 Persian names; none of
 these are common to the European languages. This fact indicates the
 antiquity of the domestication of the pigeon in the East.

 [33] English translation, 1601, Book x. ch. xxxvii.

 [34] ‘Ayeen Akbery,’ translated by F. Gladwin, 4to edit., vol. i. p.
 270.

 [35] J. M. Eaton, ‘Treatise on the Almond Tumbler,’ 1851; Preface, p.
 6.

 [36] As in the following discussion I often speak of the present time,
 I should state that this chapter was completed in the year 1858.

 [37] ‘Ornithologie,’ 1600, vol. ii. p. 360.

 [38] ‘A Treatise on Domestic Pigeons,’ dedicated to Mr. Mayor, 1765.
 Preface, p. 14.

 [39] Mr. Blyth has given a translation of part of the ‘Ayeen Akbery’
 in ‘Annals and Mag. of Nat. Hist.,’ vol. xix. 1847, p. 104.

 [40] ‘L’Histoire de la Nature des Oiseaux,’ p. 314.

 [41] ‘Treatise on Pigeons,’ 1852, p. 64.

 [42] J. M. Eaton ‘Treatise on the Breeding and Managing of the Almond
 Tumbler,’ 1851. Compare p. v. of Preface, p. 9, and p. 32.

 [43] ‘Treatise on Pigeons,’ 1852, p. 41.

 [44] Eaton’s ‘Treatise on Pigeons,’ 1858, p. 86.

 [45] _See_ Neumeister’s figure of the Florence Runt, tab. 13 in ‘Das
 Ganze der Taubenzucht.’

 [46] Mr. W. J. Moore gives a full account of the Ground Tumblers of
 India (‘Indian Medical Gazette,’ Jan. and Feb. 1873), and says the
 pricking the base of the brain, and giving hydrocyanic acid, together
 with strychnine, to an ordinary pigeon, brings on convulsive movements
 exactly like those of a Tumbler. One pigeon, the brain of which had
 been pricked, completely recovered, and ever afterwards occasionally
 made somersaults.




CHAPTER VII. FOWLS.

BRIEF DESCRIPTIONS OF THE CHIEF BREEDS—ARGUMENTS IN FAVOUR OF THEIR
DESCENT FROM SEVERAL SPECIES—ARGUMENTS IN FAVOUR OF ALL THE BREEDS
HAVING DESCENDED FROM GALLUS BANKIVA—REVERSION TO THE PARENT-STOCK IN
COLOUR—ANALOGOUS VARIATIONS—ANCIENT HISTORY OF THE FOWL—EXTERNAL
DIFFERENCES BETWEEN THE SEVERAL BREEDS—EGGS—CHICKENS—SECONDARY SEXUAL
CHARACTERS—WING-AND TAIL-FEATHERS, VOICE, DISPOSITION, ETC—OSTEOLOGICAL
DIFFERENCES IN THE SKULL, VERTEBRÆ, ETC—EFFECTS OF USE AND DISUSE ON
CERTAIN PARTS—CORRELATION OF GROWTH.


    As some naturalists may not be familiar with the chief breeds of
    the fowl, it will be advisable to give a condensed description of
    them.[1] From what I have read and seen of specimens brought from
    several quarters of the world, I believe that most of the chief
    kinds have been imported into England, but many sub-breeds are
    probably still unknown here. The following discussion on the origin
    of the various breeds and on their characteristic differences does
    not pretend to completeness, but may be of some interest to the
    naturalist. The classification of the breeds cannot, as far as I
    can see, be made natural. They differ from each other in different
    degrees, and do not afford characters in subordination to each
    other, by which they can be ranked in group under group. They seem
    all to have diverged by independent and different roads from a
    single type. Each chief breed includes differently coloured
    sub-varieties, most of which can be truly propagated, but it would
    be superfluous to describe them. I have classed the various crested
    fowls as sub-breeds under the Polish fowl; but I have great doubts
    whether this is a natural arrangement, showing true affinity or
    blood relationship. It is scarcely possible to avoid laying stress
    on the commonness of a breed; and if certain foreign sub-breeds had
    been largely kept in this country they would perhaps have been
    raised to the rank of main-breeds. Several breeds are abnormal in
    character; that is, they differ in certain points from all wild
    Gallinaceous birds. At first I made a division of the breeds into
    normal and abnormal, but the result was wholly unsatisfactory.

1. GAME BREED.—This may be considered as the typical breed, as it
deviates only slightly from the wild _Gallus bankiva,_ or, as perhaps
more correctly named, _ferrugineus._ Beak strong; comb single and
upright. Spurs long and sharp. Feathers closely appressed to the body.
Tail with the normal number of 14 feathers. Eggs often pale buff.
Disposition indomitably courageous, exhibited even in the hens and
chickens. An unusual number of differently coloured varieties exist,
such as black and brown-breasted reds, duckwings, blacks, whites,
piles, etc., with their legs of various colours.

2. MALAY BREED.—Body of great size, with head, neck, and legs
elongated; carriage erect; tail small, sloping downwards, generally
formed of 16 feathers; comb and wattle small; ear-lobe and face red;
skin yellowish; feathers closely appressed to the body; neck-hackles
short, narrow, and hard. Eggs often pale buff. Chickens feather late.
Disposition savage. Of Eastern origin.

3. COCHIN, OR SHANGAI BREED.—Size great; wing feathers short, arched,
much hidden in the soft downy plumage; barely capable of flight; tail
short, generally formed of 16 feathers, developed at a late period in
the young males; legs thick, feathered; spurs short, thick; nail of
middle toe flat and broad; an additional toe not rarely developed; skin
yellowish. Comb and wattle well developed. Skull with deep medial
furrow; occipital foramen, sub-triangular, vertically elongated. Voice
peculiar. Eggs rough, buff-coloured. Disposition extremely quiet. Of
Chinese origin.

4. DORKING BREED.—Size great; body square, compact; feet with an
additional toe; comb well developed, but varies much in form; wattles
well developed; colour of plumage various. Skull remarkably broad
between the orbits. Of English origin.

The white Dorking may be considered as a distinct sub-breed, being a
less massive bird.

Illustration: Fig. 30—Spanish Fowl

5. SPANISH BREED (fig. 30).—Tall, with stately carriage; tarsi long;
comb single, deeply serrated, of immense size; wattles largely
developed; the large ear-lobes and sides of face white. Plumage black
glossed with green. Do not incubate. Tender in constitution, the comb
being often injured by frost. Eggs white, smooth, of large size.
Chickens feather late but the young cocks show their masculine
characters, and crow at an early age. Of Mediterranean origin.

The _Andalusians_ may be ranked as a sub-breed: they are of a
slaty-blue colour, and their chickens are well feathered. A smaller,
short-legged Dutch sub-breed has been described by some authors as
distinct.

Illustration: Fig. 31—Hamburgh Fowl

6. HAMBURGH BREED (fig 31).—Size moderate; comb flat, produced
backwards, covered with numerous small points; wattle of moderate
dimensions; ear lobe white; legs blueish, thin. Do not incubate. Skull,
with the tips of the ascending branches of the premaxillary and with
the nasal bones standing a little separate from each other; anterior
margin of the frontal bones less depressed than usual.

There are two sub-breeds; the _ spangled_ Hamburgh, of English origin,
with the tips of the feathers marked with a dark spot; and the
_pencilled_ Hamburgh, of Dutch origin, with dark transverse lines
across each feather, and with the body rather smaller. Both these
sub-breeds include gold and silver varieties, as well as some other
sub-varieties. Black Hamburghs have been produced by a cross with the
Spanish breed.

Illustration: Fig. 32—Polish Fowl

7. CRESTED OR POLISH BREED (fig 32).—Head with a large, rounded crest
of feathers, supported on a hemispherical protuberance of the frontal
bones, which includes the anterior part of the brain. The ascending
branches of premaxillary bones and the inner nasal processes are much
shortened. The orifice of the nostrils raised and crescentic. Beak
short. Comb absent, or small and of crescentic shape; wattles either
present or replaced by a beard-like tuft of feathers. Legs leaden-blue.
Sexual differences appear late in life. Do not incubate. There are
several beautiful varieties which differ in colour and slightly in
other respects.

The following sub-breeds agree in having a crest, more or less
developed, with the comb, when present, of crescentic shape. The skull
presents nearly the same remarkable peculiarities of structure as in
the true Polish fowl.

    Sub-breed _(a) Sultans._—A Turkish breed, resembling white Polish
    fowls with a large crest and beard with short and well-feathered
    legs. The tail is furnished with additional sickle feathers. Do not
    incubate.[2]

Sub-breed _(b) Ptarmigans._—An inferior breed closely allied to the
last, white, rather small, legs much feathered, with the crest pointed;
comb small, cupped; wattles small.

Sub-breed _(c) Ghoondooks._—Another Turkish breed having an
extraordinary appearance; black and tailless; crest and beard large;
legs feathered. The inner processes of the two nasal bones come into
contact with each other, owing to the complete abortion of the
ascending branches of the premaxillaries. I have seen an allied white,
tailless breed from Turkey.

Sub-breed _(d) Crève-cœur._—A French breed of large size, barely
capable of flight, with short black legs, head crested, comb produced
into two points or horns, sometimes a little branched like the horns of
a stag; both beard and wattles present. Eggs large. Disposition
quiet.[3]

Sub-breed _(e) Horned fowl._—With a small crest; comb produced into two
great points, supported on two bony protuberances.

    Sub-breed _(f) Houdan._—A French breed; of moderate size,
    short-legged with five toes, well developed; plumage invariably
    mottled with black, white, and straw-yellow; head furnished with a
    crest, on a triple comb placed transversely; both wattles and beard
    present.[4]

Sub-breed _(g) Guelderlands._—No comb, head said to be surmounted by a
longitudinal crest of soft velvety feathers; nostrils said to be
crescentic; wattles well developed; legs feathered; colour black. From
North America. The Breda fowl seems to be closely allied to the
Guelderland.

8. BANTAM BREED.—Originally from Japan[5] characterised by small size
alone; carriage bold and erect. There are several sub-breeds, such as
the Cochin, Game, and Sebright Bantams, some of which have been
recently formed by various crosses. The Black Bantam has a differently
shaped skull, with the occipital foramen like that of the Cochin fowl.

    9. RUMPLESS FOWLS.—These are so variable in character[6] that they
    hardly deserve to be called a breed. Any one who will examine the
    caudal vertebræ will see how monstrous the breed is.

10. CREEPERS OR JUMPERS.—These are characterised by an almost monstrous
shortness of legs, so that they move by jumping rather than by walking;
they are said not to scratch up the ground. I have examined a Burmese
variety, which had a skull of rather unusual shape.

11. FRIZZLED OR CAFFRE FOWLS.—Not uncommon in India, with the feathers
curling backwards, and with the primary feathers of the wing and tail
imperfect; periosteum of bones black.

12. SILK FOWLS.—Feathers silky, with the primary wing and tail-feathers
imperfect; skin and periosteum of bones black; comb and wattles dark
leaden-blue; ear-lappets tinged with blue; legs thin, often furnished
with an additional toe. Size rather small.

13. SOOTY FOWLS.—An Indian breed, having the peculiar appearance of a
white bird smeared with soot, with black skin and periosteum. The hens
alone are thus characterised.

    From this synopsis we see that the several breeds differ
    considerably, and they would have been nearly as interesting for us
    as pigeons, if there had been equally good evidence that all had
    descended from one parent-species. Most fanciers believe that they
    are descended from several primitive stocks. The Rev. E. S.
    Dixon[7] argues strongly on this side of the question; and one
    fancier even denounces the opposite conclusion by asking, “Do we
    not perceive pervading this spirit, the spirit of the _Deist_?”
    Most naturalists, with the exception of a few, such as Temminck,
    believe that all the breeds have proceeded from a single species;
    but authority on such a point goes for little. Fanciers look to all
    parts of the world as the possible sources of their unknown stocks;
    thus ignoring the laws of geographical distribution. They know well
    that the several kinds breed truly even in colour. They assert,
    but, as we shall see, on very weak grounds, that most of the breeds
    are extremely ancient. They are strongly impressed with the great
    difference between the chief kinds, and they ask with force, can
    differences in climate, food, or treatment have produced birds so
    different as the black stately Spanish, the diminutive elegant
    Bantam, the heavy Cochin with its many peculiarities, and the
    Polish fowl with its great top-knot and protuberant skull? But
    fanciers, whilst admitting and even overrating the effects of
    crossing the various breeds, do not sufficiently regard the
    probability of the occasional birth, during the course of
    centuries, of birds with abnormal and hereditary peculiarities;
    they overlook the effects of correlation of growth—of the
    long-continued use and disuse of parts, and of some direct result
    from changed food and climate, though on this latter head I have
    found no sufficient evidence; and lastly, they all, as far as I
    know, entirely overlook the all-important subject of unconscious or
    unmethodical selection, though they are well aware that their birds
    differ individually and that by selecting the best birds for a few
    generations they can improve their stocks.

    An amateur writes[8] as follows: “The fact that poultry have until
    lately received but little attention at the hands of the fancier,
    and been entirely confined to the domains of the producer for the
    market, would alone suggest the improbability of that constant and
    unremitting attention having been observed in breeding, which is
    requisite to the consummating in the offspring of any two birds
    transmittable forms not exhibited by the parents.” This at first
    sight appears true. But in a future chapter on Selection, abundant
    facts will be given showing not only that careful breeding, but
    that actual selection was practised during ancient periods, and by
    barely civilised races of man. In the case of the fowl I can adduce
    no direct facts showing that selection was anciently practised; but
    the Romans at the commencement of the Christian era kept six or
    seven breeds, and Columella “particularly recommends as the best,
    those sorts that have five toes and white ears.”[9] In the
    fifteenth century several breeds were known and described in
    Europe; and in China, at nearly the same period, seven kinds were
    named. A more striking case is that at present, in one of the
    Philippine Islands, the semi-barbarous inhabitants have distinct
    native names for no less than nine sub-breeds of the Game fowl.[10]
    Azara,[11] who wrote towards the close of the last century, states
    that in the interior parts of South America, where I should not
    have expected that the least care would have been taken of poultry,
    a black-skinned and black-boned breed is kept, from being
    considered fertile and its flesh good for sick persons. Now every
    one who has kept poultry knows how impossible it is to keep several
    breeds distinct unless the utmost care be taken in separating the
    sexes. Will it then be pretended that those persons who, in ancient
    times and in semi-civilised countries took pains to keep the breeds
    distinct, and who therefore valued them, would not occasionally
    have destroyed inferior birds and occasionally have preserved their
    best birds? This is all that is required. It is not pretended that
    any one in ancient times intended to form a new breed, or to modify
    an old breed according to some ideal standard of excellence. He who
    cared for poultry would merely wish to obtain, and afterwards to
    rear, the best birds which he could; but this occasional
    preservation of the best birds would in the course of time modify
    the breed, as surely, though by no means as rapidly, as does
    methodical selection at the present day, If one person out of a
    hundred or out of a thousand attended to the breeding of his birds,
    this would be sufficient; for the birds thus tended would soon
    become superior to others, and would form a new strain; and this
    strain would, as explained in the last chapter, slowly have its
    characteristic differences augmented, and at last be converted into
    a new sub-breed or breed. But breeds would often be for a time
    neglected and would deteriorate; they would, however, partially
    retain their character, and afterwards might again come into
    fashion and be raised to a standard of perfection higher than their
    former standard; as has actually occurred quite recently with
    Polish fowls. If, however, a breed were utterly neglected, it would
    become extinct, as has recently happened with one of the Polish
    sub-breeds. Whenever in the course of past centuries a bird
    appeared with some slight abnormal structure, such as with a
    lark-like crest on its head, it would probably often have been
    preserved from that love of novelty which leads some persons in
    England to keep rumpless fowls, and others in India to keep
    frizzled fowls. And after a time any such abnormal appearance would
    be carefully preserved, from being esteemed a sign of the purity
    and excellence of the breed; for on this principle the Romans
    eighteen centuries ago valued the fifth toe and the white ear-lobe
    in their fowls.

 Thus from the occasional appearance of abnormal characters, though at
 first only slight in degree; from the effects of the use and the
 disuse of parts; possibly from the direct effects of changed climate
 and food; from correlation of growth; from occasional reversions to
 old and long-lost characters; from the crossing of breeds, when more
 than one had been formed; but, above all, from unconscious selection
 carried on during many generations, there is no insuperable
 difficulty, to the best of my judgment, in believing that all the
 breeds have descended from some one parent-source. Can any single
 species be named from which we may reasonably suppose that all are
 descended? The Gallus bankiva apparently fulfils every requirement. I
 have already given as fair an account as I could of the arguments in
 favour of the multiple origin of the several breeds; and now I will
 give those in favour of their common descent from _G. bankiva._

    But it will be convenient first briefly to describe all the known
    species of Gallus. The _G. sonneratii_ does not range into the
    northern parts of India; according to Colonel Sykes,[12] it
    presents at different heights of the Ghauts, two strongly marked
    varieties, perhaps deserving to be called species. It was at one
    time thought to be the primitive stock of all our domestic breeds,
    and this shows that it closely approaches the common fowl in
    general structure; but its hackles partially consist of highly
    peculiar, horny laminæ, transversely banded with three colours; and
    I have met no authentic account of any such character having been
    observed in any domestic breed.[13] This species also differs
    greatly from the common fowl, in the comb being finely serrated,
    and in the loins being destitute of true hackles. Its voice is
    utterly different. It crosses readily in India with domestic hens;
    and Mr. Blyth[14] raised nearly 100 hybrid chickens; but they were
    tender and mostly died whilst young. Those which were reared were
    absolutely sterile when crossed inter se or with either parent. At
    the Zoological Gardens, however, some ‘hybrids of the same
    parentage were not quite so sterile: Mr. Dixon, as he informed me,
    made, with Mr. Yarrell’s aid, particular inquiries on this subject,
    and was assured that out of 50 eggs only five or six chickens were
    reared. Some, however, of these half-bred birds were crossed with
    one of their parents, namely, a Bantam, and produced a few
    extremely feeble chickens. Mr. Dixon also procured some of these
    same birds and crossed them in several ways, but all were more or
    less infertile. Nearly similar experiments have recently been tried
    on a great scale in the Zoological Gardens with almost the same
    result.[15] Out of 500 eggs, raised from various first crosses and
    hybrids, between _G. sonneratii, bankiva,_ and _varius,_ only 12
    chickens were reared, and of these only three were the product of
    hybrids _inter se._ From these facts, and from the above-mentioned
    strongly-marked differences in structure between the domestic fowl
    and _G. sonneratii,_ we may reject this latter species as the
    parent of any domestic breed.

    Ceylon possesses a fowl peculiar to the island, viz. _G.
    stanleyii_; this species approaches so closely (except in the
    colouring of the comb) to the domestic fowl, that Messrs. Layard
    and Kellaert[16] would have considered it, as they inform me, as
    one of the parent-stocks, had it not been for its singularly
    different voice. This bird, like the last, crosses readily with
    tame hens, and even visits solitary farms and ravishes them. Two
    hybrids, a male and female, thus produced, were found by Mr.
    Mitford to be quite sterile: both inherited the peculiar voice of
    _G. stanleyii._ This species, then, may in all probability be
    rejected as one of the primitive stocks of the domestic fowl.

    Java and the islands eastward as far as Flores are inhabited by _G.
    varius_ (or _furcatus_), which differs in so many characters—green
    plumage, unserrated comb, and single median wattle—that no one
    supposes it to have been the parent of any one of our breeds; yet,
    as I am informed by Mr. Crawfurd,[17] hybrids are commonly raised
    between the male _G. varius_ and the common hen, and are kept for
    their great beauty, but are invariably sterile: this, however, was
    not the case with some bred in the Zoological Gardens. These
    hybrids were at one time thought to be specifically distinct, and
    were named _G. æneus._ Mr. Blyth and others believe that the _G.
    temminckii_[18] (of which the history is not known) is a similar
    hybrid. Sir J. Brooke sent me some skins of domestic fowls from
    Borneo, and across the tail of one of these, as Mr. Tegetmeier
    observed, there were transverse blue bands like those which he had
    seen on the tail-feathers of hybrids from _G. varius,_ reared in
    the Zoological Gardens. This fact apparently indicates that some of
    the fowls of Borneo have been slightly affected by crosses with _G.
    varius,_ but the case may possibly be one of analogous variation. I
    may just allude to the _G. giganteus,_ so often referred to in
    works on poultry as a wild species; but Marsden[19] the first
    describer, speaks of it as a tame breed; and the specimen in the
    British Museum evidently has the aspect of a domestic variety.

    The last species to be mentioned, namely, _Gallus bankiva,_ has a
    much wider geographical range than the three previous species; it
    inhabits Northern India as far west as Sinde, and ascends the
    Himalaya to a height of 4000 ft.; it inhabits Burmah, the Malay
    peninsula, the Indo-Chinese countries, the Philippine Islands, and
    the Malayan archipelago as far eastward as Timor. This species
    varies considerably in the wild state. Mr. Blyth informs me that
    the specimens, both male and female, brought from near the
    Himalaya, are rather paler coloured than those from other parts of
    India; whilst those from the Malay peninsula and Java are brighter
    coloured than the Indian birds. I have seen specimens from these
    countries, and the difference of tint in the hackles was
    conspicuous. The Malayan hens were a shade redder on the breast and
    neck than the Indian hens. The Malayan males generally had a red
    ear-lappet, instead of a white one as in India; but Mr. Blyth has
    seen one Indian specimen without the white ear-lappet. The legs are
    leaden blue in the Indian, whereas they show some tendency to be
    yellowish in the Malayan and Javan specimens. In the former Mr.
    Blyth finds the tarsus remarkably variable in length. According to
    Temminck[20] the Timor specimens differ as a local race from that
    of Java. These several wild varieties have not as yet been ranked
    as distinct species; if they should, as is not unlikely, be
    hereafter thus ranked, the circumstance would be quite immaterial
    as far as the parentage and differences of our domestic breeds are
    concerned. The wild _G. bankiva_ agrees most closely with the
    black-breasted red Game-breed, in colouring and in all other
    respects, except in being smaller, and in the tail being carried
    more horizontally. But the manner in which the tail is carried is
    highly variable in many of our breeds, for, as Mr. Brent informs
    me, the tail slopes much in the Malays, is erect in the Games and
    some other breeds, and is more than erect in Dorkings, Bantams,
    etc. There is one other difference namely, that in _G. bankiva,_
    according to Mr. Blyth, the neck-hackles when first moulted are
    replaced during two or three months not by other hackles, as with
    our domestic poultry, but by short blackish feathers.[21] Mr.
    Brent, however, has remarked that these black feathers remain in
    the wild bird after the development of the lower hackles, and
    appear in the domestic bird at the same time with them: so that the
    only difference is that the lower hackles are replaced more slowly
    in the wild than in the tame bird; but as confinement is known
    sometimes to affect the masculine plumage, this slight difference
    cannot be considered of any importance. It is a significant fact
    that the voice of both the male and female _G. bankiva_ closely
    resembles, as Mr. Blyth and others have noted, the voice of both
    sexes of the common domestic fowl; but the last note of the crow of
    the wild bird is rather less prolonged. Captain Hutton, well known
    for his researches into the natural history of India, informs me
    that he has seen several crossed fowls from the wild species and
    the Chinese bantam; these crossed fowls _bred freely_ with bantams,
    but unfortunately were not crossed _inter se._ Captain Hutton
    reared chickens from the eggs of the _Gallus bankiva_; and these,
    though at first very wild, afterwards became so tame that they
    would crowd round his feet. He did not succeed in rearing them to
    maturity; but as he remarks, “no wild gallinaceous bird thrives
    well at first on hard grain.” Mr. Blyth also found much difficulty
    in keeping _G. bankiva_ in confinement. In the Philippine Islands,
    however, the natives must succeed better, as they keep wild cocks
    to fight with their domestic game-birds.[22] Sir Walter Elliot
    informs me that the hen of a native domestic breed of Pegu is
    undistinguishable from the hen of the wild _G. bankiva_; and the
    natives constantly catch wild cocks by taking tame cocks to fight
    with them in the woods.[23] Mr. Crawfurd remarks that from
    etymology it might be argued that the fowl was first domesticated
    by the Malays and Javanese.[24] It is also a curious fact, of which
    I have been assured by Mr. Blyth, that wild specimens of the _
    Gallus bankiva,_ brought from the countries east of the Bay of
    Bengal, are far more easily tamed than those of India; nor is this
    an unparalleled fact, for, as Humboldt long ago remarked, the same
    species sometimes evinces a more tameable disposition in one
    country than in another. If we suppose that the _G. bankiva_ was
    first tamed in Malaya and afterwards imported into India, we can
    understand an observation made to me by Mr. Blyth, that the
    domestic fowls of India do not resemble the wild _G. bankiva_ of
    India more closely than do those of Europe.

    From the extremely close resemblance in colour, general structure,
    and especially in voice, between _Gallus bankiva_ and the Game
    fowl; from their fertility, as far as this has been ascertained,
    when crossed; from the possibility of the wild species being tamed,
    and from its varying in the wild state, we may confidently look at
    it as the parent of the most typical of all the domestic breeds,
    namely, the Game fowl. It is a significant fact, that almost all
    the naturalists in India, namely Sir W. Elliot, Mr. S. N. Ward, Mr.
    Layard, Mr. J. C. Jerdon, and Mr. Blyth,[25] who are familiar with
    G. bankiva, believe that it is the parent of most or all our
    domestic breeds. But even if it be admitted that G. bankiva is the
    parent of the Game breed, yet it may be urged that other wild
    species have been the parents of the other domestic breeds; and
    that these species still exist, though unknown, in some country, or
    have become extinct. The extinction, however, of several species of
    fowls, is an improbable hypothesis, seeing that the four known
    species have not become extinct in the most ancient and thickly
    peopled regions of the East. There is, in fact, not one other kind
    of domesticated bird, of which the wild parent-form is unknown,
    that is become extinct. For the discovery of new, or the
    rediscovery of old species of Gallus, we must not look, as fanciers
    often look, to the whole world. The larger gallinaceous birds, as
    Mr. Blyth has remarked,[26] generally have a restricted range: we
    see this well illustrated in India, where the genus Gallus inhabits
    the base of the Himalaya, and is succeeded higher up by
    Gallophasis, and still higher up by Phasianus. Australia, with its
    islands, is out of the question as the home for unknown species of
    the genus. It is, also, as improbable that Gallus should inhabit
    South America[27] as that a humming-bird should be found in the Old
    World. From the character of the other gallinaceous birds of
    Africa, it is not probable that Gallus is an African genus. We need
    not look to the western parts of Asia, for Messrs. Blyth and
    Crawfurd, who have attended to this subject, doubt whether Gallus
    ever existed in a wild state even as far west as Persia. Although
    the earliest Greek writers speak of the fowl as a Persian bird,
    this probably merely indicates its line of importation. For the
    discovery of unknown species we must look to India, to the
    Indo-Chinese countries, and to the northern parts of the Malay
    Archipelago. The southern portion of China is the most likely
    country; but as Mr. Blyth informs me, skins have been exported from
    China during a long period, and living birds are largely kept there
    in aviaries, so that any native species of Gallus would probably
    have become known. Mr. Birch, of the British Museum, has translated
    for me passages from a Chinese Encyclopædia published in 1609, but
    compiled from more ancient documents, in which it is said that
    fowls are creatures of the West, and were introduced into the East
    (_i.e._ China) in a dynasty 1400 B.C. Whatever may be thought of so
    ancient a date, we see that the Indo-Chinese and Indian regions
    were formerly considered by the Chinese as the source of the
    domestic fowl. From these several considerations we must look to
    the present metropolis of the genus, namely, to the south-eastern
    parts of Asia, for the discovery of species which were formerly
    domesticated, but are now unknown in the wild state; and the most
    experienced ornithologists do not consider it probable that such
    species will be discovered.

 In considering whether the domestic breeds are descended from one
 species, namely, _G. bankiva,_ or from several, we must not quite
 overlook, though we must not exaggerate, the importance of the test of
 fertility. Most of our domestic breeds have been so often crossed, and
 their mongrels so largely kept, that it is almost certain, if any
 degree of infertility had existed between them, it would have been
 detected. On the other hand, the four known species of Gallus when
 crossed with each other, or when crossed, with the exception of _G.
 bankiva,_ with the domestic fowl, produce infertile hybrids.

 Finally, we have not such good evidence with fowls as with pigeons, of
 all the breeds having descended from a single primitive stock. In both
 cases the argument of fertility must go for something; in both we have
 the improbability of man having succeeded in ancient times in
 thoroughly domesticating several supposed species,—most of these
 supposed species being extremely abnormal as compared with their
 natural allies,—all being now either unknown or extinct, though the
 parent-form of no other domesticated bird has been lost. But in
 searching for the supposed parent-stocks of the various breeds of the
 pigeon, we were enabled to confine our search to species having
 peculiar habits of life; whilst with fowls there is nothing in their
 habits in any marked manner distinct from those of other gallinaceous
 birds. In the case of pigeons, I have shown that purely-bred birds of
 every race and the crossed offspring of distinct races frequently
 resemble, or revert to, the wild rock-pigeon in general colour and in
 each characteristic mark. With fowls we have facts of a similar
 nature, but less strongly pronounced, which we will now discuss.

_Reversion and Analogous Variation._—Purely-bred Game, Malay, Cochin,
Dorking, Bantam, and, as I hear from Mr. Tegetmeier, Silk fowls, may
frequently or occasionally be met with, which are almost identical in
plumage with the wild _G. bankiva._ This is a fact well deserving
attention, when we reflect that these breeds rank amongst the most
distinct. Fowls thus coloured are called by amateurs black-breasted
reds. Hamburghs properly have a very different plumage; nevertheless,
as Mr. Tegetmeier informs me, “the great difficulty in breeding cocks
of the golden-spangled variety is their tendency to have black breasts
and red backs. The males of white Bantams and white Cochins, as they
come to maturity, often assume a yellowish or saffron tinge; and the
longer neck hackles of black Bantam cocks,”[28] when two or three years
old, not uncommonly become ruddy; these latter Bantams occasionally
“even moult brassy-winged, or actually red-shouldered.” So that in
these several cases we see a plain tendency to reversion to the hues of
_G. bankiva,_ even during the lifetime of the individual bird. With
Spanish, Polish, pencilled Hamburgh, silver-spangled Hamburgh fowls,
and with some other less common breeds, I have never heard of a
black-breasted red bird having appeared.

From my experience with pigeons, I made the following crosses. I first
killed all my own poultry, no others living near my house, and then
procured, by Mr. Tegetmeier’s assistance, a first-rate black Spanish
cock, and hens of the following pure breeds,—white Game, white Cochin,
silver-spangled Polish, silver-spangled Hamburgh, silver-pencilled
Hamburgh, and white Silk. In none of these breeds is there a trace of
red, nor when kept pure have I ever heard of the appearance of a red
feather; though such an occurrence would perhaps not be very improbable
with white Games and white Cochins. Of the many chickens reared from
the above six crosses the majority were black, both in the down and in
the first plumage; some were white, and a very few were mottled black
and white. In one lot of eleven mixed eggs from the white Game and
white Cochin by the black Spanish cock, seven of the chickens were
white, and only four black. I mention this fact to show that whiteness
of plumage is strongly inherited, and that the belief in the prepotent
power in the male to transmit his colour is not always correct. The
chickens were hatched in the spring, and in the latter part of August
several of the young cocks began to exhibit a change, which with some
of them increased during the following years. Thus a young male bird
from the silver-spangled Polish hen was in its first plumage
coal-black, and combined in its comb, crest, wattle, and beard, the
characters of both parents; but when two years old the secondary
wing-feathers became largely and symmetrically marked with white, and,
wherever in _G. bankiva_ the hackles are red, they were in this bird
greenish-black along the shaft, narrowly bordered with brownish-black,
and this again broadly bordered with very pale yellowish-brown; so that
in general appearance the plumage had become pale-coloured instead of
black. In this case, with advancing age there was a great change, but
no reversion to the red colour of _G. bankiva._

A cock with a regular rose comb derived either from the spangled or
pencilled silver Hamburgh was likewise at first quite black; but in
less than a year the neck-hackles, as in the last case, became whitish,
whilst those on the loins assumed a decided reddish-yellow tint; and
here we see the first symptom of reversion; this likewise occurred with
some other young cocks, which need not here be described. It has also
been recorded[29] by a breeder, that he crossed two silver-pencilled
Hamburgh hens with a Spanish cock, and reared a number of chickens, all
of which were black, the cocks having _ golden_ and the hens brownish
hackles; so that in this instance likewise there was a clear tendency
to reversion.

Two young cocks from my white Game hen were at first snow white; of
these, one subsequently assumed male orange-coloured hackles, chiefly
on the loins, and the other an abundance of fine orange-red hackles on
the neck, loins, and upper wing-coverts. Here again we have a more
decided, though partial, reversion to the colours of _G. bankiva._ This
second cock was in fact coloured like an inferior “pile Came cock;”—now
this sub-breed can be produced, as I am informed by Mr. Tegetmeier, by
crossing a black-breasted red Game cock with a white Game hen, and the
“pile” sub-breed thus produced can afterwards be truly propagated. So
that we have the curious fact of the glossy-black Spanish cock and the
black-breasted red Game cock when crossed with white Game hens
producing offspring of nearly the same colours.

I reared several birds from the white Silk hen by the Spanish cock: all
were coal-black, and all plainly showed their parentage in having
blackish combs and bones; none inherited the so-called silky feathers,
and the non-inheritance of this character has been observed by others.
The hens never varied in their plumage. As the young cocks grew old,
one of them assumed yellowish-white hackles, and thus resembled in a
considerable degree the cross from the Hamburgh hen; the other became a
gorgeous bird, so much so that an acquaintance had it preserved and
stuffed simply from its beauty. When stalking about it closely
resembled the wild _Gallus bankiva,_ but with the red feathers rather
darker. On close comparison one considerable difference presented
itself, namely, that the primary and secondary wing-feathers were edged
with greenish-black, instead of being edged, as in _G. bankiva,_ with
fulvous and red tints. The space, also, across the back, which bears
dark-green feathers, was broader, and the comb was blackish. In all
other respects, even in trifling details of plumage, there was the
closest accordance. Altogether it was a marvellous sight to compare
this bird first with _G. bankiva,_ and then with its father, the glossy
green-black Spanish cock, and with its diminutive mother, the white
Silk hen. This case of reversion is the more extraordinary as the
Spanish breed has long been known to breed true, and no instance is on
record of its throwing a single red feather. The Silk hen likewise
breeds true, and is believed to be ancient, for Aldrovandi, before
1600, alludes probably to this breed, and described it as covered with
wool. It is so peculiar in many characters that some writers have
considered it as specifically distinct; yet, as we now see, when
crossed with the Spanish fowl, it yields offspring closely resembling
the wild _G. bankiva._

Mr. Tegetmeier has been so kind as to repeat, at my request, the cross
between a Spanish cock and Silk hen, and he obtained similar results;
for he thus raised, besides a black hen, seven cocks, all of which were
dark-bodied with more or less orange-red hackles. In the ensuing year
he paired the black hen with one of her brothers, and raised three
young cocks, all coloured like their father, and a black hen mottled
with white.

The hens from the six above-described crosses showed hardly any
tendency to revert to the mottled-brown plumage of the female _G.
bankiva_: one hen, however, from the white Cochin, which was at first
coal-black, became slightly brown or sooty. Several hens, which were
for a long time snow-white, acquired as they grew old a few black
feathers. A hen from the white Game, which was for a long time entirely
black glossed with green, when two years old had some of the primary
wing feathers greyish-white, and a multitude of feathers over her body
narrowly and symmetrically tipped or laced with white. I had expected
that some of the chickens whilst covered with down would have assumed
the longitudinal stripes so general with gallinaceous birds; but this
did not occur in a single instance. Two or three alone were
reddish-brown about their heads. I was unfortunate in losing nearly all
the white chickens from the first crosses; so that black prevailed with
the grandchildren; but they were much diversified in colour, some being
sooty, others mottled, and one blackish chicken had its feathers oddly
tipped and barred with brown.

I will here add a few miscellaneous facts connected with reversion, and
with the law of analogous variation. This law implies, as stated in a
previous chapter, that the varieties of one species frequently mock
distinct but allied species; and this fact is explained, according to
the views which I maintain, on the principle of allied species having
descended from one primitive form. The white Silk fowl with black skin
and bones degenerates, as has been observed by Mr. Hewitt and Mr. R.
Orton, in our climate; that is, it reverts to the ordinary colour of
the common fowl in its skin and bones, due care having been taken to
prevent any cross. In Germany[30] a distinct breed with black bones,
and with black, not silky plumage, has likewise been observed to
degenerate.

Mr. Tegetmeier informs me that, when distinct breeds are crossed, fowls
are frequently produced with their feathers marked or pencilled by
narrow transverse lines of a darker colour. This may be in part
explained by direct reversion to the parent-form, the Bankiva hen; for
this bird has all its upper plumage finely mottled with dark and rufous
brown, with the mottling partially and obscurely arranged in transverse
lines. But the tendency to pencilling is probably much strengthened by
the law of analogous variation, for the hens of some other species of
Gallus are more plainly pencilled, and the hens of many gallinaceous
birds belonging to other genera, as the partridge, have pencilled
feathers. Mr. Tegetmeier has also remarked to me that, although with
domestic pigeons we have so great a diversity of colouring, we never
see either pencilled or spangled feathers; and this fact is
intelligible on the law of analogous variation, as neither the wild
rock pigeon nor any closely allied species has such feathers. The
frequent appearance of pencilling in crossed birds probably accounts
for the existence of “cuckoo” sub-breeds in the Game, Polish, Dorking,
Cochin, Andalusian, and Bantam breeds. The plumage of these birds is
slaty-blue or grey, with each feather transversely barred with darker
lines, so as to resemble in some degree the plumage of the cuckoo. It
is a singular fact, considering that the male of no species of Gallus
is in the least barred, that the cuckoo-like plumage has often been
transferred to the male, more especially in the cuckoo Dorking; and the
fact is all the more singular, as in gold- and silver-pencilled
Hamburghs, in which pencilling is characteristic of the breed, the male
is hardly at all pencilled, this kind of plumage being confined to the
female.

Another case of analogous variation is the occurrence of spangled
sub-breeds of Hamburgh, Polish, Malay, and Bantam fowls. Spangled
feathers have a dark mark, properly crescent-shaped, on their tips;
whilst pencilled feathers have several transverse bars. The spangling
cannot be due to reversion to _G. bankiva_; nor does it often follow,
as I hear from Mr. Tegetmeier, from crossing distinct breeds; but it is
a case of analogous variation, for many gallinaceous birds have
spangled feathers,—for instance, the common pheasant. Hence spangled
breeds are often called “pheasant”-fowls. Another case of analogous
variation in several domestic breeds is inexplicable; it is, that the
chickens, whilst covered with down, of the black Spanish, black Game,
black Polish, and black Bantam, all have white throats and breasts, and
often have some white on their wings.[31] The editor of the ‘Poultry
Chronicle’[32] remarks that all the breeds which properly have red
ear-lappets occasionally produce birds with white ear-Tappets. This
remark more especially applies to the Game breed, which of all comes
nearest to the _G. bankiva_; and we have seen that with this species
living in a state of nature, the ear-lappets vary in colour, being red
in the Malayan countries, and generally, but not invariably, white in
India.

In concluding this part of my subject, I may repeat that there exists
one widely-ranging, varying, and common species of Gallus, namely, _G.
bankiva,_ which can be tamed, produces fertile offspring when crossed
with common fowls, and closely resembles in its whole structure,
plumage, and voice the Game breed; hence it may be safely ranked as the
parent of this, the most typical domesticated breed. We have seen that
there is much difficulty in believing that other, now unknown, species
have been the parents of the other domestic breeds. We know that all
the breeds are most closely allied, as shown by their similarity in
most points of structure and in habits, and by the analogous manner in
which they vary. We have also seen that several of the most distinct
breeds occasionally or habitually closely resemble in plumage _G.
bankiva,_ and that the crossed offspring of other breeds, which are not
thus coloured, show a stronger or weaker tendency to revert to this
same plumage. Some of the breeds, which appear the most distinct and
the least likely to have proceeded from _G. bankiva,_ such as Polish
fowls, with their protuberant and little ossified skulls, and Cochins,
with their imperfect tail and small wings, bear in these characters the
plain marks of their artificial origin. We know well that of late years
methodical selection has greatly improved and fixed many characters;
and we have every reason to believe that unconscious selection, carried
on for many generations, will have steadily augmented each new
peculiarity, and thus have given rise to new breeds. As soon as two or
three breeds were once formed, crossing would come into play in
changing their character and in increasing their number. Brahma
Pootras, according to an account lately published in America, offer a
good instance of a breed, lately formed by a cross, which can be truly
propagated. The well-known Sebright Bantams offer another and similar
instance. Hence it may be concluded that not only the Game-breed but
that all our breeds are probably the descendants of the Malayan or
Indian variety of _G. bankiva._ If so, this species has varied greatly
since it was first domesticated; but there has been ample time, as we
shall now show.

_History of the Fowl._—Rütimeyer found no remains of the fowl in the
ancient Swiss lake-dwellings; but, according to Jeitteles,[33] such
have certainly since been found associated with extinct animals and
prehistoric remains. It is, therefore a strange fact that the fowl is
not mentioned in the Old Testament, nor figured on the ancient Egyptian
monuments. It is not referred to by Homer or Hesiod (about 900 B.C.);
but is mentioned by Theognis and Aristophanes between 400 and 500 B.C.
It is figured on some of the Babylonian cylinders, between the sixth
and seventh centuries B.C., of which Mr. Layard sent me an impression;
and on the Harpy Tomb in Lycia, about 600 B.C.: so that the fowl
apparently reached Europe in a domesticated condition somewhere about
the sixth century B.C. It had travelled still farther westward by the
time of the Christian era, for it was found in Britain by Julius Cæsar.
In India it must have been domesticated when the Institutes of Manu
were written, that is, according to Sir W. Jones, 1200 B.C., but,
according to the later authority of Mr. H. Wilson, only 800 B.C., for
the domestic fowl is forbidden, whilst the wild is permitted to be
eaten. If, as before remarked, we may trust the old Chinese
Encyclopædia, the fowl must have been domesticated several centuries
earlier, as it is said to have been introduced from the West into China
1400 B.C.

Sufficient materials do not exist for tracing the history of the
separate breeds. About the commencement of the Christian era, Columella
mentions a five-toed fighting breed, and some provincial breeds; but we
know nothing about them. He also alludes to dwarf fowls; but these
cannot have been the same with our Bantams, which, as Mr. Crawfurd has
shown, were imported from Japan into Bantam in Java. A dwarf fowl,
probably the true Bantam, is referred to in an old Japanese
Encyclopædia, as I am informed by Mr. Birch. In the Chinese
Encyclopædia published in 1596, but compiled from various sources, some
of high antiquity, seven breeds are mentioned, including what we should
now call Jumpers or Creepers, and likewise fowls with black feathers,
bones, and flesh. In 1600 Aldrovandi describes seven or eight breeds of
fowls, and this is the most ancient record from which the age of our
European breeds can be inferred. The _Gallus turcicus_ certainly seems
to be a pencilled Hamburgh; but Mr. Brent, a most capable judge, thinks
that Aldrovandi “evidently figured what he happened to see, and not the
best of the breed.” Mr. Brent, indeed, considers all Aldrovandi’s fowls
as of impure breed; but it is a far more probable view that all our
breeds have been much improved and modified since his time; for, as he
went to the expense of so many figures, he probably would have secured
characteristic specimens. The Silk fowl, however, probably then existed
in its present state, as did almost certainly the fowl with frizzled or
reversed feathers. Mr. Dixon[34] considers Aldrovandi’s Paduan fowl as
“a variety of the Polish,” whereas Mr. Brent believes it to have been
more nearly allied to the Malay. The anatomical peculiarities of the
skull of the Polish breed were noticed by P. Borelli in 1656. I may add
that in 1737 one Polish sub-breed, viz., the Golden-spangled, was
known; but judging from Albin’s description, the comb was then larger,
the crest of feathers much smaller, the breast more coarsely spotted,
and the stomach and thighs much blacker: a Golden-spangled Polish fowl
in this condition would now be of no value.

_Differences in External and Internal Structure between the Breeds:
Individual Variability._—Fowls have been exposed to diversified
conditions of life, and as we have just seen there has been ample time
for much variability and for the slow action of unconscious selection.
As there are good grounds for believing that all the breeds are
descended from Gallus bankiva, it will be worth while to describe in
some detail the chief points of difference. Beginning with the eggs and
chickens, I will pass on to their secondary sexual characters, and then
to their differences in external structure and in the skeleton. I enter
on the following details chiefly to show how variable almost every
character has become under domestication.

_Eggs._—Mr. Dixon remarks[35] that “to every hen belongs an individual
peculiarity in the form, colour, and size of her egg, which never
changes during her life-time, so long as she remains in health, and
which is as well known to those who are in the habit of taking her
produce, as the hand-writing of their nearest acquaintance.” I believe
that this is generally true, and that, if no great number of hens be
kept, the eggs of each can almost always be recognised. The eggs of
differently sized breeds naturally differ much in size; but apparently,
not always in strict relation to the size of the hen: thus the Malay is
a larger bird than the Spanish, but  she produces not such large eggs;
white Bantams are said to lay smaller eggs than other Bantams;[36]
white Cochins, on the other hand, as I hear from Mr. Tegetmeier,
certainly lay larger eggs than buff Cochins. The eggs, however, of the
different breeds vary considerably in character; for instance, Mr.
Ballance states[37] that his Malay “pullets of last year laid eggs
equal in size to those of any duck, and other Malay hens, two or three
years old, laid eggs very little larger than a good sized Bantam’s egg.
Some were as white as a Spanish hen’s egg, and others varied from a
light cream-colour to a deep rich buff, or even to a brown.” The shape
also varies, the two ends being much more equally rounded in Cochins
than in Games or Polish. Spanish fowls lay smoother eggs than Cochins,
of which the eggs are generally granulated. The shell in this latter
breed, and more especially in Malays is apt to be thicker than in Games
or Spanish; but the Minorcas, a sub-breed of Spanish, are said to lay
harder eggs than true Spanish.[38] The colour differs considerably,—the
Cochins laying buff-coloured eggs; the Malays a paler variable buff;
and Games a still paler buff. It would appear that darker-coloured eggs
characterise the breeds which have lately come from the East, or are
still closely allied to those now living there. The colour of the yolk,
according to Ferguson, as well as of the shell, differs slightly in the
sub-breeds of the Game. I am also informed by Mr. Brent that dark
partridge-coloured Cochin hens lay darker coloured eggs than the other
Cochin sub-breeds. The flavour and richness of the egg certainly differ
in different breeds. The productiveness of the several breeds is very
different. Spanish, Polish, and Hamburgh hens have lost the incubating
instinct.

_Chickens._—As the young of almost all gallinaceous birds, even of the
black curassow and black grouse, whilst covered with down, are
longitudinally striped on the back,—of which character, when adult,
neither sex retains a trace,—it might have been expected that the
chickens of all our domestic fowls would have been similarly
striped.[39] This could, however, hardly have been expected, when the
adult plumage in both sexes has undergone so great a change as to be
wholly white or black. In white fowls of various breeds the chickens
are uniformly yellowish white, passing in the black-boned Silk fowl
into bright canary-yellow. This is also generally the case with the
chickens of white Cochins, but I hear from Mr. Zurhost that they are
sometimes of a buff or oak colour, and that all those of this latter
colour, which were watched, turned out males. The chickens of buff
Cochins are of a golden-yellow, easily distinguishable from the paler
tint of the white Cochins, and are often longitudinally streaked with
dark shades: the chickens of silver-cinnamon Cochins are almost always
of a buff colour. The chickens of the white Game and white Dorking
breeds, when held in particular lights, sometimes exhibit (on the
authority of Mr. Brent) faint traces of longitudinal stripes. Fowls
which are entirely black, namely, Spanish, black Game, black Polish,
and black Bantams, display a new character, for their chickens have
their breasts and throats more or less white, with sometimes a little
white elsewhere. Spanish chickens also, occasionally (Brent), have,
where the down was white, their first true feathers tipped for a time
with white. The primordially striped character is retained by the
chickens of most of the Game sub-breeds (Brent, Dixon); by Dorkings; by
the partridge and grouse-coloured sub-breeds of Cochins (Brent), but
not, as we have seen, by the sub-breeds; by the pheasant-Malay (Dixon),
but apparently not (at which I am much surprised) by other Malays. The
following breeds and sub-breeds are barely, or not at all,
longitudinally striped: viz., gold and silver pencilled Hamburghs,
which can hardly be distinguished from each other (Brent) in the down,
both having a few dark spots on the head and rump, with occasionally a
longitudinal stripe (Dixon) on the back of the neck. I have seen only
one chicken of the silver-spangled Hamburgh, and this was obscurely
striped along the back. Gold-spangled Polish chickens (Tegetmeier) are
of a warm russet brown; and silver-spangled Polish chickens are grey,
sometimes (Dixon) with dashes of ochre on the head, wings, and breast.
Cuckoo and blue-dun fowls (Dixon) are grey in the down. The chickens of
Sebright Bantams (Dixon) are uniformly dark brown, whilst those of the
brown-breasted red Game Bantam are black, with some white on the throat
and breast. From these facts we see that young chickens of the
different breeds, and even of the same main breed, differ much in their
downy plumage; and, although longitudinal stripes characterise the
young of all wild gallinaceous birds, they disappear in several
domestic breeds. Perhaps it may be accepted as a general rule that the
more the adult plumage differs from that of the adult _G. bankiva,_ the
more completely the chickens have lost their stripes.

With respect to the period of life at which the characters proper to
each breed first appear, it is obvious that such structures as
additional toes must be formed long before birth. In Polish fowls, the
extraordinary protuberance of the anterior part of the skull is well
developed before the chickens come out of the egg;[40] but the crest,
which is supported on the protuberance, is at first feebly developed,
nor does it attain its full size until the second year. The Spanish
cock is pre-eminent for his magnificent comb, and this is developed at
an unusually early age; so that the young males can be distinguished
from the females when only a few weeks old, and therefore earlier than
in other breeds; they likewise crow very early, namely, when about six
weeks old. In the Dutch sub-breed of the Spanish fowl the white
ear-lappets are developed earlier than in the common Spanish breed.[41]
Cochins are characterised by a small tail, and in the young cocks the
tail is developed at an unusually late period.[42] Game fowls are
notorious for their pugnacity; and the young cocks crow, clap their
little wings, and fight obstinately with each other, even whilst under
their mother’s care.[43] “I have often had,” says one author,[44]
“whole broods, scarcely feathered, stone-blind from fighting; the rival
couples moping in corners, and renewing their battles on obtaining the
first ray of light.” The weapons and pugnacity of all male gallinaceous
birds evidently serve the purpose of gaining possession of the females;
so that the tendency in our Game chickens to fight at an extremely
early age is not only useless, but injurious, as they suffer much from
their wounds. The training for battle during an early age may be
natural to the wild Gallus bankiva; but as man during many generations
has gone on selecting the most obstinately pugnacious cocks, it is more
probable that their pugnacity has been unnaturally increased, and
unnaturally transferred to the young male chickens. In the same manner,
it is probable that the extraordinary development of the comb in the
Spanish cock has been unintentionally transferred to the young cocks;
for fanciers would not care whether their young birds had large combs,
but would select for breeding the adults which had the finest combs,
whether or not developed at an early period. The last point which need
here be noticed is that, though the chickens of Spanish and Malay fowls
are well covered with down, the true feathers are acquired at an
unusually late age; so that for a time the young birds are partially
naked, and are liable to suffer from cold.

_Secondary Sexual Characters._—The two sexes in the parent-form, the
_Gallus bankiva,_ differ much in colour. In our domestic breeds the
difference is never greater, but is often less, and varies much in
degree even in the sub-breeds of the same main breed. Thus in certain
Game fowls the difference is as great as in the parent-form, whilst in
the black and white sub-breeds there is no difference in plumage. Mr.
Brent informs me that he has seen two strains of black-breasted red
Games, of which the cocks could not be distinguished, whilst the hens
in one were partridge-brown and in the other fawn-brown. A similar case
has been observed in the strains of the brown-breasted red Game. The
hen of the “duck-winged Game” is “extremely beautiful,” and differs
much from the hens of all the other Game sub-breeds; but generally, as
with the blue and grey Game and with some sub-varieties of the
pile-game, a moderately close relation may be observed between the
males and females in the variation of their plumage.[45] A similar
relation is also evident when we compare the several varieties of
Cochins. In the two sexes of gold and silver-spangled and of buff
Polish fowls, there is much general similarity in the colouring and
marks of the whole plumage, excepting of course in the hackles, crest,
and beard. In spangled Hamburghs, there is likewise a considerable
degree of similarity between the two sexes. In pencilled Hamburghs, on
the other hand, there is much dissimilarity; the pencilling which is
characteristic of the hens being almost absent in the males of both the
golden and silver varieties. But, as we have already seen, it cannot be
given as a general rule that male fowls never have pencilled feathers,
for Cuckoo Dorkings are “remarkable from having nearly similar markings
in both sexes.”

It is a singular fact that the males in certain sub-breeds have lost
some of their secondary masculine characters, and from their close
resemblance in plumage to the females, are often called hennies. There
is much diversity of opinion whether these males are in any degree
sterile; that they sometimes are partially sterile seems clear,[46] but
this may have been caused by too close interbreeding. That they are not
quite sterile, and that the whole case is widely different from that of
old females assuming masculine characters, is evident from several of
these hen-like sub-breeds having been long propagated. The males and
females of gold and silver-laced Sebright Bantams can be barely
distinguished from each other, except by their combs, wattles, and
spurs, for they are coloured alike, and the males have not hackles, nor
the flowing sickle-like tail-feathers. A hen-tailed sub-breed of
Hamburghs was recently much esteemed. There is also a breed of
Game-fowls, in which the males and females resemble each other so
closely that the cocks have often mistaken their hen-feathered
opponents in the cock-pit for real hens, and by the mistake have lost
their lives.[47] The cocks, though dressed in the feathers of the hen,
“are high-spirited birds, and their courage has been often proved:” an
engraving even has been published of one celebrated hen-tailed victor.
Mr. Tegetmeier[48] has recorded the remarkable case of a brown-breasted
red Game cock which, after assuming its perfect masculine plumage,
became hen-feathered in the autumn of the following year; but he did
not lose voice, spurs, strength, nor productiveness. This bird has now
retained the same character during five seasons, and has begot both
hen-feathered and male-feathered offspring. Mr. Grantley F. Berkeley
relates the still more singular case of a celebrated strain of “polecat
Game fowls,” which produced in nearly every brood a single hen-cock.
“The great peculiarity in one of these birds was that he, as the
seasons succeeded each other, was not always a hen-cock, and not always
of the colour called the polecat, which is black. From the polecat and
hen-cock feather in one season he moulted to a full male-plumaged
black-breasted red, and in the following year he returned to the former
feather.”[49]

I have remarked in my ‘Origin of Species’ that secondary sexual
characters are apt to differ much in the species of the same genus, and
to be unusually variable in the individuals of the same species. So it
is with the breeds of the fowl, as we have already seen, as far as the
colour of plumage is concerned, and so it is with the other secondary
sexual characters. Firstly, the comb differs much in the various
breeds,[50] and its form is eminently characteristic of each kind, with
the exception of the Dorkings, in which the form has not been as yet
determined on by fanciers, and fixed by selection. A single,
deeply-serrated comb is the typical and most common form. It differs
much in size, being immensely developed in Spanish fowls; and in a
local breed called Red-caps, it is sometimes “upwards of three inches
in breadth at the front, and more than four inches in length, measured
to the end of the peak behind.”[51] In some breeds the comb is double,
and when the two ends are cemented together it forms a “cup-comb;” in
the “rose-comb” it is depressed, covered with small projections, and
produced backwards; in the horned and creve-coeur fowl it is produced
into two horns; it is triple in the pea-combed Brahmas, short and
truncated in the Malays, and absent in the Guelderlands. In the
tasselled Game a few long feathers rise from the back of the comb: in
many breeds a crest of feathers replaces the comb. The crest, when
little developed, arises from a fleshy mass, but, when much developed,
from a hemispherical protuberance of the skull. In the best Polish
fowls it is so largely developed, that I have seen birds which could
hardly pick up their food; and a German writer asserts[52] that they
are in consequence liable to be struck by hawks. Monstrous structures
of this kind would thus be suppressed in a state of nature. The
wattles, also, vary much in size, being small in Malays and some other
breeds; in certain Polish sub-breeds they are replaced by a great tuft
of feathers called a beard.

The hackles do not differ much in the various breeds, but are short and
stiff in Malays, and absent in Hennies. As in some orders male birds
display extraordinarily-shaped feathers, such as naked shafts with
discs at the end, etc., the following case may be worth giving. In the
wild _Gallus bankiva_ and in our domestic fowls, the barbs which arise
from each side of the extremities of the hackles are naked or not
clothed with barbules, so that they resemble bristles; but Mr. Brent
sent me some scapular hackles from a young Birchen Duckwing Game cock,
in which the naked barbs became densely re-clothed with barbules
towards their tips; so that these tips, which were dark coloured with a
metallic lustre, were separated from the lower parts by a
symmetrically-shaped transparent zone formed of the naked portions of
the barbs. Hence the coloured tips appeared like little separate
metallic discs.

The sickle-feathers in the tail, of which there are three pair, and
which are eminently characteristic of the male sex, differ much in the
various breeds. They are scimitar-shaped in some Hamburghs, instead of
being long and flowing as in the typical breeds. They are extremely
short in Cochins, and are not at all developed in Hennies. They are
carried, together with the whole tail, erect in Dorkings and Gaines;
but droop much in Malays and in some Cochins. Sultans are characterised
by an additional number of lateral sickle-feathers. The spurs vary
much, being placed higher or lower on the shank; being extremely long
and sharp in Games, and blunt and short in Cochins. These latter birds
seem aware that their spurs are not efficient weapons; for though they
occasionally use them, they more frequently fight, as I am informed by
Mr. Tegetmeier, by seizing and shaking each other with their beaks. In
some Indian Game cocks, received by Mr. Brent from Germany, there are,
as he informs me, three, four, or even five spurs on each leg. Some
Dorkings also have two spurs on each leg;[53] and in birds of this
breed the spur is often placed almost on the outside of the leg. Double
spurs are mentioned in an ancient Chinese Encyclopædia. Their
occurrence may be considered as a case of analogous variation, for some
wild gallinaceous birds, for instance, the Polyplectron, have double
spurs.

Judging from the differences which generally distinguish the sexes in
the Gallinaceæ, certain characters in our domestic fowls appear to have
been transferred from the one sex to the other. In all the species
(except in Turnix), when there is any conspicuous difference in plumage
between the male and female, the male is always the most beautiful; but
in golden-spangled Hamburghs the hen is equally beautiful with the
cock, and incomparably more beautiful than the hen in any natural
species of Gallus; so that here a masculine character has been
transferred to the female. On the other hand, in Cuckoo Dorkings and in
other cuckoo breeds the pencilling, which in Gallus is a female
attribute, has been transferred to the male: nor, on the principle of
analogous variation, is this transference surprising, as the males in
many gallinaceous genera are barred or pencilled. With most of these
birds head ornaments of all kinds are more fully developed in the male
than in the female; but in Polish fowls the crest or top-knot, which in
the male replaces the comb, is equally developed in both sexes. In the
males of certain other sub-breeds, which from the hen having a small
crest, are called lark-crested, “a single upright comb sometimes almost
entirely takes the place of the crest.”[54] From this latter case, and
more especially from some facts presently to be given with respect to
the protuberance of the skull in Polish fowls, the crest in this breed
must be viewed as a feminine character which has been transferred to
the male. In the Spanish breed the male, as we know, has an immense
comb, and this has been partially transferred to the female, for her
comb is unusually large, though not upright. In Game fowls the bold and
savage disposition of the male has likewise been largely transferred to
the female;[55] and she sometimes even possesses the eminently
masculine character of spurs. Many cases are on record of fertile hens
being furnished with spurs; and in Germany, according to Bechstein,[56]
the spurs in the Silk hen are sometimes very long. He mentions also
another breed similarly characterised, in which the hens are excellent
layers, but are apt to disturb and break their eggs owing to their
spurs.

Mr. Layard[57] has given an account of a breed of fowls in Ceylon with
black skin, bones, and wattle, but with ordinary feathers, and which
cannot “be more aptly described than by comparing them to a white fowl
drawn down a sooty chimney; it is, however,” adds Mr. Layard, “a
remarkable fact that a male bird of the pure sooty variety is almost as
rare as a tortoise-shell tom-cat.” Mr. Blyth found the same rule to
hold good with this breed near Calcutta. The males and females, on the
other hand, of the black-boned European breed, with silky feathers, do
not differ from each other; so that in the one breed, black skin and
bones and the same kind of plumage are common to both sexes, whilst in
the other breed, these characters are confined to the female sex.

At the present day all the breeds of Polish fowls have the great bony
protuberance on their skulls, which includes part of the brain and
supports the crest, equally developed in both sexes. But formerly in
Germany the skull of the hen alone was protuberant: Blumenbach,[58] who
particularly attended to abnormal peculiarities in domestic animals,
states, in 1805, that this was the case; and Bechstein had previously,
in 1793 observed the same fact. This latter author has carefully
described the effects on the skull of a crest not only in the case of
fowls, but of ducks, geese, and canaries. He states that with fowls,
when the crest is not much developed, it is supported on a fatty mass;
but when much developed, it is always supported on a bony protuberance
of variable size. He well describes the peculiarities of this
protuberance; he attended also to the effects of the modified shape of
the brain on the intellect of these birds, and disputes Pallas’
statement that they are stupid. He then expressly remarks that he never
observed this protuberance in male fowls. Hence there can be no doubt
that this extraordinary character in the skulls of Polish fowls was
formerly in Germany confined to the female sex, but has now been
transferred to the males, and has thus become common to both sexes.

     _External Differences, not connected with the Sexes, between the
     Breeds and between individual Birds._

The size of the body differs greatly. Mr. Tegetmeier has known a Brahma
to weigh 17 pounds; a fine Malay cock 10 pounds; whilst a first-rate
Sebright Bantam weighs hardly more than 1 pound. During the last 20
years the size of some of our breeds has been largely increased by
methodical selection, whilst that of other breeds has been much
diminished. We have already seen how greatly colour varies even within
the same breed; we know that the wild _G. bankiva_ varies slightly in
colour; we know that colour is variable in all our domestic animals;
nevertheless some eminent fanciers have so little faith in variability,
that they have actually argued that the chief Game sub-breeds, which
differ from each other in nothing but colour, are descended from
distinct wild species! Crossing often causes strange modification of
colour. Mr. Tegetmeier informs me that when buff and white Cochins are
crossed, some of the chickens are almost invariably black. According to
Mr. Brent, black and white Cochins occasionally produce chickens of a
slaty-blue tint; and this same tint results, as Mr. Tegetmeier tells
me, from crossing white Cochins with black Spanish fowls, or white
Dorkings with black Minorcas.[59] A good observer[60] states that a
first-rate silver-spangled Hamburgh hen gradually lost the most
characteristic qualities of the breed, for the black lacing to her
feathers disappeared, and her legs changed from leaden-blue to white:
but what makes the case remarkable is, that this tendency ran in the
blood for her sister changed in a similar but less strongly marked
manner; and chickens produced from this latter hen were at first almost
pure white, “but on moulting acquired black colours and some spangled
feathers with almost obliterated markings;” so that a new variety arose
in this singular manner. The skin in the different breeds differs much
in colour, being white in common kinds, yellow in Malays and Cochins,
and black in Silk fowls; thus mocking, as M. Godron[61] remarks the
three principal types of skin in mankind. The same author adds that, as
different kinds of fowls living in distant and isolated parts of the
world have black skin and bones, this colour must have appeared at
various times and places.

The shape and carriage of the body, and the shape of the head differ
much. The beak varies slightly in length and curvature, but
incomparably less than with pigeons. In most crested fowls the nostrils
offer a remarkable peculiarity in being raised with a crescentic
outline. The primary wing-feathers are short in Cochins; in a male,
which must have been more than twice as heavy as _G. bankiva,_ these
feathers were in both birds of the same length. I have counted, with
Mr. Tegetmeier’s aid, the primary wing-feathers in thirteen cocks and
hens of various breeds; in four of them, namely in two Hamburghs, a
Cochin, and Game bantam, there were 10, instead of the normal number 9;
but in counting these feathers I have followed the practice of
fanciers, and have _not_ included the first minute primary feather,
barely three-quarters of an inch in length. These feathers differ
considerably in relative length, the fourth, or the fifth, or the
sixth, being the longest; with the third either equal to, or
considerably shorter than the fifth. In wild gallinaceous species the
relative length and number of the main wing and tail-feathers are
extremely constant.

The tail differs much in erectness and size, being small in Malays and
very small in Cochins. In thirteen fowls of various breeds which I have
examined, five had the normal number of 14 feathers, including in this
number the two middle sickle-feathers; six others (viz., a Caffre cock,
Gold-spangled Polish cock, Cochin hen, Sultan hen, Game hen and Malay
hen had 16; and two (an old Cochin cock and Malay hen) had 17 feathers.
The rumpless fowl has no tail and in one which I possessed there was no
oil-gland; but this bird though the os coccygis was extremely
imperfect, had a vestige of a tail with two rather long feathers in the
position of the outer caudals. This bird came from a family where, as I
was told, the breed had kept true for twenty years; but rumpless fowls
often produce chickens with tails.[62] An eminent physiologist[63] has
recently spoken of this breed as a distinct species; had he examined
the deformed state of the os coccyx he would never have come to this
conclusion; he was probably misled by the statement, which may be found
in some works, that tailless fowls are wild in Ceylon; but this
statement, as I have been assured by Mr. Layard and Dr. Kellaert who
have so closely studied the birds of Ceylon, is utterly false.

The tarsi vary considerably in length, being relatively to the femur
considerably longer in the Spanish and Frizzled, and shorter in the
Silk and Bantam breeds, than in the wild _G. bankiva_; but in the
latter, as we have seen, the tarsi vary in length. The tarsi are often
feathered. The feet in many breeds are furnished with additional toes.
Golden-spangled Polish fowls are said[64] to have the skin between
their toes much developed: Mr. Tegetmeier observed this in one bird,
but it was not so in one which I examined. Prof. Hoffmann has sent me a
sketch of the feet of a fowl of the common breed at Giessen, with a web
extending between the three toes, for about a third of their length. In
Cochins the middle toe is said[65] to be nearly double the length of
the lateral toes, and therefore much longer than in _G. bankiva_ or in
other fowls; but this was not the case in two which I examined. The
nail of the middle toe in this same breed is surprisingly broad and
flat, but in a variable degree in two birds which I examined; of this
structure in the nail there is only a trace in _G. bankiva._

The voice differs slightly, as I am informed by Mr. Dixon, in almost
every breed. The Malays[66] have a loud, deep, somewhat prolonged crow,
but with considerable individual difference. Colonel Sykes remarks that
the domestic Kulm cock in India has not the shrill clear pipe of the
English bird, and “his scale of notes appears more limited.” Dr. Hooker
was struck with the “prolonged howling screech” of the cocks in
Sikhim.[67] The crow of the Cochin is notoriously and ludicrously
different from that of the common cock. The disposition of the
different breeds is widely different, varying from the savage and
defiant temper of the Game-cock to the extremely peaceable temper of
the Cochins. The latter, it has been asserted, “graze to a much greater
extent than any other varieties.” The Spanish fowls suffer more from
frost than other breeds.

Before we pass on to the skeleton, the degree of distinctness of the
several breeds from _G. bankiva_ ought to be noticed. Some writers
speak of the Spanish as one of the most distinct breeds, and so it is
in general aspect; but its characteristic differences are not
important. The Malay appears to me more distinct, from its tall
stature, small drooping tail with more than fourteen tail-feathers, and
from its small comb and wattles; nevertheless, one Malay sub-breed is
coloured almost exactly like _G. bankiva._ Some authors consider the
Polish fowl as very distinct; but this is a semi-monstrous breed, as
shown by the protuberant and irregularly perforated skull. The Cochin,
from its deeply furrowed frontal bones, peculiarly shaped occipital
foramen, short wing-feathers, short tail containing more than fourteen
feathers, broad nail to the middle toe, fluffy plumage, rough and
dark-coloured eggs, and especially from its peculiar voice, is probably
the most distinct of all the breeds. If any one of our breeds has
descended from some unknown species, distinct from _G. bankiva,_ it is
probably the Cochin; but the balance of evidence does not favour this
view. All the characteristic differences of the Cochin breed are more
or less variable, and may be detected in a greater or lesser degree in
other breeds. One sub-breed is coloured closely like _G. bankiva._ The
feathered legs, often furnished with an additional toe, the wings
incapable of flight, the extremely quiet disposition, indicate a long
course of domestication; and these fowls come from China, where we know
that plants and animals have been tended from a remote period with
extraordinary care, and where consequently we might expect to find
profoundly modified domestic races.

_Osteological Differences._—I have examined twenty-seven skeletons and
fifty-three skulls of various breeds, including three of _G. bankiva_:
nearly half of these skulls I owe to the kindness of Mr. Tegetmeier,
and three of the skeletons to Mr. Eyton.

Illustration: Fig. 33—Occipital Foramen of the Skulls of Fowls

The _Skull_ differs greatly in size in different breeds, being nearly
twice as long in the largest Cochins, but not nearly twice as broad, as
in Bantams. The bones at the base, from the occipital foramen to the
anterior end (including the quadrates and pterygoids), are absolutely
identical in _ shape_ in all the skulls. So is the lower jaw. In the
forehead slight differences are often perceptible between the males and
females, evidently caused by the presence of the comb. In every case I
take the skull of _G. bankiva_ as the standard of comparison. In four
Games, in one Malay hen, in an African cock, in a Frizzled cock from
Madras, in two black-boned Silk hens, no differences worth notice
occur. In three _Spanish_ cocks, the form of the forehead between the
orbits differs considerably; in one it is considerably depressed,
whilst in the two others it is rather prominent, with a deep medial
furrow; the skull of the hen is smooth. In three skulls of _Sebright
Bantams_ the crown is more globular, and slopes more abruptly to the
occiput, than in _ G. bankiva._ In a Bantam or Jumper from Burmah these
same characters are more strongly pronounced, and the supra-occiput is
more pointed. In a black Bantam the skull is not so globular, and the
occipital foramen is very large, and has nearly the same sub-triangular
outline presently to be described in Cochins; and in this skull the two
ascending branches of the premaxillary are overlapped in a singular
manner by the processes of the nasal bone, but, as I have seen only one
specimen, some of these differences may be individual. Of Cochins and
Brahmas (the latter a crossed race approaching closely to Cochins) I
have examined seven skulls; at the point where the ascending branches
of the premaxillary rest on the frontal bone the surface is much
depressed, and from this depression a deep medial furrow extends
backwards to a variable distance; the edges of this fissure are rather
prominent, as is the top of the skull behind and over the orbits. These
characters are less developed in the hens. The pterygoids, and the
processes of the lower jaw, are broader, relatively to the size of the
head, than in _G. bankiva_; and this is likewise the case with Dorkings
when of large size. The fork of the hyoid bone in Cochins is twice as
wide as in _G. bankiva,_ whereas the length of the other hyoid bones is
only as three to two. But the most remarkable character is the shape of
the occipital foramen: in _G. bankiva_ (A) the breadth in a horizontal
line exceeds the height in a vertical line, and the outline is nearly
circular; whereas in Cochins (B) the outline is sub-triangular, and the
vertical line exceeds the horizontal line in length. This same form
likewise occurs in the black Bantam above referred to, and an approach
to it may be seen in some Dorkings, and in a slight degree in certain
other breeds.

Illustration: Fig. 34—Skulls of Fowls

Of _Dorkings_ I have examined three skulls, one belonging to the
white-sub-breed; the one character deserving notice is the breadth of
the frontal bones, which are moderately furrowed in the middle; thus in
a skull which was less than once and a half the length of that of _G.
bankiva,_ the breadth between the orbits was exactly double. Of
_Hamburghs_ I have examined four skulls (male and female) of the
pencilled sub-breed, and one (male) of the spangled sub-breed; the
nasal bones stand remarkably wide apart, but in a variable degree;
consequently narrow membrane-covered spaces are left between the tips
of the two ascending branches of the pre-maxillary bones, which are
rather short, and between these branches and the nasal bones. The
surface of the frontal bone, on which the branches of the premaxillary
rest, is very little depressed. These peculiarities no doubt stand in
close relation with the broad, flattened rose-comb characteristic of
the Hamburgh breed.

Illustration: Fig. 35—Longitudinal sections of Skulls of Fowls

I have examined fourteen skulls of _ Polish and other crested breeds._
Their differences are extraordinary. First for nine skulls of different
sub-breeds of English Polish fowls. The hemispherical protuberance of
the frontal bones[68] may be seen in fig. 34, in which (B) the skull of
a white-crested Polish fowl is shown obliquely from above, with the
skull (A) of _G. bankiva_ in the same position. In fig. 35 longitudinal
sections are given of the skull of a Polish fowl, and, for comparison,
of a Cochin of the same size. The protuberance in all Polish fowls
occupies the same position but differs much in size. In one of my nine
specimens it was extremely slight. The degree to which the protuberance
is ossified varies greatly, larger or smaller portions of bone being
replaced by membrane. In one specimen there was only a single open
pore; generally, there are many variously shaped open spaces, the bone
forming an irregular reticulation. A medial, longitudinal, arched
ribbon of bone is generally retained, but in one specimen there was no
bone whatever over the whole protuberance, and the skull, when cleaned
and viewed from above, presented the appearance of an open basin. The
change in the whole internal form of the skull is surprisingly great.
The brain is modified in a corresponding manner, as is shown in the two
longitudinal sections, which deserve attentive consideration. The upper
and anterior cavity of the three into which the skull may be divided,
is the one which is so greatly modified; it is evidently much larger
than in the Cochin skull of the same size, and extends much further
beyond the interorbital septum, but laterally is less deep. This
cavity, as I hear from Mr. Tegetmeier, is entirely filled with brain.
In the skull of the Cochin and of all ordinary fowls a strong internal
ridge of bone separates the anterior from the central cavity; but this
ridge is quite absent in the Polish skull here figured. The shape of
the central cavity is circular in the Polish, and lengthened in the
Cochin skull. The shape of the posterior cavity, together with the
position, size, and number of the pores for the nerves, differ much in
these two skulls. A pit deeply penetrating the occipital bone of the
Cochin is entirely absent in this Polish skull, whilst in another
specimen it was well developed. In this second specimen the whole
internal surface of the posterior cavity likewise differs to a certain
extent in shape. I made sections of two other skulls,—namely, of a
Polish fowl with the protuberance singularly little developed, and of a
Sultan in which it was a little more developed; and when these two
skulls were placed between the two above figured (fig. 35), a perfect
gradation in the configuration of each part of the internal surface
could be traced. In the Polish skull, with a small protuberance, the
ridge between the anterior and middle cavities was present, but low;
and in the Sultan this ridge was replaced by a narrow furrow standing
on a broad raised eminence.

Illustration: Fig. 36—Skulls of Horned Fowl

It may naturally be asked whether these remarkable modifications in the
form of the brain affect the intellect of Polish fowls; some writers
have stated that they are extremely stupid, but Bechstein and Mr.
Tegetmeier have shown that this is by no means generally the case.
Nevertheless Bechstein[69] states that he had a Polish hen which “was
crazy, and anxiously wandered about all day long.” A hen in my
possession was solitary in her habits, and was often so absorbed in
reverie that she could be touched; she was also deficient in the most
singular manner in the faculty of finding her way, so that, if she
strayed a hundred yards from her feeding-place, she was completely
lost, and would then obstinately try to proceed in a wrong direction. I
have received other and similar accounts of Polish fowls appearing
stupid or half-idiotic.[70]

To return to the skull of Polish fowls. The posterior part, viewed
externally, differs little from that of _G. bankiva._ In most fowls the
posterior-lateral process of the frontal bone and the process of the
squamosal bone run together and are ossified near their extremities:
this union of the two bones, however, is not constant in any breed; and
in eleven out of fourteen skulls of crested breeds, these processes
were quite distinct. These processes, when not united, instead of being
inclined anteriorly, as in all common breeds, descend at right angles
to the lower jaw; and in this case the longer axis of the bony cavity
of the ear is likewise more perpendicular, than in other breeds. When
the squamosal process is free instead of expanding at the tip, it is
reduced to an extremely fine and pointed style, of variable length. The
pterygoid and quadrate bones present no differences. The palatine bones
are a little more curved upwards at their posterior ends. The frontal
bones, anteriorly to the protuberance, are, as in Dorkings, very broad,
but in a variable degree. The nasal bones either stand far apart, as in
Hamburghs, or almost touch each other, and in one instance were
ossified together. Each nasal bone properly sends out in front two long
processes of equal lengths, forming a fork; but in all the Polish
skulls, except one, the inner process was considerably, but in a
variable degree, shortened and somewhat upturned. In all the skulls,
except one, the two ascending branches of the premaxillary, instead of
running up between the processes of the nasal bones and resting on the
ethmoid bone, are much shortened and terminate in a blunt, somewhat
upturned point. In those skulls in which the nasal bones approach quite
close to each other or are ossified together, it would be impossible
for the ascending branches of the premaxillary to reach the ethmoid and
frontal bones; hence we see that even the relative connection of the
bones has been changed. Apparently in consequence of the branches of
the premaxillary and of the inner processes of the nasal bones being
somewhat upturned, the external orifices of the nostrils are upraised
and assume a crescentic outline.

I must still say a few words on some of the foreign Crested breeds. The
skull of a crested, rumpless, white Turkish fowl was very slightly
protuberant, and but little perforated; the ascending branches of the
premaxillary were well developed. In another Turkish breed, called
Ghoondooks, the skull was considerably protuberant and perforated; the
ascending branches of the premaxillary were so much aborted that they
projected only 1/15th of an inch; and the inner processes of the nasal
bone were so completely aborted, that the surface where they should
have projected was quite smooth. Here then we see these two bones
modified to an extreme degree. Of Sultans (another Turkish breed) I
examined two skulls; in that of the female the protuberance was much
larger than in the male. In both skulls the ascending branches of the
premaxillary were very short, and in both the nasal portion of the
inner processes of the nasal bones were ossified together. These Sultan
skulls differed from those of English Polish fowls in the frontal
bones, anteriorly to the protuberance, not being broad.

The last skull which I need describe is a unique one, lent to me by Mr.
Tegetmeier: it resembles a Polish skull in most of its characters, but
has not the great frontal protuberance; it has, however, two rounded
knobs of a different nature, which stand more in front, above the
lachrymal bones. These curious knobs, into which the brain does not
enter, are separated from each other by a deep medial furrow; and this
is perforated by a few minute pores. The nasal bones stand rather wide
apart, with their inner processes, and the ascending branches of the
premaxillary, upturned and shortened. The two knobs no doubt supported
the two great horn-like projections of the comb.

From the foregoing facts we see in how astonishing a manner some of the
bones of the skull vary in Crested fowls. The protuberance may
certainly be called in one sense a monstrosity, as being wholly unlike
anything observed in nature: but as in ordinary cases it is not
injurious to the bird, and as it is strictly inherited, it can hardly
in another sense be called a monstrosity. A series may be formed
commencing with the black-boned Silk fowl, which has a very small crest
with the skull beneath penetrated only by a few minute orifices, but
with no other change in its structure; and from this first stage we may
proceed to fowls with a moderately large crest, which rests, according
to Bechstein, on a fleshy mass, but without any protuberance in the
skull. I may add that I have seen a similar fleshy or fibrous mass
beneath the tuft of feathers on the head of the Tufted duck; and in
this case there was no actual protuberance in the skull, but it had
become a little more globular. Lastly, when we come to fowls with a
largely developed crest, the skull becomes largely protuberant and is
perforated by a multitude of irregular open spaces. The close relation
between the crest and the size of the bony protuberance is shown in
another way; for Mr. Tegetmeier informs me that if chickens lately
hatched be selected with a large bony protuberance, when adult they
will have a large crest. There can be no doubt that in former times the
breeder of Polish fowls attended solely to the crest, and not to the
skull; nevertheless, by increasing the crest, in which he has been
wonderfully successful, he has unintentionally made the skull
protuberant to an astonishing degree; and through correlation of
growth, he has at the same time affected the form and relative
connexion of the premaxillary and nasal bones, the shape of the orifice
of the nose, the breadth of the frontal bones, the shape of the
post-lateral processes of the frontal and squamosal bones, the
direction of the axis of the bony cavity of the ear, and lastly the
internal configuration of the whole skull together with the shape of
the brain.

Illustration: Fig. 37—Sixth Cervical Verterbra of Fowls

_Vertebræ._—In _G. bankiva_ there are fourteen cervical, seven dorsal
with ribs, apparently fifteen lumbar and sacral, and six caudal
vertebræ;[71] but the lumbar and sacral are so much anchylosed that I
am not sure of their number, and this makes the comparison of the total
number of vertebræ in the several breeds difficult. I have spoken of
six caudal vertebræ, because the basal one is almost completely
anchylosed with the pelvis; but if we consider the number as seven, the
caudal vertebræ agree in all the skeletons. The cervical vertebræ are,
as just stated, in appearance fourteen; but out of twenty-three
skeletons in a fit state for examination, in five of them, namely, in
two Games, in two pencilled Hamburghs, and in a Polish, the fourteenth
vertebra bore ribs, which, though small, were perfectly developed with
a double articulation. The presence of these little ribs cannot be
considered as a fact of much importance, for all the cervical vertebræ
bear representatives of ribs; but their development in the fourteenth
vertebra reduces the size of the passages in the transverse processes,
and makes this vertebra exactly like the first dorsal vertebra. The
addition of these little ribs does not affect the fourteenth cervical
alone, for properly the ribs of the first true dorsal vertebra are
destitute of processes; but in some of the skeletons in which the
fourteenth cervical bore little ribs the first pair of true ribs had
well-developed processes. When we know that the sparrow has only nine,
and the swan twenty-three cervical vertebræ,[72] we need feel no
surprise at the number of the cervical vertebræ in the fowl being, as
it appears, variable.

There are seven dorsal vertebræ bearing ribs; the first dorsal is never
anchylosed with the succeeding four, which are generally anchylosed
together. In one Sultan fowl, however, the two first dorsal vertebræ
were free. In two skeletons, the fifth dorsal was free; generally the
sixth is free (as in _G. bankiva_), but sometimes only at its posterior
end, where in contact with the seventh. The seventh dorsal vertebra, in
every case excepting in one Spanish cock, was anchylosed with the
lumbar vertebræ. So that the degree to which these middle dorsal
vertebræ are anchylosed is variable.

Seven is the normal number of true ribs, but in two skeletons of the
Sultan fowl (in which the fourteenth cervical vertebra was not
furnished with little ribs) there were eight pairs; the eighth pair
seemed to be developed on a vertebra corresponding with the first
lumbar in _G. bankiva_; the sternal portion of both the seventh and
eighth ribs did not reach the sternum. In four skeletons in which ribs
were developed on the fourteenth cervical vertebra, there were, when
these cervical ribs are included, eight pairs; but in one Game cock, in
which the fourteenth cervical was furnished with ribs, there were only
six pairs of true dorsal ribs; the sixth pair in this case did not have
processes, and thus resembled the seventh pair in other skeletons; in
this Game cock, as far as could be judged from the appearance of the
lumbar vertebræ, a whole dorsal vertebra with its ribs was missing. We
thus see that the ribs (whether or not the little pair attached to the
fourteenth cervical vertebra be counted) vary from six to eight pair.
The sixth pair is frequently not furnished with processes. The sternal
portion of the seventh pair is extremely broad in Cochins, and is
completely ossified. As previously stated, it is scarcely possible to
count the lumbo-sacral vertebræ; but they certainly do not correspond
in shape or number in the several skeletons. The caudal vertebræ are
closely similar in all the skeletons, the only difference being whether
or not the basal one is anchylosed to the pelvis; they hardly vary even
in length, not being shorter in Cochins, with their short
tail-feathers, than in other breeds; in a Spanish cock, however, the
caudal vertebræ were a little elongated. In three rumpless fowls the
caudal vertebræ were few in number, and anchylosed together into a
misformed mass.

In the individual vertebræ the differences in structure are very
slight. In the atlas the cavity for the occipital condyle is either
ossified into a ring, or is, as in Bankiva, open on its upper margin.
The upper arc of the spinal canal is a little more arched in Cochins,
in conformity with the shape of the occipital foramen, than in _G.
bankiva._ In several skeletons a difference, but not of much
importance, may be observed, which commences at the fourth cervical
vertebra, and is greatest at about the sixth, seventh, or eighth
vertebra; this consists in the hæmal descending processes being united
to the body of the vertebra by a sort of buttress. This structure may
be observed in Cochins, Polish, some Hamburghs, and probably other
breeds; but is absent, or barely developed, in Game, Dorking, Spanish,
Bantam, and several other breeds examined by me. On the dorsal surface
of the sixth cervical vertebra in Cochins three prominent points are
more strongly developed than in the corresponding vertebra of the Game
fowl or _G. bankiva._

_Pelvis._—This differs in some few points in the several skeletons. The
anterior margin of the ilium seems at first to vary much in outline,
but this is chiefly due to the degree to which the margin in the middle
part is ossified to the crest of the vertebræ; the outline, however,
does differ in being more truncated in Bantams, and more rounded in
certain breeds, as in Cochins. The outline of the ischiadic foramen
differs considerably, being nearly circular in Bantams, instead of
egg-shaped as in the Bankiva, and more regularly oval in some
skeletons, as in the Spanish. The obturator notch is also much less
elongated in some skeletons than in others. The end of the pubic bone
presents the greatest difference; being hardly enlarged in the Bankiva;
considerably and gradually enlarged in Cochins, and in a lesser degree
in some other breeds; and abruptly enlarged in Bantams. In one Bantam
this bone extended very little beyond the extremity of the ischium. The
whole pelvis in this latter bird differed widely in its proportions,
being far broader proportionally to its length than in Bankiva.

Illustration: Fig. 38—Extremity of the Furcula of Fowls

_Sternum._—This bone is generally so much deformed that it is scarcely
possible to compare its shape strictly in the several breeds. The form
of the triangular extremity of the lateral processes differs
considerably, being either almost equilateral or much elongated. The
front margin of the crest is more or less perpendicular and varies
greatly, as does the curvature of the posterior end, and the flatness
of the lower surface. The outline of the manubrial process also varies,
being wedge-shaped in the Bankiva, and rounded in the Spanish breed.
The _furculum_ differs in being more or less arched, and greatly, as
may be seen in the accompanying outlines, in the shape of the terminal
plate; but the shape of this part differed a little in two skeletons of
the wild Bankiva. The _coracoid_ presents no difference worth notice.
The _scapula_ varies in shape, being of nearly uniform breadth in
Bankiva, much broader in the middle in the Polish fowl, and abruptly
narrowed towards the apex in the two Sultan fowls.

I carefully compared each separate bone of the leg and wing, relatively
to the same bones in the wild Bankiva, in the following breeds, which I
thought were the most likely to differ; namely, in Cochin, Dorking,
Spanish, Polish, Burmese Bantam, Frizzled Indian, and black-boned Silk
fowls; and it was truly surprising to see how absolutely every process,
articulation, and pore agreed, though the bones differed greatly in
size. The agreement is far more absolute than in other parts of the
skeleton. In stating this, I do not refer to the relative thickness and
length of the several bones; for the tarsi varied considerably in both
these respects. But the other limb-bones varied little even in relative
length.

Finally, I have not examined a sufficient number of skeletons to say
whether any of the foregoing differences, except in the skull, are
characteristic of the several breeds. Apparently some differences are
more common in certain breeds than in others,—as an additional rib to
the fourteenth cervical vertebra in Hamburghs and Games, and the
breadth of the end of the pubic bone in Cochins. Both skeletons of the
Sultan fowl had eight dorsal vertebræ, and the end of the scapula in
both was somewhat attenuated. In the skull, the deep medial furrow in
the frontal bones and the vertically elongated occipital foramen seem
to be characteristic of Cochins; as is the great breadth of the frontal
bones in Dorkings; the separation and open spaces between the tips of
the ascending branches of the premaxillaries and nasal bones, as well
as the front part of the skull being but little depressed, characterise
Hamburghs; the globular shape of the posterior part of the skull seems
to be characteristic of laced Bantams; and lastly, the protuberance of
the skull with the ascending branches of the premaxillaries partially
aborted, together with the other differences before specified, are
eminently characteristic of Polish and other Crested fowls.

But the most striking result of my examination of the skeleton is the
great variability of all the bones except those of the extremities. To
a certain extent we can understand why the skeleton fluctuates so much
in structure; fowls have been exposed to unnatural conditions of life,
and their whole organisation has thus been rendered variable; but the
breeder is quite indifferent to, and never intentionally selects, any
modification in the skeleton. External characters, if not attended to
by man, such as the number of the tail and wing feathers and their
relative lengths, which in wild birds are generally constant,—fluctuate
in our domestic fowls in the same manner as the several parts of the
skeleton. An additional toe is a “point” in Dorkings, and has become a
fixed character, but is variable in Cochins and Silk fowls. The colour
of the plumage and the form of the comb are in most breeds, or even
sub-breeds, eminently fixed characters; but in Dorkings these points
have not been attended to, and are variable. When any modification in
the skeleton is related to some external character which man values, it
has been, unintentionally on his part, acted on by selection, and has
become more or less fixed. We see this in the wonderful protuberance of
the skull, which supports the crest of feathers in Polish fowls, and
which by correlation has affected other parts of the skull. We see the
same result in the two protuberances which support the horns in the
horned fowl, and in the flattened shape of the front of the skull in
Hamburghs consequent on their flattened and broad “rose-combs.” We know
not in the least whether additional ribs, or the changed outline of the
occipital foramen, or the changed form of the scapula, or of the
extremity of the furculum, are in any way correlated with other
structures, or have arisen from the changed conditions and habits of
life to which our fowls have been subjected; but there is no reason to
doubt that these various modifications in the skeleton could be
rendered, either by direct selection, or by the selection of correlated
structures, as constant and as characteristic of each breed, as are the
size and shape of the body, the colour of the plumage, and the form of
the comb.

     _Effects of the Disuse of Parts._

Judging from the habits of our European gallinaceous birds, _Gallus
bankiva_ in its native haunts would use its legs and wings more than do
our domestic fowls, which rarely fly except to their roosts. The Silk
and the Frizzled fowls, from having imperfect wing-feathers, cannot fly
at all; and there is reason to believe that both these breeds are
ancient, so that their progenitors during many generations cannot have
flown. The Cochins, also, from their short wings and heavy bodies, can
hardly fly up to a low perch. Therefore in these breeds, especially in
the two first, a considerable diminution in the wing-bones might have
been expected, but this is not the case. In every specimen, after
disarticulating and cleaning the bones, I carefully compared the
relative length of the two main bones of the wing to each other, and of
the two main bones of the leg to each other, with those of _G.
bankiva_; and it was surprising to see (except in the case of the
tarsi) how exactly the same relative length had been retained. This
fact is curious, from showing how truly the proportions of an organ may
be inherited, although not fully exercised during many generations. I
then compared in several breeds the length of the femur and tibia with
the humerus and ulna, and likewise these same bones with those of _G.
bankiva_; the result was that the wing-bones in all the breeds (except
the Burmese Jumper, which has unnaturally short legs, are slightly
shortened relatively to the leg-bones; but the decrease is so slight
that it may be due to the standard specimen of _G. bankiva_ having
accidentally had wings of slightly greater length than usual; so that
the measurements are not worth giving. But it deserves notice that the
Silk and Frizzled fowls, which are quite incapable of flight, had their
wings _less_ reduced relatively to their legs than in almost any other
breed! We have seen with domesticated pigeons that the bones of the
wings are somewhat reduced in length, whilst the primary feathers are
rather increased in length, and it is just possible, though not
probable, that in the Silk and Frizzled fowls any tendency to decrease
in the length of the wing-bones from disuse may have been checked
through the law of compensation, by the decreased growth of the
wing-feathers, and consequent increased supply of nutriment. The
wing-bones, however, in both these breeds, are found to be slightly
reduced in length when judged by the standard of the length of the
sternum or head, relatively to these same parts in _G. bankiva._

The actual weight of the main bones of the leg and wing in twelve
breeds is given in the two first columns in Table I. The calculated
weight of the wing-bones relatively to the leg-bones, in comparison
with the leg and wing-bones of _G. bankiva,_ are given in the third
column,—the weight of the wing-bones in _G. bankiva_ being called a
hundred.[73]

Table I.

Names of Breeds.     Actual
          Weight
          of
          Femur
          and
          Tibia.     Actual
          Weight of
          Humerus
          and Ulna.     Weight of Wing-
          bones relatively to
          the Leg-bones in
          comparison with
          these same bones
          in _G. bankiva._ Grains.     Grains. Gallus bankiva (wild
          male)       86       54     100 1     Cochin
          (male)     311     162       83 2     Dorking
          (male)     557     248       70 3     Spanish (Minorca)
          (male)     386     183       75 4     Gold-Spangled Polish
          (male)     306     145       75 5     Game, black-breasted
          (male)     293     143       77 6     Malay
          (female)     231     116       80 7     Sultan (male)     189      
          94       79 8     Indian Frizzled (male)     206       88       67
          9     Burmese Jumper (female)       53       36     108
          10     Hamburgh (pencilled) (male)     157     104     106
          11     Hamburgh (pencilled) (female)     114       77     108
          12     Silk (black-boned) (female)       88       57     103

In the eight first birds, belonging to distinct breeds, in this table,
we see a decided reduction in the weight of the bones of the wing.

In the Indian Frizzled fowl, which cannot fly, the reduction is carried
to the greatest extent, namely, to thirty-three per cent of their
proper proportional weight. In the next four birds, including the Silk
hen, which is incapable of flight, we see that the wings, relatively to
the legs, are slightly increased in weight; but it should be observed
that, if in these birds the legs had become from any cause reduced in
weight, this would give the false appearance of the wings having
increased in relative weight. Now a reduction of this nature has
certainly occurred with the Burmese Jumper, in which the legs are
abnormally short, and in the two Hamburghs and Silk fowl, the legs,
though not short, are formed of remarkably thin and light bones. I make
these statements, not judging by mere eyesight, but after having
calculated the weights of the leg-bones relatively to those of G.
bankiva, according to the only two standards of comparison which I
could use, namely, the relative lengths of the head and sternum; for I
do not know the weight of the body in _G. bankiva,_ which would have
been a better standard. According to these standards, the leg-bones in
these four fowls are in a marked manner far lighter than in any other
breed. It may therefore be concluded that in all cases in which the
legs have not been through some unknown cause much reduced in weight,
the wing-bones have become reduced in weight relatively to the
leg-bones, in comparison with those of _G. bankiva._ And this reduction
of weight may, I apprehend, safely be attributed to disuse.

To make Table I quite satisfactory, it ought to have been shown that in
the eight first birds the leg-bones have not actually increased in
weight out of due proportion with the rest of the body; this I cannot
show, from not knowing, as already remarked, the weight of the wild
Bankiva.[74] I am indeed inclined to suspect that the leg-bones in the
Dorking, No. 2 in the table, are proportionally too heavy; but this
bird was a very large one, weighing 7 pounds 2 ounces, though very
thin. Its leg-bones were more than ten times as heavy as those of the
Burmese Jumper! I tried to ascertain the length both of the leg-bones
and wing-bones relatively to other parts of the body and skeleton: but
the whole organisation in these birds, which have been so long
domesticated, has become so variable, that no certain conclusions could
be reached. For instance, the legs of the above Dorking cock were
nearly three-quarters of an inch too short relatively to the length of
the sternum, and more than three-quarters of an inch too long
relatively to the length of the skull, in comparison with these same
parts in _G. bankiva._

Table II.

Names of Breeds.     Length
          of
          Sternum.     Depth of
          Crest of
          Sternum     Depth of Crest
          relatively to the
          length of the
          Sternum, in
          comparison with
          _G. bankiva._ Inches.     Inches Gallus bankiva
          (male)     4·20     1·40     100 1     Cochin
          (male)     5·83     1·55     78 2     Dorking
          (male)     6·95     1·97     84 3     Spanish
          (male)     6·10     1·83     90 4     Polish
          (male)     5·07     1·50     87 5     Game
          (male)     5·55     1·55     81 6     Malay
          (female)     5·10     1·50     87 7     Sultan
          (male)     4·47     1·36     90 8     Frizzled hen
          (male)     4·25     1·20     84 9     Burmese Jumper
          (female)     3·06     0·85     81 10     Hamburgh
          (male)     5·08     1·40     81 11     Hamburgh
          (female)     4·55     1·26     81 12     Silk fowl
          (female)     4·49     1·01     66

In Table II in the two first columns we see in inches and decimals the
length of the sternum, and the extreme depth of its crest to which the
pectoral muscles are attached. In the third column we have the
calculated depth of the crest, relatively to the length of the sternum,
in comparison with these same parts in _G. bankiva._[75]

By looking to the third column we see that in every case the depth of
the crest relatively to the length of the sternum, in comparison with
_G. bankiva,_ is diminished, generally between 10 and 20 per cent. But
the degree of reduction varies much, partly in consequence of the
frequently deformed state of the sternum. In the Silk fowl, which
cannot fly, the crest is 34 per cent less deep than what it ought to
have been. This reduction of the crest in all the breeds probably
accounts for the great variability, before referred to, in the
curvature of the furculum, and in the shape of its sternal extremity.
Medical men believe that the abnormal form of the spine so commonly
observed in women of the higher ranks results from the attached muscles
not being fully exercised. So it is with our domestic fowls, for they
use their pectoral muscles but little, and, out of twenty-five sternums
examined by me, three alone were perfectly symmetrical, ten were
moderately crooked, and twelve were deformed to an extreme degree. Mr.
Romanes, however, believes that the malformation is due to fowls whilst
young resting their sternums on the sticks on which they roost.

Finally, we may conclude with respect to the various breeds of the
fowl, that the main bones of the wing have probably been shortened in a
very slight degree; that they have certainly become lighter relatively
to the leg-bones in all the breeds in which these latter bones are not
unnaturally short or delicate; and that the crest of the sternum, to
which the pectoral muscles are attached, has invariably become less
prominent, the whole sternum being also extremely liable to deformity.
These results we may attribute to the lessened use of the wings.

_Correlation of Growth._—I will here sum up the few facts which I have
collected on this obscure, but important, subject. In Cochin and Game
fowls there is perhaps some relation between the colour of the plumage
and the darkness of the egg-shell. In Sultans the additional
sickle-feathers in the tail are apparently related to the general
redundancy of the plumage, as shown by the feathered legs, large crest,
and beard. In two tailless fowls which I examined the oil-gland was
aborted. A large crest of feathers, as Mr. Tegetmeier has remarked,
seems always accompanied by a great diminution or almost entire absence
of the comb. A large beard is similarly accompanied by diminished or
absent wattles. These latter cases apparently come under the law of
compensation or balancement of growth. A large beard beneath the lower
jaw and a large top-knot on the skull often go together. The comb when
of any peculiar shape, as with Horned, Spanish, and Hamburgh fowls,
affects in a corresponding manner the underlying skull; and we have
seen how wonderfully this is the case with Crested fowls when the crest
is largely developed. With the protuberance of the frontal bones the
shape of the internal surface of the skull and of the brain is greatly
modified. The presence of a crest influences in some unknown way the
development of the ascending branches of the premaxillary bone, and of
the inner processes of the nasal bones; and likewise the shape of the
external orifice of the nostrils. There is a plain and curious
correlation between a crest of feathers and the imperfectly ossified
condition of the skull. Not only does this hold good with nearly all
crested fowls, but likewise with tufted ducks, and as Dr. Gunther
informs me with tufted geese in Germany.

Lastly, the feathers composing the crest in male Polish fowls resemble
hackles, and differ greatly in shape from those in the crest of the
female. The neck, wing-coverts, and loins in the male bird are properly
covered with hackles, and it would appear that feathers of this shape
have spread by correlation to the head of the male. This little fact is
interesting; because, though both sexes of some wild gallinaceous birds
have their heads similarly ornamented, yet there is often a difference
in the size and shape of feathers forming their crests. Furthermore,
there is in some cases, as in the male Gold and in the male Amherst
pheasants (_P. pictus_ and _amherstiæ_), a close relation in colour, as
well as in structure, between the plumes on the head and on the loins.
It would therefore appear that the same law has regulated the state of
the feathers on the head and body, both with species living under
natural conditions, and with birds which have varied under
domestication.

REFERENCES

 [1] I have drawn up this brief synopsis from various sources, but
 chiefly from information given me by Mr. Tegetmeier. This gentleman
 has kindly looked through this chapter; and from his well-known
 knowledge, the statements here given may be fully trusted. Mr.
 Tegetmeier has likewise assisted me in every possible way in obtaining
 for me information and specimens. I must not let this opportunity pass
 without expressing my cordial thanks to Mr. B. P. Brent, a well-known
 writer on poultry, for continuous assistance and the gift of many
 specimens.

 [2] The best account of Sultans is by Miss Watts in ‘The Poultry
 Yard,’ 1856, p. 79. I owe to Mr. Brent’s kindness the examination of
 some specimens of this breed.

 [3] A good description, with figures, is given of this sub-breed in
 the ‘Journal of Horticulture,’ June 10, 1862, p. 206.

 [4] A description, with figures, is given of this breed in ‘Journal of
 Horticulture,’ June 3, 1862, p. 186. Some writers describe the comb as
 two-horned.

 [5] Mr. Crawfurd ‘Descript. Dict. of the Indian Islands,’ p. 113.
 Bantams are mentioned in an ancient native Japanese Encyclopædia, as I
 am informed by Mr. Birch of the British Museum.

 [6] ‘Ornamental and Domestic Poultry,’ 1848.

 [7] ‘Ornamental and Domestic Poultry,’ 1848.

 [8] Ferguson’s ‘Illustrated Series of Rare and Prize Poultry,’ 1854,
 p. vi. Preface.

 [9] Rev. E. S. Dixon in his ‘Ornamental Poultry,’ p. 203, gives an
 account of Columella’s work.

 [10] Mr. Crawfurd ‘On the Relation of the Domesticated Animals to
 Civilization,’ separately printed, p. 6; first read before the Brit.
 Assoc. at Oxford 1860.

 [11] ‘Quadrupèdes du Paraguay,’ tom. ii. p. 324.

 [12] ‘Proc. Zoolog. Soc.,’ 1832, p. 151.

 [13] These feathers have been described by Dr. W. Marshall ‘Der
 Zoolog. Garten,’ April 1874, p. 124. I examined the feathers of some
 hybrids raised in the Zoological Gardens between the male _G.
 sonneratii_ and a red game-hen, and they exhibited the true character
 of those of _G. sonneratii,_ except that the horny laminæe were much
 smaller.

 [14] _See also_ an excellent letter on the Poultry of India, by Mr.
 Blyth, in ‘Gardener’s Chronicle,’ 1851, p. 619.

 [15] Mr. S. J. Salter, in ‘Natural History Review,’ April 1863, p.
 276.

 [16] _See also_ Mr. Layard’s paper in ‘Annals and Mag. of Nat.
 History,’ 2nd series, vol. xiv. p. 62.

 [17] _See also_ Mr. Crawfurd’s ‘Descriptive Dict. of the Indian
 Islands,’ 1856, p. 113.

 [18] Described by Mr. G. R. Gray, ‘Proc. Zoolog. Soc.,’ 1849, p. 62.

 [19] The passage from Marsden is given by Mr. Dixon in his ‘Poultry
 Book,’ p. 176. No ornithologist now ranks this bird as a distinct
 species.

 [20] ‘Coup-d’œeil général sur l’Inde Archipélagique,’ tom. iii. (1849)
 p. 177; _see also_ Mr. Blyth in ‘Indian Sporting Review,’ vol. ii. p.
 5, 1856.

 [21] Mr. Blyth, in ‘Annals and Mag. of Nat. Hist.,’ 2nd ser., vol. i.
 (1848), p. 455.

 [22] Crawfurd, ‘Desc. Dict. of Indian Islands,’ 1856, p. 112.

 [23] In Burmah, as I hear from Mr. Blyth, the wild and tame poultry
 constantly cross together, and irregular transitional forms may be
 seen.

 [24] Ibid. p. 113.

 [25] Mr. Jerdon, in the ‘Madras Journ. of Lit. and Science,’ vol.
 xxii. p. 2, speaking of _G. bankiva,_ says, “unquestionably the origin
 of most of the varieties of our common fowls.” For Mr. Blyth _see_ his
 excellent article in ‘Gardener’s Chron.,’ 1851, p. 619; and in ‘Annals
 and Mag. of Nat. Hist.,’ vol. xx., 1847, p. 388.

 [26] ‘Gardener’s Chronicle,’ 1851, p. 619.

 [27] I have consulted an eminent authority, Mr. Sclater, on this
 subject, and he thinks that I have not expressed myself too strongly.
 I am aware that one ancient author, Acosta, speaks of fowls as having
 inhabited S. America at the period of its discovery; and more
 recently, about 1795, Olivier de Serres speaks of wild fowls in the
 forests of Guiana; these were probably feral birds. Dr. Daniell tells
 me, he believes that fowls have become wild on the west coast of
 Equatorial Africa; they may, however, not be true fowls, but
 gallinaceous birds belonging to the genus Phasidus. The old voyager
 Barbut says that poultry are not natural to Guinea. Capt. W. Allen
 (‘Narrative of Niger Expedition,’ 1848, vol. ii. p. 42) describes wild
 fowls on Ilha dos Rollas, an island near St. Thomas’s on the west
 coast of Africa; the natives informed him that they had escaped from a
 vessel wrecked there many years ago; they were extremely wild and had
 “a cry quite different to that of the domestic fowl,” and their
 appearance was somewhat changed. Hence it is not a little doubtful,
 notwithstanding the statement of the natives, whether these birds
 really were fowls. That the fowl has become feral on several islands
 is certain. Mr. Fry, a very capable judge, informed Mr. Layard, in a
 letter, that the fowls which have run wild on Ascension “had nearly
 all got back to their primitive colours, red, and black cocks, and
 smoky-grey hens.” But unfortunately we do not know the colour of the
 poultry which were turned out. Fowls have become feral on the Nicobar
 Islands (Blyth in the ‘Indian Field,’ 1858, p. 62), and in the
 Ladrones (Anson’s Voyage). Those found in the Pellew Islands
 (Crawfurd) are believed to be feral; and lastly, it is asserted that
 they have become feral in New Zealand, but whether this is correct I
 know not.

 [28] Mr. Hewitt, in ‘The Poultry Book,’ by W. B. Tegetmeier, 1866, p.
 248.

 [29] ‘Journal of Horticulture,’ Jan. 14th, 1862, p. 325.

 [30] ‘Die Hühner- und Pfauenzucht,’ Ulm, 1827, s. 17. For Mr. Hewitt’s
 statement with respect to the white Silk fowl _see_ the ‘Poultry
 Book,’ by W. B. Tegetmeier, 1866, p. 222. I am indebted to Mr. Orton
 for a letter on the same subject.

 [31] Dixon ‘Ornamental and Domestic Poultry,’ p. 253, 324, 335. For
 game fowls, _see_ Ferguson on ‘Prize Poultry,’ p. 260.

 [32] ‘Poultry Chronicle,’ vol. ii. p. 71.

 [33] ‘Die vorgeschichtlichen Alterthümer,’ II. Theil, 1872, p. 5. Dr.
 Pickering, in his ‘Races of Man,’ 1850, p. 374, says that the head and
 neck of a fowl is carried in a Tribute-procession to Thoutmousis III.
 (1445 B.C.); but Mr. Birch of the British Museum doubts whether the
 figure can be identified as the head of a fowl. Some caution is
 necessary with reference to the absence of figures of the fowl on the
 ancient Egyptian monuments, on account of the strong and widely
 prevalent prejudice against this bird. I am informed by the Rev. S.
 Erhardt that on the east coast of Africa, from 4° to 6° south of the
 equator, most of the pagan tribes at the present day hold the fowl in
 aversion. The natives of the Pellew Islands would not eat the fowl nor
 will the Indians in some parts of S. America. For the ancient history
 of the fowl _ see also_ Volz ‘Beiträge zur Culturgeschichte,’ 1852, s.
 77; and Isid. Geoffroy St.-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. p.
 61. Mr. Crawfurd has given an admirable history of the fowl in his
 paper ‘On the Relation of Domesticated Animals to Civilisation,’ read
 before the Brit. Assoc. at Oxford in 1860, and since printed
 separately. I quote from him on the Greek poet Theognis, and on the
 Harpy Tomb described by Sir C. Fellowes. I quote from a letter of Mr.
 Blyth’s with respect to the Institutes of Manu.

 [34] ‘Ornamental and Domestic Poultry,’ 1847, p. 185; for passages
 translated from Columella, _see_ p. 312. For Golden Hamburghs _see_
 Albin’s ‘Natural History of Birds,’ 3 vols., with plates 1731-38.

 [35] ‘Ornamental and Domestic Poultry,’ p. 152.

 [36] Ferguson on ‘Rare Prize Poultry,’ p. 297. This writer, I am
 informed, cannot generally be trusted. He gives, however, figures and
 much information on eggs. _See_ pp. 34 and 235 on the eggs of the Game
 fowl.

 [37] _See_ ‘Poultry Book,’ by Mr. Tegetmeier, 1866, pp. 81 and 78.

 [38] ‘The Cottage Gardener,’ Oct. 1855, p. 13. On the thinness of the
 eggs of Game-fowls _see_ Mowbray on Poultry, 7th edit., p. 13.

 [39] My information, which is very far from perfect, on chickens in
 the down, is derived chiefly from Mr. Dixon’s ‘Ornamental and Domestic
 Poultry.’ Mr. B. P. Brent has also communicated to me many facts by
 letter, as has Mr. Tegetmeier. I will in each case mark my authority
 by the name within brackets. For the chickens of white Silk-fowls
 _see_ Tegetmeier’s ‘Poultry Book,’ 1866, p. 221.

 [40] As I hear from Mr. Tegetmeier; _see also_ ‘Proc. Zoolog. Soc.,’
 1856, p. 366. On the late development of the crest _ see_ ‘Poultry
 Chronicle,’ vol. ii. p. 132.

 [41] On these points, _see_ ‘Poultry Chronicle,’ vol. iii. p. 166; and
 Tegetmeier’s ‘Poultry Book,’ 1866, pp. 105 and 121.

 [42] Dixon, ‘Ornamental and Domestic Poultry,’ p. 273.

 [43] Ferguson on ‘Rare and Prize Poultry,’ p. 261.

 [44] Mowbray on Poultry, 7th edit., 1834, p. 13.

 [45] _See_ the full description of the varieties of the Game-breed in
 Tegetmeier’s ‘Poultry Book,’ 1866, p. 131. For Cuckoo Dorkings, p. 97.

 [46] Mr. Hewitt in Tegetmeier’s ‘Poultry Book,’ 1866, pp. 246 and 156.
 For hen-tailed game-cocks, _see_ p. 131.

 [47] ‘The Field,’ April 20th, 1861. The writer says he has seen
 half-a-dozen cocks thus sacrificed.

 [48] ‘Proceedings of Zoolog. Soc.,’ March 1861, p. 102. The engraving
 of the hen-tailed cock just alluded to was exhibited before the
 Society.

 [49] ‘The Field,’ April 20th, 1861.

 [50] I am much indebted to Mr. Brent for an account, with sketches, of
 all the variations of the comb known to him, and likewise with respect
 to the tail as presently to be given.

 [51] The ‘Poultry Book,’ by Tegetmeier, 1866, p. 234.

 [52] ‘Die Hühner-und Pfauenzucht,’ 1827, s. 11.

 [53] ‘Poultry Chronicle,’ vol. i. p. 595. Mr. Brent has informed me of
 the same fact. With respect to the position of the spurs in Dorkings
 _see_ ‘Cottage Gardener,’ Sept. 18th, 1860, p. 380.

 [54] Dixon, ‘Ornamental and Domestic Poultry,’ p. 320.

 [55] Mr. Tegetmeier informs me that Game hens have been found so
 combative, that it is now generally the practice to exhibit each hen
 in a separate pen.

 [56] ‘Naturgeschichte Deutschlands,’ Band iii. (1793), s. 339, 407.

 [57] On the Ornithology of Ceylon in ‘Annals and Mag. of Nat.
 History,’ 2nd series, vol. xiv. (1854), p. 63.

 [58] ‘Handbuch der vergleich. Anatomie,’ 1805, p. 85, note. Mr.
 Tegetmeier, who gives in ‘Proc. Zoolog. Soc.,’ Nov. 25th, 1856, a very
 interesting account of the skulls of Polish fowls, not knowing of
 Bechstein’s account, has disputed the accuracy of Blumenbach’s
 statement. For Bechstein _see_ ‘Naturgeschichte Deutschlands,’ Band
 iii. (1793), s. 399, note. I may add that at the first exhibition of
 Poultry at the Zoological Gardens in May, 1845, I saw some fowls,
 called Friezland fowls, of which the hens were crested, and the cocks
 furnished with a comb.

 [59] ‘Cottage Gardener,’ Jan. 3rd, 1860, p. 218.

 [60] Mr. Williams, in a paper read before the Dublin Nat. Hist. Soc.,
 quoted in ‘Cottage Gardener,’ 1856, p. 161.

 [61] ‘De l’Espèce,’ 1859, p. 442. For the occurrence of black-boned
 fowls in South America, _see_ Roulin in ‘Mém. de l’Acad. des
 Sciences,’ tom. vi. p. 351; and Azara, ‘Quadrupèdes du Paraguay,’ tom.
 ii. p. 324. A frizzled fowl sent to me from Madras had black bones.

 [62] Mr. Hewitt, in Tegetmeier’s ‘Poultry Book,’ 1866, p. 231.

 [63] Dr. Broca, in Brown-Séquard’s ‘Journal de Phys.,’ tom. ii. p.
 361.

 [64] Dixon’s ‘Ornamental Poultry,’ p. 325.

 [65] ‘Poultry Chronicle,’ vol. i. p. 485. Tegetmeier’s ‘Poultry Book,’
 1866, p. 41. On Cochins grazing, ibid., p. 46.

 [66] Ferguson on ‘Prize Poultry,’ p. 87.

 [67] Col. Sykes in ‘Proc. Zoolog. Soc.,’ 1832, p. 151. Dr. Hooker’s
 ‘Himalayan Journals,’ vol. i. p. 314.

 [68] _See_ Mr. Tegetmeier’s account with woodcuts of the skull of
 Polish fowls in ‘Proc. Zoolog. Soc.,’ Nov. 25th, 1856. For other
 references, _see_ Isid. Geoffroy Saint-Hilaire, ‘Hist. Gén. des
 Anomalies,’ tom. i. p. 287. M. C. Dareste suspects (‘Recherches sur
 les Conditions de la Vie,’ etc., Lille 1863, p. 36) that the
 protuberance is not formed by the frontal bones, but by the
 ossification of the dura mater.

 [69] ‘Naturgeschichte Deutschlands,’ Band iii. (1793), s. 400.

 [70] The ‘Field,’ May 11th, 1861. I have received communications to a
 similar effect from Messrs. Brent and Tegetmeier.

 [71] It appears that I have not correctly designated the several
 groups of vertebræ, for a great authority, Mr. W. K. Parker
 (‘Transact. Zoolog. Soc.,’ vol. v. p. 198), specifies 16 cervical, 4
 dorsal, 15 lumbar, and 6 caudal vertebræ in this genus. But I have
 used the same terms in all the following descriptions.

 [72] Macgillivray, ‘British Birds,’ vol. i. p. 25.

 [73] It may be well to explain how the calculation has been made for
 the third column. In _G. bankiva_ the leg-bones are to the wing-bones
 as 86 : 54, or as (neglecting decimals) 100 : 62;—in Cochins as 311 :
 162, or as 100 : 52;—in Dorkings as 557 : 248, or as 100 : 44; and so
 on for the other breeds. We thus get the series of 62, 52, 44 for the
 relative weights of the wing-bones in _G. bankiva,_ Cochins, Dorkings,
 etc. And now taking 100, instead of 62, for the weight of the
 wing-bones in _G. bankiva,_ we get, by another rule of three, 83 as
 the weight of the wing-bones in Cochins; 70 in the Dorkings; and so on
 for the remainder of the third column in the table.

 [74] Mr. Blyth (in ‘Annals and Mag. of Nat. Hist.,’ 2nd series, vol.
 i., 1848, p. 456) gives 3¼ pounds as the weight of a full-grown male
 _G. bankiva_; but from what I have seen of the skins and skeletons of
 various breeds, I cannot believe that my two specimens of _G. bankiva_
 could have weighed so much.

 [75] The third column is calculated on the same principle as explained
 in footnote 73 above.




CHAPTER VIII.
DUCK—GOOSE—PEACOCK—TURKEY—GUINEA-FOWL—CANARY-BIRD—GOLD-FISH—RIVER-BEES—
SILK-MOTHS.

DUCKS, SEVERAL BREEDS OF—PROGRESS OF DOMESTICATION—ORIGIN OF FROM THE
COMMON WILD-DUCK—DIFFERENCES IN THE DIFFERENT BREEDS—OSTEOLOGICAL
DIFFERENCES—EFFECTS OF USE AND DISUSE ON THE LIMB-BONES.

GOOSE, ANCIENTLY DOMESTICATED—LITTLE VARIATION OF—SEBASTOPOL BREED.

PEACOCK, ORIGIN OF BLACK-SHOULDERED BREED.

TURKEY,BREEDS OF—CROSSED WITH THE UNITED STATES SPECIES—EFFECTS OF
CLIMATE ON.

GUINEA-FOWL, CANARY-BIRD, GOLD-FISH, HIVE-BEES.

SILK-MOTHS, SPECIES AND BREEDS OF—ANCIENTLY DOMESTICATED—CARE IN THEIR
SELECTION—DIFFERENCES IN THE DIFFERENT RACES—IN THE EGG, CATERPILLAR,
AND COCOON STATES—INHERITANCE OF CHARACTERS—IMPERFECT WINGS—LOST
INSTINCTS—CORRELATED CHARACTERS.


I will, as in previous cases, first briefly describe the chief domestic
breeds of the duck:—

BREED 1. _Common Domestic Duck._—Varies much in colour and in
proportions, and differs in instincts and disposition from the wild
duck. There are several sub-breeds:—(1) The Aylesbury, of great size,
white, with pale-yellow beak and legs; abdominal dermal sack largely
developed. (2) The Rouen, of great size, coloured like the wild duck,
with green or mottled beak; dermal sack largely developed. (3) Tufted
Duck, with a large top-knot of fine downy feathers, supported on a
fleshy mass, with the skull perforated beneath. The top-knot in a duck
which I imported from Holland was two and a half inches in diameter.
(4) Labrador (or Canadian, or Buenos Ayres, or East Indian); plumage
entirely black; beak broader, relatively to its length, than in the
wild duck; eggs slightly tinted with black. This sub-breed perhaps
ought to be ranked as a breed; it includes two sub-varieties, one as
large as the common domestic duck, which I have kept alive, and the
other smaller and often capable of flight.[1] I presume it is this
latter sub-variety which has been described in France[2] as flying
well, being rather wild, and when cooked having the flavour of the wild
duck; nevertheless this sub-variety is polygamous, like other
domesticated ducks and unlike the wild duck. These black Labrador ducks
breed true; but a case is given by Dr. Turral of the French sub-variety
producing young with some white feathers on the head and neck, and with
an ochre-coloured patch on the breast.

BREED 2. _Hook-billed Duck._—This bird presents an extraordinary
appearance from the downward curvature of the beak. The head is often
tufted. The common colour is white, but some are coloured like wild
ducks. It is an ancient breed, having been noticed in 1676.[3] It shows
its prolonged domestication by almost incessantly laying eggs, like the
fowls which are called everlasting layers.[4]

BREED 3. _Call Duck._—Remarkable from its small size, and from the
extraordinary loquacity of the female. Beak short. These birds are
either white, or coloured like the wild duck.

BREED 4. _Penguin Duck._—This is the most remarkable of all the breeds,
and seems to have originated in the Malayan archipelago. It walks with
its body extremely erect, and with its thin neck stretched straight
upwards. Beak rather short. Tail upturned, including only 18 feathers.
Femur and metatarsus elongated.

Almost all naturalists admit that the several breeds are descended from
the common wild duck (_Anas boschas_); most fanciers, on the other
hand, take as usual a very different view.[5] Unless we deny that
domestication, prolonged during centuries, can affect even such
unimportant characters as colour, size, and in a slight degree
proportional dimensions and mental disposition, there is no reason
whatever to doubt that the domestic duck is descended from the common
wild species, for the one differs from the other in no important
character. We have some historical evidence with respect to the period
and progress of the domestication of the duck. It was unknown[6] to the
ancient Egyptians, to the Jews of the Old Testament, and to the Greeks
of the Homeric period. About eighteen centuries ago Columella[7] and
Varro speak of the necessity of keeping ducks in netted enclosures like
other wild fowl, so that at this period there was danger of their
flying away. Moreover, the plan recommended by Columella to those who
wish to increase their stock of ducks, namely, to collect the eggs of
the wild bird and to place them under a hen, shows, as Mr. Dixon
remarks, “that the duck had not at this time become a naturalised and
prolific inmate of the Roman poultry-yard.” The origin of the domestic
duck from the wild species is recognised in nearly every language of
Europe, as Aldrovandi long ago remarked, by the same name being applied
to both. The wild duck has a wide range from the Himalayas to North
America. It crosses readily with the domestic bird, and the crossed
offspring are perfectly fertile.

Both in North America and Europe the wild duck has been found easy to
tame and breed. In Sweden this experiment was carefully tried by
Tiburtius; he succeeded in rearing wild ducks for three generations,
but, though they were treated like common ducks, they did not vary even
in a single feather. The young birds suffered from being allowed to
swim about in cold water,[8] as is known to be the case, though the
fact is a strange one, with the young of the common domestic duck. An
accurate and well-known observer in England[9] has described in detail
his often repeated and successful experiments in domesticating the wild
duck. Young birds are easily reared from eggs hatched under a bantam;
but to succeed it is indispensable not to place the eggs of both the
wild and tame duck under the same hen, for in this case “the young wild
ducks die off, leaving their more hardy brethren in undisturbed
possession of their foster-mother’s care. The difference of habit at
the onset in the newly-hatched ducklings almost entails such a result
to a certainty.” The wild ducklings were from the first quite tame
towards those who took care of them as long as they wore the same
clothes, and likewise to the dogs and cats of the house. They would
even snap with their beaks at the dogs, and drive them away from any
spot which they coveted. But they were much alarmed at strange men and
dogs. Differently from what occurred in Sweden, Mr. Hewitt found that
his young birds always changed and deteriorated in character in the
course of two or three generations; notwithstanding that great care was
taken to prevent their crossing with tame ducks. After the third
generation his birds lost the elegant carriage of the wild species, and
began to acquire the gait of the common duck. They increased in size in
each generation, and their legs became less fine. The white collar
round the neck of the mallard became broader and less regular, and some
of the longer primary wing-feathers became more or less white. When
this occurred, Mr. Hewitt destroyed nearly the whole of his stock and
procured fresh eggs from wild nests; so that he never bred the same
family for more than five or six generations. His birds continued to
pair together, and never became polygamous like the common domestic
duck. I have given these details, because no other case, as far as I
know, has been so carefully recorded by a competent observer of the
progress of change in wild birds reared for several generations in a
domestic condition.

From these considerations there can hardly be a doubt that the wild
duck is the parent of the common domestic kind; nor need we look to
other species for the parentage of the more distinct breeds, namely,
Penguin, Call, Hook-billed, Tufted, and Labrador ducks. I will not
repeat the arguments used in the previous chapters on the improbability
of man having in ancient times domesticated several species since
become unknown or extinct, though ducks are not readily exterminated in
the wild state;—on some of the supposed parent-species having had
abnormal characters in comparison with all the other species of the
genus, as with Hook-billed and Penguin ducks;—on all the breeds, as far
as is known being fertile together;[10]—on all the breeds having the
same general disposition, instinct, etc. But one fact bearing on this
question may be noticed: in the great duck family, one species alone,
namely, the male of _A. boschas,_ has its four middle tail-feathers
curled upwardly; now in every one of the above-named domestic breeds
these curled feathers exist, and on the supposition that they are
descended from distinct species, we must assume that man formerly hit
upon species all of which had this now unique character. Moreover,
sub-varieties of each breed are coloured almost exactly like the wild
duck, as I have seen with the largest and smallest breeds, namely
Rouens and Call ducks, and, as Mr. Brent states,[11] is the case with
Hook-billed ducks. This gentleman, as he informs me, crossed a white
Aylesbury drake and a black Labrador duck, and some of the ducklings as
they grew up assumed the plumage of the wild duck.

With respect to Penguins, I have not seen many specimens, and none were
coloured precisely like the wild duck; but Sir James Brooke sent me
three skins from Lombok and Bali, in the Malayan archipelago; the two
females were paler and more rufous than the wild duck, and the drake
differed in having the whole under and upper surface (excepting the
neck, tail-coverts, tail, and wings) silver-grey, finely pencilled with
dark lines, closely like certain parts of the plumage of the wild
mallard. But I found this drake to be identical in every feather with a
variety of the common breed procured from a farm-yard in Kent, and I
have occasionally elsewhere seen similar specimens. The occurrence of a
duck bred under so peculiar a climate as that of the Malayan
archipelago, where the wild species does not exist, with exactly the
same plumage as may occasionally be seen in our farm-yards, is a fact
worth notice. Nevertheless the climate of the Malayan archipelago
apparently tends to cause the duck to vary much, for Zollinger,[12]
speaking of the Penguin breed, says that in Lombok “there is an unusual
and very wonderful variety of ducks.” One Penguin drake which I kept
alive differed from those of which the skins were sent me from Lombok,
in having its breast and back partially coloured with chestnut-brown,
thus more closely resembling the Mallard.

From these several facts, more especially from the drakes of all the
breeds having curled tail-feathers, and from certain sub-varieties in
each breed occasionally resembling in general plumage the wild duck, we
may conclude with confidence that all the breeds are descended from _A.
boschas._

I will now notice some of the peculiarities characteristic of the
several breeds. The eggs vary in colour; some common ducks laying
pale-greenish and others quite white eggs. The eggs which are first
laid during each season by the black Labrador duck, are tinted black,
as if rubbed with ink. A good observer assured me that one year his
ducks of this breed laid almost perfectly white eggs. Another curious
case shows what singular variations sometimes occur and are inherited;
Mr. Hansell[13] relates that he had a common duck which always laid
eggs with the yolk of a dark-brown colour like melted glue; and the
young ducks, hatched from these eggs, laid the same kind of eggs, so
that the breed had to be destroyed.

Illustration: Fig 39—Skulls of Ducks, viewed laterally.
A. Wild Duck. B. Hook-billed Duck.

The Hook-billed duck is highly remarkable (see fig. 39, of skull); and
its peculiar beak has been inherited at least since the year 1676. This
structure is evidently analogous with that described in the Bagadotten
carrier pigeon. Mr. Brent[14] says that, when Hook-billed ducks are
crossed with common ducks, “many young ones are produced with the upper
mandible shorter than the lower, which not unfrequently causes the
death of the bird.” With ducks a tuft of feathers on the head is by no
means a rare occurrence; namely, in the True-tufted breed, the
Hook-billed, the common farm-yard kind, and in a duck having no other
peculiarity which was sent to me from the Malayan archipelago. The tuft
is only so far interesting as it affects the skull, which is thus
rendered slightly more globular, and is perforated by numerous
apertures. Call ducks are remarkable from their extraordinary
loquacity: the drake only hisses like common drakes; nevertheless, when
paired with the common duck, he transmits to his female offspring a
strong quacking tendency. This loquacity seems at first a surprising
character to have been acquired under domestication. But the voice
varies in the different breeds; Mr. Brent[15] says that Hook-billed
ducks are very loquacious, and that Rouens utter a “dull, loud, and
monotonous cry, easily distinguishable by an experienced ear.” As the
loquacity of the Call duck is highly serviceable, these birds being
used in decoys, this quality may have been increased by selection. For
instance, Colonel Hawker says, if young wild ducks cannot be got for a
decoy, “by way of make-shift, _select_ tame birds which are the most
clamorous, even if their colour should not be like that of wild
ones.”[16] It has been erroneously asserted that Call ducks hatch their
eggs in less time than common ducks.[17]

The Penguin duck is the most remarkable of all the breeds; the thin
neck and body are carried erect; the wings are small; the tail is
upturned; and the thigh-bones and metatarsi are considerably lengthened
in proportion with the same bones in the wild duck. In five specimens
examined by me there were only eighteen tail-feathers instead of twenty
as in the wild duck; but I have also found only eighteen and nineteen
tail-feathers in two Labrador ducks. On the middle toe, in three
specimens, there were twenty-seven or twenty-eight scutellæ, whereas in
two wild ducks there were thirty-one and thirty-two. The Penguin when
crossed transmits with much power its peculiar form of body and gait to
its offspring; this was manifest with some hybrids raised in the
Zoological Gardens between one of these birds and the Egyptian
goose,[18] (_Anser ægyptiacus_) and likewise with some mongrels which I
raised between the Penguin and Labrador duck. I am not much surprised
that some writers should maintain that this breed must be descended
from an unknown and distinct species; but from the reasons already
assigned, it seems to me far more probable that it is the descendant,
much modified by domestication under an unnatural climate, of _Anas
boschas._

_Osteological Characters._—The skulls of the several breeds differ from
each other and from the skull of the wild duck in very little except in
the proportional length and curvature of the premaxillaries. These
latter bones in the Call duck are short, and a line drawn from their
extremities to the summit of the skull is nearly straight, instead of
being concave as in the common duck; so that the skull resembles that
of a small goose. In the Hook-billed duck (fig. 39), these same bones
as well as the lower jaw curve downwards in a most remarkable manner,
as represented. In the Labrador duck the premaxillaries are rather
broader than in the wild duck; and in two skulls of this breed the
vertical ridges on each side of the supra-occipital bone are very
prominent. In the Penguin the premaxillaries are relatively shorter
than in the wild duck; and the inferior points of the paramastoids more
prominent. In a Dutch tufted duck, the skull under the enormous tuft
was slightly more globular and was perforated by two large apertures;
in this skull the lachrymal bones were produced much further backwards,
so as to have a different shape and nearly to touch the post. lat.
processes of the frontal bones, thus almost completing the bony orbit
of the eye. As the quadrate and pterygoid bones are of such complex
shape and stand in relation with so many other bones, I carefully
compared them in all the principal breeds; but excepting in size they
presented no difference.

Illustration: Fig 40—Cervical Verterbræ of Ducks.

_Vertebræ and Ribs._—In one skeleton of the Labrador duck there were
the usual fifteen cervical vertebræ and the usual nine dorsal vertebræ
bearing ribs; in the other skeleton there were fifteen cervical and ten
dorsal vertebræ with ribs; nor, as far as could be judged, was this
owing merely to a rib having been developed on the first lumbar
vertebra; for in both skeletons the lumbar vertebræ agreed perfectly in
number, shape, and size with those of the wild duck. In two skeletons
of the Call duck there were fifteen cervical and nine dorsal vertebræ;
in a third skeleton small ribs were attached to the so-called fifteenth
cervical vertebra, making ten pairs of ribs; but these ten ribs do not
correspond, or arise from the same vertebra, with the ten in the
above-mentioned Labrador duck. In the Call duck, which had small ribs
attached to the fifteenth cervical vertebra, the hæmal spines of the
thirteenth and fourteenth (cervical) and of the seventeenth (dorsal)
vertebræ corresponded with the spines on the fourteenth, fifteenth, and
eighteenth vertebræ of the wild duck: so that each of these vertebræ
had acquired a structure proper to one posterior to it in position. In
the eighth cervical vertebra of this same Call duck (fig. 40, B), the
two branches of the hæmal spine stand much closer together than in the
wild duck (A), and the descending hæmal processes are much shortened.
In the Penguin duck the neck from its thinness and erectness falsely
appears (as ascertained by measurement) to be much elongated, but the
cervical and dorsal vertebræ present no difference; the posterior
dorsal vertebræ, however, are more completely anchylosed to the pelvis
than in the wild duck. The Aylesbury duck has fifteen cervical and ten
dorsal vertebræ furnished with ribs, but the same number of lumbar,
sacral, and caudal vertebræ, as far as could be traced, as in the wild
duck. The cervical vertebræ in this same duck (fig. 40, D) were much
broader and thicker relatively to their length than in the wild (C); so
much so, that I have thought it worth while to give a sketch of the
twelfth cervical vertebra in these two birds. From the foregoing
statements we see that the fifteenth cervical vertebra occasionally
becomes modified into a dorsal vertebra, and when this occurs all the
adjoining vertebræ are modified. We also see that an additional dorsal
vertebra bearing a rib is occasionally developed, the number of the
cervical and lumbar vertebræ apparently remaining the same as usual.

I examined the bony enlargement of the trachea in the males of the
Penguin, Call, Hook-billed, Labrador, and Aylesbury breeds; and in all
it was identical in shape.

The _pelvis_ is remarkably uniform; but in the skeleton of the
Hook-billed duck the anterior part is much bowed inwards; in the
Aylesbury and some other breeds the ischiadic foramen is less
elongated. In the sternum, furculum, coracoids, and scapulæ, the
differences are so slight and so variable as not to be worth notice,
except that in two skeletons of the Penguin duck the terminal portion
of the scapula was much attenuated.

In the bones of the leg and wing no modification in shape could be
observed. But in the Penguin and Hook-billed ducks, the terminal
phalanges of the wing are a little shortened. In the former, the femur,
and metatarsus (but not the tibia) are considerably lengthened,
relatively to the same bones in the wild duck, and to the wing-bones in
both birds. This elongation of the leg-bones could be seen whilst the
bird was alive, and is no doubt connected with its peculiar upright
manner of walking. In a large Aylesbury duck, on the other hand, the
tibia was the only bone of the leg which relatively to the other bones
was slightly lengthened.

_On the effects of the increased and decreased Use of the Limbs._—In
all the breeds the bones of the wing (measured separately after having
been cleaned) relatively to those of the leg have become slightly
shortened, in comparison with the same bones in the wild duck, as may
be seen in Table I.

Table I

Name of Breed     Length of Femur,
          Tibia, and Meta-
          tarsus together     Length of Humerus,
          Radius, and Meta-
          carpus together     Or as Inches     Inches Wild
          mallard     7·14       9·28     100 : 129
          Aylesbury     8·64     10·43     100 : 120 Tufted
          (Dutch)     8·25       9·83     100 : 119 Penguin     7·12      
          8·78     100 : 123 Call     6·20       7·77     100 : 125 Length
          of same
          Bones     Length of all the
          Bones of Wing Inches     Inches Wild duck (another
          specimen)     6·85     10·07     100 : 147 Common domestic
          duck     8·15     11·26     100 : 138

In Table I we see, by comparison with the wild duck, that the reduction
in the length of the bones of the wing, relatively to those of the
legs, though slight, is universal. The reduction is least in the Call
duck, which has the power and the habit of frequently flying.

In weight there is a greater relative difference between the bones of
the leg and wing, as may be seen in Table II:—

Table II

Name of Breed     Weight of Femur,
          Tibia, and
          Metatarsus     Weight of
          Humerus, Radius,
          and Metacarpus     Or as Grains     Grains Wild mallard      
          54       97     100 : 179 Aylesbury     164     204     100 : 124
          Hooked-bill     107     160     100 : 149 Tufted
          (Dutch)     111     148     100 : 133 Penguin       75
          90.5     100 : 120 Labrador     141     165     100 : 117
          Call       57       93     100 : 163 Weight of all the
          Bones of the
          Leg and Foot     Weight of all the
          Bones of the
          Wing Grains     Grains Wild (another specimen)      
          66     115     100 : 173 Common domestic
          duck     127     158     100 : 124

In these domesticated birds, the considerably lessened weight of the
bones of the wing (_i.e._ on an average, twenty-five per cent of their
proper proportional weight), as well as their slightly lessened length,
relatively to the leg-bones, might follow, not from any actual decrease
in the wing-bones, but from the increased weight and length of the
bones of the legs. Table IIIa shows that the leg-bones relatively to
the weight of the entire skeleton have really increased in weight; but
Table IIIb shows that according to the same standard the wing-bones
have also really decreased in weight; so that the relative
disproportion shown in the foregoing tables between the wing and
leg-bones, in comparison with those of the wild duck, is partly due to
the increase in weight and length of the leg-bones, and partly to the
decrease in weight and length of the wing-bones.

Table III

Name of Breed     Weight of entire
          Skeleton.
          (N.B. One Metatarsus
          and Foot was
          removed from each
          skeleton, as it had
          been accidentally lost
          in two cases.)     Weight of
          Femur,
          Tibia, and
          Metatarsus     Or as Grains     Grains Wild mallard      
          839       54     1000 : 64 Aylesbury     1925     164     1000 :
          85 Tufted (Dutch)     1404     111     1000 : 79 Penguin      
          871       75     1000 : 86 Call (from Mr. Fox)       717      
          57     1000 : 79 Weight of Skeleton
          as above.     Weight of
          Humerus,
          Radius and
          Metacarpus. Grains     Grains Wild mallard       839      
          97     1000 : 115 Aylesbury     1925     204     1000 : 105
          Tufted (Dutch)     1404     148     1000 : 105 Penguin      
          871       90     1000 : 103 Call (from Mr. Baker)      
          914     100     1000 : 109 Call (from Mr. Fox)       717      
          92     1000 : 129

With respect to Table III, I may first state that I tested them by
taking another skeleton of a wild duck and of a common domestic duck,
and by comparing the weight of _ all_ the bones of the leg with _all_
those of the wings, and the result was the same. In the first of these
tables we see that the leg-bones in each case have increased in actual
weight. It might have been expected that, with the increased or
decreased weight of the entire skeleton, the leg-bones would have
become proportionally heavier or lighter; but their greater weight in
all the breeds relatively to the other bones can be accounted for only
by these domestic birds having used their legs in walking and standing
much more than the wild, for they never fly, and the more artificial
breeds rarely swim. In the second table we see, with the exception of
one case, a plain reduction in the weight of the bones of the wing, and
this no doubt has resulted from their lessened use. The one exceptional
case, namely, in one of the Call ducks, is in truth no exception, for
this bird was constantly in the habit of flying about; and I have seen
it day after day rise from my grounds, and fly for a long time in
circles of more than a mile in diameter. In this Call duck there is not
only no decrease, but an actual increase in the weight of the
wing-bones relatively to those of the wild-duck; and this probably is
consequent on the remarkable lightness and thinness of all the bones of
the skeleton.

Lastly, I weighed the furculum, coracoids, and scapula of a wild duck
and of a common domestic duck, and I found that their weight,
relatively to that of the whole skeleton, was as one hundred in the
former to eighty-nine in the latter; this shows that these bones in the
domestic duck have been reduced eleven per cent of their due
proportional weight. The prominence of the crest of the sternum,
relatively to its length, is also much reduced in all the domestic
breeds. These changes have evidently been caused by the lessened use of
the wings.

It is well known that several birds, belonging to different Orders, and
inhabiting oceanic islands, have their wings greatly reduced in size
and are incapable of flight. I suggested in my ‘Origin of Species’
that, as these birds are not persecuted by any enemies, the reduction
of their wings had probably been caused by gradual disuse. Hence,
during the earlier stages of the process of reduction, such birds would
probably have resembled our domesticated ducks in the state of their
organs of flight. This is the case with the water-hen (_Gallinula
nesiotis_) of Tristan d’Acunha, which “can flutter a little, but
obviously uses its legs, and not its wings, as a mode of escape.” Now
Mr. Sclater[19] finds in this bird that the wings, sternum, and
coracoids are all reduced in length, and the crest of the sternum in
depth, in comparison with the same bones in the European water-hen (_G.
chloropus_). On the other hand, the thigh-bones and pelvis are
increased in length, the former by four lines, relatively to the same
bones in the common water-hen. Hence in the skeleton of this natural
species nearly the same changes have occurred, only carried a little
further, as with our domestic ducks, and in this latter case I presume
no one will dispute that they have resulted from the lessened use of
the wings and the increased use of the legs.

THE GOOSE.

This bird deserves some notice, as hardly any other anciently
domesticated bird or quadruped has varied so little. That geese were
anciently domesticated we know from certain verses in Homer; and from
these birds having been kept (388 B.C.) in the Capitol at Rome as
sacred to Juno, which sacredness implies great antiquity.[20] That the
goose has varied in some degree, we may infer from naturalists not
being unanimous with respect to its wild parent-form; though the
difficulty is chiefly due to the existence of three or four closely
allied wild European species.[21] A large majority of capable judges
are convinced that our geese are descended from the wild Grey-leg goose
(_A. ferus_); the young of which can easily be tamed.[22] This species,
when crossed with the domestic goose, produced in the Zoological
Gardens, as I was assured in 1849, perfectly fertile offspring.[23]
Yarrell[24] has observed that the lower part of the trachea of the
domestic goose is sometimes flattened, and that a ring of white
feathers sometimes surrounds the base of the beak. These characters
seem at first sight good indications of a cross at some former period
with the white-fronted goose (_A. albifrons_); but the white ring is
variable in this latter species, and we must not overlook the law of
analogous variation; that is, of one species assuming some of the
characters of allied species.

As the goose has proved so little flexible in its organisation under
long-continued domestication, the amount of variation which it has
undergone may be worth giving. It has increased in size and in
productiveness;[25] and varies from white to a dusky colour. Several
observers[26] have stated that the gander is more frequently white than
the goose, and that when old it almost invariably becomes white; but
this is not the case with the parent-form, the _A. ferus._ Here, again,
the law of analogous variation may have come into play, as the almost
snow-white male of the Rock goose (_Bernicla antarctica_) standing on
the sea-shore by his dusky partner is a sight well known to those who
have traversed the sounds of Tierra del Fuego and the Falkland Islands.
Some geese have top-knots; and the skull beneath, as before stated, is
perforated. A sub-breed has lately been formed with the feathers
reversed at the back of the head and neck.[27] The beak varies a little
in size, and is of a yellower tint than in the wild species; but its
colour and that of the legs are both slightly variable.[28] This latter
fact deserves attention, because the colour of the legs and beak is
highly serviceable in discriminating the several closely allied wild
forms.[29] At our Shows two breeds are exhibited; viz., the Embden and
Toulouse; but they differ in nothing except colour.[30] Recently a
smaller and singular variety has been imported from Sebastopol,[31]
with the scapular feathers (as I hear from Mr. Tegetmeier, who sent me
specimens) greatly elongated, curled, and even spirally twisted. The
margins of these feathers are rendered plumose by the divergence of the
barbs and barbules, so that they resemble in some degree those on the
back of the black Australian swan. These feathers are likewise
remarkable from the central shaft, which is excessively thin and
transparent, being split into fine filaments, which, after running for
a space free, sometimes coalesce again. It is a curious fact that these
filaments are regularly clothed on each side with fine down or
barbules, precisely like those on the proper barbs of the feather. This
structure of the feathers is transmitted to half-bred birds. In _
Gallus sonneratii_ the barbs and barbules blend together, and form thin
horny plates of the same nature with the shaft: in this variety of the
goose, the shaft divides into filaments which acquire barbules, and
thus resemble true barbs.

Although the domestic goose certainly differs somewhat from any known
wild species, yet the amount of variation which it has undergone, as
compared with that of most domesticated animals, is singularly small.
This fact can be partially accounted for by selection not having come
largely into play. Birds of all kinds which present many distinct races
are valued as pets or ornaments; no one makes a pet of the goose; the
name, indeed, in more languages than one, is a term of reproach. The
goose is valued for its size and flavour, for the whiteness of its
feathers which adds to their value, and for its prolificness and
tameness. In all these points the goose differs from the wild
parent-form; and these are the points which have been selected. Even in
ancient times the Roman gourmands valued the liver of the _white_
goose; and Pierre Belon[32] in 1555 speaks of two varieties, one of
which was larger, more fecund, and of a better colour than the other;
and he expressly states that good managers attended to the colour of
their goslings, so that they might know which to preserve and select
for breeding.

THE PEACOCK.

This is another bird which has hardly varied under domestication,
except in sometimes being white or piebald. Mr. Waterhouse carefully
compared, as he informs me, skins of the wild Indian and domestic bird,
and they were identical in every respect, except that the plumage of
the latter was perhaps rather thicker. Whether our birds are descended
from those introduced into Europe in the time of Alexander, or have
been subsequently imported, is doubtful. They do not breed very freely
with us, and are seldom kept in large numbers,—circumstances which
would greatly interfere with the gradual selection and formation of new
breeds. There is one strange fact with respect to the peacock, namely,
the occasional appearance in England of the “japanned” or
“black-shouldered” kind. This form has lately been named on the high
authority of Mr. Sclater as a distinct species, viz. _Pavo
nigripennis,_ which he believes will hereafter be found wild in some
country, but not in India, where it is certainly unknown. The males of
these japanned birds differ conspicuously from the common peacock in
the colour of their secondary wing-feathers, scapulars, wing-coverts,
and thighs, and are I think more beautiful; they are rather smaller
than the common sort, and are always beaten by them in their battles,
as I hear from the Hon. A. S. G. Canning. The females are much paler
coloured than those of the common kind. Both sexes, as Mr. Canning
informs me, are white when they leave the egg, and they differ from the
young of the white variety only in having a peculiar pinkish tinge on
their wings. These japanned birds, though appearing suddenly in flocks
of the common kind, propagate their kind quite truly. Although they do
not resemble the hybrids which have been raised between _P. cristatus_
and _ muticus,_ nevertheless they are in some respects intermediate in
character between these two species; and this fact favours, as Mr.
Sclater believes, the view that they form a distinct and natural
species.[33]

On the other hand, Sir H. Heron states[34] that this breed suddenly
appeared within his memory in Lord Brownlow’s large stock of pied,
white, and common peacocks. The same thing occurred in Sir J.
Trevelyan’s flock composed entirely of the common kind, and in Mr.
Thornton’s stock of common and pied peacocks. It is remarkable that in
these two latter instances the black-shouldered kind, though a smaller
and weaker bird, increased, “to the extinction of the previously
existing breed.” I have also received through Mr. Sclater a statement
from Mr. Hudson Gurney that he reared many years ago a pair of
black-shouldered peacocks from the common kind; and another
ornithologist, Prof. A. Newton, states that, five or six years ago, a
female bird, in all respects similar to the female of the
black-shouldered kind, was produced from a stock of common peacocks in
his possession, which during more than twenty years had not been
crossed with birds of any other strain. Mr. Jenner Weir informs me that
a peacock at Blackheath whilst young was white, but as it became older
gradually assumed the characters of the black-shouldered variety; both
its parents were common peacocks. Lastly, Mr. Canning has given a case
of a female of this same variety appearing in Ireland in a flock of the
ordinary kind.[35] Here, then, we have seven well authenticated cases
in Great Britain of japanned birds, having suddenly appeared within
recent times in flocks of the common peafowl. This variety must also
have formerly appeared in Europe, for Mr. Canning has seen an old
picture, and another is referred to in the ‘Field,’ with this variety
represented. These facts seem to me to indicate that the japanned
peacock is a strongly marked variety or “sport,” which tends at all
times and in many places to reappear. This view is supported by the
young being at first white like the young of the white breed, which is
undoubtedly a variation. If, on the other hand, we believe the japanned
peacock to be a distinct species, we must suppose that in all the above
cases the common breed had at some former period been crossed by it,
but had lost every trace of the cross; yet that the offspring of these
birds suddenly and completely reacquired through reversion the
characters of _P. nigripennis._ I have heard of no other such case in
the animal or vegetable kingdom. To perceive the full improbability of
such an occurrence, we may suppose that a breed of dogs had been
crossed at some former period with a wolf, but had lost every trace of
the wolf-like character, yet that the breed gave birth in seven
instances in the same country, within no great length of time, to a
wolf perfect in every character; and we must further suppose that in
two of the cases, the newly produced wolves afterwards spontaneously
increased to such an extent as to lead to the extinction of the parent
breed of dogs. So remarkable a bird as the _P. nigripennis,_ when first
imported, would have realised a large price; it is therefore improbable
that it should have been silently introduced and its history
subsequently lost. On the whole the evidence seems to me, as it did to
Sir R. Heron, to be decisive in favour of the japanned or
black-shouldered breed being a variation, induced by some unknown
cause. On this view, the case is the most remarkable one ever recorded
of the abrupt appearance of a new form, which so closely resembles a
true species that it has deceived one of the most experienced of living
ornithologists.

THE TURKEY.

It seems fairly well established by Mr. Gould,[36] that the turkey, in
accordance with the history of its first introduction, is descended
from a wild Mexican form, which had been domesticated by the natives
before the discovery of America, and which is now generally ranked as a
local race, and not as a distinct species. However this may be, the
case deserves notice because in the United States wild male turkeys
sometimes court the domestic hens, which are descended from the Mexican
form, “and are generally received by them with great pleasure.”[37]
Several accounts have likewise been published of young birds, reared in
the United States from the eggs of the wild species, crossing and
commingling with the common breed. In England, also, this same species
has been kept in several parks; from two of which the Rev. W. D. Fox
procured birds, and they crossed freely with the common domestic kind,
and during many years afterwards, as he informs me, the turkeys in his
neighbourhood clearly showed traces of their crossed parentage. We here
have an instance of a domestic race being modified by a cross with a
distinct wild race or species. F. Michaux[38] suspected in 1802 that
the common domestic turkey was not descended from the United States
species alone, but likewise from a southern form, and he went so far as
to believe that English and French turkeys differed from having
different proportions of the blood of the two parent-forms.

English turkeys are smaller than either wild form. They have not varied
in any great degree; but there are some breeds which can be
distinguished as Norfolks, Suffolks, Whites, and Copper-coloured (or
Cambridge), all of which, if precluded from crossing with other breeds
propagate their kind truly. Of these kinds, the most distinct is the
small, hardy, dull-black Norfolk turkey, of which the chickens are
black, occasionally with white patches about the head. The other breeds
scarcely differ except in colour, and their chickens are generally
mottled all over with brownish-grey.[39] The inferior tail-coverts vary
in number, and according to a German superstition the hen lays as many
eggs as the cock has feathers of this kind.[40] Albin in 1738, and
Temminck within a much later period, describe a beautiful breed,
dusky-yellowish, brown above and white beneath, with a large top-knot
of soft plumose feather. The spurs of the male were rudimentary. This
breed has been for a long time extinct in Europe; but a living specimen
has lately been imported from the east coast of Africa, which still
retains the top-knot and the same general colouring and rudimentary
spurs.[41] Mr. Wilmot has described[42] a white turkey-cock having a
crest formed of “feathers about four inches long, with bare quills, and
a tuft of soft white down growing at the end.” Many of the young birds
inherited this kind of crest, but afterwards it fell off or was pecked
out by the other birds. This is an interesting case, as with care a new
breed might probably have been formed; and a top-knot of this nature
would have been to a certain extent analogous to that borne by the
males in several allied genera, such as Euplocomus, Lophophorus, and
Pavo.

Wild turkeys, believed in every instance to have been imported from the
United States, have been kept in the parks of Lords Powis, Leicester,
Hill, and Derby. The Rev. W. D. Fox procured birds from the two
first-named parks, and he informs me that they certainly differed a
little from each other in the shape of their bodies and in the barred
plumage on their wings. These birds likewise differed from Lord Hill’s
stock. Some of the latter kept at Oulton by Sir P. Egerton, though
precluded from crossing with common turkeys, occasionally produced much
paler-coloured birds, and one that was almost white, but not an albino.
These half-wild turkeys, in thus differing slightly from each other,
present an analogous case with the wild cattle kept in the several
British parks. We must suppose that such differences have resulted from
the prevention of free intercrossing between birds ranging over a wide
area, and from the changed conditions to which they have been exposed
in England. In India the climate has apparently wrought a still greater
change in the turkey, for it is described by Mr. Blyth[43] as being
much degenerated in size, “utterly incapable of rising on the wing,” of
a black colour, and “with the long pendulous appendages over the beak
enormously developed.”

THE GUINEA FOWL.

The domesticated Guinea fowl is now believed by some naturalists to be
descended from the _Numida ptilorhynca,_ which inhabits very hot, and,
in parts, extremely arid districts in Eastern Africa; consequently it
has been exposed in this country to extremely different conditions of
life. Nevertheless it has hardly varied at all, except in the plumage
being either paler or darker-coloured. It is a singular fact that this
bird varies more in colour in the West Indies and on the Spanish Main,
under a hot though humid climate, than in Europe.[44] The Guinea fowl
has become thoroughly feral in Jamaica and in St. Domingo,[45] and has
diminished in size; the legs are black, whereas the legs of the
aboriginal African bird are said to be grey. This small change is worth
notice on account of the often-repeated statement that all feral
animals invariably revert in every character to their original type.

THE CANARY BIRD.

As this bird has been recently domesticated, namely, within the last
350 years, its variability deserves notice. It has been crossed with
nine or ten other species of Fringillidæ, and some of the hybrids are
almost completely fertile; but we have no evidence that any distinct
breed has originated from such crosses. Notwithstanding the modern
domestication of the canary, many varieties have been produced; even
before the year 1718 a list of twenty-seven varieties was published in
France,[46] and in 1779 a long schedule of the desired qualities was
printed by the London Canary Society, so that methodical selection has
been practised during a considerable period. The greater number of the
varieties differ only in colour and in the markings of their plumage.
Some breeds however, differ in shape, such as the hooped or bowed
canaries, and the Belgian canaries with their much elongated bodies.
Mr. Brent[47] measured one of the latter and found it eight inches in
length, whilst the wild canary is only five and a quarter inches long.
There are top-knotted canaries, and it is a singular fact that, if two
top-knotted birds are matched, the young, instead of having very fine
top-knots, are generally bald, or even have a wound on their heads.[48]
It would appear as if the top-knot were due to some morbid condition,
which is increased to an injurious degree when two birds in this state
are paired. There is a feather-footed breed, and another with a kind of
frill running down the breast. One other character deserves notice from
being confined to one period of life, and from being strictly inherited
at the same period; namely, the wing and tail feathers in prize
canaries being black, “but this colour is retained only until the first
moult; once moulted, the peculiarity ceases.”[49] Canaries differ much
in disposition and character, and in some small degree in song. They
produce eggs three or four times during the year.

GOLD-FISH.

Besides mammals and birds, only a few animals belonging to the other
great classes have been domesticated; but to show that it is an almost
universal law that animals, when removed from their natural conditions
of life, vary, and that races can be formed when selection is applied,
it is necessary to say a few words on gold-fish, bees, and silk-moths.

Gold-fish (_Cyprinus auratus_) were introduced into Europe only two or
three centuries ago; but they have been kept in confinement from an
ancient period in China. Mr. Blyth[50] suspects, from the analogous
variation of other fishes, that golden-coloured fish do not occur in a
state of nature. These fishes frequently live under the most unnatural
conditions, and their variability in colour, size, and in some
important points of structure is very great. M. Sauvigny has described
and given coloured drawings of no less than eighty-nine varieties.[51]
Many of the varieties, however, such as triple tail-fins, etc., ought
to be called monstrosities; but it is difficult to draw any distinct
line between a variation and a monstrosity. As gold-fish are kept for
ornament or curiosity, and as “the Chinese are just the people to have
secluded a chance variety of any kind, and to have matched and paired
from it,”[52] it might have been predicted that selection would have
been largely practised in the formation of new breeds; and this is the
case. In an old Chinese work it is said that fish with vermilion scales
were first raised in confinement during the Sung dynasty (which
commenced A.D. 960), “and now they are cultivated in families
everywhere for the sake of ornament.” In another and more ancient work,
it is said that “there is not a household where the gold-fish is not
cultivated, in _rivalry_ as to its colour, and as a source of profit,”
etc.[53] Although many breeds exist, it is a singular fact that the
variations are often not inherited. Sir R. Heron[54] kept many of these
fishes, and placed all the deformed ones, namely, those destitute of
dorsal fins and those furnished with a double anal fin, or triple tail,
in a pond by themselves; but they did “not produce a greater proportion
of deformed offspring than the perfect fishes.”

Passing over an almost infinite diversity of colour, we meet with the
most extraordinary modifications of structure. Thus, out of about two
dozen specimens bought in London, Mr. Yarrell observed some with the
dorsal fin extending along more than half the length of the back:
others with this fin reduced to only five or six rays: and one with no
dorsal fin. The anal fins are sometimes double, and the tail is often
triple. This latter deviation of structure seems generally to occur “at
the expense of the whole or part of some other fin;”[55] but Bory de
Saint-Vincent[56] saw at Madrid gold-fish furnished with a dorsal fin
and a triple tail. One variety is characterised by a hump on its back
near the head; and the Rev. L. Jenyns[57] has described a most singular
variety, imported from China, almost globular in form like a Diodon,
with “the fleshy part of the tail as if entirely cut away? the caudal
fin being set on a little behind the dorsal and immediately above the
anal.” In this fish the anal and caudal fins were double; the anal fin
being attached to the body in a vertical line: the eyes also were
enormously large and protuberant.

HIVE-BEES.

Bees have been domesticated from an ancient period; if indeed their
state can be considered one of domestication, for they search for their
own food, with the exception of a little generally given to them during
the winter. Their habitation is a hive instead of a hole in a tree.
Bees, however, have been transported into almost every quarter of the
world, so that climate ought to have produced whatever direct effect it
is capable of producing. It is frequently asserted that the bees in
different parts of Great Britain differ in size, colour, and temper;
and Godron[58] says that they are generally larger in the south than in
other parts of France; it has also been asserted that the little brown
bees of High Burgundy, when transported to La Bresse become large and
yellow in the second generation. But these statements require
confirmation. As far as size is concerned, it is known that bees
produced in very old combs are smaller, owing to the cells having
become smaller from the successive old cocoons. The best
authorities[59] concur that, with the exception of the Ligurian race or
species, presently to be mentioned, distinct breeds do not exist in
Britain or on the Continent. There is, however, even in the same stock,
some variability in colour. Thus, Mr. Woodbury states,[60] that he has
several times seen queen bees of the common kind annulated with
yellow-like Ligurian queens, and the latter dark-coloured like common
bees. He has also observed variations in the colour of the drones,
without any corresponding difference in the queens or workers of the
same hive. The great apiarian, Dzierzon, in answer to my queries on
this subject, says,[61] that in Germany bees of some stocks are
decidedly dark, whilst others are remarkable for their yellow colour.
Bees also seem to differ in habits in different districts, for Dzierzon
adds, “If many stocks with their offspring are more inclined to swarm,
whilst others are richer in honey, so that some bee-keepers even
distinguish between swarming and honey-gathering bees, this is a habit
which has become second nature, caused by the customary mode of keeping
the bees and the pasturage of the district. For example, what a
difference in this respect one may perceive to exist between the bees
of the Luneburg heath and those of this country!” . . . “Removing an
old queen and substituting a young one of the current year is here an
infallible mode of keeping the strongest stock from swarming and
preventing drone-breeding; whilst the same means if adopted in Hanover
would certainly be of no avail.” I procured a hive full of dead bees
from Jamaica, where they have long been naturalised, and, on carefully
comparing them under the microscope with my own bees, I could detect
not a trace of difference.

This remarkable uniformity in the hive-bee, wherever kept, may probably
be accounted for by the great difficulty, or rather impossibility, of
bringing selection into play by pairing particular queens and drones,
for these insects unite only during flight. Nor is there any record,
with a single partial exception, of any person having separated and
bred from a hive in which the workers presented some appreciable
difference. In order to form a new breed, seclusion from other bees
would, as we now know, be indispensable; for since the introduction of
the Ligurian bee into Germany and England, it has been found that the
drones wander at least two miles from their own hives, and often cross
with the queens of the common bee.[62] The Ligurian bee, although
perfectly fertile when crossed with the common kind, is ranked by most
naturalists as a distinct species, whilst by others it is ranked as a
variety: but this form need not here be noticed, as there is no reason
to believe that it is the product of domestication. The Egyptian and
some other bees are likewise ranked by Dr. Gerstäcker,[63] but not by
other highly competent judges, as geographical races; he grounds his
conclusion in chief part on the fact that in certain districts, as in
the Crimea and Rhodes, they vary so much in colour, that the several
geographical races can be closely connected by intermediate forms.

I have alluded to a single instance of the separation and preservation
of a particular stock of bees. Mr. Lowe[64] procured some bees from a
cottager a few miles from Edinburgh, and perceived that they differed
from the common bee in the hairs on the head and thorax being lighter
coloured and more profuse in quantity. From the date of the
introduction of the Ligurian bee into Great Britain we may feel sure
that these bees had not been crossed with this form. Mr. Lowe
propagated this variety, but unfortunately did not separate the stock
from his other bees, and after three generations the new character was
almost completely lost. Nevertheless, as he adds, “a great number of
the bees still retain traces, though faint, of the original colony.”
This case shows us what could probably be effected by careful and
long-continued selection applied exclusively to the workers, for, as we
have seen, queens and drones cannot be selected and paired.

SILK-MOTHS.

These insects are in several respects interesting to us, more
especially because they have varied largely at an early period of life,
and the variations have been inherited at corresponding periods. As the
value of the silk-moth depends entirely on the cocoon, every change in
its structure and qualities has been carefully attended to, and races
differing much in the cocoon, but hardly at all in the adult state,
have been produced. With the races of most other domestic animals, the
young resemble each other closely, whilst the adults differ much.

It would be useless, even if it were possible, to describe all the many
kinds of silkworms. Several distinct species exist in India and China
which produce useful silk, and some of these are capable of freely
crossing with the common silk-moth, as has been recently ascertained in
France. Captain Hutton[65] states that throughout the world at least
six species have been domesticated; and he believes that the silk-moths
reared in Europe belong to two or three species. This, however, is not
the opinion of several capable judges who have particularly attended to
the cultivation of this insect in France; and hardly accords with some
facts presently to be given.

The common silk-moth (_Bombyx mori_) was brought to Constantinople in
the sixth century, whence it was carried into Italy, and in 1494 into
France.[66] Everything has been favourable for the variation of this
insect. It is believed to have been domesticated in China as long ago
as 2700 B.C. It has been kept under unnatural and diversified
conditions of life, and has been transported into many countries. There
is reason to believe that the nature of the food given to the
caterpillar influences to a certain extent the character of the
breed.[67] Disuse has apparently aided in checking the development of
the wings. But the most important element in the production of the many
now existing, much modified races, no doubt has been the close
attention which has long been applied in many countries to every
promising variation. The care taken in Europe in the selection of the
best cocoons and moths for breeding is notorious,[68] and the
production of eggs is followed as a distinct trade in parts of France.
I have made inquiries through Dr. Falconer, and am assured that in
India the natives are equally careful in the process of selection. In
China the production of eggs is confined to certain favourable
districts, and the raisers are precluded by law from producing silk, so
that their whole attention may be necessarily given up to this one
object.[69]

The following details on the differences between the several breeds are
taken, when not stated to the contrary, from M. Robinet’s excellent
work,[70] which bears every sign of care and large experience. The
_eggs_ in the different races vary in colour, in shape (being round,
elliptic or oval), and in size. The eggs laid in June in the south of
France, and in July in the central provinces, do not hatch until the
following spring; and it is in vain, says M. Robinet, to expose them to
a temperature gradually raised, in order that the caterpillar may be
quickly developed. Yet occasionally, without any known cause, batches
of eggs are produced, which immediately begin to undergo the proper
changes, and are hatched in from twenty to thirty days. From these and
some other analogous facts it may be concluded that the Trevoltini
silkworms of Italy, of which the caterpillars are hatched in from
fifteen to twenty days, do not necessarily form, as has been
maintained, a distinct species. Although the breeds which live in
temperate countries produce eggs which cannot be immediately hatched by
artificial heat, yet when they are removed to and reared in a hot
country they gradually acquire the character of quick development, as
in the Trevoltini races.[71]

_Caterpillars._—These vary greatly in size and colour. The skin is
generally white, sometimes mottled with black or grey, and occasionally
quite black. The colour, however, as M. Robinet asserts, is not
constant, even in perfectly pure breeds; except in the race _tigrée,_
so called from being marked with transverse black stripes. As the
general colour of the caterpillar is not correlated with that of the
silk,[72] this character is disregarded by cultivators, and has not
been fixed by selection. Captain Hutton, in the paper before referred
to, has argued with much force that the dark tiger-like marks, which so
frequently appear during the later moults in the caterpillars of
various breeds, are due to reversion; for the caterpillars of several
allied wild species of Bombyx are marked and coloured in this manner.
He separated some caterpillars with the tiger-like marks, and in the
succeeding spring (pp. 149, 298) nearly all the caterpillars reared
from them were dark-brindled, and the tints became still darker in the
third generation. The moths reared from these caterpillars[73] also
became darker, and resembled in colouring the wild _B. huttoni._ On
this view of the tiger-like marks being due to reversion, the
persistency with which they are transmitted is intelligible.

Several years ago Mrs. Whitby took great pains in breeding silkworms on
a large scale, and she informed me that some of her caterpillars had
dark eyebrows. This is probably the first step in reversion towards the
tiger-like marks, and I was curious to know whether so trifling a
character would be inherited. At my request she separated in 1848
twenty of these caterpillars, and having kept the moths separate, bred
from them. Of the many caterpillars thus reared, “every one without
exception had eyebrows, some darker and more decidedly marked than the
others, but _all_ had eyebrows more or less plainly visible.” Black
caterpillars occasionally appear amongst those of the common kind, but
in so variable a manner, that, according to M. Robinet, the same race
will one year exclusively produce white caterpillars, and the next year
many black ones; nevertheless, I have been informed by M. A. Bossi of
Geneva, that, if these black caterpillars are separately bred from,
they reproduce the same colour; but the cocoons and moths reared from
them do not present any difference.

The caterpillar in Europe ordinarily moults four times before passing
into the cocoon stage; but there are races “à trois mues,” and the
Trevoltini race likewise moults only thrice. It might have been thought
that so important a physiological difference would not have arisen
under domestication; but M. Robinet[74] states that, on the one hand,
ordinary caterpillars occasionally spin their cocoons after only three
moults, and, on the other hand, “presque toutes les races à trois mues,
que nous avons expérimentees, ont fait quatre mues à la seconde ou à la
troisième année, ce qui semble prouver qu’il a suffi de les placer dans
des conditions favorables pour leur rendre une faculté qu’elles avaient
perdue sous des influences moins favorables.”

_Cocoons._—The caterpillar in changing into the cocoon loses about 50
per cent of its weight; but the amount of loss differs in different
breeds, and this is of importance to the cultivator. The cocoon in the
different races presents characteristic differences; being large or
small;—nearly spherical with no constriction, as in the Race de Loriol,
or cylindrical, with either a deep or slight constriction in the
middle; with the two ends, or with one end alone, more or less pointed.
The silk varies in fineness and quality, and in being nearly white, but
of two tints, or yellow. Generally the colour of the silk is not
strictly inherited: but in the chapter on Selection I shall give a
curious account how, in the course of sixty-five generations, the
number of yellow cocoons in one breed has been reduced in France from
one hundred to thirty-five in the thousand. According to Robinet, the
white race, called Sina, by careful selection during the last
seventy-five years, “est arrivée à un tel état de pureté, qu’on ne voit
pas un seul cocon jaune dans des millions de cocons blancs.”[75]
Cocoons are sometimes formed, as is well known, entirely destitute of
silk, which yet produce moths; unfortunately Mrs. Whitby was prevented
by an accident from ascertaining whether this character would prove
hereditary.

_Adult stage._—I can find no account of any constant difference in the
moths of the most distinct races. Mrs. Whitby assured me that there was
none in the several kinds bred by her; and I have received a similar
statement from the eminent naturalist, M. de Quatrefages. Captain
Hutton also says[76] that the moths of all kinds vary much in colour,
but in nearly the same inconstant manner. Considering how much the
cocoons in the several races differ, this fact is of interest, and may
probably be accounted for on the same principle as the fluctuating
variability of colour in the caterpillar, namely, that there has been
no motive for selecting and perpetuating any particular variation.

The males of the wild Bombycidæ “fly swiftly in the day-time and
evening, but the females are usually very sluggish and inactive.”[77]
In several moths of this family the females have abortive wings, but no
instance is known of the males being incapable of flight, for in this
case the species could hardly have been perpetuated. In the silk-moth
both sexes have imperfect, crumpled wings, and are incapable of flight;
but still there is a trace of the characteristic difference in the two
sexes; for though, on comparing a number of males and females, I could
detect no difference in the development of their wings, yet I was
assured by Mrs. Whitby that the males of the moths bred by her used
their wings more than the females, and could flutter downwards, though
never upwards. She also states that, when the females first emerge from
the cocoon, their wings are less expanded than those of the male. The
degree of imperfection, however, in the wings varies much in different
races and under different circumstances. M. Quatrefages[78] says that
he has seen a number of moths with their wings reduced to a third,
fourth, or tenth part of their normal dimensions, and even to mere
short straight stumps: “il me semble qu’il y a là un véritable arrêt de
développement partiel.” On the other hand, he describes the female
moths of the André Jean breed as having “leurs ailes larges et étalées.
Un seul présente quelques courbures irrégulières et des plis anormaux.”
As moths and butterflies of all kinds reared from wild caterpillars
under confinement often have crippled wings, the same cause, whatever
it may be, has probably acted on silk-moths, but the disuse of their
wings during so many generations has, it may be suspected, likewise
come into play.

The moths of many breeds fail to glue their eggs to the surface on
which they are laid,[79] but this proceeds, according to Capt.
Hutton,[80] merely from the glands of the ovipositor being weakened.

As with other long-domesticated animals, the instincts of the silk-moth
have suffered. The caterpillars, when placed on a mulberry-tree, often
commit the strange mistake of devouring the base of the leaf on which
they are feeding, and consequently fall down; but they are capable,
according to M. Robinet,[81] of again crawling up the trunk. Even this
capacity sometimes fails, for M. Martins[82] placed some caterpillars
on a tree, and those which fell were not able to remount and perished
of hunger; they were even incapable of passing from leaf to leaf.

Some of the modifications which the silk-moth has undergone stand in
correlation with one another. Thus, the eggs of the moths which produce
white cocoons and of those which produce yellow cocoons differ slightly
in tint. The abdominal feet, also, of the caterpillars which yield
white cocoons are always white, whilst those which give yellow cocoons
are invariably yellow.[83] We have seen that the caterpillars with dark
tiger-like stripes produce moths which are more darkly shaded than
other moths. It seems well established[84] that in France the
caterpillars of the races which produce white silk, and certain black
caterpillars, have resisted, better than other races, the disease which
has recently devastated the silk-districts. Lastly, the races differ
constitutionally, for some do not succeed so well under a temperate
climate as others; and a damp soil does not equally injure all the
races.[85]

From these various facts we learn that silk-moths, like the higher
animals, vary greatly under long-continued domestication. We learn also
the more important fact that variations may occur at various periods of
life, and be inherited at a corresponding period. And finally we see
that insects are amenable to the great principle of Selection.

REFERENCES

 [1] ‘Poultry Chronicle,’ 1854, vol. ii. p. 91 and vol. i. p. 330.

 [2] Dr. Turral, ‘Bull. Soc. d’Acclimat.,’ tom. vii., 1860, p. 541.

 [3] Willughby’s ‘Ornithology,’ by Ray, p. 381. This breed is also
 figured by Albin in 1734 in his ‘Nat. Hist. of Birds,’ vol. ii. p. 86.

 [4] F. Cuvier, in ‘Annales du Muséum,’ tom. ix. p. 128, says that
 moulting and incubation alone stops these ducks laying. Mr. B. P.
 Brent makes a similar remark in the ‘Poultry Chronicle,’ 1855, vol.
 iii. p. 512.

 [5] Rev. E. S. Dixon, ‘Ornamental and Domestic Poultry’ (1848), p.
 117. Mr. B. P. Brent, in ‘Poultry Chronicle,’ vol. iii., 1855, p. 512.

 [6] Crawfurd on the ‘Relation of Domesticated Animals to
 Civilisation,’ read before the Brit. Assoc. at Oxford, 1860.

 [7] Dureau de La Malle, in ‘Annales des Sciences Nat.,’ tom. xvii. p.
 164; and tom. xxi. p. 55. Rev. E. S. Dixon, ‘Ornamental Poultry,’ p.
 118. Tame ducks were not known in Aristotle’s time, as remarked by
 Volz, in his ‘Beiträge zur Kulturgeschichte,’ 1852, s. 78.

 [8] I quote this account from ‘Die Enten-und Schwanenzucht,’ Ulm 1828,
 s. 143. _See_ Audubon’s ‘Ornithological Biography,’ vol. iii. p. 168,
 on the taming of ducks on the Mississippi. For the same fact in
 England, _see_ Mr. Waterton in Loudon’s ‘Mag. of Nat. Hist.,’ vol.
 viii. 1835, p. 542; and Mr. St. John, ‘Wild Sports and Nat. Hist. of
 the Highlands,’ 1846, p. 129.

 [9] Mr. E. Hewitt, in ‘Journal of Horticulture,’ 1862, p. 773; and
 1863, p. 39.

 [10] I have met with several statements on the fertility of the
 several breeds when crossed. Mr. Yarrell assured me that Call and
 common ducks are perfectly fertile together. I crossed Hook-billed and
 common ducks, and a Penguin and Labrador, and the crossed Ducks were
 quite fertile, though they were not bred _ inter se,_ so that the
 experiment was not fully tried. Some half-bred Penguins and Labradors
 were again crossed with Penguins, and subsequently bred by me _inter
 se,_ and they were extremely fertile.

 [11] ‘Poultry Chronicle,’ 1855, vol. iii. p. 512.

 [12] ‘Journal of the Indian Archipelago,’ vol. v. p. 334.

 [13] ‘The Zoologist,’ vols. vii, viii. (1849-1850), p. 2353.

 [14] ‘Poultry Chronicle,’ 1855, vol. iii. p. 512.

 [15] ‘Poultry Chronicle,’ vol. iii. 1855, p. 312. With respect to
 Rouens _see_ ditto vol. i. 1854, p. 167.

 [16] Col. Hawker’s ‘Instructions to young Sportsmen,’ quoted by Mr.
 Dixon in his ‘Ornamental Poultry,’ p. 125.

 [17] ‘Cottage Gardener,’ April 9th, 1861.

 [18] These hybrids have been described by M. Selys-Longchamps in the
 ‘Bulletins (tom. xii. No 10) Acad. Roy. de Bruxelles.’

 [19] ‘Proc. Zoolog. Soc.,’ 1861, p. 261.

 [20] ‘Ceylon,’ by Sir J. E. Tennent, 1859, vol. i. p. 485; also J.
 Crawfurd on the ‘Relation of Domest. Animals to Civilisation,’ read
 before Brit. Assoc. 1860. _See also_ ‘Ornamental Poultry,’ by Rev. E.
 S. Dixon, 1848, p. 132. The goose figured on the Egyptian monuments
 seems to have been the Red goose of Egypt.

 [21] Macgillivray’s ‘British Birds,’ vol. iv. p. 593.

 [22] Mr. A. Strickland (‘Annals and Mag. of Nat. Hist.,’ 3rd series,
 vol. iii. 1859, p. 122) reared some young wild geese, and found them
 in habits and in all characters identical with the domestic goose.

 [23] _See also_ Hunter’s ‘Essays,’ edited by Owen, vol. ii. p. 322.

 [24] Yarrell’s ‘British Birds,’ vol. iii. p. 142.

 [25] L. Lloyd, ‘Scandinavian Adventures,’ 1854, vol. ii. p. 413, says
 that the wild goose lays from five to eight eggs, which is a much
 fewer number than that laid by our domestic goose.

 [26] The Rev. L. Jenyns (Blomefield) seems first to have made this
 observation in his ‘British Animals.’ _See also_ Yarrell, and Dixon in
 his ‘Ornamental Poultry’ (p. 139), and ‘Gardener’s Chronicle,’ 1857,
 p. 45.

 [27] Mr. Bartlet exhibited the head and neck of a bird thus
 characterised before the Zoological Soc., Feb. 1860.

 [28] W. Thompson, ‘Natural Hist. of Ireland,’ 1851, vol. iii. p. 31.
 The Rev. E. S. Dixon gave me some information on the varying colour of
 the beak and legs.

 [29] Mr. A. Strickland, in ‘Annals and Mag. of Nat. Hist.,’ 3rd
 series, vol. iii., 1859, p. 122.

 [30] ‘Poultry Chronicle,’ vol. i., 1854, p. 498; vol. iii. p. 210.

 [31] ‘The Cottage Gardener.’ Sept. 4th, 1860, p. 348.

 [32] ‘L’Hist. de la Nature des Oiseaux,’ par P. Belon, 1555, p. 156.
 With respect to the livers of white geese being preferred by the
 Romans _see_ Isid. Geoffroy St.-Hilaire ‘Hist. Nat. Gén.,’ tom. iii.
 p. 58.

 [33] Mr. Sclater on the black-shouldered peacock of Latham, ‘Proc.
 Zoolog. Soc.,’ April 24th, 1860. Mr. Swinhoe at one time believed,
 (‘Ibis,’ July, 1868) that this kind of peafowl was found wild in
 Cochin China, but he has since informed me that he feels very doubtful
 on this head.

 [34] ‘Proc. Zoolog. Soc.,’ April 14th, 1835.

 [35] ‘The Field,’ May 6th, 1871. I am much indebted to Mr. Canning for
 information with respect to his birds.

 [36] ‘Proc. Zoolog. Soc.,’ April 8th, 1856, p. 61. Prof. Baird
 believes (as quoted in Tegetmeier’s ‘Poultry Book,’ 1866, p. 269) that
 our turkeys are descended from a West Indian species now extinct. But
 besides the improbability of a bird having long ago become extinct in
 these large and luxuriant islands, it appears (as we shall presently
 see) that the turkey degenerates in India, and this fact indicates
 that it was not aboriginally an inhabitant of the lowlands of the
 tropics.

 [37] Audubon’s ‘Ornithological Biography,’ vol. i., 1831, pp. 4-13;
 and ‘Naturalist’s Library,’ vol. xiv., Birds, p. 138.

 [38] F. Michaux, ‘Travels in N. America,’ 1802, Eng. translat., p.
 217.

 [39] ‘Ornamental Poetry,’ by the Rev. E. S. Dixon, 1848, p. 34.

 [40] Bechstein, ‘Naturgesch. Deutschlands,’ B. iii., 1793, s. 309.

 [41] Mr. Bartlett in ‘Land and Water,’ Oct. 31st, 1868, p. 233; and
 Mr. Tegetmeier in the ‘Field,’ July 17th, 1869, p. 46.

 [42] ‘Gardener’s Chronicle,’ 1852, p. 699.

 [43] E. Blyth, in ‘Annals and Mag. of Nat. Hist.,’ 1847, vol. xx. p.
 391.

 [44] Roulin makes this remark in ‘Mém. de divers Savans, l’Acad. des
 Sciences,’ tom. vi., 1835, p. 349. Mr. Hill, of Spanish Town, in a
 letter to me, describes five varieties of the Guinea fowl in Jamaica.
 I have seen singular pale-coloured varieties imported from Barbadoes
 and Demerara.

 [45] For St. Domingo, _see_ M. A. Salle, in ‘Proc. Zoolog. Soc.’ 1857,
 p. 236. Mr. Hill remarks to me, in his letter, on the colour of the
 legs of the feral birds in Jamaica.

 [46] Mr. B. P. Brent, ‘The Canary, British Finches,’ etc., pp. 21, 30.

 [47] ‘Cottage Gardener,’ Dec. 11th, 1855, p. 184: an account is here
 given of all the varieties. For many measurements of the wild birds,
 _see_ Mr. E. Vernon Harcourt, ibid., Dec. 25th, 1855, p. 223.

 [48] Bechstein, ‘Naturgesch. der Stubenvögel,’ 1840, s. 243; _see_ s.
 252 on the inherited song of Canary-birds. With respect to their
 baldness _see also_ W. Kidd’s ‘Treatise on Song-Birds.’

 [49] W. Kidd’s ‘Treatise on Song-Birds,’ p. 18.

 [50] The ‘Indian Field,’ 1858, p. 255.

 [51] Yarrell’s ‘British Fishes,’ vol. i. p. 319.

 [52] Mr. Blyth in the ‘Indian Field,’ 1858, p. 255.

 [53] W. F. Mayers, ‘Chinese Notes and Queries,’ Aug. 1868, p. 123.

 [54] ‘Proc. Zoolog. Soc.’ May 25, 1842.)

 [55] Yarrell’s ‘British Fishes,’ vol. i. p. 319.

 [56] ‘Dict. Class. d’Hist. Nat.,’ tom. v. p. 276.

 [57] ‘Observations in Nat. Hist.,’ 1846, p. 211. Dr. Gray has
 described, in ‘Annals and Mag. of Nat. Hist.,’ 1860, p. 151 a nearly
 similar variety but destitute of a dorsal fin.

 [58] ‘De l’Espèce,’ 1859, p. 459. With respect to the bees of Burgundy
 _see_ M. Gerard, art. ‘Espèce,’ in ‘Dict. Univers. d’Hist. Nat.’

 [59] _See_ a discussion on this subject, in answer to a question of
 mine, in ‘Journal of Horticulture,’ 1862, pp. 225-242; also Mr. Bevan
 Fox, in ditto, 1862, p. 284.

 [60] This excellent observer may be implicitly trusted; _see_ ‘Journal
 of Horticulture,’ July 14th, 1863, p. 39.

 [61] ‘Journal of Horticulture,’ Sept. 9th, 1862, p. 463; _see also_
 Herr Kleine on same subject (Nov. 11th, p. 643, who sums up, that,
 though there is some variability in colour, no constant or perceptible
 differences can be detected in the bees of Germany.

 [62] Mr. Woodbury has published several such accounts in ‘Journal of
 Horticulture,’ 1861 and 1862.

 [63] ‘Annals and Mag. of Nat. Hist.,’ 3rd series, vol. xi. p. 339.

 [64] ‘The Cottage Gardener,’ May 1860, p. 110; and ditto in ‘Journal
 of Hort.,’ 1862, p. 242.

 [65] ‘Transact. Entomolog. Soc.’ 3rd series, vol. iii. pp. 143-173 and
 pp. 295-331.

 [66] Godron, ‘De l’Espèce,’ 1859, tom. i. p. 460. The antiquity of the
 silkworm in China is given on the authority of Stanislas Julien.

 [67] _See_ the remarks of Prof. Westwood, Gen. Hearsey and others at
 the meeting of the Entomolog. Soc. of London, July, 1861.

 [68] _See_ for instance M. A. de Quatrefages’ ‘Études sur les Maladies
 actuelles du Ver à Soie,’ 1859, p. 101.

 [69] My authorities for the statements will be given in the chapter on
 Selection.

 [70] ‘Manuel de l’Éducateur de Vers à Soie,’ 1848.

 [71] Robinet, ibid., pp. 12, 318. I may add that the eggs of N.
 American silkworms taken to the Sandwich Islands produced moths at
 very irregular periods; and the moths thus raised yielded eggs which
 were even worse in this respect. Some were hatched in ten days, and
 others not until after the lapse of many months. No doubt a regular
 early character would ultimately have been acquired. _See_ review in
 ‘Athenæum,’ 1844, p. 329, of J. Jarves’ ‘Scenes in the Sandwich
 Islands.’

 [72] ‘The Art of rearing Silk-worms,’ translated from Count Dandolo,
 1825, p. 23.

 [73] ‘Transact. Ent. Soc.,’ ut supra, pp. 153, 308.

 [74] Robinet, ibid., p. 317.

 [75] Robinet, ibid., pp. 306-317.

 [76] ‘Transact. Ent. Soc.,’ ut supra, p. 317.

 [77] Stephen’s Illustrations, ‘Haustellata,’ vol. ii. p. 35. _ See
 also_ Capt. Hutton, ‘Transact. Ent. Soc.,’ ibid., p. 152.

 [78] ‘Études sur les Maladies du Ver à Soie,’ 1859, pp. 304, 209.

 [79] Quatrefages, ‘Études,’ etc., p. 214.

 [80] ‘Transact. Ent. Soc.,’ ut supra, p. 151.

 [81] ‘Manuel de l’Educateur,’ etc., p. 26.

 [82] Godron, ‘De l’Espèce,’ p. 462.

 [83] Quatrefages, ‘Études,’ etc., pp. 12, 209, 214.

 [84] Robinet, ‘Manuel,’ etc., p. 303.

 [85] Robinet, ibid., p. 15.




CHAPTER IX. CULTIVATED PLANTS: CEREAL AND CULINARY PLANTS.

PRELIMINARY REMARKS ON THE NUMBER AND PARENTAGE OF CULTIVATED
PLANTS—FIRST STEPS IN CULTIVATION—GEOGRAPHICAL DISTRIBUTION OF
CULTIVATED PLANTS.

CEREALIA. DOUBTS ON THE NUMBER OF SPECIES—WHEAT: VARIETIES
OF—INDIVIDUAL VARIABILITY—CHANGED HABITS—SELECTION—ANCIENT HISTORY OF
THE VARIETIES—MAIZE: GREAT VARIATION OF—DIRECT ACTION OF CLIMATE ON.

CULINARY PLANTS.—CABBAGES: VARIETIES OF, IN FOLIAGE AND STEMS, BUT NOT
IN OTHER PARTS—PARENTAGE OF—OTHER SPECIES OF BRASSICA—PEAS: AMOUNT OF
DIFFERENCE IN THE SEVERAL KINDS, CHIEFLY IN THE PODS AND SEED—SOME
VARIETIES CONSTANT, SOME HIGHLY VARIABLE—DO NOT
INTERCROSS—BEANS—POTATOES: NUMEROUS VARIETIES OF—DIFFERING LITTLE
EXCEPT IN THE TUBERS—CHARACTERS INHERITED.


I shall not enter into so much detail on the variability of cultivated
plants, as in the case of domesticated animals. The subject is involved
in much difficulty. Botanists have generally neglected cultivated
varieties, as beneath their notice. In several cases the wild prototype
is unknown or doubtfully known; and in other cases it is hardly
possible to distinguish between escaped seedlings and truly wild
plants, so that there is no safe standard of comparison by which to
judge of any supposed amount of change. Not a few botanists believe
that several of our anciently cultivated plants have become so
profoundly modified that it is not possible now to recognise their
aboriginal parent-forms. Equally perplexing are the doubts whether some
of them are descended from one species, or from several inextricably
commingled by crossing and variation. Variations often pass into, and
cannot be distinguished from, monstrosities; and monstrosities are of
little significance for our purpose. Many varieties are propagated
solely by grafts, buds, layers, bulbs, etc., and frequently it is not
known how far their peculiarities can be transmitted by seminal
generation. Nevertheless, some facts of value can be gleaned: and other
facts will hereafter be incidentally given. One chief object in the two
following chapters is to show how many characters in our cultivated
plants have become variable.

Before entering on details a few general remarks on the origin of
cultivated plants may be introduced. M. Alph. De Candolle[1] in an
admirable discussion on this subject, in which he displays a wonderful
amount of knowledge, gives a list of 157 of the most useful cultivated
plants. Of these he believes that 85 are almost certainly known in
their wild state; but on this head other competent judges[2] entertain
great doubts. Of 40 of them, the origin is admitted by M. De Candolle
to be doubtful, either from a certain amount of dissimilarity which
they present when compared with their nearest allies in a wild state,
or from the probability of the latter not being truly wild plants, but
seedlings escaped from culture. Of the entire 157, 32 alone are ranked
by M. De Candolle as quite unknown in their aboriginal condition. But
it should be observed that he does not include in his list several
plants which present ill-defined characters, namely, the various forms
of pumpkins, millet, sorghum, kidney-bean, dolichos, capsicum, and
indigo. Nor does he include flowers; and several of the more anciently
cultivated flowers, such as certain roses, the common Imperial lily,
the tuberose, and even the lilac, are said[3] not to be known in the
wild state.

From the relative numbers above given, and from other arguments of much
weight, M. De Candolle concludes that plants have rarely been so much
modified by culture that they cannot be identified with their wild
prototypes. But on this view, considering that savages probably would
not have chosen rare plants for cultivation, that useful plants are
generally conspicuous, and that they could not have been the
inhabitants of deserts or of remote and recently discovered islands, it
appears strange to me that so many of our cultivated plants should be
still unknown or only doubtfully known in the wild state. If, on the
other hand, many of these plants have been profoundly modified by
culture, the difficulty disappears. The difficulty would also be
removed if they have been exterminated during the progress of
civilisation; but M. De Candolle has shown that this probably has
seldom occurred. As soon as a plant was cultivated in any country, the
half-civilised inhabitants would no longer have need to search the
whole surface of the land for it, and thus lead to its extirpation; and
even if this did occur during a famine, dormant seeds would be left in
the ground. In tropical countries the wild luxuriance of nature, as was
long ago remarked by Humboldt, overpowers the feeble efforts of man. In
anciently civilised temperate countries, where the whole face of the
land has been greatly changed, it can hardly be doubted that some
plants have become extinct; nevertheless De Candolle has shown that all
the plants historically known to have been first cultivated in Europe
still exist here in the wild state.

MM. Loiseleur-Deslongchamps[4] and De Candolle have remarked that our
cultivated plants, more especially the cereals, must originally have
existed in nearly their present state; for otherwise they would not
have been noticed and valued as objects of food. But these authors
apparently have not considered the many accounts given by travellers of
the wretched food collected by savages. I have read an account of the
savages of Australia cooking, during a dearth, many vegetables in
various ways, in the hopes of rendering them innocuous and more
nutritious. Dr. Hooker found the half-starved inhabitants of a village
in Sikhim suffering greatly from having eaten arum-roots,[5] which they
had pounded and left for several days to ferment, so as partially to
destroy their poisonous nature; and he adds that they cooked and ate
many other deleterious plants. Sir Andrew Smith informs me that in
South Africa a large number of fruits and succulent leaves, and
especially roots, are used in times of scarcity. The natives, indeed,
know the properties of a long catalogue of plants, some having been
found during famines to be eatable, others injurious to health, or even
destructive to life. He met a party of Baquanas who, having been
expelled by the conquering Zulus, had lived for years on any roots or
leaves which afforded some little nutriment and distended their
stomachs, so as to relieve the pangs of hunger. They looked like
walking skeletons, and suffered fearfully from constipation. Sir Andrew
Smith also informs me that on such occasions the natives observe as a
guide for themselves, what the wild animals, especially baboons and
monkeys, eat.

From innumerable experiments made through dire necessity by the savages
of every land, with the results handed down by tradition, the
nutritious, stimulating, and medicinal properties of the most
unpromising plants were probably first discovered. It appears, for
instance, at first an inexplicable fact that untutored man, in three
distant quarters of the world, should have discovered, amongst a host
of native plants, that the leaves of the tea-plant and mattee, and the
berries of the coffee, all included a stimulating and nutritious
essence, now known to be chemically the same. We can also see that
savages suffering from severe constipation would naturally observe
whether any of the roots which they devoured acted as aperients. We
probably owe our knowledge of the uses of almost all plants to man
having originally existed in a barbarous state, and having been often
compelled by severe want to try as food almost everything which he
could chew and swallow.

From what we know of the habits of savages in many quarters of the
world, there is no reason to suppose that our cereal plants originally
existed in their present state so valuable to man. Let us look to one
continent alone, namely, Africa: Barth[6] states that the slaves over a
large part of the central region regularly collect the seeds of a wild
grass, the _Pennisetum distichum_; in another district he saw women
collecting the seeds of a Poa by swinging a sort of basket through the
rich meadow-land. Near Tete, Livingstone observed the natives
collecting the seeds of a wild grass, and farther south, as Andersson
informs me, the natives largely use the seed of a grass of about the
size of canary-seed, which they boil in water. They eat also the roots
of certain reeds, and every one has read of the Bushmen prowling about
and digging up with a fire-hardened stake various roots. Similar facts
with respect to the collection of seeds of wild grasses in other parts
of the world could be given.[7]

Accustomed as we are to our excellent vegetables and luscious fruits,
we can hardly persuade ourselves that the stringy roots of the wild
carrot and parsnip, or the little shoots of the wild asparagus, or
crabs, sloes, etc., should ever have been valued; yet, from what we
know of the habits of Australian and South African savages, we need
feel no doubt on this head. The inhabitants of Switzerland during the
Stone-period largely collected wild crabs, sloes, bullaces, hips of
roses, elderberries, beechmast, and other wild berries and fruit.[8]
Jemmy Button, a Fuegian on board the ‘Beagle,’ remarked to me that the
poor and acid black-currants of Tierra del Fuego were too sweet for his
taste.

The savage inhabitants of each land, having found out by many and hard
trials what plants were useful, or could be rendered useful by various
cooking processes, would after a time take the first step in
cultivation by planting them near their usual abodes. Livingstone[9]
states that the savage Batokas sometimes left wild fruit-trees standing
in their gardens, and occasionally even planted them, “a practice seen
nowhere else amongst the natives.” But Du Chaillu saw a palm and some
other wild fruit-trees which had been planted; and these trees were
considered private property. The next step in cultivation, and this
would require but little forethought, would be to sow the seeds of
useful plants; and as the soil near the hovels of the natives[10] would
often be in some degree manured, improved varieties would sooner or
later arise. Or a wild and unusually good variety of a native plant
might attract the attention of some wise old savage; and he would
transplant it, or sow its seed. That superior varieties of wild
fruit-trees occasionally are found is certain, as in the case of the
American species of hawthorns, plums, cherries, grapes, and hickories,
specified by Professor Asa Gray.[11] Downing also refers to certain
wild varieties of the hickory, as being “of much larger size and finer
flavour than the common species.” I have referred to American
fruit-trees, because we are not in this case troubled with doubts
whether or not the varieties are seedlings which have escaped from
cultivation. Transplanting any superior variety, or sowing its seeds,
hardly implies more forethought than might be expected at an early and
rude period of civilisation. Even the Australian barbarians “have a law
that no plant bearing seeds is to be dug up after it has flowered;” and
Sir G. Grey[12] never saw this law, evidently framed for the
preservation of the plant, violated. We see the same spirit in the
superstitious belief of the Fuegians, that killing water-fowl whilst
very young will be followed by “much rain, snow, blow much.”[13] I may
add, as showing forethought in the lowest barbarians, that the Fuegians
when they find a stranded whale bury large portions in the sand, and
during the often-recurrent famines travel from great distances for the
remnants of the half-putrid mass.

It has often been remarked[1] that we do not owe a single useful plant
to Australia or the Cape of Good Hope, countries abounding to an
unparalleled degree with endemic species,—or to New Zealand, or to
America south of the Plata; and, according to some authors, not to
America northward of Mexico. I do not believe that any edible or
valuable plant, except the canary-grass, has been derived from an
oceanic or uninhabited island. If nearly all our useful plants, natives
of Europe; Asia, and South America, had originally existed in their
present condition, the complete absence of similarly useful plants in
the great countries just named would be indeed a surprising fact. But
if these plants have been so greatly modified and improved by culture
as no longer closely to resemble any natural species, we can understand
why the above-named countries have given us no useful plants, for they
were either inhabited by men who did not cultivate the ground at all,
as in Australia and the Cape of Good Hope, or who cultivated it very
imperfectly, as in some parts of America. These countries do yield
plants which are useful to savage man; and Dr. Hooker[15] enumerates no
less than 107 such species in Australia alone; but these plants have
not been improved, and consequently cannot compete with those which
have been cultivated and improved during thousands of years in the
civilised world.

The case of New Zealand, to which fine island we as yet owe no widely
cultivated plant, may seem opposed to this view; for, when first
discovered, the natives cultivated several plants; but all inquirers
believe, in accordance with the traditions of the natives, that the
early Polynesian colonists brought with them seeds and roots, as well
as the dog, which had been wisely preserved during their long voyage.
The Polynesians are so frequently lost on the ocean that this degree of
prudence would occur to any wandering party: hence the early colonists
of New Zealand, like the later European colonists, would not have had
any strong inducement to cultivate the aboriginal plants. According to
De Candolle we owe thirty-three useful plants to Mexico, Peru, and
Chile; nor is this surprising when we remember the civilised state of
the inhabitants, as shown by the fact of their having practised
artificial irrigation and made tunnels through hard rocks without the
use of iron or gunpowder, and who, as we shall see in a future chapter,
fully recognised, as far as animals were concerned, and therefore
probably in the case of plants, the important principle of selection.
We owe some plants to Brazil; and the early voyagers, namely, Vespucius
and Cabral, describe the country as thickly peopled and cultivated. In
North America[16] the natives cultivated maize, pumpkins, gourds,
beans, and peas, “all different from ours,” and tobacco; and we are
hardly justified in assuming that none of our present plants are
descended from these North American forms. Had North America been
civilised for as long a period, and as thickly peopled, as Asia or
Europe, it is probable that the native vines, walnuts, mulberries,
crabs, and plums, would have given rise, after a long course of
cultivation, to a multitude of varieties, some extremely different from
their parent-stocks; and escaped seedlings would have caused in the
New, as in the Old World, much perplexity with respect to their
specific distinctness and parentage.’[17]

_Cerealia._—I will now enter on details. The cereals cultivated in
Europe consist of four genera—wheat, rye, barley, and oats. Of wheat
the best modern authorities[18] make four or five, or even seven
distinct species; of rye, one; of barley, three; and of oats, two,
three, or four species. So that altogether our cereals are ranked by
different authors under from ten to fifteen distinct species. These
have given rise to a multitude of varieties. It is a remarkable fact
that botanists are not universally agreed on the aboriginal parent-form
of any one cereal plant. For instance, a high authority writes in
1855,[19] “We ourselves have no hesitation in stating our conviction,
as the result of all the most reliable evidence, that none of these
Cerealia exist, or have existed, truly wild in their present state, but
that all are cultivated varieties of species now growing in great
abundance in S. Europe or W. Asia.” On the other hand, Alph. De
Candolle[20] has adduced abundant evidence that common wheat (_Triticum
vulgare_) has been found wild in various parts of Asia, where it is not
likely to have escaped from cultivation: and there is some force in M.
Godron’s remark, that, supposing these plants to be escaped
seedlings,[21] as they have propagated themselves in a wild state for
several generations, their continued resemblance to cultivated wheat
renders it probable that the latter has retained its aboriginal
character. But the strong tendency to inheritance, which most of the
varieties of wheat evince, as we shall presently see, is here greatly
undervalued. Much weight must also be attributed to a remark by
Professor Hildebrand[22] that when the seeds or fruit of cultivated
plants possess qualities disadvantageous to them as a means of
distribution, we may feel almost sure that they no longer retain their
aboriginal condition. On the other hand, M. De Candolle insists
strongly on the frequent occurrence in the Austrian dominions of rye
and of one kind of oats in an apparently wild condition. With the
exception of these two cases, which however are rather doubtful, and
with the exception of two forms of wheat and one of barley, which he
believes to have been found truly wild, M. De Candolle does not seem
fully satisfied with the other reported discoveries of the parent-forms
of our other cereals. With respect to oats, according to Mr.
Buckmann,[23] the wild English _Avena fatua_ can be converted by a few
years of careful cultivation and selection into forms almost identical
with two very distinct cultivated races. The whole subject of the
origin and specific distinctness of the various cereal plants is a most
difficult one; but we shall perhaps be able to judge a little better
after considering the amount of variation which wheat has undergone.

Metzger describes seven species of wheat, Godron refers to five, and De
Candolle to only four. It is not improbable that, besides the kinds
known in Europe, other strongly characterised forms exist in the more
distant parts of the world; for Loiseleur-Deslongchamps[24] speaks of
three new species or varieties, sent to Europe in 1822 from Chinese
Mongolia, which he considers as being there indigenous. Moorcroft[25]
also speaks of Hasora wheat in Ladakh as very peculiar. If those
botanists are right who believe that at least seven species of wheat
originally existed, then the amount of variation in any important
character which wheat has undergone under cultivation has been slight;
but if only four or a lesser number of species originally existed, then
it is evident that varieties have arisen so strongly marked, that they
have been considered by capable judges as specifically distinct. But
the impossibility of deciding which forms ought to be ranked as species
and which as varieties, makes it useless to specify in detail the
differences between the various kinds of wheat. Speaking generally, the
organs of vegetation differ little;[26] but some kinds grow close and
upright, whilst others spread and trail along the ground. The straw
differs in being more or less hollow, and in quality. The ears[27]
differ in colour and in shape, being quadrangular, compressed, or
nearly cylindrical; and the florets differ in their approximation to
each other, in their pubescence, and in being more or less elongated.
The presence or absence of barbs is a conspicuous difference, and in
certain Gramineæ serves even as a generic character;[28] although, as
remarked by Godron,[29] the presence of barbs is variable in certain
wild grasses, and especially in those such as _Bromus secalinus_ and
_Lolium temulentum,_ which habitually grow mingled with our cereal
crops, and which have thus unintentionally been exposed to culture. The
grains differ in size, weight, and colour; in being more or less downy
at one end, in being smooth or wrinkled, in being either nearly
globular, oval, or elongated; and finally in internal texture, being
tender or hard, or even almost horny, and in the proportion of gluten
which they contain.

Nearly all the races or species of wheat vary, as Godron[30] has
remarked, in an exactly parallel manner,—in the seed being downy or
glabrous, and in colour,—and in the florets being barbed or not barbed,
etc. Those who believe that all the kinds are descended from a single
wild species may account for this parallel variation by the inheritance
of a similar constitution, and a consequent tendency to vary in the
same manner; and those who believe in the general theory of descent
with modification may extend this view to the several species of wheat,
if such ever existed in a state of nature.

Although few of the varieties of wheat present any conspicuous
difference, their number is great. Dalbret cultivated during thirty
years from 150 to 160 kinds, and excepting in the quality of the grain
they all kept true; Colonel Le Couteur possessed upwards of 150, and
Philippar 322 varieties.[31] As wheat is an annual, we thus see how
strictly many trifling differences in character are inherited through
many generations. Colonel Le Couteur insists strongly on this same
fact. In his persevering and successful attempts to raise new
varieties, he found that there was only one “secure mode to ensure the
growth of pure sorts, namely, to grow them from single grains or from
single ears, and to follow up the plan by afterwards sowing only the
produce of the most productive so as to form a stock.” But Major
Hallett[32] has gone much farther, and by the continued selection of
plants from the grains of the same ear, during successive generations,
has made his ‘Pedigree in Wheat’ (and other cereals) now famous in many
quarters of the world. The great amount of variability in the plants of
the same variety is another interesting point, which would never have
been detected except by an eye long practised to the work; thus Colonel
Le Couteur relates[33] that in a field of his own wheat, which he
considered at least as pure as that of any of his neighbours, Professor
La Gasca found twenty-three sorts; and Professor Henslow has observed
similar facts. Besides such individual variations, forms sufficiently
well marked to be valued and to become widely cultivated sometimes
suddenly appear: thus Mr. Shirreff has had the good fortune to raise in
his lifetime seven new varieties, which are now extensively grown in
many parts of Britain.[34]

As in the case of many other plants, some varieties, both old and new,
are far more constant in character than others. Colonel Le Couteur was
forced to reject some of his new sub-varieties, which he suspected had
been produced from a cross, as incorrigibly sportive. On the other hand
Major Hallett[35] has shown how wonderfully constant some varieties
are, although not ancient ones, and although cultivated in various
countries. With respect to the tendency to vary, Metzger[36] gives from
his own experience some interesting facts: he describes three Spanish
sub-varieties, more especially one known to be constant in Spain, which
in Germany assumed their proper character only during hot summers;
another variety kept true only in good land, but after having been
cultivated for twenty-five years became more constant. He mentions two
other sub-varieties which were at first inconstant, but subsequently
became, apparently without any selection, accustomed to their new
homes, and retained their proper character. These facts show what small
changes in the conditions of life cause variability, and they further
show that a variety may become habituated to new conditions. One is at
first inclined to conclude with Loiseleur-Deslongchamps, that wheat
cultivated in the same country is exposed to remarkably uniform
conditions; but manures differ, seed is taken from one soil to another,
and, what is far more important, the plants are exposed as little as
possible to struggle with other plants, and are thus enabled to exist
under diversified conditions. In a state of nature each plant is
confined to that particular station and kind of nutriment which it can
seize from the other plants by which it is surrounded.

Wheat quickly assumes new habits of life. The summer and winter kinds
were classed by Linnæus as distinct species; but M. Monnier[37] has
proved that the difference between them is only temporary. He sowed
winter-wheat in spring, and out of one hundred plants four alone
produced ripe seeds; these were sown and resown, and in three years
plants were reared which ripened all their seed. Conversely, nearly all
the plants raised from summer-wheat, which was sown in autumn, perished
from frost; but a few were saved and produced seed, and in three years
this summer-variety was converted into a winter-variety. Hence it is
not surprising that wheat soon becomes to a certain extent
acclimatised, and that seed brought from distant countries and sown in
Europe vegetates at first, or even for a considerable period,[38]
differently from our European varieties. In Canada the first settlers,
according to Kalm,[39] found their winters too severe for winter-wheat
brought from France, and their summers often too short for
summer-wheat; and they thought that their country was useless for corn
crops until they procured summer-wheat from the northern parts of
Europe, which succeeded well. It is notorious that the proportion of
gluten differs much under different climates. The weight of the grain
is also quickly affected by climate: Loiseleur-Deslongchamps[40] sowed
near Paris 54 varieties, obtained from the South of France and from the
Black Sea, and 52 of these yielded seed from 10 to 40 per cent heavier
than the parent-seed. He then sent these heavier grains back to the
South of France, but there they immediately yielded lighter seed.

All those who have closely attended to the subject insist on the close
adaptation of numerous varieties of wheat to various soils and climates
even within the same country; thus Colonel Le Couteur[41] says, “It is
the suitableness of each sort to each soil that will enable the farmer
to pay his rent by sowing one variety, where he would be unable to do
so by attempting to grow another of a seemingly better sort.” This may
be in part due to each kind becoming habituated to its conditions of
life, as Metzger has shown certainly occurs, but it is probably in main
part due to innate differences between the several varieties.

Much has been written on the deterioration of wheat; that the quality
of the flour, size of grain, time of flowering, and hardness, may be
modified by climate and soil, seems nearly certain; but that the whole
body of any one sub-variety ever becomes changed into another and
distinct sub-variety, there is no reason to believe. What apparently
does take place, according to Le Couteur,[42] is, that some one
sub-variety out of the many which may always be detected in the same
field is more prolific than the others, and gradually supplants the
variety which was first sown.

With respect to the natural crossing of distinct varieties the evidence
is conflicting, but preponderates against its frequent occurrence. Many
authors maintain that impregnation takes place in the closed flower,
but I am sure from my own observation that this is not the case, at
least with those varieties to which I have attended. But as I shall
have to discuss this subject in another work, it may be here passed
over.

In conclusion, all authors admit that numerous varieties of wheat have
arisen; but their differences are unimportant, unless, indeed, some of
the so-called species are ranked as varieties. Those who believe that
from four to seven wild species of Triticum originally existed in
nearly the same condition as at present, rest their belief chiefly on
the great antiquity of the several forms.[43] It is an important fact,
which we have recently learnt from the admirable researches of
Heer,[44] that the inhabitants of Switzerland, even so early as the
Neolithic period, cultivated no less than ten cereal plants, namely,
five kinds of wheat, of which at least four are commonly looked at as
distinct species, three kinds of barley, a panicum, and a setaria. If
it could be shown that at the earliest dawn of agriculture five kinds
of wheat and three of barley had been cultivated, we should of course
be compelled to look at these forms as distinct species. But, as Heer
has remarked, agriculture even at the Neolithic period, had already
made considerable progress; for, besides the cereals, peas, poppies,
flax, and apparently apples, were cultivated. It may also be inferred,
from one variety of wheat being the so called Egyptian, and from what
is known of the native country of the panicum and setaria, as well as
from the nature of the weeds which then grew mingled with the crops,
that the lake-inhabitants either still kept up commercial intercourse
with some southern people or had originally proceeded as colonists from
the South.

Loiseleur-Deslongchamps[45] has argued that, if our cereal plants have
been greatly modified by cultivation, the weeds which habitually grow
mingled with them would have been equally modified. But this argument
shows how completely the principle of selection has been overlooked.
That such weeds have not varied, or at least do not vary now in any
extreme degree, is the opinion of Mr. H. C. Watson and Professor Asa
Gray, as they inform me; but who will pretend to say that they do not
vary as much as the individual plants of the same sub-variety of wheat?
We have already seen that pure varieties of wheat, cultivated in the
same field, offer many slight variations, which can be selected and
separately propagated; and that occasionally more strongly pronounced
variations appear, which, as Mr. Shirreff has proved, are well worthy
of extensive cultivation. Not until equal attention be paid to the
variability and selection of weeds, can the argument from their
constancy under unintentional culture be of any value. In accordance
with the principles of selection we can understand how it is that in
the several cultivated varieties of wheat the organs of vegetation
differ so little; for if a plant with peculiar leaves appeared, it
would be neglected unless the grains of corn were at the same time
superior in quality or size. the selection of seed-corn was strongly
recommended[46] in ancient times by Columella and Celsus; and as Virgil
says,—

      “I’ve seen the largest seeds, tho’ view’d with care,
      Degenerate, unless th’ industrious hand
      Did yearly cull the largest.”

But whether in ancient times selection was methodically pursued we may
well doubt, when we hear how laborious the work has been found by Le
Coutour and Hallett. Although the principle of selection is so
important, yet the little which man has effected, by incessant
efforts[47] during thousands of years, in rendering the plants more
productive or the grains more nutritious than they were in the time of
the old Egyptians, would seem to speak strongly against its efficacy.
But we must not forget that at each successive period the state of
agriculture and the quantity of manure supplied to the land will have
determined the maximum degree of productiveness; for it would be
impossible to cultivate a highly productive variety, unless the land
contained a sufficient supply of the necessary chemical elements.

We now know that man was sufficiently civilised to cultivate the ground
at an immensely remote period; so that wheat might have been improved
long ago up to that standard of excellence which was possible under the
then existing state of agriculture. One small class of facts supports
this view of the slow and gradual improvement of our cereals. In the
most ancient lake-habitations of Switzerland, when men employed only
flint-tools, the most extensively cultivated wheat was a peculiar kind,
with remarkably small ears and grains.[48] “Whilst the grains of the
modern forms are in section from seven to eight millimetres in length,
the larger grains from the lake-habitations are six, seldom seven, and
the smaller ones only four. The ear is thus much narrower, and the
spikelets stand out more horizontally, than in our present forms.” So
again with barley, the most ancient and most extensively cultivated
kind had small ears, and the grains were “smaller, shorter, and nearer
to each other, than in that now grown; without the husk they were 2½
lines long, and scarcely 1½ broad, whilst those now grown have a length
of three lines, and almost the same in breadth.”[49] These
small-grained varieties of wheat and barley are believed by Heer to be
the parent-forms of certain existing allied varieties, which have
supplanted their early progenitors.

Heer gives an interesting account of the first appearance and final
disappearance of the several plants which were cultivated in greater or
less abundance in Switzerland during former successive periods, and
which generally differed more or less from our existing varieties. The
peculiar small-eared and small-grained wheat, already alluded to, was
the commonest kind during the Stone period; it lasted down to the
Helvetico-Roman age, and then became extinct. A second kind was rare at
first, but afterwards became more frequent. A third, the Egyptian wheat
(_T. turgidum_), does not agree exactly with any existing variety, and
was rare during the Stone period. A fourth kind (_T. dicoccum_) differs
from all known varieties of this form. A fifth kind (_T. monococcum_)
is known to have existed during the Stone period only by the presence
of a single ear. A sixth kind, the common _T. spelta,_ was not
introduced into Switzerland until the Bronze age. Of barley, besides
the short-eared and small-grained kind, two others were cultivated, one
of which was very scarce, and resembled our present common _H.
distichum._ During the Bronze age rye and oats were introduced; the
oat-grains being somewhat smaller than those produced by our existing
varieties. The poppy was largely cultivated during the Stone period,
probably for its oil; but the variety which then existed is not now
known. A peculiar pea with small seeds lasted from the Stone to the
Bronze age, and then became extinct; whilst a peculiar bean, likewise
having small seeds, came in at the Bronze period and lasted to the time
of the Romans. These details sound like the descriptions given by
palæontologists of the first appearance, the increasing rarity, and
final extinction or modification of fossil species, embedded in the
successive stages of a geological formation.

Finally, every one must judge for himself whether it is more probable
that the several forms of wheat, barley, rye, and oats are descended
from between ten and fifteen species, most of which are now either
unknown or extinct, or whether they are descended from between four and
eight species, which may have either closely resembled our present
cultivated forms, or have been so widely different as to escape
identification. In this latter case we must conclude that man
cultivated the cereals at an enormously remote period, and that he
formerly practised some degree of selection, which in itself is not
improbable. We may, perhaps, further believe that, when wheat was first
cultivated the ears and grains increased quickly in size, in the same
manner as the roots of the wild carrot and parsnip are known to
increase quickly in bulk under cultivation.

_Maize or Indian Corn: Zea mays._—Botanists are nearly unanimous that
all the cultivated kinds belong to the same species. It is
undoubtedly[50] of American origin, and was grown by the aborigines
throughout the continent from New England to Chili. Its cultivation
must have been extremely ancient, for Tschudi[51] describes two kinds,
now extinct or not known in Peru, which were taken from tombs
apparently prior to the dynasty of the Incas. ‘But there is even
stronger evidence of antiquity, for I found on the coast of Peru[52]
heads of maize, together with eighteen species of recent sea-shell,
embedded in a beach which had been upraised at least 85 feet above the
level of the sea. In accordance with this ancient cultivation, numerous
American varieties have arisen. The aboriginal form has not as yet been
discovered in the wild state. A peculiar kind,[53] in which the grains,
instead of being naked, are concealed by husks as much as eleven lines
in length, has been stated, but on insufficient evidence, to grow wild
in Brazil. It is almost certain that the aboriginal form would have had
its grains thus protected;[54] but the seeds of the Brazilian variety
produce, as I hear from Professor Asa Gray, and as is stated in two
published accounts, either common or husked maize; and it is not
credible that a wild species, when first cultivated, should vary so
quickly and in so great a degree.

Maize has varied in an extraordinary and conspicuous manner.
Metzger,[55] who paid particular attention to the cultivation of this
plant, makes twelve races (unter-art) with numerous sub-varieties: of
the latter some are tolerably constant, others quite inconstant. The
different races vary in height from 15-18 feet to only 16-18 inches, as
in a dwarf variety described by Bonafous. The whole ear is variable in
shape, being long and narrow, or short and thick, or branched. The ear
in one variety is more than four times as long as in a dwarf kind. The
seeds are arranged in the ear in from six to even twenty rows, or are
placed irregularly. The seeds are coloured—white, pale-yellow, orange,
red, violet, or elegantly streaked with black;[56] and in the same ear
there are sometimes seeds of two colours. In a small collection I found
that a single grain of one variety nearly equalled in weight seven
grains of another variety. The shape of the seed varies greatly, being
very flat, or nearly globular, or oval; broader than long, or longer
than broad; without any point, or produced into a sharp tooth, and this
tooth is sometimes recurved. One variety (the rugosa of Bonafous, and
which is extensively cultivated in the United States as sweet corn) has
its seeds curiously wrinkled, giving to the whole ear a singular
appearance. Another variety (the cymosa of Bon.) carries its ears so
crowded together that it is called _maïs à bouquet._ The seeds of some
varieties contain much glucose instead of starch. Male flowers
sometimes appear amongst the female flowers, and Mr. J. Scott has
lately observed the rarer case of female flowers on a true male
panicle, and likewise hermaphrodite flowers.[57] Azara describes[58] a
variety in Paraguay the grains of which are very tender, and he states
that several varieties are fitted for being cooked in various ways. The
varieties also differ greatly in precocity, and have different powers
of resisting dryness and the action of violent wind.[59] Some of the
foregoing differences would certainly be considered of specific value
with plants in a state of nature.

Le Comte Ré states that the grains of all the varieties which he
cultivated ultimately assumed a yellow colour. But Bonafous[60] found
that most of those which he sowed for ten consecutive years kept true
to their proper tints; and he adds that in the valleys of the Pyrenees
and on the plains of Piedmont a white maize has been cultivated for
more than a century, and has undergone no change.

The tall kinds grown in southern latitudes, and therefore exposed to
great heat, require from six to seven months to ripen their seed;
whereas the dwarf kinds, grown in northern and colder climates, require
only from three to four months.[61] Peter Kalm,[62] who particularly
attended to this plant, says, that in the United States, in proceeding
from south to north, the plants steadily diminish in bulk. Seeds
brought from lat. 37° in Virginia, and sown in lat. 43°-44° in New
England, produce plants which will not ripen their seed, or ripen them
with the utmost difficulty. So it is with seed carried from New England
to lat. 45°-47° in Canada. By taking great care at first, the southern
kinds after some years’ culture ripen their seed perfectly in their
northern homes, so that this is an analogous case with that of the
conversion of summer into winter wheat, and conversely. When tall and
dwarf maize are planted together, the dwarf kinds are in full flower
before the others have produced a single flower; and in Pennsylvania
they ripen their seeds six weeks earlier than the tall maize. Metzger
also mentions a European maize which ripens its seed four weeks earlier
than another European kind. With these facts, so plainly showing
inherited acclimatisation, we may readily believe Kalm, who states that
in North America maize and some other plants have gradually been
cultivated further and further northward. All writers agree that to
keep the varieties of maize pure they must be planted separately so
that they shall not cross.

The effects of the climate of Europe on the American varieties is
highly remarkable. Metzger obtained seed from various parts of America,
and cultivated several kinds in Germany. I will give an abstract of the
changes observed[63] in one case, namely, with a tall kind
(Breit-korniger mais, _Zea altissima_) brought from the warmer parts of
America. During the first year the plants were twelve feet high, and a
few seeds were perfected; the lower seeds in the ear kept true to their
proper form, but the upper seeds became slightly changed. In the second
generation the plants were from nine to ten feet in height, and ripened
their seed better; the depression on the outer side of the seed had
almost disappeared, and the original beautiful white colour had become
duskier. Some of the seeds had even become yellow, and in their now
rounded form they approached common European maize. In the third
generation nearly all resemblance to the original and very distinct
American parent-form was lost. In the sixth generation this maize
perfectly resembled a European variety, described as the second
sub-variety of the fifth race. When Metzger published his book, this
variety was still cultivated near Heidelberg, and could be
distinguished from the common kind only by a somewhat more vigorous
growth. Analogous results were obtained by the cultivation of another
American race, the “white-tooth corn,” in which the tooth nearly
disappeared even in the second generation. A third race, the
“chicken-corn,” did not undergo so great a change, but the seeds became
less polished and pellucid. In the above cases the seeds were carried
from a warm to a colder climate. But Fritz Müller informs me that a
dwarf variety with small rounded seeds (papa-gaien-mais), introduced
from Germany into S. Brazil, produces plants as tall, with seeds as
flat, as those of the kind commonly cultivated there.

These facts afford the most remarkable instance known to me of the
direct and prompt action of climate on a plant. It might have been
expected that the tallness of the stem, the period of vegetation, and
the ripening of the seed, would have been thus affected; but it is a
much more surprising fact that the seeds should have undergone so rapid
and great a change. As, however, flowers, with their product the seed,
are formed by the metamorphosis of the stem and leaves, any
modification in these latter organs would be apt to extend, through
correlation, to the organs of fructification.

_Cabbage (Brassica oleracea)._—Every one knows how greatly the various
kinds of cabbage differ in appearance. In the Island of Jersey, from
the effects of particular culture and of climate a stalk has grown to
the height of sixteen feet, and “had its spring shoots at the top
occupied by a magpie’s nest:” the woody stems are not unfrequently from
ten to twelve feet in height, and are there used as rafters[64] and as
walking-sticks. We are thus reminded that in certain countries plants
belonging to the generally herbaceous order of the Cruciferæ are
developed into trees. Every one can appreciate the difference between
green or red cabbages with great single heads; Brussel-sprouts with
numerous little heads; broccolis and cauliflowers with the greater
number of their flowers in an aborted condition, incapable of producing
seed, and borne in a dense corymb instead of an open panicle; savoys
with their blistered and wrinkled leaves; and borecoles and kails,
which come nearest to the wild parent-form. There are also various
frizzled and laciniated kinds, some of such beautiful colours that
Vilmorin in his Catalogue of 1851 enumerates ten varieties which are
valued solely for ornament. Some kinds are less commonly known, such as
the Portuguese Couve Tronchuda, with the ribs of its leaves greatly
thickened; and the Kohlrabi or choux-raves, with their stems enlarged
into great turnip-like masses above the ground; and the recently formed
new race[65] of the choux-raves, already including nine sub-varieties,
in which the enlarged part lies beneath the ground like a turnip.

Although we see such great differences in the shape, size, colour,
arrangement, and manner of growth of the leaves and stem, and of the
flower-stems in the broccoli and cauliflower, it is remarkable that the
flowers themselves, the seed-pods and seeds, present extremely slight
differences or none at all.[66] I compared the flowers of all the
principal kinds; those of the Couve Tronchuda are white and rather
smaller than in common cabbages; those of the Portsmouth broccoli have
narrower sepals, and smaller, less elongated petals; and in no other
cabbage could any difference be detected. With respect to the
seed-pods, in the purple Kohlrabi alone, do they differ, being a little
longer and narrower than usual. I made a collection of the seeds of
twenty-eight different kinds, and most of them were undistinguishable;
when there was any difference it was excessively slight; thus, the
seeds of various broccolis and cauliflowers, when seen in mass, are a
little redder; those of the early green Ulm savoy are rather smaller;
and those of the Breda kail slightly larger than usual, but not larger
than the seeds of the wild cabbage from the coast of Wales. What a
contrast in the amount of difference is presented if, on the one hand,
we compare the leaves and stems of the various kinds of cabbage with
their flowers, pods, and seeds, and on the other hand the corresponding
parts in the varieties of maize and wheat! The explanation is obvious;
the seeds alone are valued in our cereals, and their variations have
been selected; whereas the seeds, seed-pods, and flowers, have been
utterly neglected in the cabbage, whilst many useful variations in
their leaves and stems have been noticed and preserved from an
extremely remote period, for cabbages were cultivated by the old
Celts.[67]

It would be useless to give a classified description[68] of the
numerous races, sub-races, and varieties of the cabbage; but it may be
mentioned that Dr. Lindley has lately proposed[69] a system founded on
the state of development of the terminal and lateral leaf-buds. Thus:
I. All the leaf-buds active and open, as in the wild-cabbage, kail,
etc. II. All the leaf-buds active, but forming heads, as in
Brussel-sprouts, etc. III. Terminal leaf-bud alone active, forming a
head as in common cabbages, savoys, etc. IV. Terminal leaf-bud alone
active, and open, with most of the flowers abortive and succulent, as
in the cauliflower and broccoli. V. All the leaf-buds active and open,
with most of the flowers abortive and succulent, as in the
sprouting-broccoli. This latter variety is a new one, and bears the
same relation to common broccoli, as Brussel-sprouts do to common
cabbages; it suddenly appeared in a bed of common broccoli, and was
found faithfully to transmit its newly-acquired and remarkable
characters.

The principal kinds of cabbage existed at least as early as the
sixteenth century,[70] so that numerous modifications of structure have
been inherited for a long period. This fact is the more remarkable as
great care must be taken to prevent the crossing of the different
kinds. To give proof of this: I raised 233 seedlings from cabbages of
different kinds, which had purposely been planted near each other, and
of the seedlings no less than 155 were plainly deteriorated and
mongrelised; nor were the remaining 78 all perfectly true. It may be
doubted whether many permanent varieties have been formed by
intentional or accidental crosses; for such crossed plants are found to
be very inconstant. One kind, however, called “Cottager’s Kail,” has
lately been produced by crossing common kail and Brussel-sprouts,
recrossed with purple broccoli,[71] and is said to be true; but plants
raised by me were not nearly so constant in character as any common
kind of cabbage.

Although most of the kinds keep true if carefully preserved from
crossing, yet the seed-beds must be yearly examined, and a few
seedlings are generally found false; but even in this case the force of
inheritance is shown, for, as Metzger has remarked[72] when speaking of
Brussel-sprouts, the variations generally keep to their “unter art,” or
main race. But in order that any kind may be truly propagated there
must be no great change in the conditions of life; thus cabbages will
not form heads in hot countries, and the same thing has been observed
with an English variety grown during an extremely warm and damp autumn
near Paris.[73] Extremely poor soil also affects the characters of
certain varieties.

Most authors believe that all the races are descended from the wild
cabbage found on the western shores of Europe; but Alph. De
Candolle[74] forcibly argues, on historical and other grounds, that it
is more probable that two or three closely allied forms, generally
ranked as distinct species, still living in the Mediterranean region,
are the parents, now all commingled together, of the various cultivated
kinds. In the same manner as we have often seen with domesticated
animals, the supposed multiple origin of the cabbage throws no light on
the characteristic differences between the cultivated forms. If our
cabbages are the descendants of three or four distinct species, every
trace of any sterility which may originally have existed between them
is now lost, for none of the varieties can be kept distinct without
scrupulous care to prevent intercrossing.

The other cultivated forms of the genus Brassica are descended,
according to the view adopted by Godron and Metzger,[75] from two
species, _B. napus_ and _rapa_; but according to other botanists from
three species; whilst others again strongly suspect that all these
forms, both wild and cultivated, ought to be ranked as a single
species. _Brassica napus_ has given rise to two large groups, namely,
Swedish turnips (believed to be of hybrid origin)[76] and Colzas, the
seeds of which yield oil. _Brassica rapa_ (of Koch) has also given rise
to two races, namely, common turnips and the oil-giving rape. The
evidence is unusually clear that these latter plants, though so
different in external appearance, belong to the same species; for the
turnip has been observed by Koch and Godron to lose its thick roots in
uncultivated soil; and when rape and turnips are sown together they
cross to such a degree that scarcely a single plant comes true.[77]
Metzger by culture converted the biennial or winter rape into the
annual or summer rape,—varieties which have been thought by some
authors to be specifically distinct.[78]

In the production of large, fleshy, turnip-like stems, we have a case
of analogous variation in three forms which are generally considered as
distinct species. But scarcely any modification seems so easily
acquired as a succulent enlargement of the stem or root—that is, a
store of nutriment laid up for the plant’s own future use. We see this
in our radishes, beet, and in the less generally known “turnip-rooted”
celery, and in the finocchio, or Italian variety of the common fennel.
Mr. Buckman has lately proved by his interesting experiments bow
quickly the roots of the wild parsnip can be enlarged, as Vilmorin
formerly proved in the case of the carrot.[79]

This latter plant, in its cultivated state, differs in scarcely any
character from the wild English carrot, except in general luxuriance
and in the size and quality of its roots; but ten varieties, differing
in the colour, shape, and quality of the root, are cultivated in
England and come true by seed.[80] Hence with the carrot, as in so many
other cases, for instance with the numerous varieties and sub-varieties
of the radish, that part of the plant which is valued by man, falsely
appears alone to have varied. The truth is that variations in this part
alone have been selected; and the seedlings inheriting a tendency to
vary in the same way, analogous modifications have been again and again
selected, until at last a great amount of change has been effected.

With respect to the radish, M. Carrière, by sowing the seed of the wild
_Raphanus raphanistrum_ in rich soil, and by continued selection during
several generations, raised many varieties, closely like the cultivated
radish (_R. sativus_) in their roots, as well as the wonderful Chinese
variety, _R. caudatus_: (see ‘Journal d’Agriculture pratique,’ tom. i,
1869, p. 159; also a separate essay ‘Origine des Plantes Domestiques,’
1869.) _Raphanus raphanistrum_ and _sativus_ have often been ranked as
distinct species, and owing to differences in their fruit even as
distinct genera; but Professor Hoffman (‘Bot. Zeitung,’ 1872, p. 482)
has now shown that these differences, remarkable as they are, graduate
away, the fruit of _R. caudatus_ being intermediate. By cultivating _R.
raphanistrum_ during several generations (ibid., 1873, p. 9), Professor
Hoffman also obtained plants bearing fruits like those of _R. sativus._

_Pea (Pisum sativum)._—Most botanists look at the garden-pea as
specifically distinct from the field-pea (_P. arvense_). The latter
exists in a wild state in Southern Europe; but the aboriginal parent of
the garden-pea has been found by one collector alone, as he states, in
the Crimea.[81] Andrew Knight crossed, as I am informed by the Rev. A.
Fitch, the field-pea with a well-known garden variety, the Prussian
pea, and the cross seems to have been perfectly fertile. Dr. Alefield
has recently studied[82] the genus with care, and, after having
cultivated about fifty varieties, concludes that certainly they all
belong to the same species. It is an interesting fact already alluded
to, that, according to O. Heer,[83] the peas found in the
lake-habitations of Switzerland of the Stone and Bronze ages, belong to
an extinct variety, with exceedingly small seeds, allied to _P.
arvense_ or the field-pea. The varieties of the common garden-pea are
numerous, and differ considerably from one another. For comparison I
planted at the same time forty-one, English and French varieties. They
differed greatly in height,— namely from between 6 and 12 inches to 8
feet,[84]—in manner of growth, and in period of maturity. Some differ
in general aspect even while only two or three inches in height. The
stems of the _Prussian_ pea are much branched. The tall kinds have
larger leaves than the dwarf kinds, but not in strict proportion to
their height:—_Hair’s Dwarf Monmouth_ has very large leaves, and the
_Pois nain hatif,_ and the moderately tall _ Blue Prussian,_ have
leaves about two-thirds of the size of the tallest kind. In the
_Danecroft_ the leaflets are rather small and a little pointed; in the
_Queen of Dwarfs_ rather rounded; and in the _Queen of England_ broad
and large. In these three peas the slight differences in the shape of
the leaves are accompanied by slight differences in colour, in the
_Pois géant sans parchemin,_ which bears purple flowers, the leaflets
in the young plant are edged with red; and in all the peas with purple
flowers the stipules are marked with red.

In the different varieties, one, two, or several flowers in a small
cluster, are borne on the same peduncle; and this is a difference which
is considered of specific value in some of the Leguminosæ. In all the
varieties the flowers closely resemble each other except in colour and
size. They are generally white, sometimes purple, but the colour is
inconstant even in the same variety. In _Warner’s Emperor,_ which is a
tall kind, the flowers are nearly double the size of the _Pois nain
hatif_; but _Hair’s Dwarf Monmouth,_ which has large leaves, likewise
has large flowers. The calyx in the _Victoria Marrow_ is large, and in
_Bishop’s Long Pod_ the sepals are rather narrow. In no other kind is
there any difference in the flower.

The pods and seeds, which with natural species afford such constant
characters, differ greatly in the cultivated varieties of the pea; and
these are the valuable, and consequently the selected parts. _Sugar
peas,_ or _P_, are remarkable from their thin pods, which, whilst
young, are cooked and eaten whole; and in this group, which, according
to Mr. Gordon includes eleven sub-varieties, it is the pod which
differs most; thus _Lewis’s Negro-podded pea_ has a straight, broad,
smooth, and dark-purple pod, with the husk not so thin as in the other
kinds; the pod of another variety is extremely bowed; that of the _Pois
géant_ is much pointed at the extremity; and in the variety “à grands
cosses” the peas are seen through the husk in so conspicuous a manner
that the pod, especially when dry, can hardly at first be recognised as
that of a pea.

In the ordinary varieties the pods also differ much in size;—in colour,
that of _Woodford’s Green Marrow_ being bright-green when dry, instead
of pale brown, and that of the purple-podded pea being expressed by its
name;—in smoothness, that of _Danecroft_ being remarkably glossy,
whereas that of the _Ne plus ultra_ is rugged; in being either nearly
cylindrical, or broad and flat;—in being pointed at the end, as in
_Thurston’s Reliance,_ or much truncated, as in the _American Dwarf._
In the _Auvergne pea_ the whole end of the pod is bowed upwards. In the
_Queen of the Dwarfs_ and in _Scimitar peas_ the pod is almost elliptic
in shape. I here give drawings of the four most distinct pods produced
by the plants cultivated by me.

Illustration: Fig. 41.—Pods of the Common Pea

In the pea itself we have every tint between almost pure white, brown,
yellow, and intense green; in the varieties of the _Sugar peas_ we have
these same tints, together with red passing through fine purple into a
dark chocolate tint. These colours are either uniform or distributed in
dots, striæ, or moss-like marks; they depend in some cases on the
colour of the cotyledons seen through the skin, and in other cases on
the outer coats of the pea itself. In the different varieties, the pods
contain, according to Mr. Gordon, from eleven or twelve to only four or
five peas. The largest peas are nearly twice as much in diameter as the
smallest; and the latter are not always borne by the most dwarfed
kinds. Peas differ much in shape, being smooth and spherical, smooth
and oblong, nearly oval in the _Queen of the Dwarfs,_ and nearly
cubical and crumpled in many of the larger kinds.

With respect to the value of the differences between the chief
varieties, it cannot be doubted that, if one of the tall _Sugar-peas,_
with purple flowers, thin-skinned pods of an extraordinary shape,
including large, dark-purple peas, grew wild by the side of the lowly
_Queen of the Dwarfs,_ with white flowers, greyish-green, rounded
leaves, scimitar-like pods, containing oblong, smooth, pale-coloured
peas, which became mature at a different season: or by the side of one
of the gigantic sorts, like the _Champion of England,_ with leaves of
great size, pointed pods, and large, green, crumpled, almost cubical
peas,—all three kinds would be ranked as distinct species.

Andrew Knight[85] has observed that the varieties of peas keep very
true, because they are not crossed by insects. As far as the fact of
keeping true is concerned, I hear from Mr. Masters of Canterbury, well
known as the originator of several new kinds, that certain varieties
have remained constant for a considerable time,—for instance, _Knight’s
Blue Dwarf,_ which came out about the year 1820.[86] But the greater
number of varieties have a singularly short existence: thus Loudon
remarks[87] that “sorts which were highly approved in 1821, are now, in
1833, nowhere to be found;” and on comparing the lists of 1833 with
those of 1855, I find that nearly all the varieties have changed. Mr.
Masters informs me that the nature of the soil causes some varieties to
lose their character. As with other plants, certain varieties can be
propagated truly, whilst others show a determined tendency to vary;
thus two peas differing in shape, one round and the other wrinkled,
were found by Mr. Masters within the same pod, but the plants raised
from the wrinkled kind always evinced a strong tendency to produce
round peas. Mr. Masters also raised from a plant of another variety
four distinct sub-varieties, which bore blue and round, white and
round, blue and wrinkled, and white and wrinkled peas; and although he
sowed these four varieties separately during several successive years,
each kind always reproduced all four kinds mixed together!

With respect to the varieties not naturally intercrossing, I have
ascertained that the pea, which in this respect differs from some other
Leguminosæ, is perfectly fertile without the aid of insects. Yet I have
seen humble-bees whilst sucking the nectar depress the keel-petals, and
become so thickly dusted with pollen, that it could hardly fail to be
left on the stigma of the next flower which was visited. Nevertheless,
distinct varieties growing closely together rarely cross; and I have
reason to believe that this is due to their stigmas being prematurely
fertilised in this country by pollen from the same flower. The
horticulturists who raise seed-peas are thus enabled to plant distinct
varieties close together without any bad consequences; and it is
certain, as I have myself found, that true seed may be saved during at
least several generations under these circumstances.[88] Mr. Fitch
raised, as he informs me, one variety for twenty years, and it always
came true, though grown close to other varieties. From the analogy of
kidney-beans I should have expected[89] that varieties thus
circumstanced would have occasionally crossed; and I shall give in the
eleventh chapter two cases of this having occurred, as shown (in a
manner hereafter to be explained) by the pollen of the one variety
having acted directly on the seeds of the other. Whether many of the
new varieties which incessantly appear are due to such occasional and
accidental crosses, I do not know. Nor do I know whether the short
existence of almost all the numerous varieties is the result of mere
change of fashion, or of their having a weak constitution, from being
the product of long-continued self-fertilisation. It may, however, be
noticed that several of Andrew Knight’s varieties, which have endured
longer than most kinds, were raised towards the close of the last
century by artificial crosses; some of them, I believe, were still
vigorous in 1860; but now, in 1865, a writer, speaking[90] of Knight’s
four kinds of marrows, says, they have acquired a famous history, but
their glory has departed.

With respect to Beans (_Faba vulgaris_), I will say but little. Dr.
Alefield has given[91] short diagnostic characters of forty varieties.
Everyone who has seen a collection must have been struck with the great
difference in shape, thickness, proportional length and breadth,
colour, and size which beans present. What a contrast between a Windsor
and Horse-bean! As in the case of the pea, our existing varieties were
preceded during the Bronze age in Switzerland[92] by a peculiar and now
extinct variety producing very small beans.[93]

_Potato (Solanum tuberosum)._—There is little doubt about the parentage
of this plant; for the cultivated varieties differ extremely little in
general appearance from the wild species, which can be recognised in
its native land at the first glance.[94] The varieties cultivated in
Britain are numerous; thus Lawson[95] gives a description of 175 kinds.
I planted eighteen kinds in adjoining rows; their stems and leaves
differed but little, and in several cases there was as great a
difference between the individuals of the same variety as between the
different varieties. The flower varied in size, and in colour between
white and purple, but in no other respect, except that in one kind the
sepals were somewhat elongated. One strange variety has been described
which always produces two sorts of flowers, the first double and
sterile, the second single and fertile.[96] The fruit or berries also
differ, but only in a slight degree.[97] The varieties are liable in
very different degree to the attack of the Colorado potato-beetle.[98]

The tubers, on the other hand, present a wonderful amount of diversity.
This fact accords with the principle that the valuable and selected
parts of all cultivated productions present the greatest amount of
modification. They differ much in size and shape, being globular, oval,
flattened, kidney-like, or cylindrical. One variety from Peru is
described[99] as being quite straight, and at least six inches in
length, though no thicker than a man’s finger. The eyes or buds differ
in form, position, and colour. The manner in which the tubers are
arranged on the so-called roots or rhizomes is different; thus, in the
_gurken-kartoffeln_ they form a pyramid with the apex downwards, and in
another variety they bury themselves deep in the ground. The roots
themselves run either near the surface or deep in the ground. The
tubers also differ in smoothness and colour, being externally white,
red, purple, or almost black, and internally white, yellow, or almost
black. They differ in flavour and quality, being either waxy or mealy;
in their period of maturity, and in their capacity for long
preservation.

As with many other plants which have been long propagated by bulbs,
tubers, cuttings, etc., by which means the same individual is exposed
during a length of time to diversified conditions, seedling potatoes
generally display innumerable slight differences. Several varieties,
even when propagated by tubers, are far from constant, as will be seen
in the chapter on Bud-variation. Dr. Anderson[100] procured seed from
an Irish purple potato, which grew far from any other kind, so that it
could not at least in this generation have been crossed, yet the many
seedlings varied in almost every possible respect, so that “scarcely
two plants were exactly alike.” Some of the plants which closely
resembled each other above ground, produced extremely dissimilar
tubers; and some tubers which externally could hardly be distinguished,
differed widely in quality when cooked. Even in this case of extreme
variability, the parent-stock had some influence on the progeny, for
the greater number of the seedlings resembled in some degree the parent
Irish potato. Kidney potatoes must be ranked amongst the most highly
cultivated and artificial races; nevertheless their peculiarities can
often be strictly propagated by seed. A great authority, Mr.
Rivers,[101] states that “seedlings from the ash-leaved kidney always
bear a strong resemblance to their parent. Seedlings from the
fluke-kidney are still more remarkable for their adherence to their
parent stock, for, on closely observing a great number during two
seasons, I have not been able to observe the least difference, either
in earliness, productiveness, or in the size or shape of their tubers.”

REFERENCES

 [1] ‘Géographie botanique raisonnée,’ 1855, pp. 810 to 991.

 [2] Review by Mr. Bentham in ‘Hort. Journal,’ vol. ix 1855, p. 133,
 entitled, ‘Historical Notes on cultivated Plants,’ by Dr. A.
 Targioni-Tozzetti. _See also_ ‘Edinburgh Review,’ 1866, p. 510.

 [3] ‘Hist. Notes,’ as above by Targioni-Tozzetti.

 [4] ‘Considérations sur les Céréales,’ 1842, p. 37. ‘Géographie Bot.,’
 1855, p. 930. “Plus on suppose l’agriculture ancienne et remontant à
 une époque d’ignorance, plus il est probable que les cultivateurs
 avaient choisi des especes offrant à l’origine meme un avantage
 incontestable.”

 [5] Dr. Hooker has given me this information. _See also_ his
 ‘Himalayan Journals,’ 1854, vol. ii. p. 49.

 [6] ‘Travels in Central Africa,’ Eng. translat. vol. i. pp. 529 and
 390; vol. ii. pp. 29, 265, 270. Livingstone’s ‘Travels,’ p. 551.

 [7] For instance in both North and South America. Mr. Edgeworth
 (‘Journal Proc. Linn. Soc.,’ vol. vi. Bot., 1862, p. 181) states that
 in the deserts of the Punjab poor women sweep up, “by a whisk into
 straw baskets,” the seeds of four genera of grasses, namely, of
 Agrostis, Panicum, Cenchrus, and Pennisetum, as well as the seeds of
 four other genera belonging to distinct families.

 [8] Prof. O. Heer, ‘Die Pflanzen der Pfahlbauten, 1866, aus dem
 Neujahr. Naturforsch. Geselschaft,’ 1866; and Dr. H. Christ in
 Rutimeyer’s ‘Die Fauna der Pfahlbauten,’ 1861, s. 226.

 [9] ‘Travels,’ p. 535. Du Chaillu, ‘Adventures in Equatorial Africa,’
 1861, p. 445.

 [10] In Tierra del Fuego the spot where wigwams had formerly stood
 could be distinguished at a great distance by the bright green tint of
 the native vegetation.

 [11] ‘American Acad. of Arts and Sciences,’ April 10th, 1860, p. 413.
 Downing, ‘The Fruits of America,’ 1845, p. 261.

 [12] ‘Journals of Expeditions in Australia,’ 1841, vol. ii. p. 292.

 [13] Darwin’s ‘Journal of Researches,’ 1845, p. 215.

 [14] De Candolle has tabulated the facts in the most interesting
 manner in his ‘Géographie Bot.,’ p. 986.

 [15] ‘Flora of Australia,’ Introduction, p. 110.

 [16] For Canada, _see_ J. Cartier’s Voyage in 1534; for Florida, _see_
 Narvaez and Ferdinand de Soto’s Voyages. As I have consulted these and
 other old Voyages in more than one general collection of Voyages, I do
 not give precise references to the pages. _See also,_ for several
 references Asa Gray, in the ‘American Journal of Science,’ vol. xxiv.
 Nov. 1857, p. 441. For the traditions of the natives of New Zealand
 _see_ Crawfurd’s ‘Grammar and Dict. of the Malay Language,’ 1852, p.
 260.

 [17] _See,_ for example, Mr. Hewett C. Watson’s remarks on our wild
 plums and cherries and crabs: ‘Cybele Britannica,’ vol. i. pp. 330,
 334, etc. Van Mons (in his ‘Arbres Fruitiers,’ 1835, tom. i. p. 444)
 declares that he has found the types of all our cultivated varieties
 in wild seedlings, but then he looks on these seedlings as so many
 aboriginal stocks.

 [18] _See_ A. De Candolle, ‘Géograph. Bot.,’ 1855, p. 928 _et seq._
 Godron, ‘De l’Espèce,’ 1859, tom. ii. p. 70; and Metzger, ‘Die
 Getreidearten,’ etc., 1841.

 [19] Mr. Bentham, in his review, entitled ‘Hist. Notes on cultivated
 Plants,’ by Dr. A. Targioni-Tozzetti, in ‘Journal of Hort. Soc.,’ vol.
 ix., 1855, p. 133. He informs me that he still retains the same
 opinion.

 [20] ‘Géograph. Bot.,’ p. 928. The whole subject is discussed with
 admirable fulness and knowledge.

 [21] Godron, ‘De l’Espèce,’ tom. ii. p. 72. A few years ago the
 excellent, though misinterpreted, observations of M. Fabre led many
 persons to believe that wheat was a modified descendant of Ægilops;
 but M. Godron (tom. i. p. 165) has shown by careful experiments that
 the first step in the series, viz. _ Ægilops triticoides,_ is a hybrid
 between wheat and _ Æ. ovata._ The frequency with which these hybrids
 spontaneously arise, and the gradual manner in which the _ Æ.
 triticoides_ becomes converted into true wheat, alone leave any doubt
 with respect to M. Godron’s conclusions.

 [22] ‘Die Verbreitungsmittel der Pflanzen,’ 1873, p. 129.

 [23] Report to British Association for 1857, p. 207.

 [24] ‘Considérations sur les Céréales,’ 1842-43, p. 29.

 [25] ‘Travels in the Himalayan Provinces,’ etc., 1841, vol. i. p. 224.

 [26] Col. J. Le Couteur on the ‘Varieties of Wheat,’ pp. 23, 79.

 [27] Loiseleur-Deslongchamps, ‘Consid. sur les Céréales,’ p. 11.

 [28] _See_ an excellent review in Hooker’s ‘Journ. of Botany,’ vol.
 viii. p. 82 note.

 [29] ‘De l’Espèce,’ tom. ii. p. 73.

 [30] Ibid., tom. ii. p. 75.

 [31] For Dalbret and Philippar, _see_ Loiseleur-Deslongchamps ‘Consid.
 sur les Céréales,’ pp. 45, 70. Le Couteur on Wheat, pp. 6, 14-17.

 [32] _See_ his Essay on ‘Pedigree in Wheat,’ 1862; also paper read
 before the British Association, 1869, and other publications.

 [33] ‘Varieties of Wheat,’ Introduction, p. 6. Marshall, in his ‘Rural
 Economy of Yorkshire,’ vol. ii. p. 9, remarks that “in every field of
 corn there is as much variety as in a herd of cattle.”

 [34] ‘Gardener’s Chron.’ and ‘Agricult. Gazette,’ 1862, p. 963.

 [35] ‘Gardener’s Chron.’ Nov. 1868, p. 1199.

 [36] ‘Getreidearten,’ 1841, s. 66, 91, 92, 116, 117.

 [37] Quoted by Godron, ‘De l’Espèce,’ vol. ii. p. 74. So it is,
 according to Metzger (‘Getreidearten,’ s. 18), with summer and winter
 barley.

 [38] Loiseleur-Deslongchamps, ‘Céréales,’ part ii. p. 224. Le Couteur,
 p. 70. Many other accounts could be added.

 [39] ‘Travels in North America,’ 1753-1761, Eng. translat., vol. iii
 p. 165.

 [40] ‘Céréales,’ part ii. pp. 179-183.

 [41] ‘On the Varieties of Wheat,’ Introduct., p. 7. _See_ Marshall
 ‘Rural Econ. of Yorkshire,’ vol. ii. p. 9. With respect to similar
 cases of adaptation in the varieties of oats, _ see_ some interesting
 papers in the ‘Gardener’s Chron. and Agricult. Gazette,’ 1850, pp.
 204, 219.

 [42] ‘On the Varieties of Wheat,’ p. 59. Mr. Shirreff, and a higher
 authority cannot be given (‘Gard. Chron. and Agricult. Gazette,’ 1862,
 p. 963), says, “I have never seen grain which has either been improved
 or degenerated by cultivation, so as to convey the change to the
 succeeding crop.”

 [43] Alph. De Candolle, ‘Géograph. Bot.,’ p. 930.

 [44] ‘Pflanzen der Pfahlbauten,’ 1866.

 [45] ‘Les Céréales,’ p. 94.

 [46] Quoted by Le Couteur, p. 16.

 [47] A. De Candolle, ‘Geograph. Bot.,’ p. 932.

 [48] O. Heer ‘Die Pflanzen der Pfahlbauten,’ 1866. The following
 passage is quoted from Dr. Christ, in ‘Die Fauna der Pfahlbauten, von
 Dr. Rütimeyer,’ 1861, s. 225.

 [49] Heer, as quoted by Carl Vogt, ‘Lectures on Man,’ Eng. translat.,
 p. 355.

 [50] _See_ Alph. De Candolle’s long discussion in his ‘Géograph.
 Bot.,’ p. 942. With respect to New England, _ see_ Silliman’s
 ‘American Journal,’ vol. xliv. p. 99.

 [51] ‘Travels in Peru,’ Eng. translat., p. 177.

 [52] ‘Geolog. Observ. on S. America,’ 1846, p. 49.

 [53] This maize is figured in Bonafous’ magnificent work, ‘Hist. Nat.
 du Mais,’ 1836, Pl. v. bis, and in the ‘Journal of Hort. Soc.,’ vol.
 i. 1846, p. 115, where an account is given of the result of sowing the
 seed. A young Guarany Indian, on seeing this kind of maize, told
 Auguste St. Hilaire (_see_ De Candolle, ‘Géograph. Bot.,’ p. 951) that
 it grew wild in the humid forests of his native land. Mr.
 Teschemacher. in ‘Proc. Boston Soc. Hist.,’ Oct. 19th, 1842, gives an
 account of sowing the seed.

 [54] Moquin-Tandon, ‘Eléments de Tératologie,’ 1841, p. 126.

 [55] ‘Die Getreidearten,’ 1841, s. 208. I have modified a few of
 Metzger’s statements in accordance with those made by Bonafous in his
 great work ‘Hist. Nat. du Mais,’ 1836.

 [56] Godron ‘De l’Espèce,’ tom. ii. p. 80; Al. De Candolle, ibid., p.
 951.

 [57] ‘Transact. Bot. Soc. of Edinburgh,’ vol. viii. p. 60.

 [58] ‘Voyages dans l’Amérique Méridionale,’ tom. i. p. 147.

 [59] Bonafous’ ‘Hist. Nat. du Maïs,’ p. 31.

 [60] Ibid., p. 31.

 [61] Metzger, ‘Getreidearten,’ s. 206.

 [62] ‘Description of Maize,’ by P. Kalm, 1752, in ‘Swedish Acts,’ vol.
 iv. I have consulted an old English MS. translation.

 [63] ‘Getreidearten,’ s. 208.

 [64] Cabbage Timber, ‘Gardener’s Chron.,’ 1856, p. 744, quoted from
 Hooker’s ‘Journal of Botany.’ A walking-stick made from a
 cabbage-stalk is exhibited in the Museum at Kew.

 [65] ‘Journal de la Soc. Imp. d’Horticulture,’ 1855, p. 254, quoted
 from ‘Gartenflora,’ April, 1855.

 [66] Godron ‘De l’Espèce,’ tom. ii. p. 52; Metzger, ‘Syst.
 Beschreibung der Kult. Kohlarten,’ 1833, s. 6.

 [67] Regnier, ‘De l’Economie Publique des Celtes,’ 1818, p. 438.

 [68] _See_ the elder De Candolle, in ‘Transact. of Hort. Soc.,’ vol.
 v.; and Metzger ‘Kohlarten,’ etc.

 [69] ‘Gardener’s Chronicle,’ 1859, p. 992.

 [70] Alph. De Candolle, ‘Géograph. Bot.’ pp. 842 and 989.

 [71] ‘Gardener’s Chron.,’ Feb. 1858, p. 128.

 [72] ‘Kohlarten,’ s. 22.

 [73] Godron, ‘De l’Espèce,’ tom. ii. p. 52; Metzger, ‘Kohlarten,’ s.
 22.

 [74] ‘Géograph. Bot.,’ p. 840.

 [75] Godron, ‘De l’Espèce,’ tom. ii. p. 54; Metzger, ‘Kohlarten,’ s.
 10.

 [76] ‘Gardener’s Chron. and Agricult. Gazette,’ 1856, p. 729. _ See,_
 more especially, ibid., 1868, p. 275: the writer asserts that he
 planted a variety of cabbage (_B. oleracea_) close to turnips (_B.
 rapa_) and raised from the crossed seedlings true Swedish turnips.
 These latter plants ought, therefore, to be classed with cabbages or
 turnips, and not under _B. napus._

 [77] ‘Gardener’s Chron. and Agricult. Gazette,’ 1855, p. 730.

 [78] Metzger, ‘Kohlarten,’ s. 51.

 [79] These experiments by Vilmorin have been quoted by many writers.
 An eminent botanist, Prof. Decaisne, has lately expressed doubts on
 the subject from his own negative results, but these cannot be valued
 equally with positive results. On the other hand, M. Carrière has
 lately stated (‘Gard. Chronicle,’ 1865, p. 1154), that he took seed
 from a wild carrot, growing far from any cultivated land, and even in
 the first generation the roots of his seedlings differed in being
 spindle-shaped, longer, softer, and less fibrous than those of the
 wild plant. From these seedlings he raised several distinct varieties.

 [80] Loudon’s ‘Encyclop. of Gardening,’ p. 835.

 [81] Alph. De Candolle ‘Géograph. Bot.,’ 960. Mr. Bentham (‘Hort.
 Journal,’ vol. ix. 1855, p. 141) believes that garden and field peas
 belong to the same species, and in this respect he differs from Dr.
 Targioni.

 [82] ‘Botanische Zeitung,’ 1860, s. 204.

 [83] ‘Die Pflanzen der Pfahlbauten,’ 1866, s. 23.

 [84] A variety called the Rounciva attains this height, as is stated
 by Mr. Gordon in ‘Transact. Hort. Soc.’ (2nd series), vol. i. 1835, p.
 374, from which paper I have taken some facts.

 [85] ‘Phil. Tract.,’ 1799, p. 196.

 [86] ‘Gardener’s Magazine,’ vol. i., 1826, p. 153.

 [87] ‘Encyclopædia of Gardening,’ p. 823.

 [88] _See_ Dr. Anderson to the same effect in the ‘Bath Soc.
 Agricultural Papers,’ vol. iv. p. 87.

 [89] I have published full details of experiments on this subject in
 the ‘Gardener’s Chronicle,’ 1857, Oct. 25th.

 [90] ‘Gardener’s Chronicle,’ 1865, p. 387.

 [91] ‘Bonplandia,’ x., 1862, s. 348.

 [92] Heer, ‘Die Pflanzen der Pfahlbauten,’ 1866, s. 22.

 [93] Mr. Bentham informs me that in Poitou and the adjoining parts of
 France, varieties of _Phaseolus vulgaris_ are extremely numerous, and
 so different that they were described by Savi as distinct species. Mr.
 Bentham believes that all are descended from an unknown eastern
 species. Although the varieties differ so greatly in stature and in
 their seeds, “there is a remarkable sameness in the neglected
 characters of foliage and flowers, and especially in the bracteoles,
 an insignificant character in the eyes even of botanists.”

 [94] Darwin, ‘Journal of Researches,’ 1845, p. 285. Sabine, in
 ‘Transact. Hort. Soc.,’ vol. v. p. 249.

 [95] ‘Synopsis of the Vegetable Products of Scotland,’ quoted in
 Wilson’s ‘British Farming,’ p. 317.

 [96] Sir G. Mackenzie, in ‘Gardener’s Chronicle,’ 1845, p. 790.

 [97] Putsche und Vertuch ‘Versuch einer Monographie der Kartoffeln,’
 1819, s. 9, 15. _See also_ Dr. Anderson ‘Recreations in Agriculture,’
 vol. iv. p. 325.

 [98] Walsh, ‘The American Entomologist,’ 1869, p. 160. Also S. Tenney,
 ‘The American Naturalist,’ May 1871, p. 171.

 [99] ‘Gardener’s Chronicle,’ 1862, p. 1052.

 [100] ‘Bath Society Agricult. Papers,’ vol. v. p. 127. And
 ‘Recreations in Agriculture,’ vol. v. p. 86.

 [101] ‘Gardener’s Chronicle,’ 1863, p. 643.




CHAPTER X. PLANTS _continued_—FRUITS—ORNAMENTAL TREES—FLOWERS.

FRUITS. GRAPES: VARY IN ODD AND TRIFLING PARTICULARS—MULBERRY: THE
ORANGE GROUP—SINGULAR RESULTS FROM CROSSING— PEACH AND NECTARINE: BUD
VARIATION—ANALOGOUS VARIATION—RELATION TO THE ALMOND—APRICOT—PLUMS:
VARIATION IN THEIR STONES— CHERRIES: SINGULAR VARIETIES
OF—APPLE—PEAR—STRAWBERRY: INTERBLENDING OF THE ORIGINAL
FORMS—GOOSEBERRY: STEADY INCREASE IN SIZE OF THE FRUIT—VARIETIES
OF—WALNUT—NUT—CUCURBITACEOUS PLANTS: WONDERFUL VARIATION OF.

ORNAMENTAL TREES. THEIR VARIATION IN DEGREE AND
KIND—ASH-TREE—SCOTCH-FIR—HAWTHORN.

FLOWERS. MULTIPLE ORIGIN OF MANY KINDS—VARIATION IN CONSTITUTIONAL
PECULIARITIES—KIND OF VARIATION—ROSES: SEVERAL SPECIES
CULTIVATED—PANSY—DAHLIA—HYACINTH: HISTORY AND VARIATION OF.


_The Vine (Vitis vinifera)._—The best authorities consider all our
grapes as the descendants of one species which now grows wild in
western Asia, which grew wild during the Bronze age in Italy,[1] and
which has recently been found fossil in a tufaceous deposit in the
south of France.[2] Some authors, however, entertain much doubt about
the single parentage of our cultivated varieties, owing to the number
of semi-wild forms found in Southern Europe, especially as described by
Clemente[3] in a forest in Spain; but as the grape sows itself freely
in Southern Europe, and as several of the chief kinds transmit their
characters by seed,[4] whilst others are extremely variable, the
existence of many different escaped forms could hardly fail to occur in
countries where this plant has been cultivated from the remotest
antiquity. That the vine varies much when propagated by seed, we may
infer from the largely increased number of varieties since the earlier
historical records. New hot-house varieties are produced almost every
year; for instance,[5] a golden-coloured variety has been recently
raised in England from a black grape without the aid of a cross. Van
Mons[6] reared a multitude of varieties from the seed of one vine,
which was completely separated from all others, so that there could
not, at least in this generation, have been any crossing, and the
seedlings presented “les analogues de toutes les sortes,” and differed
in almost every possible character both in the fruits and foliage.

The cultivated varieties are extremely numerous; Count Odart says that
he will not deny that there may exist throughout the world 700 or 800,
perhaps even 1000 varieties, but not a third of these have any value.
In the catalogue of fruit cultivated in the Horticultural Gardens of
London, published in 1842, 99 varieties are enumerated. Wherever the
grape is grown many varieties occur: Pallas describes 24 in the Crimea,
and Burnes mentions 10 in Cabool. The classification of the varieties
has much perplexed writers, and Count Odart is reduced to a
geographical system; but I will not enter on this subject, nor on the
many and great differences between the varieties. I will merely specify
a few curious and trifling peculiarities, all taken from Odart’s highly
esteemed work[7] for the sake of showing the diversified variability of
this plant. Simon has classed grapes into two main divisions, those
with downy leaves, and those with smooth leaves, but he admits that in
one variety, namely the Rebazo, the leaves are either smooth, or downy;
and Odart (p. 70) states that some varieties have the nerves alone, and
other varieties their young leaves, downy, whilst the old ones are
smooth. The Pedro-Ximenes grape (Odart, p. 397) presents a peculiarity
by which it can be at once recognised amongst a host of other
varieties, namely, that when the fruit is nearly ripe the nerves of the
leaves or even the whole surface becomes yellow. The Barbera d’Asti is
well marked by several characters (p. 426), amongst others, “by some of
the leaves, and it is always the lowest on the branches, suddenly
becoming of a dark red colour.” Several authors in classifying grapes
have founded their main divisions on the berries being either round or
oblong; and Odart admits the value of this character; yet there is one
variety, the Maccabeo (p. 71), which often produces small round, and
large oblong, berries in the same bunch. Certain grapes called Nebbiolo
(p. 429) present a constant character, sufficient for their
recognition, namely, “the slight adherence of that part of the pulp
which surrounds the seeds to the rest of the berry, when cut through
transversely.” A Rhenish variety is mentioned (p. 228) which likes a
dry soil; the fruit ripens well, but at the moment of maturity, if much
rain falls, the berries are apt to rot; on the other hand, the fruit of
a Swiss variety (p. 243) is valued for well sustaining prolonged
humidity. This latter variety sprouts late in the spring, yet matures
its fruit early; other varieties (page 362) have the fault of being too
much excited by the April sun, and in consequence suffer from frost. A
Styrian variety (p. 254) has brittle foot-stalks, so that the clusters
of fruit are often blown off; this variety is said to be particularly
attractive to wasps and bees. Other varieties have tough stalks, which
resist the wind. Many other variable characters could be given, but the
foregoing facts are sufficient to show in how many small structural and
constitutional details the vine varies. During the vine disease in
France certain old groups of varieties[8] have suffered far more from
mildew than others. Thus “the group of Chasselas, so rich in varieties,
did not afford a single fortunate exception;” certain other groups
suffered much less; the true old Burgundy, for instance, was
comparatively free from disease, and the Carminat likewise resisted the
attack. The American vines, which belong to a distinct species,
entirely escaped the disease in France; and we thus see that those
European varieties which best resist the disease must have acquired in
a slight degree the same constitutional peculiarities as the American
species.

_White Mulberry (Morus alba)._—I mention this plant because it has
varied in certain characters, namely, in the texture and quality of the
leaves, fitting them to serve as food for the domesticated silkworm, in
a manner not observed with other plants; but this has arisen simply
from such variations in the mulberry having been attended to, selected,
and rendered more or less constant. M. de Quatrefages[9] briefly
describes six kinds cultivated in one valley in France: of these the _
amourouso_ produces excellent leaves, but is rapidly being abandoned
because it produces much fruit mingled with the leaves: the _antofino_
yields deeply cut leaves of the finest quality, but not in great
quantity: the _claro_ is much sought for because the leaves can be
easily collected: lastly, the _roso_ bears strong hardy leaves,
produced in large quantity, but with the one inconvenience, that they
are best adapted for the worms after their fourth moult. MM.
Jacquemet-Bonnefont, of Lyon, however, remark in their catalogue (1862)
that two sub-varieties have been confounded under the name of the roso,
one having leaves too thick for the caterpillars, the other being
valuable because the leaves can easily be gathered from the branches
without the bark being torn.

In India the mulberry has also given rise to many varieties. The Indian
form is thought by many botanists to be a distinct species; but as
Royle remarks,[10] “so many varieties have been produced by cultivation
that it is difficult to ascertain whether they all belong to one
species;” they are, as he adds, nearly as numerous as those of the
silkworm.

_The Orange Group._—We here meet with great confusion in the specific
distinction and parentage of the several kinds. Gallesio,[11] who
almost devoted his life-time to the subject, considers that there are
four species, namely, sweet and bitter oranges, lemons, and citrons,
each of which has given rise to whole groups of varieties, monsters,
and supposed hybrids. One high authority[12] believes that these four
reputed species are all varieties of the wild _Citrus medica,_ but that
the shaddock (_Citrus decumana_), which is not known in a wild state,
is a distinct species; though its distinctness is doubted by another
writer “of great authority on such matters,” namely, Dr. Buchanan
Hamilton. Alph. De Candolle,[13] on the other hand—and there cannot be
a more capable judge—advances what he considers sufficient evidence of
the orange (he doubts whether the bitter and sweet kinds are
specifically distinct), the lemon, and citron, having been found wild,
and consequently that they are distinct. He mentions two other forms
cultivated in Japan and Java, which he ranks undoubted species; he
speaks rather more doubtfully about the shaddock, which varies much,
and has not been found wild; and finally he considers some forms, such
as Adam’s apple and the bergamotte, as probably hybrids.

I have briefly abstracted these opinions for the sake of showing those
who have never attended to such subjects, how perplexing they are. It
would, therefore, be useless for my purpose to give a sketch of the
conspicuous differences between the several forms. Besides the
ever-recurrent difficulty of determining whether forms found wild are
truly aboriginal or are escaped seedlings, many of the forms, which
must be ranked as varieties, transmit their characters almost perfectly
by seed. Sweet and bitter oranges differ in no important respect except
in the flavour of their fruit, but Gallesio[14] is most emphatic that
both kinds can be propagated by seed with absolute certainty.
Consequently, in accordance with his simple rule, he classes them as
distinct species; as he does sweet and bitter almonds, the peach and
nectarine, etc. He admits, however, that the soft-shelled pine-tree
produces not only soft-shelled but some hard-shelled seedlings, so that
a little greater force in the power of inheritance would, according to
this rule, raise a soft-shelled pine-tree into the dignity of an
aboriginally created species. The positive assertion made by
Macfayden[15] that the pips of sweet oranges produced in Jamaica,
according to the nature of the soil in which they are sown, either
sweet or bitter oranges, is probably an error; for M. Alph. De Candolle
informs me that since the publication of his great work he has received
accounts from Guiana, the Antilles, and Mauritius, that in these
countries sweet oranges faithfully transmit their character. Gallesio
found that the willow-leafed and the Little China oranges reproduced
their proper leaves and fruit; but the seedlings were not quite equal
in merit to their parents. The red-fleshed orange, on the other hand,
fails to reproduce itself. Gallesio also observed that the seeds of
several other singular varieties all reproduced trees having a peculiar
physiognomy, partly resembling their parent-forms. I can adduce another
case: the myrtle leaved orange is ranked by all authors as a variety,
but is very distinct in general aspect: in my father’s greenhouse,
during many years, it rarely yielded any fruit, but at last produced
one; and a tree thus raised was identical with the parent-form.

Another and more serious difficulty in determining the rank of the
several forms is that, according to Gallesio,[16] they largely
intercross without artificial aid; thus he positively states that seeds
taken from lemon-trees (_C. lemonum_) growing mingled with the citron
(_C. medica_), which is generally considered as a distinct species,
produced a graduated series of varieties between these two forms.
Again, an Adam’s apple was produced from the seed of a sweet orange,
which grew close to lemons and citrons. But such facts hardly aid us in
determining whether to rank these forms as species or varieties; for it
is now known that undoubted species of Verbascum, Cistus, Primula,
Salix, etc., frequently cross in a state of nature. If indeed it were
proved that plants of the orange tribe raised from these crosses were
even partially sterile, it would be a strong argument in favour of
their rank as species. Gallesio asserts that this is the case; but he
does not distinguish between sterility from hybridism and from the
effects of culture; and he almost destroys the force of this statement
by another[17] namely, that when he impregnated the flowers of the
common orange with the pollen taken from undoubted _varieties_ of the
orange, monstrous fruits were produced, which included “little pulp,
and had no seeds, or imperfect seeds.”

In this tribe of plants we meet with instances of two highly remarkable
facts in vegetable physiology: Gallesio[18] impregnated an orange with
pollen from a lemon, and the fruit borne on the mother tree had a
raised stripe of peel like that of a lemon both in colour and taste,
but the pulp was like that of an orange and included only imperfect
seeds. The possibility of pollen from one variety or species directly
affecting the fruit produced by another variety of species, is a
subject which I shall fully discuss in the following chapter.

The second remarkable fact is, that two supposed hybrids[19] (for their
hybrid nature was not ascertained), between an orange and either a
lemon or citron, produced on the same tree leaves, flowers, and fruit
of both pure parent-forms, as well as of a mixed or crossed nature. A
bud taken from any one of the branches and grafted on another tree
produces either one of the pure kinds or a capricious tree reproducing
the three kinds. Whether the sweet lemon, which includes within the
same fruit segments of differently flavoured pulp,[20] is an analogous
case, I know not. But to this subject I shall have to recur.

I will conclude by giving from A. Risso[21] a short account of a very
singular variety of the common orange. It is the “_citrus aurantium
fructu variabili,_” which on the young shoots produces rounded-oval
leaves spotted with yellow, borne on petioles with heart-shaped wings;
when these leaves fall off, they are succeeded by longer and narrower
leaves, with undulated margins, of a pale-green colour embroidered with
yellow, borne on footstalks without wings. The fruit whilst young is
pear-shaped, yellow, longitudinally striated, and sweet; but as it
ripens, it becomes spherical, of a reddish-yellow, and bitter.

_Peach and Nectarine (Amygdalus persica)._—The best authorities are
nearly unanimous that the peach has never been found wild. It was
introduced from Persia into Europe a little before the Christian era,
and at this period few varieties existed. Alph. De Candolle,[22] from
the fact of the peach not having spread from Persia at an earlier
period, and from its not having pure Sanscrit or Hebrew names, believes
that it is not an aboriginal of Western Asia, but came from the _terra
incognita_ of China. The supposition, however, that the peach is a
modified almond which acquired its present character at a comparatively
late period, would, I presume, account for these facts; on the same
principle that the nectarine, the offspring of the peach, has few
native names, and became known in Europe at a still later period.

Illustration: Peach and Almond Stones.

Andrew Knight,[23] from finding that a seedling-tree, raised from a
sweet almond fertilised by the pollen of a peach, yielded fruit quite
like that of a peach, suspected that the peach-tree is a modified
almond; and in this he has been followed by various authors.[24] A
first-rate peach, almost globular in shape, formed of soft and sweet
pulp, surrounding a hard, much furrowed, and slightly flattened stone,
certainly differs greatly from an almond, with its soft, slightly
furrowed, much flattened, and elongated stone, protected by a tough,
greenish layer of bitter flesh. Mr. Bentham[25] has particularly called
attention to the stone of the almond being so much more flattened than
that of the peach. But in the several varieties of the almond, the
stone differs greatly in the degree to which it is compressed, in size,
shape, strength, and in the depth of the furrows, as may be seen in
fig. 42 (Nos. 4 to 8) of such kinds as I have been able to collect.
With peach-stones also (Nos. 1 to 3) the degree of compression and
elongation is seen to vary; so that the stone of the Chinese
Honey-peach (No. 3) is much more elongated and compressed than that of
the (No. 8) Smyrna almond. Mr. Rivers, of Sawbridgeworth, to whom I am
indebted for some of the specimens above figured, and who has had such
great horticultural experience, has called my attention to several
varieties which connect the almond and the peach. In France there is a
variety called the Peach-Almond, which Mr. Rivers formerly cultivated,
and which is correctly described in a French catalogue as being oval
and swollen, with the aspect of a peach, including a hard stone
surrounded by a fleshy covering, which is sometimes eatable.[26] A
remarkable statement by M. Luizet has recently appeared in the ‘Revue
Horticole,’[27] namely, that a Peach-almond, grafted on a peach, bore,
during 1863 and 1864 almonds alone, but in 1865 bore six peaches and no
almonds. M. Carriere, in commenting on this fact, cites the case of a
double-flowered almond which, after producing during several years
almonds, suddenly bore for two years in succession spherical fleshy
peach-like fruits, but in 1865 reverted to its former state and
produced large almonds.

Again, as I hear from Mr. Rivers, the double-flowering Chinese peaches
resemble almonds in their manner of growth and in their flowers; the
fruit is much elongated and flattened, with the flesh both bitter and
sweet, but not uneatable, and it is said to be of better quality in
China. From this stage one small step leads us to such inferior peaches
as are occasionally raised from seed. For instance, Mr. Rivers sowed a
number of peach-stones imported from the United States, where they are
collected for raising stocks, and some of the trees raised by him
produced peaches which were very like almonds in appearance, being
small and hard, with the pulp not softening till very late in the
autumn. Van Mons[28] also states that he once raised from a peach-stone
a peach having the aspect of a wild tree, with fruit like that of the
almond. From inferior peaches, such as these just described, we may
pass by small transitions, through clingstones of poor quality, to our
best and most melting kinds. From this gradation, from the cases of
sudden variation above recorded, and from the fact that the peach has
not been found wild, it seems to me by far the most probable view, that
the peach is the descendant of the almond, improved and modified in a
marvellous manner.

One fact, however, is opposed to this conclusion. A hybrid, raised by
Knight from the sweet almond by the pollen of the peach, produced
flowers with little or no pollen, yet bore fruit, having been
apparently fertilised by a neighbouring nectarine. Another hybrid, from
a sweet almond by the pollen of a nectarine, produced during the first
three years imperfect blossoms, but afterwards perfect flowers with an
abundance of pollen. If this slight degree of sterility cannot be
accounted for by the youth of the trees (and this often causes lessened
fertility), or by the monstrous state of the flowers, or by the
conditions to which the trees were exposed, these two cases would
afford a good argument against the peach being the descendant of the
almond.

Whether or not the peach has proceeded from the almond, it has
certainly given rise to nectarines, or smooth peaches, as they are
called by the French. Most of the varieties, both of the peach and
nectarine, reproduce themselves truly by seed. Gallesio[29] says he has
verified this with respect to eight races of the peach. Mr. Rivers[30]
has given some striking instances from his own experience, and it is
notorious that good peaches are constantly raised in North America from
seed. Many of the American sub-varieties come true or nearly true to
their kind, such as the white-blossom, several of the yellow-fruited
freestone peaches, the blood clingstone, the heath, and the lemon
clingstone. On the other hand, a clingstone peach has been known to
give rise to a freestone.[31] In England it has been noticed that
seedlings inherit from their parents flowers of the same size and
colour. Some characters, however, contrary to what might have been
expected, often are not inherited; such as the presence and form of the
glands on the leaves.[32] With respect to nectarines, both cling and
freestones are known in North America to reproduce themselves by
seed.[33] In England the new white nectarine was a seedling of the old
white, and Mr. Rivers[34] has recorded several similar cases. From this
strong tendency to inheritance, which both peach and nectarine trees
exhibit,—from certain slight constitutional differences[35] in their
nature,—and from the great difference in their fruit both in appearance
and flavour, it is not surprising, notwithstanding that the trees
differ in no other respects and cannot even be distinguished, as I am
informed by Mr. Rivers, whilst young, that they have been ranked by
some authors as specifically distinct. Gallesio does not doubt that
they are distinct; even Alph. De Candolle does not appear perfectly
assured of their specific identity: and an eminent botanist has quite
recently[36] maintained that the nectarine “probably constitutes a
distinct species.”

Hence it may be worth while to give all the evidence on the origin of
the nectarine. The facts in themselves are curious, and will hereafter
have to be referred to when the important subject of bud-variation is
discussed. It is asserted[37] that the Boston nectarine was produced
from a peach-stone, and this nectarine reproduced itself by seed.[38]
Mr. Rivers states[39] that from stones of three distinct varieties of
the peach he raised three varieties of nectarine; and in one of these
cases no nectarine grew near the parent peach-tree. In another instance
Mr. Rivers raised a nectarine from a peach, and in the succeeding
generation another nectarine from this nectarine.[40] Other such
instances have been communicated to me, but they need not be given. Of
the converse case, namely, of nectarine-stones yielding peach-trees
(both free and clingstones), we have six undoubted instances recorded
by Mr. Rivers; and in two of these instances the parent nectarines had
been seedlings from other nectarines.[41]

With respect to the more curious case of full-grown peach-trees
suddenly producing nectarines by bud-variation (or sports as they are
called by gardeners), the evidence is superabundant; there is also good
evidence of the same tree producing both peaches and nectarines, or
half-and-half fruit; by this term I mean a fruit with the one-half a
perfect peach, and the other half a perfect nectarine.

Peter Collinson in 1741 recorded the first case of a peach-tree
producing a nectarine,[42] and in 1766 he added two other instances. In
the same work, the editor, Sir J. E. Smith, describes the more
remarkable case of a tree in Norfolk which usually bore both perfect
nectarines and perfect peaches; but during two seasons some of the
fruit were half and half in nature.

Mr. Salisbury in 1808[43] records six other cases of peach-trees
producing nectarines. Three of the varieties are named; viz., the
Alberge, Belle Chevreuse, and Royal George. This latter tree seldom
failed to produce both kinds of fruit. He gives another case of a
half-and-half fruit.

At Radford in Devonshire[44] a clingstone peach, purchased as the
Chancellor, was planted in 1815, and in 1824, after having previously
produced peaches alone, bore on one branch twelve nectarines; in 1825
the same branch yielded twenty-six nectarines, and in 1826 thirty-six
nectarines, together with eighteen peaches. One of the peaches was
almost as smooth on one side as a nectarine. The nectarines were as
dark as, but smaller than, the Elruge.

At Beccles a Royal George peach[45] produced a fruit, “three parts of
it being peach and one part nectarine, quite distinct in appearance as
well as in flavour.” The lines of division were longitudinal, as
represented in the woodcut. A nectarine-tree grew five yards from this
tree.

Professor Chapman states[46] that he has often seen in Virginia very
old peach-trees bearing nectarines.

A writer in the ‘Gardener’s Chronicle’ says that a peach tree planted
fifteen years previously[47] produced this year a nectarine between two
peaches; a nectarine-tree grew close by.

In 1844[48] a Vanguard peach-tree produced, in the midst of its
ordinary fruit, a single red Roman nectarine.

Mr. Calver is stated[49] to have raised in the United States a seedling
peach which produced a mixed crop of both peaches and nectarines.

Near Dorking[50] a branch of the Téton de Vénus peach, which reproduces
itself truly by seed,[51] bore its own fruit “so remarkable for its
prominent point, and a nectarine rather smaller but well formed and
quite round.”

The previous cases all refer to peaches suddenly producing nectarines,
but at Carclew[52] the unique case occurred, of a nectarine-tree,
raised twenty years before from seed and never grafted, producing a
fruit half peach and half nectarine; subsequently bore a perfect peach.

To sum up the foregoing facts; we have excellent evidence of
peach-stones producing nectarine-trees, and of nectarine-stones
producing peach-Trees,—of the same tree bearing peaches and
nectarines,—of peach-trees suddenly producing by bud-variation
nectarines (such nectarines reproducing nectarines by seed), as well as
fruit in part nectarine and in part peach,—and, lastly, of one
nectarine-tree first bearing half-and-half fruit, and subsequently true
peaches. As the peach came into existence before the nectarine, it
might have been expected from the law of reversion that nectarines
would have given birth by bud-variation or by seed to peaches, oftener
than peaches to nectarines; but this is by no means the case.

Two explanations have been suggested to account for these conversions.
First, that the parent trees have been in every case hybrids[53]
between the peach and nectarine, and have reverted by bud-variation or
by seed to one of their pure parent forms. This view in itself is not
very improbable; for the Mountaineer peach, which was raised by Knight
from the red nutmeg-peach by pollen of the violette hâtive
nectarine,[54] produces peaches, but these are said _sometimes_ to
partake of the smoothness and flavour of the nectarine. But let it be
observed that in the previous list no less than six well-known
varieties and several unnamed varieties of the peach have once suddenly
produced perfect nectarines by bud variation: and it would be an
extremely rash supposition that all these varieties of the peach, which
have been cultivated for years in many districts, and which show not a
vestige of a mixed parentage, are, nevertheless, hybrids. A second
explanation is, that the fruit of the peach has been directly affected
by the pollen of the nectarine: although this certainly is possible, it
cannot here apply; for we have not a shadow of evidence that a branch
which has borne fruit directly affected by foreign pollen is so
profoundly modified as afterwards to produce buds which continue to
yield fruit of the new and modified form. Now it is known that when a
bud on a peach-tree has once borne a nectarine the same branch has in
several instances gone on during successive years producing nectarines.
The Carclew nectarine, on the other hand, first produced half-and-half
fruit, and subsequently pure peaches. Hence we may confidently accept
the common view that the nectarine is a variety of the peach, which may
be produced either by bud-variation or from seed. In the following
chapter many analogous cases of bud-variation will he given.

The varieties of the peach and the nectarine run in parallel lines. In
both classes the kinds differ from each other in the flesh of the fruit
being white, red, or yellow; in being clingstones or freestones; in the
flowers being large or small, with certain other characteristic
differences; and in the leaves being serrated without glands, or
crenated and furnished with globose or reniform glands.[55] We can
hardly account for this parallelism by supposing that each variety of
the nectarine is descended from a corresponding variety of the peach;
for though our nectarines are certainly the descendants of several
kinds of peaches, yet a large number are the descendants of other
nectarines, and they vary so much when thus reproduced that we can
scarcely admit the above explanation.

The varieties of the peach have largely increased in number since the
Christian era, when from two to five varieties were known;[56] and the
nectarine was unknown. At the present time, besides many varieties said
to exist in China, Downing describes, in the United States,
seventy-nine native and imported varieties of the peach; and a few
years ago Lindley[57] enumerated one hundred and sixty-four varieties
of the peach and nectarine grown in England. I have already indicated
the chief points of difference between the several varieties.
Nectarines, even when produced from distinct kinds of peaches, always
possess their own peculiar flavour, and are smooth and small.
Clingstone and freestone peaches, which differ in the ripe flesh either
firmly adhering to the stone, or easily separating from it, also differ
in the character of the stone itself; that of the freestones or melters
being more deeply fissured, with the sides of the fissures smoother
than in clingstones. In the various kinds the flowers differ not only
in size, but in the larger flowers the petals are differently shaped,
more imbricated, generally red in the centre and pale towards the
margin: whereas in the smaller flowers the margin of the petal is
usually more darkly coloured. One variety has nearly white flowers. The
leaves are more or less serrated, and are either destitute of glands,
or have globose or reniform glands;[58] and some few peaches, such as
the Brugnen, bear on the same tree both globular and kidney-shaped
glands.[59] According to Robertson[60] the trees with glandular leaves
are liable to blister, but not in any great degree to mildew; whilst
the non-glandular trees are more subject to curl, to mildew, and to the
attacks of aphides. The varieties differ in the period of their
maturity, in the fruit keeping well, and in hardiness,—the latter
circumstance being especially attended to in the United States. Certain
varieties, such as the Bellegarde, stand forcing in hot-houses better
than other varieties. The flat-peach of China is the most remarkable of
all the varieties; it is so much depressed towards the summit, that the
stone is here covered only by roughened skin and not by a fleshy
layer.[61] Another Chinese variety, called the Honey-peach, is
remarkable from the fruit terminating in a long sharp point; its leaves
are glandless and widely dentate.[62] The Emperor of Russia peach is a
third singular variety, having deeply double-serrated leaves; the fruit
is deeply cleft with one-half projecting considerably beyond the other:
it originated in America, and its seedlings inherit similar leaves.[63]

The peach has also produced in China a small class of trees valued for
ornament, namely the double-flowered; of these, five varieties are now
known in England, varying from pure white, through rose, to intense
crimson.[64] One of these varieties, called the camellia-flowered,
bears flowers above 2¼ inches in diameter, whilst those of the
fruit-bearing kinds do not at most exceed 1¼ inch in diameter. The
flowers of the double-flowered peaches have the singular property[65]
of frequently producing double or treble fruit. Finally, there is good
reason to believe that the peach is an almond profoundly modified; but
whatever its origin may have been, there can be no doubt that it has
yielded during the last eighteen centuries many varieties, some of them
strongly characterised, belonging both to the nectarine and peach form.

_Apricot (Prunus armeniaca)._—It is commonly admitted that this tree is
descended from a single species, now found wild in the Caucasian
region.[66] On this view the varieties deserve notice, because they
illustrate differences supposed by some botanists to be of specific
value in the almond and plum. The best monograph on the apricot is by
Mr. Thompson,[67] who describes seventeen varieties. We have seen that
peaches and nectarines vary in a strictly parallel manner; and in the
apricot, which forms a closely allied genus, we again meet with
variations analogous to those of the peach, as well as to those of the
plum. The varieties differ considerably in the shape of their leaves,
which are either serrated or crenated, sometimes with ear-like
appendages at their bases, and sometimes with glands on the petioles.
The flowers are generally alike, but are small in the Masculine. The
fruit varies much in size, shape, and in having the suture little
pronounced or absent; in the skin being smooth, or downy, as in the
orange-apricot; and in the flesh clinging to the stone, as in the
last-mentioned kind, or in readily separating from it, as in the
Turkey-apricot. In all these differences we see the closest analogy
with the varieties of the peach and nectarine. In the stone we have
more important differences, and these in the case of the plum have been
esteemed of specific value: in some apricots the stone is almost
spherical, in others much flattened, being either sharp in front or
blunt at both ends, sometimes channelled along the back, or with a
sharp ridge along both margins. In the Moorpark, and generally in the
Hemskirke, the stone presents a singular character in being perforated,
with a bundle of fibres passing through the perforation from end to
end. The most constant and important character, according to Thompson,
is whether the kernel is bitter or sweet: yet in this respect we have a
graduated difference, for the kernel is very bitter in Shipley’s
apricot; in the Hemskirke less bitter than in some other kinds;
slightly bitter in the Royal; and “sweet like a hazel-nut” in the
Breda, Angoumois, and others. In the case of the almond, bitterness has
been thought by some high authorities to indicate specific difference.

In N. America the Roman apricot endures “cold and unfavourable
situations, where no other sort, except the Masculine, will succeed;
and its blossoms bear quite a severe frost without injury.”[68]
According to Mr. Rivers,[69] seedling apricots deviate but little from
the character of their race: in France the Alberge is constantly
reproduced from seed with but little variation. In Ladakh, according to
Moorcroft,[70] ten varieties of the apricot, very different from each
other, are cultivated, and all are raised from seed, excepting one,
which is budded.

Illustration: Plum Stones.

_Plums (Prunus insititia)._—Formerly the sloe, _P. spinosa,_ was
thought to be the parent of all our plums; but now this honour is very
commonly accorded to _P. insititia_ or the bullace, which is found wild
in the Caucasus and N.-Western India, and is naturalised in
England.[71] It is not at all improbable, in accordance with some
observations made by Mr. Rivers,[72] that both these forms, which some
botanists rank as a single species, may be the parents of our
domesticated plums. Another supposed parent-form, the _P. domestica,_
is said to be found wild in the region of the Caucasus. Godron
remarks[73] that the cultivated varieties may be divided into two main
groups, which he supposes to be descended from two aboriginal stocks;
namely, those with oblong fruit and stones pointed at both ends, having
narrow separate petals and upright branches; and those with rounded
fruit, with stones blunt at both ends, with rounded petals and
spreading branches. From what we know of the variability of the flowers
in the peach and of the diversified manner of growth in our various
fruit-trees, it is difficult to lay much weight on these latter
characters. With respect to the shape of the fruit, we have conclusive
evidence that it is extremely variable: Downing[74] gives outlines of
the plums of two seedlings, namely, the red and imperial gages, raised
from the greengage; and the fruit of both is more elongated than that
of the greengage. The latter has a very blunt broad stone, whereas the
stone of the imperial gage is “oval and pointed at both ends.” These
trees also differ in their manner of growth: “the greengage is a very
short-jointed, slow-growing tree, of spreading and rather dwarfish
habit;” whilst its offspring, the imperial gage, “grows freely and
rises rapidly, and has long dark shoots.” The famous Washington plum
bears a globular fruit, but its offspring, the emerald drop, is nearly
as much elongated as the most elongated plum figured by Downing,
namely, Manning’s prune. I have made a small collection of the stones
of twenty-five kinds, and they graduate in shape from the bluntest into
the sharpest kinds. As characters derived from seeds are generally of
high systematic importance, I have thought it worth while to give
drawings of the most distinct kinds in my small collection; and they
may be seen to differ in a surprising manner in size, outline,
thickness, prominence of the ridges, and state of surface. It deserves
notice that the shape of the stone is not always strictly correlated
with that of the fruit: thus the Washington plum is spherical and
depressed at the pole, with a somewhat elongated stone, whilst the
fruit of the Goliath is more elongated, but the stone less so, than in
the Washington. Again, Denyer’s Victoria and Goliath bear fruit closely
resembling each other, but their stones are widely different. On the
other hand, the Harvest and Black Margate plums are very dissimilar,
yet include closely similar stones.

The varieties of the plum are numerous, and differ greatly in size,
shape, quality, and colour,—being bright yellow, green, almost white,
blue, purple, or red. There are some curious varieties, such as the
double or Siamese, and the Stoneless plum: in the latter the kernel
lies in a roomy cavity surrounded only by the pulp. The climate of
North America appears to be singularly favourable for the production of
new and good varieties; Downing describes no less than forty, of which
seven of first-rate quality have been recently introduced into
England.[75] Varieties occasionally arise having an innate adaptation
for certain soils, almost as strongly pronounced as with natural
species growing on the most distinct geological formations; thus in
America the imperial gage, differently from almost all other kinds, “is
peculiarly fitted for _dry light_ soils where many sorts drop their
fruit,” whereas on rich heavy soils the fruit is often insipid.[76] My
father could never succeed in making the Wine-Sour yield even a
moderate crop in a sandy orchard near Shrewsbury, whilst in some parts
of the same county and in its native Yorkshire it bears abundantly: one
of my relations also repeatedly tried in vain to grow this variety in a
sandy district in Staffordshire.

Mr. Rivers has given[77] a number of interesting facts, showing how
truly many varieties can be propagated by seed. He sowed the stones of
twenty bushels of the greengage for the sake of raising stocks, and
closely observed the seedlings; all had the smooth shoots, the
prominent buds, and the glossy leaves of the greengage, but the greater
number had smaller leaves and thorns. There are two kinds of damson,
one the Shropshire with downy shoots, and the other the Kentish with
smooth shoots, and these differ but slightly in any other respect: Mr.
Rivers sowed some bushels of the Kentish damson, and all the seedlings
had smooth shoots, but in some the fruit was oval, in others round or
roundish, and in a few the fruit was small, and, except in being sweet,
closely resembled that of the wild sloe. Mr. Rivers gives several other
striking instances of inheritance: thus, he raised eighty thousand
seedlings from the common German Quetsche plum, and “not one could be
found varying in the least, in foliage or habit.” Similar facts were
observed with the Petite Mirabelle plum, yet this latter kind (as well
as the Quetsche) is known to have yielded some well-established
varieties; but, as Mr. Rivers remarks, they all belong to the same
group with the Mirabelle.

_Cherries (Prunus cerasus, avium, etc.)._—Botanists believe that our
cultivated cherries are descended from one, two, four, or even more
wild stocks.[78] That there must be at least two parent species we may
infer from the sterility of twenty hybrids raised by Mr. Knight from
the morello fertilised by pollen of the Elton cherry; for these hybrids
produced in all only five cherries, and one alone of these contained a
seed.[79] Mr. Thompson[80] has classified the varieties in an
apparently natural method in two main groups by characters taken from
the flowers, fruit, and leaves; but some varieties which stand widely
separate in this classification are quite fertile when crossed; thus
Knight’s Early Black cherries are the product of a cross between two
such kinds.

Mr. Knight states that seedling cherries are more variable than those
of any other fruit-tree.[81] In the Catalogue of the Horticultural
Society for 1842 eighty varieties are enumerated. Some varieties
present singular characters: thus, the flower of the Cluster cherry
includes as many as twelve pistils, of which the majority abort; and
they are said generally to produce from two to five or six cherries
aggregated together and borne on a single peduncle. In the Ratafia
cherry several flower-peduncles arise from a common peduncle, upwards
of an inch in length. The fruit of Gascoigne’s Heart has its apex
produced into a globule or drop; that of the white Hungarian Gean has
almost transparent flesh. The Flemish cherry is “a very odd-looking
fruit,” much flattened at the summit and base, with the latter deeply
furrowed, and borne on a stout, very short footstalk. In the Kentish
cherry the stone adheres so firmly to the footstalk, that it could be
drawn out of the flesh; and this renders the fruit well fitted for
drying. The Tobacco-leaved cherry, according to Sageret and Thompson,
produces gigantic leaves, more than a foot and sometimes even eighteen
inches in length, and half a foot in breadth. The weeping cherry, on
the other hand, is valuable only as an ornament, and, according to
Downing, is “a charming little tree, with slender, weeping branches,
clothed with small, almost myrtle-like foliage.” There is also a
peach-leaved variety.

Sageret describes a remarkable variety, _le griottier de la Toussaint,_
which bears at the same time, even as late as September, flowers and
fruit of all degrees of maturity. The fruit, which is of inferior
quality, is borne on long, very thin footstalks. But the extraordinary
statement is made that all the leaf-bearing shoots spring from old
flower-buds. Lastly, there is an important physiological distinction
between those kinds of cherries which bear fruit on young or on old
wood; but Sageret positively asserts that a Bigarreau in his garden
bore fruit on wood of both ages.[82]

_Apple (Pyrus malus)._—The one source of doubt felt by botanists with
respect to the parentage of the apple is whether, besides _P. malus,_
two or three other closely allied wild forms, namely, _P. acerba_ and _
præcox_ or _paradisiaca,_ do not deserve to be ranked as distinct
species. The _P. præcox_ is supposed by some authors[83] to be the
parent of the dwarf paradise stock, which, owing to the fibrous roots
not penetrating deeply into the ground, is so largely used for
grafting; but the paradise stocks, it is asserted,[84] cannot be
propagated true by seed. The common wild crab varies considerably in
England; but many of the varieties are believed to be escaped
seedlings.[85] Every one knows the great difference in the manner of
growth, in the foliage, flowers, and especially in the fruit, between
the almost innumerable varieties of the apple. The pips or seeds (as I
know by comparison) likewise differ considerably in shape, size, and
colour. The fruit is adapted for eating or for cooking in various ways,
and keeps for only a few weeks or for nearly two years. Some few kinds
have the fruit covered with a powdery secretion, called bloom, like
that on plums; and “it is extremely remarkable that this occurs almost
exclusively among varieties cultivated in Russia.”[86] Another Russian
apple, the white Astracan, possesses the singular property of becoming
transparent, when ripe, like some sorts of crabs. The _api étoilé_ has
five prominent ridges, hence its name; the _api noir_ is nearly black:
the _twin cluster pippin_ often bears fruit joined in pairs.[87] The
trees of the several sorts differ greatly in their periods of leafing
and flowering; in my orchard the _Court Pendu Plat_ produces leaves so
late, that during several springs I thought that it was dead. The
Tiffin apple scarcely bears a leaf when in full bloom; the Cornish
crab, on the other hand, bears so many leaves at this period that the
flowers can hardly be seen.[88] In some kinds the fruit ripens in
mid-summer; in others, late in the autumn. These several differences in
leafing, flowering, and fruiting, are not at all necessarily
correlated; for, as Andrew Knight has remarked,[89] no one can judge
from the early flowering of a new seedling, or from the early shedding
or change of colour of the leaves, whether it will mature its fruit
early in the season.

The varieties differ greatly in constitution. It is notorious that our
summers are not hot enough for the Newtown Pippin,[90] which is the
glory of the orchards near New York; and so it is with several
varieties which we have imported from the Continent. On the other hand,
our Court of Wick succeeds well under the severe climate of Canada. The
_Caville rouge de Micoud_ occasionally bears two crops during the same
year. The Burr Knot is covered with small excrescences, which emit
roots so readily that a branch with blossom-buds may be stuck in the
ground, and will root and bear a few fruit even during the first
year.[91] Mr. Rivers has recently described[92] some seedlings valuable
from their roots running near the surface. One of these seedlings was
remarkable from its extremely dwarfed size, “forming itself into a bush
only a few inches in height.” Many varieties are particularly liable to
canker in certain soils. But perhaps the strangest constitutional
peculiarity is that the Winter Majetin is not attacked by the mealy bug
or coccus; Lindley[93] states that in an orchard in Norfolk infested
with these insects the Majetin was quite free, though the stock on
which it was grafted was affected: Knight makes a similar statement
with respect to a cider apple, and adds that he only once saw these
insects just above the stock, but that three days afterwards they
entirely disappeared; this apple, however, was raised from a cross
between the Golden Harvey and the Siberian Crab; and the latter, I
believe, is considered by some authors as specifically distinct.

The famous St. Valery apple must not be passed over; the flower has a
double calyx with ten divisions, and fourteen styles surmounted by
conspicuous oblique stigmas, but is destitute of stamens or corolla.
The fruit is constricted round the middle, and is formed of five
seed-cells, surmounted by nine other cells.[94] Not being provided with
stamens, the tree requires artificial fertilisation; and the girls of
St. Valery annually go to “_faire ses pommes,_” each marking her own
fruit with a ribbon; and as different pollen is used the fruit differs,
and we here have an instance of the direct action of foreign pollen on
the mother plant. These monstrous apples include, as we have seen,
fourteen seed-cells; the pigeon-apple,[95] on the other hand, has only
four, instead of, as with all common apples, five cells; and this
certainly is a remarkable difference.

In the catalogue of apples published in 1842 by the Horticultural
Society, 897 varieties are enumerated; but the differences between most
of them are of comparatively little interest, as they are not strictly
inherited. No one can raise, for instance, from the seed of the Ribston
Pippin, a tree of the same kind; and it is said that the “Sister
Ribston Pippin” was a white semi-transparent, sour-fleshed apple, or
rather large crab.[96] Yet it was a mistake to suppose that with most
varieties the characters are not to a certain extent inherited. In two
lots of seedlings raised from two well-marked kinds, many worthless
crab-like seedlings will appear, but it is now known that the two lots
not only usually differ from each other, but resemble to a certain
extent their parents. We see this indeed in the several sub-groups of
Russetts, Sweetings, Codlins, Pearmains, Reinettes, etc.,[97] which are
all believed, and many are known, to be descended from other varieties
bearing the same names.

_Pears (Pyrus communis)._—I need say little on this fruit, which varies
much in the wild state, and to an extraordinary degree when cultivated,
in its fruit, flowers, and foliage. One of the most celebrated
botanists in Europe, M. Decaisne, has carefully studied the many
varieties;[98] although he formerly believed that they were derived
from more than one species, he now thinks that all belong to one. He
has arrived at this conclusion from finding in the several varieties a
perfect gradation between the most extreme characters; so perfect is
this gradation that he maintains it to be impossible to classify the
varieties by any natural method. M. Decaisne raised many seedlings from
four distinct kinds, and has carefully recorded the variations in each.
Notwithstanding this extreme degree of variability, it is now
positively known that many kinds reproduce by seed the leading
characters of their race.[99]

_Strawberries (Fragaria)._—This fruit is remarkable on account of the
number of species which have been cultivated, and from their rapid
improvement within the last fifty or sixty years. Let any one compare
the fruit of one of the largest varieties exhibited at our Shows with
that of the wild wood strawberry, or, which will be a fairer
comparison, with the somewhat larger fruit of the wild American
Virginian Strawberry, and he will see what prodigies horticulture has
effected.[100] The number of varieties has likewise increased in a
surprisingly rapid manner. Only three kinds were known in France, in
1746, where this fruit was early cultivated. In 1766 five species had
been introduced, the same which are now cultivated, but only five
varieties of _Fragaria vesca,_ with some sub-varieties, had been
produced. At the present day the varieties of the several species are
almost innumerable. The species consist of, firstly, the wood or Alpine
cultivated strawberries, descended from _F. vesca,_ a native of Europe
and of North America. There are eight wild European varieties, as
ranked by Duchesne, of _F. vesca,_ but several of these are considered
species by some botanists. Secondly, the green strawberries, descended
from the European _F. collina,_ and little cultivated in England.
Thirdly, the Hautbois, from the European _F. elatior._ Fourthly, the
Scarlets, descended from _F. virginiana,_ a native of the whole breadth
of North America. Fifthly, the Chili, descended from _F. chiloensis,_
an inhabitant of the west coast of the temperate parts both of North
and South America. Lastly, the pines or Carolinas (including the old
Blacks), which have been ranked by most authors under the name of _F.
grandiflora_ as a distinct species, said to inhabit Surinam; but this
is a manifest error. This form is considered by the highest authority,
M. Gay, to be merely a strongly marked race of _F. chiloensis._[101]
These five or six forms have been ranked by most botanists as
specifically distinct; but this may be doubted, for Andrew Knight,[102]
who raised no less than 400 crossed strawberries, asserts that the _ F.
virginiana, chiloensis_ and _grandiflora_ “may be made to breed
together indiscriminately,” and he found, in accordance with the
principle of analogous variation, “that similar varieties could be
obtained from the seeds of any one of them.”

Since Knight’s time there is abundant and additional evidence[103] of
the extent to which the American forms spontaneously cross. We owe
indeed to such crosses most of our choicest existing varieties. Knight
did not succeed in crossing the European wood-strawberry with the
American Scarlet or with the Hautbois. Mr. Williams of Pitmaston,
however, succeeded; but the hybrid offspring from the Hautbois, though
fruiting well, never produced seed, with the exception of a single one,
which reproduced the parent hybrid form.[104] Major R. Trevor Clarke
informs me that he crossed two members of the Pine class (Myatt’s B.
Queen and Keen’s Seedling) with the wood and hautbois, and that in each
case he raised only a single seedling; one of these fruited, but was
almost barren. Mr. W. Smith, of York, has raised similar hybrids with
equally poor success.[105] We thus see[106] that the European and
American species can with some difficulty be crossed; but it is
improbable that hybrids sufficiently fertile to be worth cultivation
will ever be thus produced. This fact is surprising, as these forms
structurally are not widely distinct, and are sometimes connected in
the districts where they grow wild, as I hear from Professor Asa Gray,
by puzzling intermediate forms.

The energetic culture of the Strawberry is of recent date, and the
cultivated varieties can in most cases be classed under some one of the
above native stocks. As the American strawberries cross so freely and
spontaneously, we can hardly doubt that they will ultimately become
inextricably confused. We find, indeed, that horticulturists at present
disagree under which class to rank some few of the varieties; and a
writer in the ‘Bon Jardinier’ of 1840 remarks that formerly it was
possible to class all of them under some one species, but that now this
is quite impossible with the American forms, the new English varieties
having completely filled up the gaps between them.[107] The blending
together of two or more aboriginal forms, which there is every reason
to believe has occurred with some of our anciently cultivated
productions, we see now actually occurring with our strawberries.

The cultivated species offer some variations worth notice. The Black
Prince, a seedling from Keen’s Imperial (this latter being a seedling
of a very white strawberry, the white Carolina), is remarkable from
“its peculiar dark and polished surface, and from presenting an
appearance entirely unlike that of any other kind.”[108] Although the
fruit in the different varieties differs so greatly in form, size,
colour, and quality, the so-called seed (which corresponds with the
whole fruit in the plum) with the exception of being more or less
deeply embedded in the pulp, is, according to De Jonghe,[109]
absolutely the same in all: and this no doubt may be accounted for by
the seed being of no value, and consequently not having been subjected
to selection. The strawberry is properly three-leaved, but in 1761
Duchesne raised a single-leaved variety of the European
wood-strawberry, which Linnæus doubtfully raised to the rank of a
species. Seedlings of this variety, like those of most varieties not
fixed by long-continued selection, often revert to the ordinary form,
or present intermediate states.[110] A variety raised by Mr.
Myatt,[111] apparently belonging to one of the American forms presents
a variation of an opposite nature, for it has five leaves; Godron and
Lambertye also mention a five-leaved variety of _F. collina._

The Red Bush Alpine strawberry (one of the _F. vesca_ section) does not
produce stolons or runners, and this remarkable deviation of structure
is reproduced truly by seed. Another sub-variety, the White Bush
Alpine, is similarly characterised, but when propagated by seed it
often degenerates and produces plants with runners.[112] A strawberry
of the American Pine section is also said to make but few runners.[113]

Much has been written on the sexes of strawberries; the true Hautbois
properly bears the male and female organs on separate plants,[114] and
was consequently named by Duchesne _dioica_; but it frequently produces
hermaphrodites; and Lindley,[115] by propagating such plants by
runners, at the same time destroying the males, soon raised a
self-prolific stock. The other species often showed a tendency towards
an imperfect separation of the sexes, as I have noticed with plants
forced in a hot-house. Several English varieties, which in this country
are free from any such tendency, when cultivated in rich soils under
the climate of North America[116] commonly produce plants with separate
sexes. Thus a whole acre of Keen’s Seedlings in the United States has
been observed to be almost sterile from the absence of male flowers;
but the more general rule is, that the male plants overrun the females.
Some members of the Cincinnati Horticultural Society, especially
appointed to investigate this subject, report that “few varieties have
the flowers perfect in both sexual organs,” etc. The most successful
cultivators in Ohio plant for every seven rows of “pistillata,” or
female plants, one row of hermaphrodites, which afford pollen for both
kinds; but the hermaphrodites, owing to their expenditure in the
production of pollen, bear less fruit than the female plants.

The varieties differ in constitution. Some of our best English kinds,
such as Keen’s Seedlings, are too tender for certain parts of North
America, where other English and many American varieties succeed
perfectly. That splendid fruit, the British Queen, can be cultivated
but in few places either in England or France: but this apparently
depends more on the nature of the soil than on the climate; a famous
gardener says that “no mortal could grow the British Queen at Shrubland
Park unless the whole nature of the soil was altered.”[117] La
Constantine is one of the hardiest kinds, and can withstand Russian
winters, but it is easily burnt by the sun, so that it will not succeed
in certain soils either in England or the United States.[118] The
Filbert Pine Strawberry “requires more water than any other variety;
and if the plants once suffer from drought, they will do little or no
good afterwards.”[119] Cuthill’s Black Prince Strawberry evinces a
singular tendency to mildew; no less than six cases have been recorded
of this variety suffering severely, whilst other varieties growing
close by, and treated in exactly the same manner, were not at all
infested by this fungus.[120] The time of maturity differs much in the
different varieties: some belonging to the wood or alpine section
produce a succession of crops throughout the summer.

_Gooseberry (Ribes grossularia)._—No one, I believe, has hitherto
doubted that all the cultivated kinds are sprung from the wild plant
bearing this name, which is common in Central and Northern Europe;
therefore it will be desirable briefly to specify all the points,
though not very important, which have varied. If it be admitted that
these differences are due to culture, authors perhaps will not be so
ready to assume the existence of a large number of unknown wild
parent-stocks for our other cultivated plants. The gooseberry is not
alluded to by writers of the classical period. Turner mentions it in
1573, and Parkinson specifies eight varieties in 1629; the Catalogue of
the Horticultural Society for 1842 gives 149 varieties, and the lists
of the Lancashire nurserymen are said to include above 300 names.[121]
In the ‘Gooseberry Grower’s Register’ for 1862 I find that 243 distinct
varieties have won prizes at various periods, so that a vast number
must have been exhibited. No doubt the difference between many of the
varieties is very small; but Mr. Thompson in classifying the fruit for
the Horticultural Society found less confusion in the nomenclature of
the gooseberry than of any other fruit, and he attributes this “to the
great interest which the prize-growers have taken in detecting sorts
with wrong names,” and this shows that all the kinds, numerous as they
are, can be recognised with certainty.

The bushes differ in their manner of growth, being erect, or spreading,
or pendulous. The periods of leafing and flowering differ both
absolutely and relatively to each other; thus the Whitesmith produces
early flowers, which from not being protected by the foliage, as it is
believed, continually fail to produce fruit.[122] The leaves vary in
size, tint, and in depth of lobes; they are smooth, downy, or hairy on
the upper surface. The branches are more or less downy or spinose; “the
Hedgehog has probably derived its name from the singular bristly
condition of its shoots and fruit.” The branches of the wild
gooseberry, I may remark, are smooth, with the exception of thorns at
the bases of the buds. The thorns themselves are either very small, few
and single, or very large and triple; they are sometimes reflexed and
much dilated at their bases. In the different varieties the fruit
varies in abundance, in the period of maturity, in hanging until
shrivelled, and greatly in size, “some sorts having their fruit large
during a very early period of growth, whilst others are small, until
nearly ripe.” The fruit varies also much in colour, being red, yellow,
green, and white—the pulp of one dark-red gooseberry being tinged with
yellow; in flavour; in being smooth or downy,—few, however, of the Red
gooseberries, whilst many of the so-called Whites, are downy; or in
being so spinose that one kind is called Henderson’s Porcupine. Two
kinds acquire when mature a powdery bloom on their fruit. The fruit
varies in the thickness and veining of the skin, and, lastly, in shape,
being spherical, oblong, oval, or obovate.[123]

I cultivated fifty-four varieties, and, considering how greatly the
fruit differs, it was curious how closely similar the flowers were in
all these kinds. In only a few I detected a trace of difference in the
size or colour of the corolla. The calyx differed in a rather greater
degree, for in some kinds it was much redder than in others; and in one
smooth white gooseberry it was unusually red. The calyx also differed
in the basal part being smooth or woolly, or covered with glandular
hairs. It deserves notice, as being contrary to what might have been
expected from the law of correlation, that a smooth red gooseberry had
a remarkably hairy calyx. The flowers of the Sportsman are furnished
with very large coloured bracteæ; and this is the most singular
deviation of structure which I have observed. These same flowers also
varied much in the number of the petals, and occasionally in the number
of the stamens and pistils; so that they were semi-monstrous in
structure, yet they produced plenty of fruit. Mr. Thompson remarks that
in the Pastime gooseberry “extra bracts are often attached to the sides
of the fruit.”[124]

The most interesting point in the history of the gooseberry is the
steady increase in the size of the fruit. Manchester is the metropolis
of the fanciers, and prizes from five shillings to five or ten pounds
are yearly given for the heaviest fruit. The ‘Gooseberry Growers
Register’ is published annually; the earliest known copy is dated 1786,
but it is certain that meetings for the adjudication of prizes were
held some years previously.[125] The ‘Register’ for 1845 gives an
account of 171 Gooseberry Shows, held in different places during that
year; and this fact shows on how large a scale the culture has been
carried on. The fruit of the wild gooseberry is said[126] to weigh
about a quarter of an ounce or 5 dwts., that is, 120 grains; about the
year 1786 gooseberries were exhibited weighing 10 dwts., so that the
weight was then doubled; in 1817 26 dwts. 17 grs. was attained; there
was no advance till 1825, when 31 dwts. 16 grs. was reached; in 1830
“Teazer” weighed 32 dwts. 13 grs.; in 1841 “Wonderful” weighed 32 dwts.
16 grs.; in 1844 “London” weighed 35 dwts. 12 grs., and in the
following year 36 dwts. 16 grs.; and in 1852 in Staffordshire, the
fruit of the same variety reached the astonishing weight of 37 dwts. 7
grs.[127] or 896 grs.; that is, between seven or eight times the weight
of the wild fruit. I find that a small apple, 6½ inches in
circumference, has exactly this same weight. The “London” gooseberry
(which in 1852 had altogether gained 333 prizes) has, up to the present
year of 1875, never reached a greater weight than that attained in
1852. Perhaps the fruit of the gooseberry has now reached the greatest
possible weight, unless in the course of time some new and distinct
variety shall arise.

This gradual, and on the whole steady increase of weight from the
latter part of the last century to the year 1852, is probably in large
part due to improved methods of cultivation, for extreme care is now
taken; the branches and roots are trained, composts are made, the soil
is mulched, and only a few berries are left on each bush;[128] but the
increase no doubt is in main part due to the continued selection of
seedlings which have been found to be more and more capable of yielding
such extraordinary fruit. Assuredly the “Highwayman” in 1817 could not
have produced fruit like that of the “Roaring Lion” in 1825; nor could
the “Roaring Lion,” though it was grown by many persons in many places,
gain the supreme triumph achieved in 1852 by the “London” Gooseberry.

_Walnut (Juglans regia)._—This tree and the common nut belong to a
widely different order from the foregoing fruits, and are therefore
here noticed. The walnut grows wild on the Caucasus and in the
Himalaya, where Dr. Hooker[129] found the fruit of full size, but “as
hard as a hickory-nut.” It has been found fossil, as M. de Saporta
informs me, in the tertiary formation, of France.

In England the walnut presents considerable differences, in the shape
and size of the fruit, in the thickness of the husk, and in the
thinness of the shell; this latter quality has given rise to a variety
called the thin-shelled, which is valuable, but suffers from the
attacks of tit-mice.[130] The degree to which the kernel fills the
shell varies much. In France there is a variety called the Grape or
cluster-walnut, in which the nuts grow in “bunches of ten, fifteen, or
even twenty together.” There is another variety which bears on the same
tree differently shaped leaves, like the heterophyllous hornbeam; this
tree is also remarkable from having pendulous branches, and bearing
elongated, large, thin-shelled nuts.[131] M. Cardan has minutely
described[132] some singular physiological peculiarities in the
June-leafing variety, which produces its leaves and flowers four or
five weeks later than the common varieties; and although in August it
is apparently in exactly the same state of forwardness as the other
kinds, it retains its leaves and fruit much later in the autumn. These
constitutional peculiarities are strictly inherited. Lastly,
walnut-trees, which are properly monoicous, sometimes entirely fail to
produce male flowers.[133]

_Nuts (Corylus avellana)._—Most botanists rank all the varieties under
the same species, the common wild nut.[134] The husk, or involucre,
differs greatly, being extremely short in Barr’s Spanish, and extremely
long in filberts, in which it is contracted so as to prevent the nut
falling out. This kind of husk also protects the nut from birds, for
titmice (_Parus_) have been observed [135] to pass over filberts, and
attack cobs and common nuts growing in the same orchard. In the
purple-filbert the husk is purple, and in the frizzled-filbert it is
curiously laciniated; in the red-filbert the pellicle of the kernel is
red. The shell is thick in some varieties, but is thin in
Cosford’s-nut, and in one variety is of a bluish colour. The nut itself
differs much in size and shape, being ovate and compressed in filberts,
nearly round and of great size in cobs and Spanish nuts, oblong and
longitudinally striated in Cosford’s, and obtusely four-sided in the
Downton Square nut.

_Cucurbitaceous plants._—These plants have been for a long period the
opprobrium of botanists; numerous varieties have been ranked as
species, and, what happens more rarely, forms which now must be
considered as species have been classed as varieties. Owing to the
admirable experimental researches of a distinguished botanist, M.
Naudin,[136] a flood of light has recently been thrown on this group of
plants. M. Naudin, during many years, observed and experimented on
above 1200 living specimens, collected from all quarters of the world.
Six species are now recognised in the genus Cucurbita; but three alone
have been cultivated and concern us, namely, _C. maxima_ and _pepo,_
which include all pumpkins, gourds, squashes, and the vegetable marrow,
and _C. moschata._ These three species are not known in a wild state;
but Asa Gray[137] gives good reason for believing that some pumpkins
are natives of N. America.

These three species are closely allied, and have the same general
habit, but their innumerable varieties can always be distinguished,
according to Naudin, by certain almost fixed characters; and what is
still more important, when crossed they yield no seed, or only sterile
seed; whilst the varieties spontaneously intercross with the utmost
freedom. Naudin insists strongly (p. 15), that, though these three
species have varied greatly in many characters, yet it has been in so
closely an analogous manner that the varieties can he arranged in
almost parallel series, as we have seen with the forms of wheat, with
the two main races of the peach, and in other cases. Though some of the
varieties are inconstant in character, yet others, when grown
separately under uniform conditions of life, are, as Naudin repeatedly
(pp. 6, 16, 35) urges, “douées d’une stabilité presque comparable à
celle des espèces les mieux caractérisées.” One variety, l’Orangin (pp.
43, 63), has such prepotency in transmitting its character, that when
crossed with other varieties a vast majority of the seedlings come
true. Naudin, referring (p. 47) to _C. pepo,_ says that its races “ne
different des espèces veritables qu’en ce qu’elles peuvent s’allier les
unes aux autres par voie d’hybridité, sans que leur descendance perde
la faculté de se perpétuer.” If we were to trust to external
differences alone, and give up the test of sterility, a multitude of
species would have to be formed out of the varieties of these three
species of Cucurbita. Many naturalists at the present day lay far too
little stress, in my opinion, on the test of sterility; yet it is not
improbable that distinct species of plants after a long course of
cultivation and variation may have their mutual sterility eliminated,
as we have every reason to believe has occurred with domesticated
animals. Nor, in the case of plants under cultivation, should we be
justified in assuming that varieties never acquire a slight degree of
mutual sterility, as we shall more fully see in a future chapter when
certain facts are given on the high authority of Gärtner and
Kölreuter.[138]

The forms of _C. pepo_ are classed by Naudin under seven sections, each
including subordinate varieties. He considers this plant as probably
the most variable in the world. The fruit of one variety (pp. 33, 46)
exceeds in value that of another by more than two thousand fold! When
the fruit is of very large size, the number produced is few (p. 45);
when of small size, many are produced. No less astonishing (p. 33) is
the variation in the shape of the fruit, the typical form apparently is
egg-like, but this becomes either drawn out into a cylinder, or
shortened into a flat disc. We have also an almost infinite diversity
in the colour and state of surface of the fruit, in the hardness both
of the shell and of the flesh, and in the taste of the flesh, which is
either extremely sweet, farinaceous, or slightly bitter. The seeds also
differ in a slight degree in shape, and wonderfully in size (p. 34),
namely, from six or seven to more than twenty-five millimètres in
length.

In the varieties which grow upright or do not run and climb, the
tendrils, though useless (p. 31), are either present or are represented
by various semi-monstrous organs, or are quite absent. The tendrils are
even absent in some running varieties in which the stems are much
elongated. It is a singular fact that (p. 31) in all the varieties with
dwarfed stems, the leaves closely resemble each other in shape.

Those naturalists who believe in the immutability of species often
maintain that, even in the most variable forms, the characters which
they consider of specific value are unchangeable. To give an example
from a conscientious writer,[139] who, relying on the labours of M.
Naudin, and referring to the species of Cucurbita, says, “au milieu de
toutes les variations du fruit, les tiges, les feuilles, les calices,
les corolles, les étamines restent invariables dans chacune d’elles.”
Yet M. Naudin, in describing _ Cucurbita pepo_ (p. 30), says, “Ici,
d’ailleurs, ce ne sont pas seulement les fruits qui varient, c’est
aussi le feuillage et tout le port de la plante. Néanmoins, je crois
qu’on la distinguera toujours facilement des deux autres espèces, si
l’on veut ne pas perdre de vue les caractères différentiels que je
m’efforce de faire ressortir. Ces caractères sont quelquefois peu
marqués: il arrive meme que plusieurs d’entre eux s’effacent presque
entièrement, mais ii en reste toujours quelques-uns qui remettent
l’observateur sur la voie.” Now let it be noted what a difference, with
regard to the immutability of the so-called specific characters this
paragraph produces on the mind, from that above quoted from M. Godron.

I will add another remark: naturalists continually assert that no
important organ varies; but in saying this they unconsciously argue in
a vicious circle; for if an organ, let it be what it may, is highly
variable, it is regarded as unimportant, and under a systematic point
of view this is quite correct. But as long as constancy is thus taken
as the criterion of importance, it will indeed be long before an
important organ can be shown to be inconstant. The enlarged form of the
stigmas, and their sessile position on the summit of the ovary, must be
considered as important characters, and were used by Gasparini to
separate certain pumpkins as a _distinct genus_; but Naudin says (p.
20), these parts have no constancy, and in the flowers of the Turban
varieties of _C. maxima_ they sometimes resume their ordinary
structure. Again, in _C. maxima,_ the carpels (p. 19) which form the
turban project even as much as two-thirds of their length out of the
receptacle, and this latter part is thus reduced to a sort of platform;
but this remarkable structure occurs only in certain varieties, and
graduates into the common form in which the carpels are almost entirely
enveloped within the receptacle. In _ C. moschata_ the ovarium (p. 50)
varies greatly in shape, being oval, nearly spherical, or cylindrical,
more or less swollen in the upper part, or constricted round the
middle, and either straight or curved. When the ovarium is short and
oval the interior structure does not differ from that of _C. maxima_
and _pepo,_ but when it is elongated the carpels occupy only the
terminal and swollen portion. I may add that in one variety of the
cucumber (_Cucumis sativus_) the fruit regularly contains five carpels
instead of three.[140] I presume that it will not be disputed that we
here have instances of great variability in organs of the highest
physiological importance, and with most plants of the highest
classificatory importance.

Sageret[141] and Naudin found that the cucumber (_C. sativus_) could
not be crossed with any other species of the genus; therefore no doubt
it is specifically distinct from the melon. This will appear to most
persons a superfluous statement; yet we hear from Naudin[142] that
there is a race of melons, in which the fruit is so like that of the
cucumber, “both externally and internally, that it is hardly possible
to distinguish the one from the other except by the leaves.” The
varieties of the melon seem to be endless, for Naudin after six years’
study had not come to the end of them: he divides them into ten
sections, including numerous sub-varieties which all intercross with
perfect ease.[143] Of the forms considered by Naudin to be varieties,
botanists have made thirty distinct species! “and they had not the
slightest acquaintance with the multitude of new forms which have
appeared since their time.” Nor is the creation of so many species at
all surprising when we consider how strictly their characters are
transmitted by seed, and how wonderfully they differ in appearance:
“Mira est quidem foliorum et habitus diversitas, sed multo magis
fructuum,” says Naudin. The fruit is the valuable part, and this, in
accordance with the common rule, is the most modified part. Some melons
are only as large as small plums, others weigh as much as sixty-six
pounds. One variety has a scarlet fruit! Another is not more than an
inch in diameter, but sometimes more than a yard in length, “twisting
about in all directions like a serpent.” It is a singular fact that in
this latter variety many parts of the plant, namely, the stems, the
footstalks of the female flowers, the middle lobe of the leaves, and
especially the ovarium, as well as the mature fruit, all show a strong
tendency to become elongated. Several varieties of the melon are
interesting from assuming the characteristic features of distinct
species and even of distinct though allied genera: thus the
serpent-melon has some resemblance to the fruit of _Trichosanthes
anguina_; we have seen that other varieties closely resemble cucumbers;
some Egyptian varieties have their seeds attached to a portion of the
pulp, and this is characteristic of certain wild forms. Lastly, a
variety of melon from Algiers is remarkable from announcing its
maturity by “a spontaneous and almost sudden dislocation,” when deep
cracks suddenly appear, and the fruit falls to pieces; and this occurs
with the wild _C. momordica._ Finally, M. Naudin well remarks that this
“extraordinary production of races and varieties by a single species
and their permanence when not interfered with by crossing, are
phenomena well calculated to cause reflection.”

      USEFUL AND ORNAMENTAL TREES.

Trees deserve a passing notice on account of the numerous varieties
which they present, differing in their precocity, in their manner of
growth, their foliage, and bark. Thus of the common ash (_Fraxinus
excelsior_) the catalogue of Messrs. Lawson of Edinburgh includes
twenty-one varieties, some of which differ much in their bark; there is
a yellow, a streaked reddish-white, a purple, a wart-barked and a
fungous-barked variety.[144] Of hollies no less than eighty-four
varieties are grown alongside each other in Mr. Paul’s nursery.[145] In
the case of trees, all the recorded varieties, as far as I can find
out, have been suddenly produced by one single act of variation. The
length of time required to raise many generations, and the little value
set on the fanciful varieties, explains how it is that successive
modifications have not been accumulated by selection; hence, also, it
follows that we do not here meet with sub-varieties subordinate to
varieties, and these again subordinate to higher groups. On the
Continent, however, where the forests are more carefully attended to
than in England, Alph. De Candolle[146] says that there is not a
forester who does not search for seeds from that variety which he
esteems the most valuable.

Our useful trees have seldom been exposed to any great change of
conditions; they have not been richly manured, and the English kinds
grow under their proper climate. Yet in examining extensive beds of
seedlings in nursery-gardens considerable differences may be generally
observed in them; and whilst touring in England I have been surprised
at the amount of difference in the appearance of the same species in
our hedgerows and woods. But as plants vary so much in a truly wild
state, it would be difficult for even a skilful botanist to pronounce
whether, as I believe to be the case, hedgerow trees vary more than
those growing in a primeval forest. Trees when planted by man in woods
or hedges do not grow where they would naturally be able to hold their
place against a host of competitors, and are therefore exposed to
conditions not strictly natural: even this slight change would probably
suffice to cause seedlings raised from such trees to be variable.
Whether or not our half-wild English trees, as a general rule, are more
variable than trees growing in their native forests, there can hardly
be a doubt that they have yielded a greater number of strongly-marked
and singular variations of structure.

In manner of growth, we have weeping or pendulous varieties of the
willow, ash, elm, oak, and yew, and other trees; and this weeping habit
is sometimes inherited, though in a singularly capricious manner. In
the Lombardy poplar, and in certain fastigiate or pyramidal varieties
of thorns, junipers, oaks, etc., we have an opposite kind of growth.
The Hessian oak,[147] which is famous from its fastigiate habit and
size, bears hardly any resemblance in general appearance to a common
oak; “its acorns are not sure to produce plants of the same habit;
some, however, turn out the same as the parent-tree.” Another
fastigiate oak is said to have been found wild in the Pyrenees, and
this is a surprising circumstance; it generally comes so true by seed,
that De Candolle considered it as specifically distinct.[148] The
fastigiate Juniper (_J. suecica_) likewise transmits its character by
seed.[149] Dr. Falconer informs me that in the Botanic Gardens at
Calcutta the great heat caused apple-trees to become fastigiate; and we
thus see the same result following from the effects of climate and from
some unknown cause.[150]

In foliage we have variegated leaves which are often inherited; dark
purple or red leaves, as in the hazel, barberry, and beech, the colour
in these two latter trees being sometimes strongly and sometimes weakly
inherited;[151] deeply-cut leaves; and leaves covered with prickles, as
in the variety of the holly well called _ ferox,_ which is said to
reproduce itself by seed.[152] In fact, nearly all the peculiar
varieties evince a tendency, more or less strongly marked, to reproduce
themselves by seed.[153] This is to a certain extent the case,
according to Bosc,[154] with three varieties of the elm, namely, the
broad-leafed, lime-leafed, and twisted elm, in which latter the fibres
of the wood are twisted. Even with the heterophyllous hornbeam
(_Carpinus betulus_), which bears on each twig leaves of two shapes,
several plants raised from seed all retained “the same
peculiarity.”[155] I will add only one other remarkable case of
variation in foliage, namely, the occurrence of two sub-varieties of
the ash with simple instead of pinnated leaves, and which generally
transmit their character by seed.[156] The occurrence, in trees
belonging to widely different orders, of weeping and fastigiate
varieties, and of trees bearing deeply cut, variegated, and purple
leaves, shows that these deviations of structure must result from some
very general physiological laws.

Differences in general appearance and foliage, not more strongly marked
than those above indicated, have led good observers to rank as distinct
species certain forms which are now known to be mere varieties. Thus, a
plane-tree long cultivated in England was considered by almost every
one as a North American species: but is now ascertained by old records,
as I am informed by Dr. Hooker, to be a variety. So, again, the _Thuja
pendula_ or _filiformis_ was ranked by such good observers as Lambert,
Wallich, and others, as a true species; but it is now known that the
original plants, five in number, suddenly appeared in a bed of
seedlings, raised at Mr. Loddige’s nursery, from _T. orientalis_; and
Dr. Hooker has adduced excellent evidence that at Turin seeds of _T.
pendula_ have reproduced the parent form, _T. orientalis._[157]

Every one must have noticed how certain individual trees regularly put
forth and shed their leaves earlier or later than others of the same
species. There is a famous horse-chestnut in the Tuileries which is
named from leafing so much earlier than the others. There is also an
oak near Edinburgh which retains its leaves to a very late period.
These differences have been attributed by some authors to the nature of
the soil in which the trees grow; but Archbishop Whately grafted an
early thorn on a late one, and _vice versa,_ and both grafts kept to
their proper periods, which differed by about a fortnight, as if they
still grew on their own stocks.[158] There is a Cornish variety of the
elm which is almost an evergreen, and is so tender that the shoots are
often killed by the frost; and the varieties of the Turkish oak (_Q.
cerris_) may be arranged as deciduous, sub-evergreen, and
evergreen.[159]

_Scotch Fir (Pinus sylvestris)._—I allude to this tree as it bears on
the question of the greater variability of our hedgerow trees compared
with those under strictly natural conditions. A well-informed
writer[160] states that the Scotch fir presents few varieties in its
native Scotch forests; but that it “varies much in figure and foliage,
and in the size, shape, and colour of its cones, when several
generations have been produced away from its native locality.” There is
little doubt that the highland and lowland varieties differ in the
value of their timber, and that they can be propagated truly by seed;
thus justifying Loudon’s remark, that “a variety is often of as much
importance as a species, and sometimes far more so.”[161] I may mention
one rather important point in which this tree occasionally varies; in
the classification of the Coniferæ, sections are founded on whether
two, three, or five leaves are included in the same sheath; the Scotch
fir has properly only two leaves thus enclosed, but specimens have been
observed with groups of three leaves in a sheath.[162] Besides these
differences in the semi-cultivated Scotch fir, there are in several
parts of Europe natural or geographical races, which have been ranked
by some authors as distinct species.[163] Loudon[164] considers _P.
pumilio,_ with its several sub-varieties, as _mughus, nana,_ etc.,
which differ much when planted in different soils, and only come
“tolerably true from seed,” as alpine varieties of the Scotch fir; if
this were proved to be the case, it would be an interesting fact as
showing that dwarfing from long exposure to a severe climate is to a
certain extent inherited.

The _Hawthorn (Cratægus oxyacantha)._ has varied much. Besides endless
slighter variations in the form of the leaves, and in the size,
hardness, fleshiness, and shape of the berries, Loudon[165] enumerates
twenty-nine well-marked varieties. Besides those cultivated for their
pretty flowers, there are others with golden-yellow, black, and whitish
berries; others with woolly berries, and others with re-curved thorns.
Loudon truly remarks that the chief reason why the hawthorn has yielded
more varieties than most other trees, is that nurserymen select any
remarkable variety out of the immense beds of seedlings which are
annually raised for making hedges. The flowers of the hawthorn usually
include from one to three pistils; but in two varieties, named monogyna
and sibirica, there is only a single pistil; and d’Asso states that the
common thorn in Spain is constantly in this state.[166] There is also a
variety which is apetalous, or has its petals reduced to mere
rudiments. The famous Glastonbury thorn flowers and leafs towards the
end of December, at which time it bears berries produced from an
earlier crop of flowers.[167] It is worth notice that several varieties
of the hawthorn, as well as of the lime and juniper, are very distinct
in their foliage and habit whilst young, but in the course of thirty or
forty years become extremely like each other;[168] thus reminding us of
the well-known fact that the deodar, the cedar of Lebanon, and that of
the Atlas, are distinguished with the greatest ease whilst young, but
with difficulty when old.

      FLOWERS.

I shall not for several reasons treat the variability of plants which
are cultivated for their flowers alone at any great length. Many of our
favourite kinds in their present state are the descendants of two or
more species crossed and commingled together, and this circumstance
alone would render it difficult to detect the difference due to
variation. For instance, our Roses, Petunias, Calceolarias, Fuchsias,
Verbenas, Gladioli, Pelargoniums, etc., certainly have had a multiple
origin. A botanist well acquainted with the parent-forms would probably
detect some curious structural differences in their crossed and
cultivated descendant; and he would certainly observe many new and
remarkable constitutional peculiarities. I will give a few instances,
all relating to the Pelargonium, and taken chiefly from Mr. Beck,[169]
a famous cultivator of this plant: some varieties require more water
than others; some are “very impatient of the knife if too greedily used
in making cuttings;” some, when potted, scarcely “show a root at the
outside of the ball of the earth;” one variety requires a certain
amount of confinement in the pot to make it throw up a flower-stem;
some varieties bloom well at the commencement of the season, others at
the close; one variety is known,[170] which will stand “even pine-apple
top and bottom heat, without looking any more drawn than if it had
stood in a common greenhouse; and Blanche Fleur seems as if made on
purpose for growing in winter, like many bulbs, and to rest all
summer.” These odd constitutional peculiarities would enable a plant in
a state of nature to become adapted to widely different circumstances
and climates.

Flowers possess little interest under our present point of view,
because they have been almost exclusively attended to and selected for
their beautiful colour, size, perfect outline, and manner of growth. In
these particulars hardly one long-cultivated flower can be named which
has not varied greatly. What does a florist care for the shape and
structure of the organs of fructification, unless, indeed, they add to
the beauty of the flower? When this is the case, flowers become
modified in important points; stamens and pistils may be converted into
petals, and additional petals may be developed, as in all double
flowers. The process of gradual selection by which flowers have been
rendered more and more double, each step in the process of conversion
being inherited, has been recorded in several instances. In the
so-called double flowers of the Compositæ, the corollas of the central
florets are greatly modified, and the modifications are likewise
inherited. In the columbine (_Aquilegia vulgaris_) some of the stamens
are converted into petals having the shape of nectaries, one neatly
fitting into the other; but in one variety they are converted into
simple petals.[171] In the “hose in hose” primulæ, the calyx becomes
brightly coloured and enlarged so as to resemble a corolla; and Mr. W.
Wooler informs me that this peculiarity is transmitted; for he crossed
a common polyanthus with one having a coloured calyx,[172] and some of
the seedlings inherited the coloured calyx during at least six
generations. In the “hen-and-chicken” daisy the main flower is
surrounded by a brood of small flowers developed from buds in the axils
of the scales of the involucre. A wonderful poppy has been described,
in which the stamens are converted into pistils; and so strictly was
this peculiarity inherited that, out of 154 seedlings, one alone
reverted to the ordinary and common type.[173] Of the cock’s-comb
(_Celosia cristata_), which is an annual, there are several races in
which the flower-stem is wonderfully “fasciated” or compressed; and one
has been exhibited[174] actually eighteen inches in breadth. Peloric
races of _Gloxinia speciosa_ and _Antirrhinum majus_ can be propagated
by seed, and they differ in a wonderful manner from the typical form
both in structure and appearance.

A much more remarkable modification has been recorded by Sir William
and Dr. Hooker[175] in _Begonia frigida._ This plant properly produces
male and female flowers on the same fascicles; and in the female
flowers the perianth is superior; but a plant at Kew produced, besides
the ordinary flowers, others which graduated towards a perfect
hermaphrodite structure; and in these flowers the perianth was
inferior. To show the importance of this modification under a
classificatory point of view, I may quote what Prof. Harvey says,
namely, that had it “occurred in a state of nature, and had a botanist
collected a plant with such flowers, he would not only have placed it
in a distinct genus from Begonia, but would probably have considered it
as the type of a new natural order.” This modification cannot in one
sense be considered as a monstrosity, for analogous structures
naturally occur in other orders, as with Saxifragæ and Aristolochiaceæ.
The interest of the case is largely added to by Mr. C. W. Crocker’s
observation that seedlings from the _normal_ flowers produced plants
which bore, in about the same proportion as the parent-plant,
hermaphrodite flowers having inferior perianths. The hermaphrodite
flowers fertilised with their own pollen were sterile.

If florists had attended to, selected, and propagated by seed other
modifications of structure besides those which are beautiful, a host of
curious varieties would certainly have been raised; and they would
probably have transmitted their characters so truly that the cultivator
would have felt aggrieved, as in the case of culinary vegetables, if
his whole bed had not presented a uniform appearance. Florists have
attended in some instances to the leaves of their plant, and have thus
produced the most elegant and symmetrical patterns of white, red, and
green, which, as in the case of the pelargonium, are sometimes strictly
inherited.[176] Any one who will habitually examine highly-cultivated
flowers in gardens and greenhouses will observe numerous deviations in
structure; but most of these must be ranked as mere monstrosities, and
are only so far interesting as showing how plastic the organisation
becomes under high cultivation. From this point of view such works as
Professor Moquin-Tandon’s ‘Tératologie’ are highly instructive.

_Roses._—These flowers offer an instance of a number of forms generally
ranked as species, namely, _R. centifolia, gallica, alba, damascena,
spinosissima, bracteata, indica, semperflorens, moschata,_ etc., which
have largely varied and been intercrossed. The genus Rosa is a
notoriously difficult one, and, though some of the above forms are
admitted by all botanists to be distinct species, others are doubtful;
thus, with respect to the British forms, Babington makes seventeen, and
Bentham only five species. The hybrids from some of the most distinct
forms—for instance, from _R. indica,_ fertilised by the pollen of _R.
centifolia_—produce an abundance of seed; I state this on the authority
of Mr. Rivers,[177] from whose work I have drawn most of the following
statements. As almost all the aboriginal forms brought from different
countries have been crossed and re-crossed, it is no wonder that
Targioni-Tozzetti, in speaking of the common roses of the Italian
gardens, remarks that “the native country and precise form of the wild
type of most of them are involved in much uncertainty.”[178]
Nevertheless, Mr. Rivers in referring to _R. indica_ (p. 68) says that
the descendants of each group may generally be recognised by a close
observer. The same author often speaks of roses as having been a little
hybridised; but it is evident that in very many cases the differences
due to variation and to hybridisation can now only be conjecturally
distinguished.

The species have varied both by seed and by bud; such modified buds
being often called by gardeners sports. In the following chapter I
shall fully discuss this latter subject, and shall show that
bud-variations can be propagated not only by grafting and budding, but
often by seed. Whenever a new rose appears with any peculiar character,
however produced, if it yields seed, Mr. Rivers (p. 4) fully expects it
to become the parent-type of a new family. The tendency to vary is so
strong in some kinds, as in the Village Maid (Rivers, p. 16), that when
grown in different soils it varies so much in colour that it has been
thought to form several distinct kinds. Altogether the number of kinds
is very great: thus M. Desportes, in his Catalogue for 1829, enumerates
2562 as cultivated in France; but no doubt a large proportion of these
are merely nominal.

It would be useless to specify the many points of difference between
the various kinds, but some constitutional peculiarities may be
mentioned. Several French roses (Rivers, p. 12) will not succeed in
England; and an excellent horticulturist[179] remarks, that “Even in
the same garden you will find that a rose that will do nothing under a
south wall will do well under a north one. That is the case with Paul
Joseph here. It grows strongly and blooms beautifully close to a north
wall. For three years seven plants have done nothing under a south
wall.” Many roses can be forced, “many are totally unfit for forcing,
among which is General Jacqueminot.”[180] From the effects of crossing
and variation Mr. Rivers enthusiastically anticipates (p. 87) that the
day will come when all our roses, even moss-roses, will have evergreen
foliage, brilliant and fragrant flowers, and the habit of blooming from
June till November. “A distant view this seems, but perseverance in
gardening will yet achieve wonders,” as assuredly it has already
achieved wonders.

It may be worth while briefly to give the well-known history of one
class of roses. In 1793 some wild Scotch roses (_R. spinosissima_) were
transplanted into a garden;[181] and one of these bore flowers slightly
tinged with red, from which a plant was raised with semi-monstrous
flowers, also tinged with red; seedlings from this flower were
semi-double, and by continued selection, in about nine or ten years,
eight sub-varieties were raised. In the course of less than twenty
years these double Scotch roses had so much increased in number and
kind, that twenty-six well-marked varieties, classed in eight sections,
were described by Mr. Sabine. In 1841[182] it is said that three
hundred varieties could be procured in the nursery-gardens near
Glasgow; and these are described as blush, crimson, purple, red,
marbled, two-coloured, white, and yellow, and as differing much in the
size and shape of the flower.

_Pansy or Heartsease (Viola tricolor, etc.)._—The history of this
flower seems to be pretty well known; it was grown in Evelyn’s garden
in 1687; but the varieties were not attended to till 1810-1812, when
Lady Monke, together with Mr. Lee, the well-known nursery-man,
energetically commenced their culture; and in the course of a few years
twenty varieties could be purchased.[183] At about the same period,
namely in 1813 or 1814, Lord Gambier collected some wild plants, and
his gardener, Mr. Thomson, cultivated them, together with some common
garden varieties, and soon effected a great improvement. The first
great change was the conversion of the dark lines in the centre of the
flower into a dark eye or centre, which at that period had never been
seen, but is now considered one of the chief requisites of a first-rate
flower. In 1835 a book entirely devoted to this flower was published,
and four hundred named varieties were on sale. From these circumstances
this plant seemed to me worth studying, more especially from the great
contrast between the small, dull, elongated, irregular flowers of the
wild pansy, and the beautiful, flat, symmetrical, circular, velvet-like
flowers, more than two inches in diameter, magnificently and variously
coloured, which are exhibited at our shows. But when I came to enquire
more closely, I found that, though the varieties were so modern, yet
that much confusion and doubt prevailed about their parentage. Florists
believe that the varieties[184] are descended from several wild stocks,
namely, _V. tricolor, lutea, grandiflora, amœna,_ and _altaica,_ more
or less intercrossed. And when I looked to botanical works to ascertain
whether these forms ought to be ranked as species, I found equal doubt
and confusion. _Viola altaica_ seems to be a distinct form, but what
part it has played in the origin of our varieties I know not; it is
said to have been crossed with _V. lutea. Viola amœna_[185] is now
looked at by all botanists as a natural variety of _V. grandiflora_;
and this and _V. sudetica_ have been proved to be identical with _V.
lutea._ The latter and _V. tricolor_ (including its admitted variety
_V. arvensis_) are ranked as distinct species by Babington, and
likewise by M. Gay,[186] who has paid particular attention to the
genus; but the specific distinction between _V. lutea_ and _tricolor_
is chiefly grounded on the one being strictly and the other not
strictly perennial, as well as on some other slight and unimportant
differences in the form of the stem and stipules. Bentham unites these
two forms; and a high authority on such matters, Mr. H. C. Watson,[187]
says that, “while _V. tricolor_ passes into _V. arvensis_ on the one
side, it approximates so much towards _V. lutea_ and _V. Curtisii_ on
the other side, that a distinction becomes scarcely more easy between
them.”

Hence, after having carefully compared numerous varieties, I gave up
the attempt as too difficult for any one except a professed botanist.
Most of the varieties present such inconstant characters, that when
grown in poor soil, or when flowering out of their proper season, they
produced differently coloured and much smaller flowers. Cultivators
speak of this or that kind as being remarkably constant or true; but by
this they do not mean, as in other cases, that the kind transmits its
character by seed, but that the individual plant does not change much
under culture. The principle of inheritance, however, does hold good to
a certain extent even with the fleeting varieties of the Heartsease,
for to gain good sorts it is indispensable to sow the seed of good
sorts. Nevertheless, in almost every large seed-bed a few, almost wild
seedlings reappear through reversion. On comparing the choicest
varieties with the nearest allied wild forms, besides the difference in
the size, outline, and colour of the flowers, the leaves sometimes
differ in shape, as does the calyx occasionally in the length and
breadth of the sepals. The differences in the form of the nectary more
especially deserve notice; because characters derived from this organ
have been much used in the discrimination of most of the species of
Viola. In a large number of flowers compared in 1842 I found that in
the greater number the nectary was straight; in others the extremity
was a little turned upwards, or downwards, or inwards, so as to be
completely hooked; in others, instead of being hooked, it was first
turned rectangularly downwards, and then backwards and upwards; in
others, the extremity was considerably enlarged; and lastly, in some
the basal part was depressed, becoming, as usual, laterally compressed
towards the extremity. In a large number of flowers, on the other hand,
examined by me in 1856 from a nursery-garden in a different part of
England, the nectary hardly varied at all. Now M. Gay says that in
certain districts, especially in Auvergne, the nectary of the wild _V.
grandiflora_ varies in the manner just described. Must we conclude from
this that the cultivated varieties first mentioned were all descended
from _V. grandiflora,_ and that the second lot, though having the same
general appearance, were descended from _V. tricolor,_ of which the
nectary, according to M. Gay, is subject to little variation? Or is it
not more probable that both these wild forms would be found under other
conditions to vary in the same manner and degree, thus showing that
they ought not to be ranked as specifically distinct?

The _Dahlia_ has been referred to by almost every author who has
written on the variation of plants, because it is believed that all the
varieties are descended from a single species, and because all have
arisen since 1802 in France, and since 1804 in England.[188] Mr. Sabine
remarks that “it seems as if some period of cultivation had been
required before the fixed qualities of the native plant gave way and
began to sport into those changes which now so delight us.”[189] The
flowers have been greatly modified in shape from a flat to a globular
form. Anemone and ranunculus-like races[190] which differ in the form
and arrangement of the florets, have arisen; also dwarfed races, one of
which is only eighteen inches in height. The seeds vary much in size.
The petals are uniformly coloured or tipped or striped, and present an
almost infinite diversity of tints. Seedlings of fourteen different
colours[191] have been raised from the same plant; yet, as Mr. Sabine
has remarked, “many of the seedlings follow their parents in colour.”
The period of flowering has been considerably hastened, and this has
probably been effected by continued selection. Salisbury, writing 1808,
says that they then flowered from September to November; in 1828 some
new dwarf varieties began flowering in June;[192] and Mr. Grieve
informs me that the dwarf purple Zelinda in his garden is in full bloom
by the middle of June and sometimes even earlier. Slight constitutional
differences have been observed between certain varieties: thus, some
kinds succeed much better in one part of England than in another;[193]
and it has been noticed that some varieties require much more moisture
than others.[194]

Such flowers as the carnation, common tulip, and hyacinth, which are
believed to be descended, each from a single wild form, present
innumerable varieties, differing almost exclusively in the size, form,
and colour of the flowers. These and some other anciently cultivated
plants which have been long propagated by offsets, pipings, bulbs,
etc., become so excessively variable, that almost each new plant raised
from seed forms a new variety, “all of which to describe particularly,”
as old Gerarde wrote in 1597, “were to roll Sisyphus’s stone, or to
number the sands.”

_Hyacinth (Hyacinthus orientalis)._—It may, however, be worth while to
give a short account of this plant, which was introduced into England
in 1596 from the Levant.[195] The petals of the original flower, says
Mr. Paul, were narrow, wrinkled, pointed, and of a flimsy texture; now
they are broad, smooth, solid, and rounded. The erectness, breadth, and
length of the whole spike, and the size of the flowers, have all
increased. The colours have been intensified and diversified. Gerarde,
in 1597, enumerates four, and Parkinson, in 1629, eight varieties. Now
the varieties are very numerous, and they were still more numerous a
century ago. Mr. Paul remarks that “it is interesting to compare the
Hyacinths of 1629 with those of 1864, and to mark the improvement. Two
hundred and thirty-five years have elapsed since then, and this simple
flower serves well to illustrate the great fact that the original forms
of nature do not remain fixed and stationary, at least when brought
under cultivation. While looking at the extremes, we must not, however,
forget that there are intermediate stages which are for the most part
lost to us. Nature will sometimes indulge herself with a leap, but as a
rule her march is slow and gradual.” He adds that the cultivator should
have “in his mind an ideal of beauty, for the realisation of which he
works with head and hand.” We thus see how clearly Mr. Paul, an
eminently successful cultivator of this flower, appreciates the action
of methodical selection.

In a curious and apparently trustworthy treatise, published at
Amsterdam[196] in 1768, it is stated that nearly 2,000 sorts were then
known; but in 1864 Mr. Paul found only 700 in the largest garden at
Haarlem. In this treatise it is said that not an instance is known of
any one variety reproducing itself truly by seed: the white kinds,
however, now[197] almost always yield white hyacinths, and the yellow
kinds come nearly true. The hyacinth is remarkable from having given
rise to varieties with bright blue, pink, and distinctly yellow
flowers. These three primary colours do not occur in the varieties of
any other species; nor do they often all occur even in the distinct
species of the same genus. Although the several kinds of hyacinths
differ but slightly from each other except in colour, yet each kind has
its own individual character, which can be recognised by a highly
educated eye; thus the writer of the Amsterdam treatise asserts (p. 43)
that some experienced florists, such as the famous G. Voorhelm, seldom
failed in a collection of above twelve hundred sorts to recognise each
variety by the bulb alone! This same writer mentions some few singular
variations: for instance, the hyacinth commonly produces six leaves,
but there is one kind (p. 35) which scarcely ever has more than three
leaves; another never more than five; whilst others regularly produce
either seven or eight leaves. A variety, called la Coryphee, invariably
produces (p. 116) two flower-stems, united together and covered by one
skin. The flower-stem in another kind (p. 128) comes out of the ground
in a coloured sheath, before the appearance of the leaves, and is
consequently liable to suffer from frost. Another variety always pushes
a second flower-stem after the first has begun to develop itself.
Lastly, white hyacinths with red, purple, or violet centres (p. 129)
are the most liable to rot. Thus, the hyacinth, like so many previous
plants, when long cultivated and closely watched, is found to offer
many singular variations.

In the two last chapters I have given in some detail the range of
variation, and the history, as far as known, of a considerable number
of plants, which have been cultivated for various purposes. But some of
the most variable plants, such as Kidney-beans, Capsicum, Millets,
Sorghum, etc., have been passed over; for botanists are not at all
agreed which kinds ought to rank as species and which as varieties; and
the wild parent-species are unknown.[198] Many plants long cultivated
in tropical countries, such as the Banana, have produced numerous
varieties; but as these have never been described with even moderate
care, they are here also passed over. Nevertheless, a sufficient, and
perhaps more than sufficient, number of cases have been given, so that
the reader may be enabled to judge for himself on the nature and great
amount of variation which cultivated plants have undergone.

REFERENCES

 [1] Heer, ‘Pflanzen der Pfahlbauten,’ 1866, s. 28.

 [2] Alph. De Candolle ‘Géograph. Bot.,’ p. 872; Dr. A.
 Targioni-Tozzetti in ‘Jour. Hort. Soc.,’ vol. ix. p. 133. For the
 fossil vine found by Dr. G. Planchon _See_ ‘Nat. Hist. Review,’ 1865,
 April, p. 224. _See also_ the valuable works of M. de Saporta on the
 ‘Tertiary Plants of France.’

 [3] Godron, ‘De l’Espèce,’ tom. ii. p. 100.

 [4] _See_ an account of M. Vibert’s experiments, by Alex. Jordan, in
 ‘Mém. de l’Acad. de Lyon,’ tom. ii. 185,2 p. 108.

 [5] ‘Gardener’s Chronicle,’ 1864, p. 488.

 [6] ‘Arbres Fruitiers,’ 1836, tom. ii. p. 290.

 [7] Odart, ‘Ampelographie Universelle,’ 1849.

 [8] M. Bouchardat, in ‘Comptes Rendus,’ Dec. 1st, 1851, quoted in
 ‘Gardener’s Chron.,’ 1852, p. 435. _See_ also C. V. Riley on the
 manner in which some few of the varieties of the American Labruscan
 Vine escape the attacks of the Phylloxera: ‘Fourth Annual Report on
 the Insects of Missouri,’ 1872, p. 63, and ‘Fifth Report,’ 1873, p.
 66.

 [9] ‘Etudes sur les Maladies actuelles du Ver à Soie,’ 1859, p. 321.

 [10] ‘Productive Resources of India,’ p. 130.

 [11] ‘Traité du Citrus,’ 1811. ‘Teoria della Riproduzione Vegetale,’
 1816. I quote chiefly from this second work. In 1839 Gallesio
 published in folio ‘Gli Agrumi dei Giard. Bot. di Firenze,’ in which
 he gives a curious diagram of the supposed relationship of all the
 forms.

 [12] Mr. Bentham, ‘Review of Dr. A. Targioni-Tozzetti, Journal of
 Hort. Soc.,’ vol. ix. p. 133.

 [13] ‘Géograph. Bot.,’ p. 863.

 [14] ‘Teoria della Riproduzione,’ pp. 52-57.

 [15] Hooker’s ‘Bot. Misc.,’ vol. i. p. 302; vol. ii. p. 111.

 [16] ‘Teoria della Riproduzione,’ p. 53.

 [17] Gallesio, ‘Teoria della Riproduzione,’ p. 69.

 [18] Ibid. p. 67.

 [19] Gallesio, ‘Teoria della Riproduzione,’ pp. 75, 76.

 [20] ‘Gardener’s Chronicle,’ 1841, p. 613.

 [21] ‘Annales du Muséum,’ tom. xx. p. 188.

 [22] ‘Géograph. Bot.,’ p. 882.

 [23] ‘Transactions of Hort. Soc.,’ vol. iii. p. 1, and vol. iv. p.
 396, and note to p. 370. A coloured drawing is given of this hybrid.

 [24] ‘Gardener’s Chronicle,’ 1856, p. 532. A writer, it may be
 presumed Dr. Lindley, remarks on the perfect series which may be
 formed between the almond and the peach. Another high authority, Mr.
 Rivers, who has had such wide experience, strongly suspects
 (‘Gardener’s Chronicle,’ 1863, p. 27) that peaches, if left to a state
 of nature, would in the course of time retrograde into thick-fleshed
 almonds.

 [25] ‘Journal of Hort. Soc.,’ vol. ix. p. 168.

 [26] Whether this is the same variety as one lately mentioned (‘Gard.
 Chron.’ 1865, p. 1154) by M. Carrière under the name of _persica
 intermedia,_ I know not; this variety is said to be intermediate in
 nearly all its characters between the almond and peach; it produces
 during successive years very different kinds of fruit.

 [27] Quoted in ‘Gard. Chron.’ 1866, p. 800.

 [28] Quoted in ‘Journal de La Soc. Imp. d’Horticulture,’ 1855, p. 238.

 [29] ‘Teoria della Riproduzione Vegetale,’ 1816, p. 86.

 [30] ‘Gardener’s Chronicle,’ 1862, p. 1195.

 [31] Mr. Rivers, ‘Gardener’s Chron.,’ 1859, p. 774.

 [32] Downing, ‘The Fruits of America,’ 1845, pp. 475, 489, 492, 494,
 496. _See also_ F. Michaux, ‘Travels in N. America’ (Eng. translat.),
 p. 228. For similar cases in France _See_ Godron, ‘De l’Espèce,’ tom.
 ii. p. 97.

 [33] Brickell’s ‘Nat. Hist. of N. Carolina,’ p. 102, and Downing’s
 ‘Fruit Trees,’ p. 505.

 [34] ‘Gardener’s Chronicle,’ 1862, p. 1196.

 [35] The peach and nectarine do not succeed equally well in the some
 soil: _See_ Lindley’s ‘Horticulture,’ p. 351.

 [36] Godron, ‘De l’Espèce,’ tom. ii., 1859, p. 97.

 [37] ‘Transact. Hort. Soc.,’ vol. vi. p. 394.

 [38] Downing’s ‘Fruit Trees,’ p. 502.

 [39] ‘Gardener’s Chronicle,’ 1862, p. 1195.

 [40] ‘Journal of Horticulture,’ Feb. 5th, 1866, p. 102.

 [41] Mr. Rivers, in ‘Gardener’s ‘Chron.,’ 1859, p. 774, 1862, p. 1195;
 1865, p. 1059; and ‘Journal of Hort.,’ 1866, p. 102.

 [42] ‘Correspondence of Linnæus,’ 1821, pp. 7, 8, 70.

 [43] ‘Transact. Hort. Soc.,’ vol. i. p. 103.

 [44] Loudon’s ‘Gardener’s Mag.,’ 1826, vol. i. p. 471.

 [45] Loudon’s ‘Gardener’s Mag.,’ 1828, p. 53.

 [46] Ibid., 1830, p. 597.

 [47] ‘Gardener’s Chronicle,’ 1841, p. 617.

 [48] ‘Gardener’s Chronicle,’ 1844, p. 589.

 [49] ‘Phytologist,’ vol. iv. p. 299.

 [50] ‘Gardener’s Chron.,’ 1856, p. 531.

 [51] Godron, ‘De l’Espèce,’ tom. ii. p. 97.

 [52] ‘Gardener’s Chron.,’ 1856, p. 531.

 [53] Alph. De Candolle, ‘Géograph. Bot.’ p. 886.

 [54] Thompson, in Loudon’s ‘Encyclop. of Gardening,’ p. 911.

 [55] ‘Catalogue of Fruit in Garden of Hort. Soc.,’ 1842, p. 105.

 [56] Dr. A. Targioni-Tozzetti, ‘Journal Hort. Soc.,’ vol. ix. p. 167.
 Alph. de Candolle, ‘Géograph. Bot.,’ p. 885.

 [57] ‘Transact. Hort. Soc.,’ vol. v. p. 554. _See also_ Carrière,
 ‘Description et Class. des Variétés de Pêchers.’

 [58] Loudon’s ‘Encyclop. of Gardening,’ p. 907.

 [59] M. Carrière, in ‘Gard. Chron.,’ 1865, p. 1154.

 [60] ‘Transact. Hort. Soc.,’ vol. iii. p. 332. _See also_ ‘Gardener’s
 Chronicle,’ 1865, p. 271 to same effect. Also ‘Journal of
 Horticulture,’ Sept. 26th, 1865, p. 254.

 [61] ‘Transact. Hort. Soc.,’ vol. iv. p. 512.

 [62] ‘Journal of Horticulture,’ Sept. 8th, 1853 p. 188.

 [63] ‘Transact. Hort. Soc.,’ vol. vi. p. 412.

 [64] ‘Gardener’s Chronicle,’ 1857, p. 216.

 [65] ‘Journal of Hort. Soc.,’ vol. ii. 283.

 [66] Alph. de Candolle ‘Géograph. Bot.,’ p. 879.

 [67] ‘Transact. Hort. Soc.’ (2nd series), vol. i. 1835, p. 56. _ See
 also_ ‘Cat. of Fruit in Garden of Hort. Soc.,’ 3rd edit. 1842.

 [68] Downing, ‘The Fruits of America,’ 1845, p. 157: with respect to
 the Alberge apricot in France _See_ p. 153.

 [69] ‘Gardener’s Chronicle,’ 1863, p. 364.

 [70] ‘Travels in the Himalayan Provinces,’ vol. i. 1841, p. 295.

 [71] _See_ an excellent discussion on this subject in Hewett C.
 Watson’s ‘Cybele Britannica,’ vol. iv. p. 80.

 [72] ‘Gardener’s Chronicle,’ 1865, p. 27.

 [73] ‘De l’Espèce,’ tom. ii. p. 94. On the parentage of our plums _see
 also_ Alph. De Candolle ‘Géograph. Bot.,’ p. 878. Also
 Targioni-Tozzetti, ‘Journal Hort. Soc.,’ vol. ix. p. 164. Also
 Babington ‘Manual of Brit. Botany,’ 1851, p. 87.

 [74] ‘Fruits of America,’ pp. 276, 278, 284, 310, 314. Mr. Rivers
 raised (‘Gard. Chron.,’ 1863, p. 27) from the Prune-pêche, which bears
 large, round, red plums on stout, robust shoots, a seedling which
 bears oval, smaller fruit on shoots that are so slender as to be
 almost pendulous.

 [75] ‘Gardener’s Chronicle,’ 1855, p. 726.

 [76] Downing’s ‘Fruit Trees,’ p. 278.

 [77] ‘Gardener’s Chronicle,’ 1863, p. 27. Sageret, in his ‘Pomologie
 Phys.,’ p. 346, enumerates five kinds which can be propagated in
 France by seed: _see also_ Downing’s ‘Fruit Trees of America,’ pp.
 305, 312, etc.

 [78] Compare Alph. De Candolle ‘Géograph. Bot.,’ p. 877; Bentham and
 Targioni-Tozzetti, in ‘Hort. Journal,’ vol. ix. p. 163; Godron, ‘De
 l’Espèce,’ tom. ii. p. 92.

 [79] ‘Transact. Hort. Soc.,’ vol. v. 1824, p. 295.

 [80] Ibid., second series, vol. i. 1835, p. 248.

 [81] Ibid., vol. ii. p. 138.

 [82] These several statements are taken from the four following works,
 which may, I believe, be trusted: Thompson, in ‘Hort. Transact.,’
 _see_ above; Sageret’s ‘Pomologie Phys.,’ 1830, pp. 358, 364, 367,
 379; ‘Catalogue of the Fruit in the Garden of Hort. Soc.,’ 1842, pp.
 57, 60; Downing, ‘The Fruits of America,’ 1845, pp. 189, 195, 200.

 [83] Mr. Lowe states in his ‘Flora of Madeira’ (quoted in ‘Gard.
 Chron.,’ 1862, p. 215) that the _P. malus,_ with its nearly sessile
 fruit, ranges farther south than the long-stalked _P. acerba,_ which
 is entirely absent in Madeira, the Canaries, and apparently in
 Portugal. This fact supports the belief that these two forms deserve
 to be called species. But the characters separating them are of slight
 importance, and of a kind known to vary in other cultivated
 fruit-trees.

 [84] _See_ ‘Journ. of Hort. Tour, by Deputation of the Caledonian
 Hort. Soc.,’ 1823, p. 459.

 [85] H. C. Watson, ‘Cybele Britannica,’ vol. i. p. 334.

 [86] Loudon’s ‘Gardener’s Mag.,’ vol. vi., 1830, p. 83.

 [87] _See_ ‘Catalogue of Fruit in Garden of Hort. Soc.,’ 1842, and
 Downing’s ‘American Fruit Trees.’

 [88] Loudon’s ‘Gardener’s Magazine,’ vol. iv., 1828, p. 112.

 [89] ‘The Culture of the Apple,’ p. 43. Van Mons makes the same remark
 on the pear, ‘Arbres Fruitiers,’ tom. ii., 1836, p. 414.

 [90] Lindley’s ‘Horticulture,’ p. 116. _See also_ Knight on the
 Apple-Tree, in ‘Transact. of Hort. Soc.,’ vol. vi., p. 229.

 [91] Transact. Hort. Soc.’ vol. i. 1812, p. 120.

 [92] ‘Journal of Horticulture,’ March 13th, 1866, p. 194.

 [93] ‘Transact. Hort. Soc.,’ vol. iv. p. 68. For Knight’s case _ see_
 vol. vi. p. 547. When the _coccus_ first appeared in this country it
 is said (vol. ii. p. 163) that it was more injurious to crab-stocks
 than to the apples grafted on them. The Majetin apple has been found
 equally free of the coccus at Melbourne in Australia (‘Gard. Chron.,’
 1871, p. 1065). The wood of this tree has been there analysed, and it
 is said (but the fact seems a strange one) that its ash contained over
 50 per cent of lime, while that of the crab exhibited not quite 23 per
 cent. In Tasmania Mr. Wade (‘Transact. New Zealand Institute,’ vol.
 iv. 1871, p. 431) raised seedlings of the Siberian Bitter Sweet for
 stocks, and he found barely one per cent of them attacked by the
 coccus. Riley shows (‘Fifth Report on Insects of Missouri,’ 1873, p.
 87) that in the United States some varieties of apples are highly
 attractive to the coccus and others very little so. Turning to a very
 different pest, namely, the caterpillar of a moth (_Carpocapsa
 pomonella_), Walsh affirms (‘The American Entomologist,’ April, 1869,
 p. 160) that the maiden-blush “is entirely exempt from apple-worms.”
 So, it is said, are some few other varieties; whereas others are
 “peculiarly subject to the attacks of this little pest.”

 [94] ‘Mém. de La Soc. Linn. de Paris,’ tom. iii. 1825, p. 164; and
 Seringe ‘Bulletin Bot.’ 1830, p. 117.

 [95] Gardener’s Chronicle,’ 1849, p. 24.

 [96] R. Thompson, in ‘Gardener’s Chronicle,’ 1850, p. 788.

 [97] Sageret ‘Pomologie Physiologique,’ 1830, p. 263. Downing’s ‘Fruit
 Trees,’ pp. 130, 134, 139, etc. Loudon’s ‘Gardener’s Mag.’ vol. viii.
 p. 317. Alexis Jordan, ‘De l’Origine des diverses Variétés,’ in ‘Mém.
 de l’Acad. Imp. de Lyon,’ tom. ii. 1852, pp. 95, 114. ‘Gardener’s
 Chronicle,’ 1850, pp. 774, 788.

 [98] ‘Comptes Rendus,’ July 6th, 1863.

 [99] ‘Gardener’s Chronicle,’ 1856, p. 804; 1857, p. 820; 1862, p.
 1195.

 [100] Most of the largest cultivated strawberries are the descendants
 of _F. grandiflora_ or _chiloensis,_ and I have seen no account of
 these forms in their wild state. Methuen’s Scarlet (Downing, ‘Fruits,’
 p. 527) has “immense fruit of the largest size,” and belongs to the
 section descended from _F. virginiana;_ and the fruit of this species,
 as I hear from Prof. A. Gray, is only a little larger than that of _F.
 vesca,_ or our common wood-strawberry.

 [101] ‘Le Fraisier,’ par le Comte L. de Lambertye, 1864, p. 50.

 [102] ‘Transact. Hort. Soc.,’ vol. iii. 1820, p. 207.

 [103] _See_ an account by Prof. Decaisne, and by others in ‘Gardener’s
 Chronicle,’ 1862, p. 335, and 1858, p. 172; and Mr. Barnet’s paper in
 ‘Hort. Soc. Transact.,’ vol. vi. 1826, p. 170.

 [104] ‘Transact. Hort. Soc.,’ vol. v. 1824, p. 294.

 [105] ‘Journal of Horticulture,’ Dec. 30th, 1862, p. 779. _See also_
 Mr. Prince to the same effect, ibid., 1863, p. 418.

 [106] For additional evidence _see_ ‘Journal of Horticulture,’ Dec.
 9th, 1862, p. 721.

 [107] ‘Le Fraisier,’ par le Comte L. de Lambertye, pp. 221, 230.

 [108] ‘Transact. Hort. Soc.,’ vol. vi. p. 200.

 [109] ‘Gardener’s Chronicle,’ 1858, p. 173.

 [110] Godron ‘De l’Espèce,’ tom. i. p. 161.

 [111] ‘Gardener’s Chronicle,’ 1851, p. 440.

 [112] F. Gloede in ‘Gardener’s Chronicle,’ 1862, p. 1053.

 [113] Downing’s ‘Fruits,’ p. 532.

 [114] Barnet, in ‘Hort. Transact.,’ vol. vi. p. 210.

 [115] ‘Gardener’s Chronicle,’ 1847, p. 539.

 [116] For the several statements with respect to the American
 strawberries _see_ Downing, ‘Fruits,’ p. 524; ‘Gardener’s Chronicle,’
 1843, p. 188; 1847, p. 539; 1861, p. 717.

 [117] Mr. D. Beaton, in ‘Cottage Gardener,’ 1860, p. 86. _See also_
 ‘Cottage Gardener,’ 1855, p. 88, and many other authorities. For the
 Continent, _see_ F. Gloede, in ‘Gardener’s Chronicle,’ 1862, p. 1053.

 [118] Rev. W. F. Radclyffe, in ‘Journal of Hort.,’ March 14th, 1865,
 p. 207.

 [119] Mr. H. Doubleday in ‘Gardener’s Chronicle,’ 1862, p. 1101.

 [120] ‘Gardener’s Chronicle,’ 1854, p. 254.

 [121] Loudon’s ‘Encyclop. of Gardening,’ p. 930; and Alph. De Candolle
 ‘Géograph. Bot.,’ p. 910.

 [122] Loudon’s ‘Gardener’s Magazine,’ vol. iv. 1828, p. 112.

 [123] The fullest account of the gooseberry is given by Mr. Thompson
 in ‘Transact. Hort. Soc.,’ vol. i., 2nd series, 1835, p. 218, from
 which most of the foregoing facts are taken.

 [124] ‘Catalogue of Fruits of Hort. Soc. Garden,’ 3rd edit., 1842.

 [125] Mr. Clarkson of Manchester, on the Culture of the Gooseberry, in
 Loudon’s ‘Gardener’s Magazine,’ vol. iv. 1828, p. 482.

 [126] Downing’s ‘Fruits of America,’ p. 213.

 [127] ‘Gardener’s Chronicle,’ 1844, p. 811, where a table is given;
 and 1845, p. 819. For the extreme weights gained, _see_ ‘Journal of
 Horticulture,’ July 26th, 1864, p. 61.

 [128] Mr. Saul, of Lancaster, in Loudon’s ‘Gardener’s Mag.,’ vol. iii.
 1828, p. 421; and vol. x. 1834, p. 42.

 [129] ‘Himalayan Journals,’ 1854, vol. ii. p. 334. Moorcroft
 (‘Travels,’ vol. ii. p. 146) describes four varieties cultivated in
 Kashmir.

 [130] ‘Gardener’s Chronicle,’ 1850, p. 723.

 [131] Paper translated in Loudon’s ‘Gardener’s Mag.,’ 1829, vol. v. p.
 202.

 [132] Quoted in ‘Gardener’s Chronicle,’ 1849, p. 101.

 [133] ‘Gardener’s Chronicle,’ 1847, pp. 541 and 558.

 [134] The following details are taken from the ‘Catalogue of Fruits,
 1842, in Garden of Hort. Soc.,’ p. 103; and from Loudon’s ‘Encyclop.
 of Gardening,’ p. 943.

 [135] ‘Gardener’s Chronicle,’ 1860, p. 956.

 [136] ‘Annales des Sc. Nat. Bot.,’ 4th series, vol. vi. 1856, p. 5.

 [137] ‘American Journ. of Science,’ 2nd series, vol. xxiv. 1857, p.
 442.

 [138] Gärtner ‘Bastarderzeugung,’ 1849, s. 87, and s. 169 with respect
 to Maize; on Verbascum, ibid., s. 92 and 181; also his ‘Kenntniss der
 Befruchtung,’ s. 137. With respect to Nicotiana _see_ Kölreuter
 ‘Zweite Forts.,’ 1764, s. 53; though this is a somewhat different
 case.

 [139] ‘De l’Espèce,’ par M. Godron, tom. ii. p. 64.

 [140] Naudin, in ‘Annal. des Sc. Nat.,’ 4th series, Bot. tom. xi.
 1859, p. 28.

 [141] ‘Mèmoire sur les Cucurbitacées,’ 1826, pp. 6, 24.

 [142] ‘Flore des Serres,’ Oct. 1861, quoted in ‘Gardener’s Chronicle,’
 1861, p. 1135. I have often consulted and taken some facts from M.
 Naudin’s Memoir on Cucumis in ‘Annal. des Sc. Nat.,’ 4th series, Bot.
 tom. xi. 1859, p. 5.

 [143] _See also_ Sageret’s ‘Mémoire’ p. 7.

 [144] Loudon’s ‘Arboretum et Fruticetum,’ vol. ii. p. 1217.

 [145] ‘Gardener’s Chronicle,’ 1866, p. 1096.

 [146] ‘Géograph. Bot.,’ p. 1096.

 [147] ‘Gardener’s Chronicle,’ 1842, p. 36.

 [148] Loudon’s ‘Arboretum et Fruticetum,’ vol. iii. p. 1731.

 [149] Ibid., vol. iv. p. 2489.

 [150] Godron (‘De l’Espèce’ tom. ii. p. 91) describes four varieties
 of Robinia remarkable from their manner of growth.

 [151] ‘Journal of a Horticultural Tour, by Caledonian Hort. Soc.,’
 1823, p. 107. Alph. De Candolle, ‘Géograph. Bot.,’ p. 1083. Verlot,
 ‘Sur La Production des Variétés,’ 1865; p. 55 for the Barberry.

 [152] Loudon’s ‘Arboretum et Fruticetum,’ vol. ii. p. 508.

 [153] Verlot ‘Des Variétés,’ 1865, p. 92.

 [154] Loudon’s ‘Arboretum et Fruticetum,’ vol. iii. p. 1376.

 [155] ‘Gardener’s Chronicle,’ 1841, p. 687.

 [156] Godron, ‘De l’Espèce,’ tom. ii. p. 89. In Loudon’s ‘Gardener’s
 Mag.,’ vol. xii. 1836, p. 371, a variegated bushy ash is described and
 figured, as having simple leaves; it originated in Ireland.

 [157] ‘Gardener’s Chronicle,’ 1863, p. 575.

 [158] Quoted from Royal Irish Academy in ‘Gardener’s Chronicle,’ 1841,
 p. 767.

 [159] Loudon’s ‘Arboretum et Fruticetum:’ for Elm, _see_ vol. iii. p.
 1376; for Oak, p. 1846.

 [160] ‘Gardener’s Chronicle,’ 1849, p. 822.

 [161] ‘Arboretum et Fruticetum,’ vol. iv. p. 2150.

 [162] ‘Gardener’s Chronicle,’ 1852, p. 693.

 [163] _See_ ‘Beiträge zur Kenntniss Europäischer Pinus-arten von Dr.
 Christ: Flora, 1864.’ He shows that in the Ober-Engadin _P.
 sylvestris_ and _montana_ are connected by intermediate links.

 [164] ‘Arboretum et Fruticetum,’ vol. iv. pp. 2159 and 2189.

 [165] Ibid., vol. ii. p. 830; Loudon’s ‘Gardener’s Mag.,’ vol. vi.
 1830, p. 714.

 [166] Loudon’s ‘Arboretum et Fruticetum,’ vol. ii. p. 834.

 [167] Loudon’s ‘Gardener’s Mag.,’ vol. ix. 1833, p. 123.

 [168] Ibid., vol. xi. 1835, p. 503.

 [169] ‘Gardener’s Chronicle,’ 1845, p. 623.

 [170] D. Beaton, in ‘Cottage Gardener,’ 1860, p. 377. _See also_ Mr.
 Beck, on the habits of Queen Mab, in ‘Gardener’s Chronicle,’ 1845, p.
 226.

 [171] Moquin-Tandon, ‘Eléments de Tératologie,’ 1841, p. 213.

 [172] _See also_ ‘Cottage Gardener,’ 1860, p. 133.

 [173] Quoted by Alph. de Candolle, ‘Bibl. Univ.,’ November 1862, p.
 58.

 [174] Knight, ‘Transact. Hort. Soc.,’ vol. iv. p. 322.

 [175] ‘Botanical Magazine,’ tab. 5160, fig. 4; Dr. Hooker, in
 ‘Gardener’s Chronicle,’ 1860, p. 190; Prof. Harvey, in ‘Gardener’s
 Chronicle,’ 1860, p. 145; Mr. Crocker, in ‘Gardener’s Chronicle,’
 1861, p. 1092.

 [176] Alph. de Candolle, ‘Géograph. Bot.,’ p. 1083; ‘Gardener’s
 Chronicle,’ 1861, p. 433. The inheritance of the white and golden
 zones in Pelargonium largely depends on the nature of the soil. _See_
 D. Beaton, in ‘Journal of Horticulture,’ 1861, p. 64.

 [177] ‘Rose Amateur’s Guide,’ T. Rivers, 1837, p. 21.

 [178] ‘Journal Hort. Soc.,’ vol. ix. 1855, p. 182.

 [179] The Rev. W. F. Radclyffe, in ‘Journal of Horticulture,’ March
 14th, 1865, p. 207.

 [180] ‘Gardener’s Chronicle,’ 1831, p. 46.

 [181] Mr. Sabine, in ‘Transact. Hort. Soc.,’ vol. iv. p. 285.

 [182] ‘An Encyclop. of Plants,’ by J. C. Loudon, 1841, p. 443.

 [183] Loudon’s ‘Gardener’s Magazine,’ vol. xi. 1835, p. 427; also
 ‘Journal of Horticulture,’ April 14th, 1863, p. 275.

 [184] Loudon’s ‘Gardener’s Magazine,’ vol. viii. p. 575: vol. ix. p.
 689.

 [185] Sir J. E. Smith, ‘English Flora,’ vol. i. p. 306. H. C. Watson,
 ‘Cybele Britannica,’ vol. i. 1847, p. 181.

 [186] Quoted from ‘Annales des Sciences,’ in the Companion to the
 ‘Bot. Mag.,’ vol. i. 1835, p. 159.

 [187] ‘Cybele Britannica,’ vol. i. p. 173. _See also_ Dr. Herbert on
 the changes of colour in transplanted specimens, and on the natural
 variations of _V. grandiflora,_ in ‘Transact. Hort. Soc.,’ vol. iv. p.
 19.

 [188] Salisbury, in ‘Transact. Hort. Soc.,’ vol. i. 1812, pp. 84, 92.
 A semi-double variety was produced in Madrid in 1790.

 [189] ‘Transact. Hort. Soc.,’ vol. iii. 1820, p. 225.

 [190] Loudon’s ‘Gardener’s Mag.,’ vol. vi. 1830, p. 77.

 [191] Loudon’s ‘Encyclop. of Gardening,’ p. 1035.

 [192] ‘Transact. Hort. Soc.,’ vol. i. p. 91; and Loudon’s ‘Gardener’s
 Mag.,’ vol. iii. 1828, p. 179.

 [193] Mr. Wildman, in ‘Gardener’s Chronicle,’ 1843, p. 87. ‘Cottage
 Gardener,’ April 8th, 1856, p. 33.

 [194] M. Faivre has given an interesting account of the successive
 variations of the Chinese primrose, since its introduction into Europe
 about the year 1820: ‘Revue des Cours Scientifiques,’ June, 1869, p.
 428.

 [195] The best and fullest account of this plant which I have met with
 is by a famous horticulturist, Mr. Paul, of Waltham, in the
 ‘Gardener’s Chronicle,’ 1864, p. 342.

 [196] ‘Des Jacinthes, de leur Anatomie, Reproduction, et Culture,’
 Amsterdam, 1768.

 [197] Alph. de Candolle, ‘Géograph. Bot.,’ p. 1082.

 [198] Alph. De Candolle, ‘Géograph. Bot.,’ p. 983.




CHAPTER XI. ON BUD-VARIATION, AND ON CERTAIN ANOMALOUS MODES OF
REPRODUCTION AND VARIATION.

BUD-VARIATION IN THE PEACH, PLUM, CHERRY, VINE, GOOSEBERRY, CURRANT,
AND BANANA, AS SHOWN BY THE MODIFIED FRUIT—IN FLOWERS: CAMELLIAS,
AZALEAS, CHRYSANTHEMUMS, ROSES, ETC—ON THE RUNNING OF THE COLOUR IN
CARNATIONS—BUD-VARIATIONS IN LEAVES—VARIATIONS BY SUCKERS, TUBERS, AND
BULBS—ON THE BREAKING OF TULIPS—BUD-VARIATIONS GRADUATE INTO CHANGES
CONSEQUENT ON CHANGED CONDITIONS OF LIFE—GRAFT-HYBRIDS—ON THE
SEGREGATION OF THE PARENTAL CHARACTERS IN SEMINAL HYBRIDS BY
BUD-VARIATION—ON THE DIRECT OR IMMEDIATE ACTION OF FOREIGN POLLEN ON
THE MOTHER-PLANT—ON THE EFFECTS IN FEMALE ANIMALS OF A PREVIOUS
IMPREGNATION ON THE SUBSEQUENT OFFSPRING—CONCLUSION AND SUMMARY


This chapter will be chiefly devoted to a subject in many respects
important, namely, bud-variation. By this term I include all those
sudden changes in structure or appearance which occasionally occur in
full-grown plants in their flower-buds or leaf-buds. Gardeners call
such changes “Sports;” but this, as previously remarked, is an
ill-defined expression, as it has often been applied to strongly marked
variations in seedling plants. The difference between seminal and bud
reproduction is not so great as it at first appears; for each bud is in
one sense a new and distinct individual; but such individuals are
produced through the formation of various kinds of buds without the aid
of any special apparatus, whilst fertile seeds are produced by the
concourse of the two sexual elements. The modifications which arise
through bud-variation can generally be propagated to any extent by
grafting, budding, cuttings, bulbs, etc., and occasionally even by
seed. Some few of our most beautiful and useful productions have arisen
by bud-variation.

Bud-variations have as yet been observed only in the vegetable kingdom;
but it is probable that if compound animals, such as corals, etc., had
been subjected to a long course of domestication, they would have
varied by buds; for they resemble plants in many respects. For
instance, any new or peculiar character presented by a compound animal
is propagated by budding, as occurs with differently coloured Hydras,
and as Mr. Gosse has shown to be the case with a singular variety of a
true coral. Varieties of the Hydra have also been grafted on other
varieties, and have retained their character.

I will in the first place give all the cases of bud variations which I
have been able to collect, and afterwards show their importance.[1]
These cases prove that those authors who, like Pallas, attribute all
variability to the crossing either of distinct races, or of distinct
individuals belonging to the same race but somewhat different from each
other, are in error; as are those authors who attribute all variability
to the mere act of sexual union. Nor can we account in all cases for
the appearance through bud-variation of new characters by the principle
of reversion to long-lost characters. He who wishes to judge how far
the conditions of life directly cause each particular variation ought
to reflect well on the cases immediately to be given. I will commence
with bud-variations, as exhibited in the fruit, and then pass on to
flowers, and finally to leaves.

_Peach (Amygdalus persica)._—In the last chapter I gave two cases of a
peach-almond and a double-flowered almond which suddenly produced fruit
closely resembling true peaches. I have also given many cases of
peach-trees producing buds, which, when developed into branches, have
yielded nectarines. We have seen that no less than six named and
several unnamed varieties of the peach have thus produced several
varieties of nectarine. I have shown that it is highly improbable that
all these peach-trees, some of which are old varieties, and have been
propagated by the million, are hybrids from the peach and nectarine,
and that it is opposed to all analogy to attribute the occasional
production of nectarines on peach-trees to the direct action of pollen
from some neighbouring nectarine-tree. Several of the cases are highly
remarkable, because, firstly, the fruit thus produced has sometimes
been in part a nectarine and in part a peach; secondly, because
nectarines thus suddenly produced have reproduced themselves by seed;
and thirdly, because nectarines are produced from peach-trees from seed
as well as from buds. The seed of the nectarine, on the other hand,
occasionally produces peaches; and we have seen in one instance that a
nectarine-tree yielded peaches by bud-variation. As the peach is
certainly the oldest or primary variety, the production of peaches from
nectarines, either by seeds or buds, may perhaps be considered as a
case of reversion. Certain trees have also been described as
indifferently bearing peaches or nectarines, and this may be considered
as bud-variation carried to an extreme degree.

The _grosse mignonne_ peach at Montreuil produced “from a sporting
branch” the _grosse mignonne tardive,_ “a most excellent variety,”
which ripens its fruit a fortnight later than the parent tree, and is
equally good.[2] This same peach has likewise produced by bud-variation
the _early grosse mignonne._ Hunt’s large tawny nectarine “originated
from Hunt’s small tawny nectarine, but not through seminal
reproduction.”[3]

_Plums._—Mr. Knight states that a tree of the yellow magnum bonum plum,
forty years old, which had always borne ordinary fruit, produced a
branch which yielded red magnum bonums.[4] Mr. Rivers, of
Sawbridgeworth, informs me (Jan. 1863) that a single tree out of 400 or
500 trees of the Early Prolific plum, which is a purple kind, descended
from an old French variety bearing purple fruit, produced when about
ten years old bright yellow plums; these differed in no respect except
colour from those on the other trees, but were unlike any other known
kind of yellow plum.[5]

_Cherry (Prunus cerasus)._—Mr. Knight has recorded (ibid.) the case of
a branch of a May-Duke cherry, which, though certainly never grafted,
always produced fruit, ripening later, and more oblong than the fruit
on the other branches. Another account has been given of two May-Duke
cherry-trees in Scotland, with branches bearing oblong and very fine
fruit, which invariably ripened, as in Knight’s case, a fortnight later
than the other cherries.[6] M. Carrière gives (p. 37) numerous
analogous cases, and one of the same tree bearing three kinds of fruit.

_Grapes (Vitis vinifera)._—The black or purple Frontignan in one case
produced during two successive years (and no doubt permanently), spurs
which bore white Frontignan grapes. In another case, on the same
footstalk, the lower berries “were well-coloured black Frontignans;
those next the stalk were white, with the exception of one black and
one streaked berry;” and altogether there were fifteen black and twelve
white berries on the same stalk. In another kind of grape, black and
amber-coloured berries were produced in the same cluster.[7] Count
Odart describes a variety which often bears on the same stalk small
round and large oblong berries; though the shape of the berry is
generally a fixed character.[8] Here is another striking case given on
the excellent authority of M. Carrière:[9] “a black Hamburg grape
(Frankenthal) was cut down, and produced three suckers; one of these
was layered, and after a time produced much smaller berries, which
always ripened at least a fortnight earlier than the others. Of the
remaining two suckers, one produced every year fine grapes, whilst the
other, although it set an abundance of fruit, matured only a few, and
these of inferior quality.”

_Gooseberry (Ribes grossularia)._—A remarkable case has been described
by Dr. Lindley[10] of a bush which bore at the same time no less than
four kinds of berries, namely, hairy and red,—smooth, small and
red,—green,—and yellow tinged with buff; the two latter kinds had a
different flavour from the red berries, and their seeds were coloured
red. Three twigs on this bush grew close together; the first bore three
yellow berries and one red; the second twig bore four yellow and one
red; and the third four red and one yellow. Mr. Laxton also informs me
that he has seen a Red Warrington gooseberry bearing both red and
yellow fruit on the same branch.

_Currant (Ribes rubrum)._—A bush purchased as the Champagne, which is a
variety that bears blush-coloured fruit intermediate between red and
white, produced during fourteen years on separate branches and mingled
on the same branch, berries of the red, white, and champagne kinds.[11]
The suspicion naturally arises that this variety may have originated
from a cross between a red and white variety, and that the above
transformation may be accounted for by reversion to both parent-forms;
but from the foregoing complex case of the gooseberry this view is
doubtful. In France, a branch of a red-currant bush, about ten years
old, produced near the summit five white berries) and lower down,
amongst the red berries, one berry half red and half white.[12]
Alexander Braun[13] also has often seen branches on white currant-trees
bearing red berries.

_Pear (Pyrus communis)._—Dureau de la Malle states that the flowers on
some trees of an ancient variety, the _doyenné galeux,_ were destroyed
by frost: other flowers appeared in July, which produced six pears;
these exactly resembled in their skin and taste the fruit of a distinct
variety, the _gros doyenne blanc,_ but in shape were like the
_bon-chrétien_: it was not ascertained whether this new variety could
be propagated by budding or grafting. The same author grafted a
_bon-chrétien_ on a quince, and it produced, besides its proper fruit,
an apparently new variety, of a peculiar form with thick and rough
skin.[14]

_Apple (Pyrus malus)._—In Canada, a tree of the variety called Pound
Sweet, produced,[15] between two of its proper fruit, an apple which
was well russeted, small in size, different in shape, and with a short
peduncle. As no russet apple grew anywhere near, this case apparently
cannot be accounted for by the direct action of foreign pollen. M.
Carrière (p. 38) mentions an analogous instance. I shall hereafter give
cases of apple-trees which regularly produce fruit of two kinds, or
half-and-half fruit; these trees are generally supposed, and probably
with truth, to be of crossed parentage, and that the fruit reverts to
both parent-forms.

_Banana (Musa sapientium)._—Sir R. Schomburgk states that he saw in St.
Domingo a raceme on the Fig Banana which bore towards the base 125
fruits of the proper kind; and these were succeeded, as is usual,
higher up the raceme, by barren flowers, and these by 420 fruits,
having a widely different appearance, and ripening earlier than the
proper fruit. The abnormal fruit closely resembled, except in being
smaller, that of the _Musa chinensis_ or _cavendishii,_ which has
generally been ranked as a distinct species.[16]

Flowers.—Many cases have been recorded of a whole plant, or single
branch, or bud, suddenly producing flowers different from the proper
type in colour, form, size, doubleness, or other character. Half the
flower, or a smaller segment, sometimes changes colour.

_Camellia._—The myrtle-leaved species (_C. myrtifolia_), and two or
three varieties of the common species, have been known to produce
hexagonal and imperfectly quadrangular flowers; and the branches
producing such flowers have been propagated by grafting.[17] The Pompon
variety often bears “four distinguishable kinds of flowers,—the pure
white and the red-eyed, which appear promiscuously; the brindled pink
and the rose-coloured, which may be kept separate with tolerable
certainty by grafting from the branches that bear them.” A branch,
also, on an old tree of the rose-coloured variety has been seen to
“revert to the pure white colour, an occurrence less common than the
departure from it.”[18]

_Cratægus oxyacantha._—A dark pink hawthorn has been known to throw out
a single tuft of pure white blossoms;[19] and Mr. A. Clapham,
nurseryman, of Bedford, informs me that his father had a deep crimson
thorn grafted on a white thorn, which during several years, always
bore, high above the graft, bunches of white, pink and deep crimson
flowers.

_Azalea indica_ is well known often to produce new varieties by buds. I
have myself seen several cases. A plant of _Azalea indica variegata_
has been exhibited bearing a truss of flowers of A. ind. gledstanesii
“as true as could possibly be produced, thus evidencing the origin of
that fine variety.” On another plant of _A. ind. variegata_ a perfect
flower of _A. ind. lateritia_ was produced; so that both _
gledstanesii_ and _lateritia_ no doubt originally appeared as sporting
branches of _A. ind. variegata._[20]

_Hibiscus (Paritium tricuspis)._—A seedling of this plant, when some
years old, produced, at Saharunpore,[21] some branches “which bore
leaves and flowers widely different from the normal form.” “The
abnormal leaf is much less divided, and not acuminated. The petals are
considerably larger, and quite entire. There is also in the fresh state
a conspicuous, large, oblong gland, full of a viscid secretion, on the
back of each of the calycine segments.” Dr. King, who subsequently had
charge of these Gardens, informs me that a tree of _Paritium tricuspis_
(probably the very same plant) growing there, had a branch buried in
the ground, apparently by accident; and this branch changed its
character wonderfully, growing like a bush, and producing flowers and
leaves, resembling in shape those of another species, viz., _ P.
tiliaceum._ A small branch springing from this bush near the ground,
reverted to the parent-form. Both forms were extensively propagated
during several years by cuttings and kept perfectly true.

_Althæa rosea._—A double yellow Hollyhock suddenly turned one year into
a pure white single kind; subsequently a branch bearing the original
double yellow flowers reappeared in the midst of the branches of the
single white kind.[22]

_Pelargonium._—These highly cultivated plants seem eminently liable to
bud-variation. I will give only a few well-marked cases. Gärtner has
seen[23] a plant of _P. zonale_ with a branch having white edges, which
remained constant for years, and bore flowers of a deeper red than
usual. Generally speaking, such branches present little or no
difference in their flowers: thus a writer[24] pinched off the leading
shoot of a seedling _P. zonale,_ and it threw out three branches, which
differed in the size and colour of their leaves and stems; but on all
three branches “the flowers were identical,” except in being largest in
the green-stemmed variety, and smallest in that with variegated
foliage: these three varieties were subsequently propagated and
distributed. Many branches, and some whole plants, of a variety called
_compactum,_ which bears orange-scarlet flowers, have been seen to
produce pink flowers.[25] Hill’s Hector, which is a pale red variety,
produced a branch with lilac flowers, and some trusses with both red
and lilac flowers. This apparently is a case of reversion, for Hill’s
Hector was a seedling from a lilac variety.[26] Here is a better case
of reversion: a variety produced from a complicated cross, after having
been propagated for five generations by seed, yielded by bud-variation
three very distinct varieties which were undistinguishable from plants,
“known to have been at some time ancestors of the plant in
question.”[27] Of all Pelargoniums, Rollisson’s Unique seems to be the
most sportive; its origin is not positively known, but is believed to
be from a cross. Mr. Salter, of Hammersmith, states[28] that he has
himself known this purple variety to produce the lilac, the
rose-crimson or _conspicuum,_ and the red or _coccineum_ varieties; the
latter has also produced the _rose d’amour_; so that altogether four
varieties have originated by bud variation from Rollisson’s Unique. Mr.
Salter remarks that these four varieties “may now be considered as
fixed, although they occasionally produce flowers of the original
colour. This year _ coccineum_ has pushed flowers of three different
colours, red, rose, and lilac, upon the same truss, and upon other
trusses are flowers half red and half lilac.” Besides these four
varieties, two other scarlet Uniques are known to exist, both of which
occasionally produce lilac flowers identical with Rollisson’s
Unique;[29] but one at least of these did not arise through
bud-variation, but is believed to be a seedling from Rollisson’s
Unique.[30] There are, also, in the trade[31] two other slightly
different varieties, of unknown origin, of Rollisson’s Unique: so that
altogether we have a curiously complex case of variation both by buds
and seeds.[32] Here is a still more complex case: M. Rafarin states
that a pale rose-coloured variety produced a branch bearing deep red
flowers. “Cuttings were taken from this ‘sport,’ from which 20 plants
were raised, which flowered in 1867, when it was found that scarcely
two were alike.” Some resembled the parent-form, some resembled the
sport, some bore both kinds of flowers; and even some of the petals on
the same flower were rose-coloured and others red.[33] An English wild
plant, the _Geranium pratense,_ when cultivated in a garden, has been
seen to produce on the same plant both blue and white, and striped blue
and white flowers.[34]

_Chrysanthemum._—This plant frequently sports, both by its lateral
branches and occasionally by suckers. A seedling raised by Mr. Salter
has produced by bud-variation six distinct sorts, five different in
colour and one in foliage, all of which are now fixed.[35] A variety
called _cedo nulli_ bears small yellow flowers, but habitually produces
branches with white flowers; and a specimen was exhibited, which Prof.
T. Dyer saw, before the Horticultural Society. The varieties which were
first introduced from China were so excessively variable, “that it was
extremely difficult to tell which was the original colour of the
variety, and which was the sport.” The same plant would produce one
year only buff-coloured, and next year only rose-coloured flowers; and
then would change again, or produce at the same time flowers of both
colours. These fluctuating varieties are now all lost, and, when a
branch sports into a new variety, it can generally be propagated and
kept true; but, as Mr. Salter remarks, “every sport should be
thoroughly tested in different soils before it can be really considered
as fixed, as many have been known to run back when planted in rich
compost; but when sufficient care and time are expended in proving,
there will exist little danger of subsequent disappointment.” Mr.
Salter informs me that with all the varieties the commonest kind of
bud-variation is the production of yellow flowers, and, as this is the
primordial colour, these cases may be attributed to reversion. Mr.
Salter has given me a list of seven differently coloured
chrysanthemums, which have all produced branches with yellow flowers;
but three of them have also sported into other colours. With any change
of colour in the flower, the foliage generally changes in a
corresponding manner in lightness or darkness.

Another Compositous plant, namely, Centauria cyanus, when cultivated in
a garden, not unfrequently produces on the same root flowers of four
different colours, viz., blue, white, dark-purple, and
parti-coloured.[36] The flowers of Anthemis also vary on the same
plant.[37]

_Roses._—Many varieties of the Rose are known or are believed to have
originated by bud-variation.[38] The common double moss-rose was
imported into England from Italy about the year 1735.[39] Its origin is
unknown, but from analogy it probably arose from the Provence rose (_R.
centifolia_) by bud-variation; for the branches of the common moss-rose
have several times been known to produce Provence roses, wholly or
partially destitute of moss: I have seen one such instance, and several
others have been recorded.[40] Mr. Rivers also informs me that he
raised two or three roses of the Provence class from seed of the old
single moss-rose;[41] and this latter kind was produced in 1807 by
bud-variation from the common moss-rose. The white moss-rose was also
produced in 1788 by an offset from the common red moss-rose: it was at
first pale blush-coloured, but became white by continued budding. On
cutting down the shoots which had produced this white moss-rose, two
weak shoots were thrown up, and buds from these yielded the beautiful
striped moss-rose. The common moss-rose has yielded by bud-variation,
besides the old single red moss-rose, the old scarlet semi-double
moss-rose, and the sage-leaf moss-rose, which “has a delicate
shell-like form, and is of a beautiful blush colour; it is now (1852)
nearly extinct.”[42] A white moss-rose has been seen to bear a flower
half white and half pink.[43] Although several moss-roses have thus
certainly arisen by bud-variation, the greater number probably owe
their origin to seed of moss-roses. For Mr. Rivers informs me that his
seedlings from the old single moss-rose almost always produced
moss-roses; and the old single moss-rose was, as we have seen, the
product by bud-variation of the double moss-rose originally imported
from Italy. That the original moss-rose was the product of
bud-variation is probable, from the facts above given and from the de
Meaux moss-rose (also a variety of _R. centifolia_)[44] having appeared
as a sporting branch on the common rose de Meaux. Prof. Caspary has
carefully described[45] the case of a six-year-old white moss-rose,
which sent up several suckers, one of which was thorny, and produced
red flowers, destitute of moss, exactly like those of the Provence rose
(_R. centifolia_): another shoot bore both kinds of flowers, and in
addition longitudinally striped flowers. As this white moss-rose had
been grafted on the Provence rose, Prof. Caspary attributes the above
changes to the influence of the stock; but from the facts already
given, and from others to be given, bud-variation, with reversion, is
probably a sufficient explanation.

Many other instances could be added of roses varying by buds. The white
Provence rose apparently originated in this way.[46] M. Carrière states
(p. 36) that he himself knows of five varieties thus produced by the
Baronne Prévost. The double and highly-coloured Belladonna rose has
produced by suckers both semi-double and almost single white roses;[47]
whilst suckers from one of these semi-double white roses reverted to
perfectly characterised Belladonnas. In St. Domingo, varieties of the
China rose propagated by cuttings often revert after a year or two into
the old China rose.[48] Many cases have been recorded of roses suddenly
becoming striped or changing their character by segments: some plants
of the Comtesse de Chabrillant, which is properly rose-coloured, were
exhibited in 1862,[49] with crimson flakes on a rose ground. I have
seen the Beauty of Billiard with a quarter and with half the flower
almost white. ‘The Austrian bramble _R. lutea_ not rarely[50] produces
branches with pure yellow flowers; and Prof. Henslow has seen exactly
half the flower of a pure yellow, and I have seen narrow yellow streaks
on a single petal, of which the rest was of the usual copper colour.

The following cases are highly remarkable. Mr. Rivers, as I am informed
by him, possessed a new French rose with delicate smooth shoots, pale
glaucous-green leaves, and semi-double pale flesh-coloured flowers
striped with dark red; and on branches thus characterised there
suddenly appeared in more than one instance, the famous old rose called
the Baronne Prevost, with its stout thorny shoots, and immense,
uniformly and richly coloured double flowers; so that in this case the
shoots, leaves, and flowers, all at once changed their character by
bud-variation. According to M. Verlot,[51] a variety called _Rosa
cannabifolia,_ which has peculiarly shaped leaflets, and differs from
every member of the family in the leaves being opposite instead of
alternate, suddenly appeared on a plant of _R. alba_ in the gardens of
the Luxembourg. Lastly, “a running shoot” was observed by Mr. H.
Curtis[52] on the old Aimée Vibert Noisette, and he budded it on
Celine; thus a climbing Aimée Vibert was first produced and afterwards
propagated.

_Dianthus._—It is quite common with the Sweet William (_D. barbatus_)
to see differently coloured flowers on the same root; and I have
observed on the same truss four differently coloured and shaded
flowers. Carnations and pinks (_D. caryophyllus,_ etc.) occasionally
vary by layers; and some kinds are so little certain in character that
they are called by floriculturists “catch-flowers.”[53] Mr. Dickson has
ably discussed the “running” of particoloured or striped carnations,
and says it cannot be accounted for by the compost in which they are
grown: “layers from the same clean flower would come part of them clean
and part foul, even when subjected to precisely the same treatment; and
frequently one flower alone appears influenced by the taint, the
remainder coming perfectly clean.”[54] This running of the
parti-coloured flowers apparently is a case of reversion by buds to the
original uniform tint of the species.

I will briefly mention some other cases of bud-variation to show how
many plants belonging to many orders have varied in their flowers; and
many others might be added. I have seen on a snap-dragon (_Antirrhinum
majus_) white, pink, and striped flowers on the same plant, and
branches with striped flowers on a red-coloured variety. On a double
stock (_Matthiola incana_) I have seen a branch bearing single flowers;
and on a dingy-purple double variety of the wall-flower (_Cheiranthus
cheiri_), a branch which had reverted to the ordinary copper colour. On
other branches of the same plant, some flowers were exactly divided
across the middle, one half being purple and the other coppery; but
some of the smaller petals towards the centre of these same flowers
were purple longitudinally streaked with coppery colour, or coppery
streaked with purple. A Cyclamen[55] has been observed to bear white
and pink flowers of two forms, the one resembling the Persicum strain,
and the other the Coum strain. _Oenothera biennis_ has been seen[56]
bearing flowers of three different colours. The hybrid _Gladiolus
colvilii_ occasionally bears uniformly coloured flowers, and one case
is recorded[57] of all the flowers on a plant thus changing colour. A
Fuchsia has been seen[58] bearing two kinds of flowers. _ Mirabilis
jalapa_ is eminently sportive, sometimes bearing on the same root pure
red, yellow, and white flowers, and others striped with various
combinations of these three colours.[59] The plants of the Mirabilis,
which bear such extraordinarily variable flowers in most, probably in
all, cases, owe their origin, as shown by Prof. Lecoq, to crosses
between differently coloured varieties.

_Leaves and Shoots._—Changes, through bud-variation, in fruits and
flowers have hitherto been treated of; incidentally some remarkable
modifications in the leaves and shoots of the rose and Paritium, and in
a lesser degree in the foliage of the Pelargonium and Chrysanthemum,
have been noticed. I will now add a few more cases of variation in
leaf-buds. Verlot[60] states that on _Aralia trifoliata,_ which
properly has leaves with three leaflets, branches frequently appear
bearing simple leaves of various forms; these can be propagated by buds
or by grafting, and have given rise, as he states, to several nominal
species.

With respect to trees, the history of but few of the many varieties
with curious or ornamental foliage is known; but several probably have
originated by bud-variation. Here is one case:—An old ash-tree
(_Fraxinus excelsior_) in the grounds of Necton, as Mr. Mason states,
“for many years has had one bough of a totally different character to
the rest of the tree, or of any other ash-tree which I have seen; being
short-jointed and densely covered with foliage.” It was ascertained
that this variety could be propagated by grafts.[61] The varieties of
some trees with cut leaves, as the oak-leaved laburnum, the
parsley-leaved vine, and especially the fern-leaved beech, are apt to
revert by buds to the common forms.[62] The fern-like leaves of the
beech sometimes revert only partially, and the branches display here
and there sprouts bearing common leaves, fern-like, and variously
shaped leaves. Such cases differ but little from the so-called
heterophyllus varieties, in which the tree habitually bears leaves of
various forms; but it is probable that most heterophyllous trees have
originated as seedlings. There is a sub-variety of the weeping willow
with leaves rolled up into a spiral coil; and Mr. Masters states that a
tree of this kind kept true in his garden for twenty-five years, and
then threw out a single upright shoot bearing flat leaves.[63]

I have often noticed single twigs and branches on beech and other trees
with their leaves fully expanded before those on the other branches had
opened; and as there was nothing in their exposure or character to
account for this difference, I presume that they had appeared as
bud-variations, like the early and late fruit-maturing varieties of the
peach and nectarine.

Cryptogamic plants are liable to bud-variation, for fronds on the same
fern often display remarkable deviations of structure. Spores, which
are of the nature of buds, taken from such abnormal fronds, reproduce,
with remarkable fidelity, the same variety, after passing through the
sexual stage.[64]

With respect to colour, leaves often become by bud-variation zoned,
blotched, or spotted with white, yellow, and red; and this occasionally
occurs even with plants in a state of nature. Variegation, however,
appears still more frequently in plants produced from seed; even the
cotyledons or seed-leaves being thus affected.[65] There have been
endless disputes whether variegation should be considered as a disease.
In a future chapter we shall see that it is much influenced, both in
the case of seedlings and of mature plants, by the nature of the soil.
Plants which have become variegated as seedlings, generally transmit
their character by seed to a large proportion of their progeny; and Mr.
Salter has given me a list of eight genera in which this occurred.[66]
Sir F. Pollock has given me more precise information: he sowed seed
from a variegated plant of _Ballota nigra_ which was found growing
wild, and thirty per cent of the seedlings were variegated; seed from
these latter being sown, sixty per cent came up variegated. When
branches become variegated by bud-variation, and the variety is
attempted to be propagated by seed, the seedlings are rarely
variegated: Mr. Salter found this to be the case with plants belonging
to eleven genera, in which the greater number of the seedlings proved
to be green-leaved; yet a few were slightly variegated, or were quite
white, but none were worth keeping. Variegated plants, whether
originally produced from seeds or buds, can generally be propagated by
budding, grafting, etc.; but all are apt to revert by bud-variation to
their ordinary foliage. This tendency, however, differs much in the
varieties of even the same species; for instance, the golden-striped
variety of _Euonymus japonicus_ “is very liable to run back to the
green-leaved, while the silver-striped variety hardly ever
changes.”[67] I have seen a variety of the holly, with its leaves
having a central yellow patch, which had everywhere partially reverted
to the ordinary foliage, so that on the same small branch there were
many twigs of both kinds. In the pelargonium, and in some other plants,
variegation is generally accompanied by some degree of dwarfing, as is
well exemplified in the “Dandy” pelargonium. When such dwarf varieties
sport back by buds or suckers to the ordinary foliage, the dwarfed
stature still remains.[68] It is remarkable that plants propagated from
branches which have reverted from variegated to plain leaves[69] do not
always (or never, as one observer asserts) perfectly resemble the
original plain-leaved plant from which the variegated branch arose: it
seems that a plant, in passing by bud-variation from plain leaves to
variegated, and back again from variegated to plain, is generally in
some degree affected so as to assume a slightly different aspect.

_Bud-variation by Suckers, Tubers, and Bulbs._—All the cases hitherto
given of bud-variation in fruits, flowers, leaves, and shoots, have
been confined to buds on the stems or branches, with the exception of a
few cases incidentally noticed of varying suckers in the rose,
pelargonium, and chrysanthemum. I will now give a few instances of
variation in subterranean buds, that is, by suckers, tubers, and bulbs;
not that there is any essential difference between buds above and
beneath the ground. Mr. Salter informs me that two variegated varieties
of Phlox originated as suckers; but I should not have thought these
worth mentioning, had not Mr. Salter found, after repeated trials, that
he could not propagate them by “root-joints,” whereas, the variegated
_Tussilago farfara_ can thus be safely propagated;[70] but this latter
plant may have originated as a variegated seedling, which would account
for its greater fixedness of character. The Barberry (_Berberis
vulgaris_) offers an analogous case; there is a well-known variety with
seedless fruit, which can be propagated by cuttings or layers; but
suckers always revert to the common form, which produces fruit
containing seeds.[71] My father repeatedly tried this experiment, and
always with the same result. I may here mention that maize and wheat
sometimes produce new varieties from the stock or root, as does the
sugar-cane.[72]

Turning now to tubers: in the common Potato (_Solanum tuberosum_) a
single bud or eye sometimes varies and produces a new variety; or,
occasionally, and this is a much more remarkable circumstance, all the
eyes in a tuber vary in the same manner and at the same time, so that
the whole tuber assumes a new character. For instance, a single eye in
a tuber of the old _Forty-fold potato,_ which is a purple variety, was
observed[73] to become white; this eye was cut out and planted
separately, and the kind has since been largely propagated. _Kemp’s
potato_ is properly white, but a plant in Lancashire produced two
tubers which were red, and two which were white; the red kind was
propagated in the usual manner by eyes, and kept true to its new
colour, and, being found a more productive variety, soon became widely
known under the name of _ Taylor’s forty-fold._[74] The old _Forty-fold
potato,_ as already stated, is a purple variety; but a plant long
cultivated on the same ground produced, not, as in the case above
given, a single white eye, but a whole white tuber, which has since
been propagated and keeps true.[75] Several cases have been recorded of
large portions of whole rows of potatoes slightly changing their
character.[76]

Dahlias propagated by tubers under the hot climate of St. Domingo vary
much; Sir R. Schomburgk gives the case of the “Butterfly variety,”
which the second year produced on the same plant “double and single
flowers; here white petals edged with maroon; there of a uniform deep
maroon.”[77] Mr. Bree also mentions a plant “which bore two different
kinds of self-coloured flowers, as well as a third kind which partook
of both colours beautifully intermixed.”[78] Another case is described
of a dahlia with purple flowers which bore a white flower streaked with
purple.[79]

Considering how long and extensively many Bulbous plants have been
cultivated, and how numerous are the varieties produced from seed,
these plants have not perhaps varied so much by offsets,—that is, by
the production of new bulbs,—as might have been expected. With the
Hyacinth, however, several instances have been given by M. Carrière. A
case also has been recorded of a blue variety which for three
successive years gave offsets producing white flowers with a red
centre.[80] Another hyacinth bore[81] on the same truss a perfectly
pink and a perfectly blue flower. I have seen a bulb producing at the
same time one stalk or truss with fine blue flowers, another with fine
red flowers, and a third with blue flowers on one side and red on the
other; several of the flowers being also longitudinally striped red and
blue.

Mr. John Scott informs me that in 1862 _Imatophyllum miniatum,_ in the
Botanic Gardens of Edinburgh, threw up a sucker which differed from the
normal form, in the leaves being two-ranked instead of four-ranked. The
leaves were also smaller, with the upper surface raised instead of
being channelled.

In the propagation of _Tulips,_ seedlings are raised, called _selfs_ or
_breeders,_ which, “consist of one plain colour on a white or yellow
bottom. These, being cultivated on a dry and rather poor soil, become
broken or variegated and produce new varieties. The time that elapses
before they break varies from one to twenty years or more, and
sometimes this change never takes place.”[82] The broken or variegated
colours which give value to all tulips are due to bud-variation; for
although the Bybloemens and some other kinds have been raised from
several distinct breeders, yet all the Baguets are said to have come
from a single breeder or seedling. This bud-variation, in accordance
with the views of MM. Vilmorin and Verlot,[83] is probably an attempt
to revert to that uniform colour which is natural to the species. A
tulip, however, which has already become broken, when treated with too
strong manure, is liable to flush or lose by a second act of reversion
its variegated colours. Some kinds, as Imperatrix Florum, are much more
liable than others to flushing; and Mr. Dickson maintains[84] that this
can no more be accounted for than the variation of any other plant. He
believes that English growers, from care in choosing seed from broken
flowers instead of from plain flowers, have to a certain extent
diminished the tendency in flowers already broken to flushing or
secondary reversion. _Iris xiphium,_ according to M. Carrière (p. 65),
behaves in nearly the same manner, as do so many tulips.

During two consecutive years all the early flowers in a bed of
_Tigridia conchiflora_[85] resembled those of the old _T. pavonia_; but
the later flowers assumed their proper colour of fine yellow, spotted
with crimson. An apparently authentic account has been published[86] of
two forms of Hemerocallis, which have been universally considered as
distinct species, changing into each other; for the roots of the
large-flowered tawny _H. fulva,_ being divided and planted in a
different soil and place, produced the small-flowered _H. flava,_ as
well as some intermediate forms. It is doubtful whether such cases as
these latter, as well as the “flushing” of broken tulips and the
“running” of particoloured carnations,—that is, their more or less
complete return to a uniform tint,—ought to be classed under
bud-variation, or ought to be retained for the chapter in which I treat
of the direct action of the conditions of life on organic beings. These
cases, however, have this much in bud-variation, that the change is
effected through buds and not through seminal reproduction. But, on the
other hand, there is this difference—that in ordinary cases of
bud-variation, one bud alone changes, whilst in the foregoing cases all
the buds on the same plant were modified together. With the potato, we
have seen an intermediate case, for all the eyes in one tuber
simultaneously changed their character.

I will conclude with a few allied cases, which may be ranked either
under bud-variation, or under the direct action of the conditions of
life. When the common Hepatica is transplanted from its native woods,
the flowers change colour, even during the first year.[87] It is
notorious that the improved varieties of the Heartsease (_Viola
tricolor_), when transplanted, often produce flowers widely different
in size, form, and colour: for instance, I transplanted a large
uniformly-coloured dark purple variety, whilst in full flower, and it
then produced much smaller, more elongated flowers, with the lower
petals yellow; these were succeeded by flowers marked with large purple
spots, and ultimately, towards the end of the same summer, by the
original large dark purple flowers. The slight changes which some
fruit-trees undergo from being grafted and regrafted on various
stocks,[88] were considered by Andrew Knight[89] as closely allied to
“sporting branches,” or bud-variations. Again, we have the case of
young fruit-trees changing their character as they grow old; seedling
pears, for instance, lose with age their spines and improve in the
flavour of their fruit. Weeping birch-trees, when grafted on the common
variety, do not acquire a perfect pendulous habit until they grow old:
on the other hand, I shall hereafter give the case of some weeping
ashes which slowly and gradually assumed an upright habit of growth.
All such changes, dependent on age, may be compared with the changes,
alluded to in the last chapter, which many trees naturally undergo; as
in the case of the Deodar and Cedar of Lebanon, which are unlike in
youth, whilst they closely resemble each other in old age; and as with
certain oaks, and with some varieties of the lime and hawthorn.[90]

_Graft-hybrids._—Before giving a summary on Bud-variation I will
discuss some singular and anomalous cases, which are more or less
closely related to this same subject. I will begin with the famous case
of Adam’s laburnum or _Cytisus adami,_ a form or hybrid intermediate
between two very distinct species, namely, _C. laburnum_ and
_purpureus,_ the common and purple laburnum; but as this tree has often
been described, I will be as brief as I can.

Throughout Europe, in different soils and under different climates,
branches on this tree have repeatedly and suddenly reverted to the two
parent species in their flowers and leaves. To behold mingled on the
same tree tufts of dingy-red, bright yellow, and purple flowers, borne
on branches having widely different leaves and manner of growth, is a
surprising sight. The same raceme sometimes bears two kinds of flowers;
and I have seen a single flower exactly divided into halves, one side
being bright yellow and the other purple; so that one half of the
standard-petal was yellow and of larger size, and the other half purple
and smaller. In another flower the whole corolla was bright yellow, but
exactly half the calyx was purple. In another, one of the dingy-red
wing-petals had a narrow bright yellow stripe on it; and lastly, in
another flower, one of the stamens, which had become slightly
foliaceous, was half yellow and half purple; so that the tendency to
segregation of character or reversion affects even single parts and
organs.[91] The most remarkable fact about this tree is that in its
intermediate state, even when growing near both parent-species, it is
quite sterile; but when the flowers become pure yellow or pure purple
they yield seed. I believe that the pods from the yellow flowers yield
a full complement of seed; they certainly yield a larger number. Two
seedlings raised by Mr. Herbert from such seed[92] exhibited a purple
tinge on the stalks of their flowers; but several seedlings raised by
myself resembled in every character the common laburnum, with the
exception that some of them had remarkably long racemes: these
seedlings were perfectly fertile. That such purity of character and
fertility should be suddenly reacquired from so hybridised and sterile
a form is an astonishing phenomenon. The branches with purple flowers
appear at first sight exactly to resemble those of _C. purpureus_; but
on careful comparison I found that they differed from the pure species
in the shoots being thicker, the leaves a little broader, and the
flowers slightly shorter, with the corolla and calyx less brightly
purple: the basal part of the standard-petal also plainly showed a
trace of the yellow stain. So that the flowers, at least in this
instance, had not perfectly recovered their true character; and in
accordance with this, they were not perfectly fertile, for many of the
pods contained no seed, some produced one, and very few contained as
many as two seeds; whilst numerous pods on a tree of the pure _C.
purpureus_ in my garden contained three, four, and five fine seeds. The
pollen, moreover, was very imperfect, a multitude of grains being small
and shrivelled; and this is a singular fact; for, as we shall
immediately see, the pollen-grains in the dingy-red and sterile flowers
on the parent-tree, were, in external appearance, in a much better
state, and included very few shrivelled grains. Although the pollen of
the reverted purple flowers was in so poor a condition, the ovules were
well formed, and the seeds, when mature, germinated freely with me. Mr.
Herbert raised plants from seeds of the reverted purple flowers, and
they differed a _very little_ from the usual state of _C. purpureus._
Some which I raised in the same manner did not differ at all, either in
the character of their flowers or of the whole bush, from the pure _C.
purpureus._

Prof. Caspary has examined the ovules of the dingy-red and sterile
flowers in several plants of _C. adami_ on the Continent,[93] and finds
them generally monstrous. In three plants examined by me in England,
the ovules were likewise monstrous, the nucleus varying much in shape,
and projecting irregularly beyond the proper coats. The pollen grains,
on the other hand, judging from their external appearance, were
remarkably good, and readily protruded their tubes. By repeatedly
counting, under the microscope, the proportional number of bad grains,
Prof. Caspary ascertained that only 2·5 per cent were bad, which is a
less proportion than in the pollen of three pure species of Cytisus in
their cultivated state, viz., _C. purpureus, laburnum,_ and _alpinus._
Although the pollen of _C. adami_ is thus in appearance good, it does
not follow, according to M. Naudin’s observation[94] on Mirabilis, that
it would be functionally effective. The fact of the ovules of _C.
adami_ being monstrous, and the pollen apparently sound, is all the
more remarkable, because it is opposed to what usually occurs not only
with most hybrids,[95] but with two hybrids in the same genus, namely
in _C. purpureo-elongatus,_ and _C. alpino-laburnum._ In both these
hybrids, the ovules, as observed by Prof. Caspary and myself, were
well-formed, whilst many of the pollen-grains were ill-formed; in the
latter hybrid 20.3 per cent, and in the former no less than 84·8 per
cent of the grains were ascertained by Prof. Caspary to be bad. This
unusual condition of the male and female reproductive elements in _C.
adami_ has been used by Prof. Caspary as an argument against this plant
being considered as an ordinary hybrid produced from seed; but we
should remember that with hybrids the ovules have not been examined
nearly so frequently as the pollen, and they may be much oftener
imperfect than is generally supposed. Dr. E. Bornet, of Antibes,
informs me (through Mr. J. Traherne Moggridge) that with hybrid Cisti
the ovarium is frequently deformed, the ovules being in some cases
quite absent, and in other cases incapable of fertilisation.

Several theories have been propounded to account for the origin of _C.
adami,_ and for the transformations which it undergoes. The whole case
has been attributed by some authors to bud-variation; but considering
the wide difference between _C. laburnum_ and _purpureus,_ both of
which are natural species, and considering the sterility of the
intermediate form, this view may be summarily rejected. We shall
presently see that, with hybrid plants, two embryos differing in their
characters may be developed within the same seed and cohere; and it has
been supposed that _C. adami_ thus originated. Many botanists maintain
that _C. adami_ is a hybrid produced in the common way by seed, and
that it has reverted by buds to its two parent-forms. Negative results
are not of much value; but Reisseck, Caspary, and myself, tried in vain
to cross _C. laburnum_ and _purpureus_; when I fertilised the former
with pollen of the latter, I had the nearest approach to success, for
pods were formed, but in sixteen days after the withering of the
flowers, they fell off. Nevertheless, the belief that _C. adami_ is a
spontaneously produced hybrid between these two species is supported by
the fact that such hybrids have arisen in this genus. In a bed of
seedlings from _C. elongatus,_ which grew near to _C. purpureus,_ and
was probably fertilised by it through the agency of insects (for these,
as I know by experiment, play an important part in the fertilisation of
the laburnum), the sterile hybrid _C. purpureo-elongatus_ appeared.[96]
Thus, also, Waterer’s laburnum, the _C. alpino-laburnum,_[97]
spontaneously appeared, as I am informed by Mr. Waterer, in a bed of
seedlings.

On the other hand, we have a clear and distinct account given to
Poiteau,[98] by M. Adam, who raised the plant, showing that _C. adami_
is not an ordinary hybrid; but is what may be called a graft-hybrid,
that is, one produced from the united cellular tissue of two distinct
species. M. Adam inserted in the usual manner a shield of the bark of
_C. purpureus_ into a stock of _C. laburnum_; and the bud lay dormant,
as often happens, for a year; the shield then produced many buds and
shoots, one of which grew more upright and vigorous with larger leaves
than the shoots of _C. purpureus,_ and was consequently propagated. Now
it deserves especial notice that these plants were sold by M. Adam, as
a variety of _C. purpureus,_ before they had flowered; and the account
was published by Poiteau after the plants had flowered, but before they
had exhibited their remarkable tendency to revert into the two parent
species. So that there was no conceivable motive for falsification, and
it is difficult to see how there could have been any error.[99] If we
admit as true M. Adam’s account, we must admit the extraordinary fact
that two distinct species can unite by their cellular tissue, and
subsequently produce a plant bearing leaves and sterile flowers
intermediate in character between the scion and stock, and producing
buds liable to reversion; in short, resembling in every important
respect a hybrid formed in the ordinary way by seminal reproduction.

I will therefore give all the facts which I have been able to collect
on the formation of hybrids between distinct species or varieties,
without the intervention of the sexual organs. For if, as I am now
convinced, this is possible, it is a most important fact, which will
sooner or later change the views held by physiologists with respect to
sexual reproduction. A sufficient body of facts will afterwards be
adduced, showing that the segregation or separation of the characters
of the two parent-forms by bud-variation, as in the case of _Cytisus
adami,_ is not an unusual though a striking phenomenon. We shall
further see that a whole bud may thus revert, or only half, or some
smaller segment.

The famous _bizzarria Orange_ offers a strictly parallel case to that
of _Cytisus adami._ The gardener who in 1644 in Florence raised this
tree, declared that it was a seedling which had been grafted; and after
the graft had perished, the stock sprouted and produced the bizzarria.
Gallesio, who carefully examined several living specimens and compared
them with the description given by the original describer, P.
Nato,[100] states that the tree produces at the same time leaves,
flowers, and fruit identical with the bitter orange and with the citron
of Florence, and likewise compound fruit, with the two kinds either
blended together, both externally and internally, or segregated in
various ways. This tree can be propagated by cuttings, and retains its
diversified character. The so-called trifacial orange of Alexandria and
Smyrna[101] resembles in its general nature the bizzarria, and differs
only in the orange being of the sweet kind; this and the citron are
blended together in the same fruit, or are separately produced on the
same tree; nothing is known of its origin. In regard to the bizzarria,
many authors believe that it is a graft-hybrid; Gallesio, on the other
hand, thinks that it is an ordinary hybrid, with the habit of partially
reverting by buds to the two parent-forms; and we have seen that the
species in this genus often cross spontaneously.

It is notorious that when the variegated Jessamine is budded on the
common kind, the stock sometimes produces buds bearing variegated
leaves: Mr. Rivers, as he informs me, has seen instances of this. The
same thing occurs with the Oleander.[102] Mr. Rivers, on the authority
of a trustworthy friend, states that some buds of a golden-variegated
ash, which were inserted into common ashes, all died except one; but
the ash-stocks were affected,[103] and produced, both above and below
the points of insertion of the plates of bark bearing the dead buds,
shoots which bore variegated leaves. Mr. J. Anderson Henry has
communicated to me a nearly similar case: Mr. Brown, of Perth, observed
many years ago, in a Highland glen, an ash-tree with yellow leaves; and
buds taken from this tree were inserted into common ashes, which in
consequence were affected, and produced the _Blotched Breadalbane Ash._
This variety has been propagated, and has preserved its character
during the last fifty years. Weeping ashes, also, were budded on the
affected stocks, and became similarly variegated. It has been
repeatedly proved that several species of Abutilon, on which the
variegated _A. thompsonii_ has been grafted, become variegated.[104]

Many authors consider variegation as the result of disease; and the
foregoing cases may be looked at as the direct result of the
inoculation of a disease or some weakness. This has been almost proved
to be the case by Morren in the excellent paper just referred to, who
shows that even a leaf inserted by its footstalk into the bark of the
stock is sufficient to communicate variegation to it, though the leaf
soon perishes. Even fully formed leaves on the stock of Abutilon are
sometimes affected by the graft and become variegated. Variegation is
much influenced, as we shall hereafter see, by the nature of the soil
in which the plants are grown; and it does not seem improbable that
whatever change in the sap or tissues certain soils induce, whether or
not called a disease, might spread from the inserted piece of bark to
the stock. But a change of this kind cannot be considered to be of the
nature of a graft-hybrid.

There is a variety of the hazel with dark-purple leaves, like those of
the copper-beech: no one has attributed this colour to disease, and it
apparently is only an exaggeration of a tint which may often be seen on
the leaves of the common hazel. When this variety is grafted on the
common hazel,[105] it sometimes colours, as has been asserted, the
leaves below the graft; although negative evidence is not of much
value, I may add that Mr. Rivers, who has possessed hundreds of such
grafted trees, has never seen an instance.

Gärtner[106] quotes two separate accounts of branches of dark and
white-fruited vines which had been united in various ways, such as
being split longitudinally, and then joined, etc.; and these branches
produced distinct bunches of grapes of the two colours, and other
bunches with berries, either striped, or of an intermediate and new
tint. Even the leaves in one case were variegated. These facts are the
more remarkable because Andrew Knight never succeeded in raising
variegated grapes by fertilising white kinds by pollen of dark kinds;
though, as we have seen, he obtained seedlings with variegated fruits
and leaves, by fertilising a white variety by the already variegated
dark Aleppo grape. Gärtner attributes the above-quoted cases merely to
bud-variation; but it is a strange coincidence that the branches which
had been grafted in a peculiar manner should alone thus have varied;
and H. Adorne de Tscharner positively asserts that he produced the
described result more than once, and could do so at will, by splitting
and uniting the branches in the manner described by him.

I should not have quoted the following case had not the author of ‘Des
Jacinthes’[107] impressed me with the belief not only of his extensive
knowledge, but of his truthfulness: he says that bulbs of blue and red
hyacinths may be cut in two, and that they will grow together and throw
up a united stem (and this I have myself seen) with flowers of the two
colours on the opposite sides. But the remarkable point is, that
flowers are sometimes produced with the two colours blended together,
which makes the case closely analogous with that of the blended colours
of the grapes on the united vine branches.

In the case of roses it is supposed that several graft-hybrids have
been formed, but there is much doubt about these cases, owing to the
frequency of ordinary bud-variations. The most trustworthy instance
known to me is one, recorded by Mr. Poynter,[108] who assures me in a
letter of the entire accuracy of the statement. _ Rosa devoniensis_ had
been budded some years previously on a white Banksian rose; and from
the much enlarged point of junction, whence the Devoniensis and
Banksian still continued to grow, a third branch issued, which was
neither pure Banksian nor pure Devoniensis, but partook of the
character of both; the flowers resembled, but were superior in
character to those of the variety called _Lamarque_ (one of the
Noisettes), while the shoots were similar in their manner of growth to
those of the Banksian rose, with the exception that the longer and more
robust shoots were furnished with prickles. This rose was exhibited
before the Floral Committee of the Horticultural Society of London. Dr.
Lindley examined it and concluded that it had certainly been produced
by the mingling of _R. banksiæ_ with some rose like _R. devoniensis,_
“for while it was very greatly increased in vigour and in size of all
the parts, the leaves were half-way between a Banksian and Tea-scented
rose.” It appears that rose-growers were previously aware that the
Banksian rose sometimes affects other roses. As Mr. Poynter’s new
variety is intermediate in its fruit and foliage between the stock and
scion, and as it arose from the point of junction between the two, it
is very improbable that it owes its origin to mere bud-variation,
independently of the mutual influence of the stock and scion.

Lastly, with respect to potatoes. Mr. R. Trail stated in 1867 before
the Botanical Society of Edinburgh (and has since given me fuller
information), that several years ago he cut about sixty blue and white
potatoes into halves through the eyes or buds, and then carefully
joined them, destroying at the same time the other eyes. Some of these
united tubers produced white, and others blue tubers; some, however,
produced tubers partly white and partly blue; and the tubers from about
four or five were regularly mottled with the two colours. In these
latter cases we may conclude that a stem had been formed by the union
of the bisected buds, that is, by graft-hybridisation.

In the ‘Botanische Zeitung’ (May 16, 1868), Professor Hildebrand gives
an account with a coloured figure, of his experiments on two varieties
which were found during the same season to be constant in character,
namely, a somewhat elongated rough-skinned red potato and a rounded
smooth white one. He inserted buds reciprocally into both kinds,
destroying the other buds. He thus raised two plants, and each of these
produced a tuber intermediate in character between the two
parent-forms. That from the red bud grafted into the white tuber, was
at one end red and rough, as the whole tuber ought to have been if not
affected; in the middle it was smooth with red stripes, and at the
other end smooth and altogether white like that of the stock.

Mr. Taylor, who had received several accounts of potatoes having been
grafted by wedge-shaped pieces of one variety inserted into another,
though sceptical on the subject, made twenty-four experiments which he
described in detail before the Horticultural Society.[109] He thus
raised many new varieties, some like the graft or like the stock;
others having an intermediate character. Several persons witnessed the
digging up of the tubers from these graft-hybrids; and one of them, Mr.
Jameson, a large dealer in potatoes, writes thus, “They were such a
mixed lot, as I have never before or since seen. They were of all
colours and shapes, some very ugly and some very handsome.” Another
witness says “some were round, some kidney, pink-eyed kidney, piebald,
and mottled red and purple, of all shapes and sizes.” Some of these
varieties have been found valuable, and have been extensively
propagated. Mr. Jameson took away a large piebald potato which he cut
into five sets and propagated; these yielded round, white, red, and
piebald potatoes.

Mr. Fitzpatrick followed a different plan;[110] he grafted together not
the tubers but the young stems of varieties producing black, white, and
red potatoes. The tubers borne by three of these twin or united plants
were coloured in an extraordinary manner; one was almost exactly half
black and half white, so that some persons on seeing it thought that
two potatoes had been divided and rejoined; other tubers were half red
and half white, or curiously mottled with red and white, or with red
and black, according to the colours of the graft and stock.

The testimony of Mr. Fenn is of much value, as he is “a well known
potato-grower” who has raised many new varieties by crossing different
kinds in the ordinary manner. He considers it “demonstrated” that new,
intermediate varieties can be produced by grafting the tubers, though
he doubts whether such will prove valuable.[111] He made many trials
and laid the results, exhibiting specimens, before the Horticultural
Society. Not only were the tubers affected, some being smooth and white
at one end and rough and red at the other, but the stems and leaves
were modified in their manner of growth, colour and precocity. Some of
these graft-hybrids after being propagated for three years still showed
in their haulms their new character, different from that of the kind
from which the eyes had been taken. Mr. Fenn gave twelve of the tubers
of the third generation to Mr. Alex. Dean, who grew them, and was thus
converted into a believer in graft-hybridisation, having previously
been a complete sceptic. For comparison he planted the pure
parent-forms alongside the twelve tubers; and found that many of the
plants from the latter[112] were intermediate between the two
parent-forms in precocity, in the tallness, uprightness, jointing, and
robustness of the stems, and in the size and colour of the leaves.

Another experimentalist, Mr. Rintoul, grafted no less than fifty-nine
tubers, which differed in shape (some being kidneys) in smoothness and
colour,[113] and many of the plants thus raised “were intermediate in
the tubers as well as in the haulms.” He describes the more striking
cases.

In 1871 I received a letter from Mr. Merrick, of Boston, U.S.A., who
states that, “Mr. Fearing Burr, a very careful experimenter and author
of a much valued book, ‘The Garden Vegetables of America’ has succeeded
in producing distinctly mottled and most curious potatoes—evidently
graft-hybrids, by inserting eyes from blue or red potatoes into the
substance of white ones, after removing the eyes of the latter. I have
seen the potatoes, and they are very curious.”

We will now turn to the experiments made in Germany, since the
publication of Prof. Hildebrand’s paper. Herr Magnus relates[114] the
results of numerous trials made by Herren Reuter and Lindemuth, both
attached to the Royal Gardens of Berlin. They inserted the eyes of red
potatoes into white ones, and _vice versa._ Many different forms
partaking of the characters of the inserted bud and of the stock were
thus obtained; for instance, some of the tubers were white with red
eyes.

Herr Magnus also exhibited in the following year before the same
Society (Nov. 19, 1872), the produce of grafts between black, white,
and red potatoes, made by Dr. Neubert. These were made by uniting not
the tubers but the young stems, as was done by Mr. Fitzpatrick. The
result was remarkable, inasmuch as all the tubers thus produced were
intermediate in character, though in a variable degree. Those between
the black and the white or the red were the most striking in
appearance. Some from between the white and red had one half of one
colour and the other half of the other colour.

At the next meeting of the society Herr Magnus communicated the results
of Dr. Heimann’s experiments in grafting together the tubers of red
Saxon, blue, and elongated white potatoes. The eyes were removed by a
cylindrical instrument, and inserted into corresponding holes in other
varieties. The plants thus produced yielded a great number of tubers,
which were intermediate between the two parent-forms in shape, and in
the colour both of the flesh and skin.

Herr Reuter experimented,[115] by inserting wedges of the elongated
White Mexican potato into a Black Kidney potato. Both sorts are known
to be very constant, and differ much not only in form and colour, but
in the eyes of the Black Kidney being deeply sunk, whereas those of the
White Mexican are superficial and of a different shape. The tubers
produced by these hybrids were intermediate in colour and form; and
some which resembled in form the graft, _i.e._ the Mexican, had eyes
deeply sunk and of the same shape as in the stock or Black Kidney.

Any one who will attentively consider the abstract now given, of the
experiments made by many observers in several countries, will, I think,
be convinced that by grafting two varieties of the potato together in
various ways, hybridised plants can be produced. It should be observed
that several of the experimentalists are scientific horticulturists,
and some of them potato-growers on a large scale, who, though
beforehand sceptical, have been fully convinced of the possibility,
even of the ease, of making graft-hybrids. The only way of escaping
from this conclusion is to attribute all the many recorded cases to
simple bud-variation. Undoubtedly the potato, as we have seen in this
chapter, does sometimes, though not often, vary by buds; but it should
be especially noted that it is experienced potato-growers, whose
business it is to look out for new varieties, who have expressed
unbounded astonishment at the number of new forms produced by
graft-hybridisation. It may be argued that it is merely the operation
of grafting, and not the union of two kinds, which causes so
extraordinary an amount of bud-variation; but this objection is at once
answered by the fact that potatoes are habitually propagated by the
tubers being cut into pieces, and the sole difference in the case of
graft-hybrids is that either a half or a smaller segment or a cylinder
is placed in close opposition with the tissue of another variety.
Moreover, in two cases, the young stems were grafted together, and the
plants thus united yielded the same results as when the tubers were
united. It is an argument of the greatest weight that when varieties
are produced by simple bud-variation, they frequently present quite new
characters; whereas in all the numerous cases above given, as Herr
Magnus likewise insists, the graft-hybrids are intermediate in
character between the two forms employed. That such a result should
follow if the one kind did not affect the other is incredible.

Characters of all kinds are affected by graft hybridisation, in
whatever way the grafting may have been effected. The plants thus
raised yield tubers which partake of the widely different colours,
form, state of surface, position and shape of the eye of the parents;
and according to two careful observers they are also intermediate in
certain constitutional peculiarities. But we should bear in mind that
in all the varieties of the potato, the tubers differ much more than
any other part.

The potato affords the best evidence of the possibility of the
formation of graft-hybrids, but we must not overlook the account given
of the origin of the famous _Cytisus adami_ by M. Adam, who had no
conceivable motive for deception, and the exactly parallel account of
the origin of the Bizzarria orange, namely by graft-hybridisation. Nor
must the cases be undervalued in which different varieties or species
of vines, hyacinths and roses, have been grafted together, and have
yielded intermediate forms. It is evident that graft-hybrids can be
made much more easily with some plants, as the potato, than with
others, for instance our common fruit trees; for these latter have been
grafted by the million during many centuries, and though the graft is
often slightly affected, it is very doubtful whether this may not be
accounted for, merely by a more or less free supply of nutriment.
Nevertheless, the cases above given seem to me to prove that under
certain unknown conditions graft-hybridisation can be effected.

Herr Magnus asserts with much truth that graft-hybrids resemble in all
respects seminal hybrids, including their great diversity of character.
There is, however, a partial exception, inasmuch as the characters of
the two parent forms are not often homogeneously blended together in
graft-hybrids. They much more commonly appear in a segregated
condition,—that is, in segments either at first, or subsequently
through reversion. It would seem that the reproductive elements are not
so completely blended by grafting as by sexual generation. But
segregation of this kind occurs by no means rarely, as will be
immediately shown, in seminal hybrids. Finally it must, I think, be
admitted that we learn from the foregoing cases a highly important
physiological fact, namely, that the elements that go to the production
of a new being, are not necessarily formed by the male and female
organs. They are present in the cellular tissue in such a state that
they can unite without the aid of the sexual organs, and thus give rise
to a new bud partaking of the characters of the two parent-forms.

_On the segregation of the parental characters in seminal hybrids by
bud-variation._—I will now give a sufficient number of cases to show
that segregation of this kind, namely, by buds, may occur in ordinary
hybrids raised from seed.

Hybrids were raised by Gärtner between _Tropæolum minus_ and
_majus_[116] which at first produced flowers intermediate in size,
colour, and structure between their two parents; but later in the
season some of these plants produced flowers in all respects like those
of the mother-form, mingled with flowers still retaining the usual
intermediate condition. A hybrid Cereus between _C. speciosissimus_ and
_phyllanthus,_[117] plants which are widely different in appearance,
produced for the first three years angular, five-sided stems, and then
some flat stems like those of _C. phyllanthus._ Kölreuter also gives
cases of hybrid Lobelias and Verbascums, which at first produced
flowers of one colour, and later in the season, flowers of a different
colour.[118] Naudin[119] raised forty hybrids from _Datura lævis_
fertilised by _D. stramonium_; and three of these hybrids produced many
capsules, of which a half, or quarter, or lesser segment was smooth and
of small size, like the capsule of the pure _D. lævis,_ the remaining
part being spinose and of larger size, like the capsule of the pure _D.
stramonium_: from one of these composite capsules, plants perfectly
resembling both parent-forms were raised.

Turning now to varieties. A _ seedling_ apple, conjectured to be of
crossed parentage, has been described in France,[120] which bears fruit
with one half larger than the other, of a red colour, acid taste, and
peculiar odour; the other side being greenish-yellow and very sweet: it
is said scarcely ever to include perfectly developed seed. I suppose
that this is not the same tree as that which Gaudichaud[121] exhibited
before the French institute, bearing on the same branch two distinct
kinds of apples, one a _reinette rouge,_ and the other like a _reinette
canada jaunâtre_: this double-bearing variety can be propagated by
grafts, and continues to produce both kinds; its origin is unknown. The
Rev. J. D. La Touche sent me a coloured drawing of an apple which he
brought from Canada, of which half, surrounding and including the whole
of the calyx and the insertion of the foot-stalk, is green, the other
half being brown and of the nature of the _pomme gris_ apple, with the
line of separation between the two halves exactly defined. The tree was
a grafted one, and Mr. La Touche thinks that the branches which bore
this curious apple sprung from the point of junction of the graft and
stock: had this fact been ascertained, the case would probably have
come into the class of graft-hybrids already given. But the branch may
have sprung from the stock, which no doubt was a seedling.

Prof. H. Lecoq, who has made a great number of crossings between the
differently coloured varieties of _Mirabilis jalapa,_[122] finds that
in the seedlings the colours rarely combine, but form distinct stripes;
or half the flower is of one colour and half of a different colour.
Some varieties regularly bear flowers striped with yellow, white, and
red; but plants of such varieties occasionally produce on the same root
branches with uniformly coloured flowers of all three tints, and other
branches with half-and-half coloured flowers, and others with marbled
flowers. Gallesio[123] crossed reciprocally white and red carnations,
and the seedlings were striped; but some of the striped plants also
bore entirely white and entirely red flowers. Some of these plants
produced one year red flowers alone, and in the following year striped
flowers; or conversely, some plants, after having borne for two or
three years striped flowers, would revert and bear exclusively red
flowers. It may be worth mentioning that I fertilised the _Purple
Sweet-pea (Lathyrus odoratus)_ with pollen from the light-coloured
_Painted Lady_: seedlings raised from the same pod were not
intermediate in character, but perfectly resembled either parent. Later
in the summer, the plants which had at first borne flowers identical
with those of the _Painted Lady,_ produced flowers streaked and
blotched with purple; showing in these darker marks a tendency to
reversion to the mother-variety. Andrew Knight[124] fertilised two
white grapes with pollen of the Aleppo grape, which is darkly
variegated both in its leaves and fruit. The result was that the young
seedlings were not at first variegated, but all became variegated
during the succeeding summer; besides this, many produced on the same
plant bunches of grapes which were all black, or all white, or
lead-coloured striped with white, or white dotted with minute black
stripes; and grapes of all these shades could frequently be found on
the same foot-stalk.

I will append a very curious case, not of bud-variation, but of two
cohering embryos, different in character and contained within the same
seed. A distinguished botanist, Mr. G. H. Thwaites,[125] states that a
seed from _Fuchsia coccinea_ fertilised by _F. fulgens,_ contained two
embryos, and was “a true vegetable twin.” The two plants produced from
the two embryos were “extremely different in appearance and character,”
though both resembled other hybrids of the same parentage produced at
the same time. These twin plants “were closely coherent, below the two
pairs of cotyledon-leaves, into a single cylindrical stem, so that they
had subsequently the appearance of being branches on one trunk.” Had
the two united stems grown up to their full height, instead of dying, a
curiously mixed hybrid would have been produced. A mongrel melon
described by Sageret[126] may perhaps have thus originated; for the two
main branches, which arose from two cotyledon-buds, produced very
different fruit,—on the one branch like that of the paternal variety,
and on the other branch like to a certain extent that of the maternal
variety, the melon of China.

In most of these cases of crossed varieties, and in some of the cases
of crossed species, the colours proper to both parents appeared in the
seedlings, as soon as they first flowered, in the form of stripes or
larger segments, or as whole flowers or fruit of different kinds borne
on the same plant; and in this case the appearance of the two colours
cannot strictly be said to be due to reversion, but to some incapacity
of fusion. When, however, the later flowers or fruit produced during
the same season, or during a succeeding year or generation, become
striped or half-and-half, etc., the segregation of the two colours is
strictly a case of reversion by bud-variation. Whether all the many
recorded cases of striped flowers and fruit are due to previous
hybridisation and reversion is by no means clear, for instance with
peaches and nectarines, moss-roses, etc. In a future chapter I shall
show that, with animals of crossed parentage, the same individual has
been known to change its character during growth, and to revert to one
of its parents which it did not at first resemble. Finally, from the
various facts now given, there can be no doubt that the same individual
plant, whether a hybrid or a mongrel, sometimes returns in its leaves,
flowers, and fruit, either wholly or by segments, to both parent-forms.

_On the direct or immediate action of the male element on the mother
form._—Another remarkable class of facts must be here considered,
firstly, because they have a high physiological importance, and
secondly, because they have been supposed to account for some cases of
bud-variation. I refer to the direct action of the male element, not in
the ordinary way on the ovules, but on certain parts of the female
plant, or in case of animals on the subsequent progeny of the female by
a second male. I may premise that with plants the ovarium and the coats
of the ovules are obviously parts of the female, and it could not have
been anticipated that they would have been affected by the pollen of a
foreign variety or species, although the development of the embryo,
inside the embryonic sack, inside the ovule and ovarium, of course,
depends on the male element.

Even as long ago as 1729 it was observed[127] that white and blue
varieties of the Pea, when planted near each other, mutually crossed,
no doubt through the agency of bees, and in the autumn blue and white
peas were found within the same pods. Wiegmann made an exactly similar
observation in the present century. The same result has followed
several times when a variety with peas of one colour has been
artificially crossed by a differently-coloured variety.[128] These
statements led Gärtner, who was highly sceptical on the subject,
carefully to try a long series of experiments: he selected the most
constant varieties, and the result conclusively showed that the colour
of the skin of the pea is modified when pollen of a differently
coloured variety is used. This conclusion has since been confirmed by
experiments made by the Rev. J. M. Berkeley.[129]

Mr. Laxton of Stamford, whilst making experiments on peas for the
express purpose of ascertaining the influence of foreign pollen on the
mother-plant, has recently[130] observed an important additional fact.
He fertilised the Tall Sugar-pea, which bears very thin green pods,
becoming brownish-white when dry, with pollen of the Purple-podded pea,
which, as its name expresses, has dark-purple pods with very thick
skin, becoming pale reddish purple when dry. Mr. Laxton has cultivated
the tall sugar-pea during twenty years, and has never seen or heard of
it producing a purple pod: nevertheless, a flower fertilised by pollen
from the purple-pod yielded a pod clouded with purplish-red which Mr.
Laxton kindly gave to me. A space of about two inches in length towards
the extremity of the pod, and a smaller space near the stalk, were thus
coloured. On comparing the colour with that of the purple pod, both
pods having been first dried and then soaked in water, it was found to
be identically the same; and in both the colour was confined to the
cells lying immediately beneath the outer skin of the pod. The valves
of the crossed pod were also decidedly thicker and stronger than those
of the pods of the mother-plant, but this may possibly have been an
accidental circumstance, for I know not how far their thickness is a
variable character in the Tall Sugar-pea.

The peas of the Tall Sugar-pea, when dry, are pale greenish-brown,
thickly covered with dots of dark purple so minute as to be visible
only through a lens, and Mr. Laxton has never seen or heard of this
variety producing a purple pea; but in the crossed pod one of the peas
was of a uniform beautiful violet-purple tint, and a second was
irregularly clouded with pale purple. The colour lies in the outer of
the two coats which surround the pea. As the peas of the purple-podded
variety when dry are of a pale greenish-buff, it would at first appear
that this remarkable change of colour in the peas in the crossed pod
could not have been caused by the direct action of the pollen of the
purple-pod: but when we bear in mind that this latter variety has
purple flowers, purple marks on its stipules, and purple pods; and that
the Tall Sugar-pea likewise has purple flowers and stipules, and
microscopically minute purple dots on the peas, we can hardly doubt
that the tendency to the production of purple in both parents has in
combination modified the colour of the peas in the crossed pod. After
having examined these specimens, I crossed the same two varieties, and
the peas in one pod but not the pods themselves, were clouded and
tinted with purplish-red in a much more conspicuous manner than the
peas in the uncrossed pods produced at the same time by the same
plants. I may notice as a caution that Mr. Laxton sent me various other
crossed peas slightly, or even greatly, modified in colour; but the
change in these cases was due, as had been suspected by Mr. Laxton, to
the altered colour of the cotyledons, seen through the transparent
coats of the peas; and as the cotyledons are parts of the embryo, these
cases are not in any way remarkable.

Turning now to the genus Matthiola. The pollen of one kind of stock
sometimes affects the colour of the seeds of another kind, used as the
mother-plant. I give the following case the more readily, as Gärtner
doubted similar statements previously made with respect to the stock by
other observers. A well-known horticulturist, Major Trevor Clarke,
informs me[131] that the seeds of the large red-flowered _biennial_
stock, _Matthiola annua_ (_Cocardeau_ of the French), are light brown,
and those of the purple branching Queen stock (_M. incana_) are
violet-black; and he found that, when flowers of the red stock were
fertilised by pollen from the purple stock, they yielded about fifty
per cent of _black_ seeds. He sent me four pods from a red flowered
plant, two of which had been fertilised by their own pollen, and they
included pale brown seed; and two which had been crossed by pollen from
the purple kind, and they included seeds all deeply tinged with black.
These latter seeds yielded purple-flowered plants like their father;
whilst the pale brown seeds yielded normal red-flowered plants; and
Major Clarke, by sowing similar seeds, has observed on a greater scale
the same result. The evidence in this case of the direct action of the
pollen of one species on the colour of the seeds of another species
appears to me conclusive.

Gallesio[132] fertilised the flowers of an orange with pollen from the
lemon; and one fruit thus produced bore a longitudinal stripe of peel
having the colour, flavour, and other characters of the lemon. Mr.
Anderson[133] fertilised a green-fleshed melon with pollen from a
scarlet-fleshed kind; in two of the fruits “a sensible change was
perceptible: and four other fruits were somewhat altered both
internally and externally.” The seeds of the two first-mentioned fruits
produced plants partaking of the good properties of both parents. In
the United States, where Cucurbitaceæ are largely cultivated, it is the
popular belief[134] that the fruit is thus directly affected hy foreign
pollen; and I have received a similar statement with respect to the
cucumber in England. It is believed that grapes have been thus affected
in colour, size, and shape: in France a pale-coloured grape had its
juice tinted by the pollen of the dark-coloured Teinturier; in Germany
a variety bore berries which were affected by the pollen of two
adjoining kinds; some of the berries being only partially affected or
mottled.[135]

As long ago as 1751[136] it was observed that, when
differently-coloured varieties of maize grew near each other, they
mutually affected each other’s seeds, and this is now a popular belief
in the United States. Dr. Savi[137] tried the experiment with care: he
sowed yellow and black-seeded maize together, and on the same ear some
of the seeds were yellow, some black, and some mottled, the differently
coloured seeds being arranged irregularly or in rows. Prof. Hildebrand
has repeated the experiment[138] with the precaution of ascertaining
that the mother-plant was true. A kind bearing yellow grains was
fertilised with pollen of a kind having brown grains, and two ears
produced yellow grains mingled with others of a dirty violet tint. A
third ear had only yellow grains, but one side of the spindle was
tinted of a reddish-brown; so that here we have the important fact of
the influence of the foreign pollen extending to the axis. Mr. Arnold,
in Canada, varied the experiment in an interesting manner: “a female
flower was subjected first to the action of pollen from a yellow
variety, and then to that from a white variety; the result was an ear,
each grain of which was yellow below and white above.”[139] With other
plants it has occasionally been observed that the crossed offspring
showed the influence of two kinds of pollen, but in this case the two
kinds affected the mother-plant.

Mr. Sabine states[140] that he has seen the form of the nearly globular
seed-capsule of _Amaryllis vittata_ altered by the application of the
pollen of another species, of which the capsule has gibbous angles.
With an allied genus, a well-known botanist, Maximowicz, has described
in detail the striking results of reciprocally fertilising _Lilium
bulbiferum_ and _ davuricum_ with each other’s pollen. Each species
produced fruit not like its own, but almost identical with that of the
pollen-bearing species; but from an accident only the fruit of the
latter species was carefully examined; the seeds were intermediate in
the development of their wings.[141]

Fritz Müller fertilised _Cattleya leopoldi_ with pollen of _Epidendron
cinnabarinum_; and the capsules contained very few seeds; but these
presented a most wonderful appearance, which, from the description
given, two botanists, Hildebrand and Maximowicz, attribute to the
direct action of the pollen of the Epidendron.[142]

Mr. J. Anderson Henry[143] crossed _Rhododendron dalhousiæ_ with the
pollen of _R. nuttallii,_ which is one of the largest-flowered and
noblest species of the genus. The largest pod produced by the former
species, when fertilised with its own pollen, measured 1¼ inch in
length and 1½ in girth; whilst three of the pods which had been
fertilised by pollen of _R. nuttallii_ measured 1-5/8 inch in length
and no less than 2 inches in girth. Here the effect of the foreign
pollen was apparently confined to increasing the size of the ovarium;
but we must be cautious in assuming, as the following case shows, that
size had been transferred from the male parent to the capsule of the
female plant. Mr. Henry fertilised _Arabis blepharophylla_ with pollen
of _A. soyeri,_ and the pods thus produced, of which he was so kind as
to send me detailed measurements and sketches, were much larger in all
their dimensions than those naturally produced by either the male or
female parent-species. In a future chapter we shall see that the organs
of vegetation in hybrid plants, independently of the character of
either parent, are sometimes developed to a monstrous size; and the
increased size of the pods in the foregoing cases may be an analogous
fact. On the other hand, M. de Saporta informs me that an isolated
female plant of _Pistacia vera_ is very apt to be fertilised by the
pollen of neighbouring plants of _P. terebinthus,_ and in this case the
fruits are only half their proper size, which he attributes to the
influence of the pollen of _P. terebinthus._

No case of the direct action of the pollen of one variety on another is
better authenticated or more remarkable than that of the common apple.
The fruit here consists of the lower part of the calyx and of the upper
part of the flower-peduncle[144] in a metamorphosed condition, so that
the effect of the foreign pollen has extended even beyond the limits of
the ovarium. Cases of apples thus affected were recorded by Bradley in
the early part of the last century; and other cases are given in old
volumes of the ‘Philosophical Transactions’;[145] in one of these a
Russeting apple and an adjoining kind mutually affected each other’s
fruit; and in another case a smooth apple affected a rough-coated kind.
Another instance has been given[146] of two very different apple-trees
growing close to each other, which bore fruit resembling each other,
but only on the adjoining branches. It is, however, almost superfluous
to adduce these or other cases, after that of the St. Valery apple, the
flowers which, from the abortion of the stamens, do not produce pollen,
but are fertilised by the girls of the neighbourhood with pollen of
many kinds; and they bear fruit, “differing from one another in size,
flavour, and colour, but resembling in character the hermaphrodite
kinds by which they have been fertilised.”[147]

I have now shown, on the authority of several excellent observers, in
the case of plants belonging to widely different orders, that the
pollen of one species or variety, when applied to the female of a
distinct form, occasionally causes the coats of the seeds, the ovarium
or fruit, including even the calyx and upper part of the peduncle of
the apple, and the axis of the ear in maize, to be modified. Sometimes
the whole ovarium or all the seeds are thus affected; sometimes only a
certain number of the seeds, as in the case of the pea, or only a part
of the ovarium, as with the striped orange, mottled grapes, and maize,
is thus affected. It must not be supposed that any direct or immediate
effect invariably follows the use of foreign pollen: this is far from
being the case; nor is it known on what conditions the result depends.
Mr. Knight[148] expressly states that he has never seen the fruit thus
affected, though he crossed thousands of apple and other fruit-trees.

There is not the least reason to believe that a branch which has borne
seed or fruit directly modified by foreign pollen is itself affected,
so as afterwards to produce modified buds; such an occurrence, from the
temporary connection of the flower with the stem, would be hardly
possible. Hence, but very few, if any, of the cases of bud-variation in
the fruit of trees, given in the early part of this chapter can be
accounted for by the action of foreign pollen; for such fruits have
commonly been propagated by budding or grafting. It is also obvious
that changes of colour in flowers, which necessarily supervene long
before they are ready for fertilisation, and changes in the shape or
colour of leaves, when due to the appearance of modified buds, can have
no relation to the action of foreign pollen.

The proofs of the action of foreign pollen on the mother-plant have
been given in considerable detail, because this action, as we shall see
in a future chapter, is of the highest theoretical importance, and
because it is in itself a remarkable and apparently anomalous
circumstance. That it is remarkable under a physiological point of view
is clear, for the male element not only affects, in accordance with its
proper function, the germ, but at the same time various parts of the
mother-plant, in the same manner, as it affects the same part in the
seminal offspring from the same two parents. We thus learn that an
ovule is not indispensable for the reception of the influence of the
male element. But this direct action of the male element is not so
anomalous as it at first appears, for it comes into play in the
ordinary fertilisation of many flowers. Gärtner gradually increased the
number of pollen grains until he succeeded in fertilising a Malva, and
has[149] proved that many grains are first expended in the development,
or, as he expresses it, in the satiation, of the pistil and ovarium.
Again, when one plant is fertilised by a widely distinct species, it
often happens that the ovarium is fully and quickly developed without
any seeds being formed; or the coats of the seeds are formed without
any embryo being developed within. Prof. Hildebrand, also, has lately
shown[150] that, in the normal fertilisation of several Orchideæ, the
action of the plant’s own pollen is necessary for the development of
the ovarium; and that this development takes place not only long before
the pollen-tubes have reached the ovules, but even before the placentæ
and ovules have been formed; so that with these orchids the pollen acts
directly on the ovarium. On the other hand, we must not overrate the
efficacy of pollen in the case of hybridised plants, for an embryo may
be formed and its influence excite the surrounding tissues of the
mother-plant, and then perish at a very early age and be thus
overlooked. Again, it is well known that with many plants the ovarium
may be fully developed, though pollen be wholly excluded. Lastly, Mr.
Smith, the late Curator at Kew (as I hear through Dr. Hooker), observed
with an orchid, the _Bonatea speciosa,_ the singular fact that the
development of the ovarium could be effected by the mechanical
irritation of the stigma. Nevertheless, from the number of the
pollen-grains expended “in the satiation of the ovarium and
pistil,”—from the generality of the formation of the ovarium and
seed-coats in hybridised plants which produce no seeds,—and from Dr.
Hildebrand’s observations on orchids, we may admit that in most cases
the swelling of the ovarium, and the formation of the seed-coats are at
least aided, if not wholly caused, by the direct action of the pollen,
independently of the intervention of the fertilised germ. Therefore, in
the previously given cases we have only to believe in the further power
of pollen, when applied to a distinct species or variety, to influence
the shape, size, colour, texture, etc., of certain parts of the
mother-plant.

Turning now to the animal kingdom. If we could imagine the same flower
to yield seeds during successive years, then it would not be very
surprising that a flower of which the ovarium had been modified by
foreign pollen should next year produce, when self-fertilised,
offspring modified by the previous male influence. Closely analogous
cases have actually occurred with animals. In the case often quoted
from Lord Morton,[151] a nearly purely-bred Arabian chestnut mare bore
a hybrid to a quagga; she was subsequently sent to Sir Gore Ouseley,
and produced two colts by a black Arabian horse. These colts were
partially dun-coloured, and were striped on the legs more plainly than
the real hybrid, or even than the quagga. One of the two colts had its
neck and some other parts of its body plainly marked with stripes.
Stripes on the body, not to mention those on the legs, are extremely
rare,—I speak after having long attended to the subject,—with horses of
all kinds in Europe, and are almost unknown in the case of Arabians.
But what makes the case still more striking is that in these colts the
hair of the mane resembled that of the quagga, being short, stiff, and
upright. Hence there can be no doubt that the quagga affected the
character of the offspring subsequently begot by the black Arabian
horse. Mr. Jenner Weir informs me of a strictly parallel case: his
neighbour Mr. Lethbridge, of Blackheath, has a horse, bred by Lord
Mostyn, which had previously borne a foal by a quagga. This horse is
dun with a dark stripe down the back, faint stripes on the forehead
between the eyes, plain stripes on the inner side of the fore-legs and
rather more faint ones on the hind-legs, with no shoulder-stripe. The
mane grows much lower on the forehead than in the horse, but not so low
as in the quagga or zebra. The hoofs are proportionally longer than in
the horse,—so much so that the farrier who first shod this animal, and
knew nothing of its origin, said, “Had I not seen I was shoeing a
horse, I should have thought I was shoeing a donkey.”

With respect to the varieties of our domesticated animals, many similar
and well-authenticated facts have been published,[152] and others have
been communicated to me, plainly showing the influence of the first
male on the progeny subsequently borne by the mother to other males. It
will suffice to give a single instance, recorded in the ‘Philosophical
Transactions,’ in a paper following that by Lord Morton: Mr. Giles put
a sow of Lord Western’s black and white Essex breed to a wild boar of a
deep chestnut colour; and the “pigs produced partook in appearance of
both boar and sow, but in some the chestnut colour of the boar strongly
prevailed.” After the boar had long been dead, the sow was put to a
boar of her own black and white breed—a kind which is well known to
breed very true and never to show any chestnut colour,—yet from this
union the sow produced some young pigs which were plainly marked with
the same chestnut tint as in the first litter. Similar cases have so
frequently occurred, that careful breeders avoid putting a choice
female of any animal to an inferior male, on account of the injury to
her subsequent progeny which may be expected to follow.

Some physiologists have attempted to account for these remarkable
results from a previous impregnation, by the imagination of the mother
having been strongly affected; but it will hereafter be seen that there
are very slight grounds for any such belief. Other physiologists
attribute the result to the close attachment and freely
intercommunicating blood-vessels between the modified embryo and
mother. But the analogy from the action of foreign pollen on the
ovarium, seed-coats, and other parts of the mother-plant, strongly
supports the belief that with animals the male element acts directly on
the female, and not through the crossed embryo. With birds there is no
close connection between the embryo and mother; yet a careful observer,
Dr. Chapuis, states[153] that with pigeons the influence of a first
male sometimes makes itself perceived in the succeeding broods; but
this statement requires confirmation.

_Conclusion and Summary of the Chapter._—The facts given in the latter
half of this chapter are well worthy of consideration, as they show us
in how many extraordinary modes the union of one form with another may
lead to the modification of the seminal offspring or of the buds,
afterwards produced.

There is nothing surprising in the offspring of species or varieties
crossed in the ordinary manner being modified; but the case of two
plants within the same seed, which cohere and differ from each other,
is curious. When a bud is formed after the cellular tissue of two
species or two varieties have been united, and it partakes of the
characters of both parents, the case is wonderful. But I need not here
repeat what has been so lately said on this subject. We have also seen
that in the case of plants the male element may affect in a direct
manner the tissues of the mother, and with animals may lead to the
modification of her future progeny. In the vegetable kingdom the
offspring from a cross between two species or varieties, whether
effected by seminal generation or by grafting, often revert, to a
greater or less degree, in the first or in a succeeding generation, to
the two parent-forms; and this reversion may affect the whole flower,
fruit, or leaf-bud, or only the half or a smaller segment of a single
organ. In some cases, however, such segregation of character apparently
depends on an incapacity for union rather than on reversion, for the
flowers or fruit which are first produced display by segments the
characters of both parents. The various facts here given ought to be
well considered by any one who wishes to embrace under a single point
of view the many modes of reproduction by gemmation, division, and
sexual union, the reparation of lost parts, variation, inheritance,
reversion, and other such phenomena. Towards the close of the second
volume I shall attempt to connect these facts together by the
hypothesis of pangenesis.

In the early half of the present chapter I have given a long list of
plants in which through bud-variation, that is, independently of
reproduction by seed, the fruit has suddenly become modified in size,
colour, flavour, hairiness, shape, and time of maturity; flowers have
similarly changed in shape, colour, in being double, and greatly in the
character of the calyx; young branches or shoots have changed in
colour, in bearing spines and in habit of growth, as in climbing or in
weeping; leaves have changed in becoming variegated, in shape, period
of unfolding, and in their arrangement on the axis. Buds of all kinds,
whether produced on ordinary branches or on subterranean stems, whether
simple or much modified and supplied with a stock of nutriment, as in
tubers and bulbs, are all liable to sudden variations of the same
general nature.

In the list, many of the cases are certainly due to reversion to
characters not acquired from a cross, but which were formerly present
and have since been lost for a longer or shorter time;—as when a bud on
a variegated plant produces plain leaves, or when the
variously-coloured flowers of the Chrysanthemum revert to the
aboriginal yellow tint. Many other cases included in the list are
probably due to the plants being of crossed parentage, and to the buds
reverting either completely or by segments to one of the two
parent-forms.[154]

We may suspect that the strong tendency in the Chrysanthemum to produce
by bud-variation differently-coloured flowers, results from the
varieties having been at some time intentionally or accidentally
crossed; and this is certainly the case with some kinds of Pelargonium.
So it may be to a large extent with the bud-varieties of the Dahlia,
and with the “broken colours” of Tulips. When, however, a plant reverts
by bud-variation to its two parent forms, or to one of them, it
sometimes does not revert perfectly, but assumes a somewhat new
character,—of which fact, instances have been given, and Carrière
gives[155] another in the cherry.

Many cases of bud-variation, however, cannot be attributed to
reversion, but to so-called spontaneous variability, as is so common
with cultivated plants raised from seed. As a single variety of the
Chrysanthemum has produced by buds six other varieties, and as one
variety of the gooseberry has borne at the same time four distinct
kinds of fruit, it is scarcely possible to believe that all these
variations are due to reversion. We can hardly believe, as remarked in
a previous chapter, that all the many peaches which have yielded
nectarine-buds are of crossed parentage. Lastly, in such cases as that
of the moss-rose, with its peculiar calyx, and of the rose which bears
opposite leaves, in that of the Imatophyllum, etc., there is no known
natural species or variety from which the characters in question could
have been derived by a cross. We must attribute all such cases to the
appearance of absolutely new characters in the buds. The varieties
which have thus arisen cannot be distinguished by any external
character from seedlings; this is notoriously the case with the
varieties of the Rose, Azalea, and many other plants. It deserves
notice that all the plants which have yielded bud-variations have
likewise varied greatly by seed.

The plants which have varied by buds belong to so many orders that we
may infer that almost every plant would be liable to variation, if
placed under the proper exciting conditions. These conditions, as far
as we can judge, mainly depend on long-continued and high cultivation;
for almost all the plants in the foregoing list are perennials, and
have been largely propagated in many soils, under different climates,
by cuttings, offsets, bulbs, tubers, and especially by budding or
grafting. The instances of annuals varying by buds, or producing on the
same plant differently coloured flowers, are comparatively rare:
Hopkirk[156] has seen this with _ Convolvulus tricolor_; and it is not
uncommon with the Balsam and annual Delphinium. According to Sir R.
Schomburgk, plants from the warmer temperate regions, when cultivated
under the hot climate of St. Domingo, are eminently liable to
bud-variation. I am informed by Mr. Sedgwick that moss-roses which have
often been taken to Calcutta always there lose their mossiness; but
change of climate is by no means a necessary contingent, as we see with
the gooseberry, currant, and in many other cases. Plants living under
their natural conditions are very rarely subject to bud-variation.
Variegated leaves have, however, been observed under such
circumstances; and I have given an instance of variation by buds on an
ash-tree planted in ornamental grounds, but it is doubtful whether such
a tree can be considered as living under strictly natural conditions.
Gärtner has seen white and dark-red flowers produced from the same root
of the wild _Achillea millefolium_; and Prof. Caspary has seen a
completely wild _ Viola lutea_ bearing flowers of two different colours
and sizes.[157]

As wild plants are so rarely liable to bud-variation, whilst highly
cultivated plants long propagated by artificial means have yielded many
varieties by this form of reproduction, we are led through a series
such as the following,—namely, all the eyes in the same tuber of the
potato varying in the same manner,—all the fruit on a purple plum-tree
suddenly becoming yellow,—all the fruit on a double-flowered almond
suddenly becoming peach like,—all the buds on grafted trees being in a
very slight degree affected by the stock on which they have been
worked,—all the flowers on a transplanted heartsease changing for a
time in colour, size, and shape,—we are led by such a series to look at
every case of bud-variation as the direct result of the conditions of
life to which the plant has been exposed. On the other hand, plants of
the same variety may be cultivated in two adjoining beds, apparently
under exactly the same conditions, and those in the one bed, as
Carrière insists,[158] will produce many bud-variations, and those in
the other not a single one. Again, if we look to such cases as that of
a peach-tree which, after having been cultivated by tens of thousands
during many years in many countries, and after having annually produced
millions of buds, all of which have apparently been exposed to
precisely the same conditions, yet at last suddenly produces a single
bud with its whole character greatly transformed, we are driven to the
conclusion that the transformation stands in no _direct_ relation to
the conditions of life.

We have seen that varieties produced from seeds and from buds resemble
each other so closely in general appearance that they cannot be
distinguished. Just as certain species and groups of species, when
propagated by seed, are more variable than other species or genera, so
it is in the case of certain bud-varieties. Thus, the Queen of England
Chrysanthemum has produced by this latter process no less than six, and
Rollisson’s Unique Pelargonium four distinct varieties; moss-roses have
also produced several other moss-roses. The Rosaceæ have varied by buds
more than any other group of plants; but this may be in large part due
to so many members having been long cultivated; but within this same
group, the peach has often varied by buds, whilst the apple and pear,
both grafted trees extensively cultivated, have afforded, as far as I
can ascertain, extremely few instances of bud-variation.

The law of analogous variation holds good with varieties produced by
buds, as with those produced from seed: more than one kind of rose has
sported into a moss-rose; more than one kind of camellia has assumed an
hexagonal form; and at least seven or eight varieties of the peach have
produced nectarines.

The laws of inheritance seem to be nearly the same with seminal and
bud-varieties. We know how commonly reversion comes into play with
both, and it may affect the whole, or only segments of a leaf, flower,
or fruit. When the tendency to reversion affects many buds on the same
tree, it becomes covered with different kinds of leaves, flowers, or
fruit; but there is reason to believe that such fluctuating varieties
have generally arisen from seed. It is well known that, out of a number
of seedling varieties, some transmit their character much more truly by
seed than others; so with bud-varieties, some retain their character by
successive buds more truly than others; of which instances have been
given with two kinds of variegated Euonymus and with certain kinds of
tulips and pelargoniums. Notwithstanding the sudden production of
bud-varieties, the characters thus acquired are sometimes capable of
transmission by seminal reproduction: Mr. Rivers has found that
moss-roses generally reproduce themselves by seed; and the mossy
character has been transferred by crossing from one species of rose to
another. The Boston nectarine, which appeared as a bud-variation,
produced by seed a closely allied nectarine. On the other hand,
seedlings from some bud-variations have proved variable to an extreme
degree.[159] We have also heard, on the authority of Mr. Salter, that
seeds taken from a branch with leaves variegated through bud-variation,
transmit this character very feebly; whilst many plants, which were
variegated as seedlings, transmit variegation to a large proportion of
their progeny.

Although I have been able to collect a good many cases of
bud-variation, as shown in the previous lists, and might probably, by
searching foreign horticultural works, have collected very many more
cases, yet their total number is as nothing in comparison with that of
seminal varieties. With seedlings raised from the more variable
cultivated plants, the variations are almost infinitely numerous, but
their differences are generally slight: only at long intervals of time
a strongly marked modification appears. On the other hand, it is a
singular and inexplicable fact that, when plants vary by buds, the
variations, though they occur with comparative rarity, are often, or
even generally, strongly pronounced. It struck me that this might
perhaps be a delusion, and that slight changes often occurred in buds,
but were overlooked or not recorded from being of no value.
Accordingly, I applied to two great authorities on this subject,
namely, to Mr. Rivers with respect to fruit-trees, and to Mr. Salter
with respect to flowers. Mr. Rivers is doubtful, but does not remember
having noticed very slight variations in fruit-buds. Mr. Salter informs
me that with flowers such do occur, but, if propagated, they generally
lose their new character in the following year; yet he concurs with me
that bud-variations usually at once assume a decided and permanent
character. We can hardly doubt that this is the rule, when we reflect
on such cases as that of the peach, which has been so carefully
observed, and of which such trifling seminal varieties have been
propagated, yet this tree has repeatedly produced by bud-variation
nectarines, and only twice (as far as I can learn) any other variety,
namely, the Early and Late Grosse Mignonne peaches; and these differ
from the parent-tree in hardly any character except the period of
maturity.

To my surprise, I hear from Mr. Salter that he brings the principle of
selection to bear on variegated plants propagated by buds, and has thus
greatly improved and fixed several varieties. He informs me that at
first a branch often produces variegated leaves on one side alone, and
that the leaves are marked only with an irregular edging or with a few
lines of white and yellow. To improve and fix such varieties, he finds
it necessary to encourage the buds at the bases of the most distinctly
marked leaves, and to propagate from them alone. By following with
perseverance this plan during three or four successive seasons, a
distinct and fixed variety can generally be secured.

Finally, the facts given in this chapter prove in how close and
remarkable a manner the germ of a fertilised seed and the small
cellular mass forming a bud, resemble each other in all their
functions—in their power of inheritance with occasional reversion,—and
in their capacity for variation of the same general nature, in
obedience to the same laws. This resemblance, or rather identity of
character, is shown in the most striking manner by the fact that the
cellular tissue of one species or variety, when budded or grafted on
another, may give rise to a bud having an intermediate character. We
have seen that variability does not depend on sexual generation, though
much more frequently its concomitant than of bud reproduction. We have
seen that bud-variability is not solely dependent on reversion or
atavism to long-lost characters, or to those formerly acquired from a
cross, but appears often to be spontaneous. But when we ask ourselves
what is the cause of any particular bud-variation, we are lost in
doubt, being driven in some cases to look to the direct action of the
external conditions of life as sufficient, and in other cases to feel a
profound conviction that these have played a quite subordinate part, of
not more importance than the nature of the spark which ignites a mass
of combustible matter.

REFERENCES

 [1] Since the publication of the first edition of this work, I have
 found that M. Carrière, _Chef des Pépinières au Mus. d’Hist. Nat.,_ in
 his excellent Essay ‘Production et Fixation des Variétés, 1865,’ has
 given a list of bud-variations far more extensive than mine; but as
 these relate chiefly to cases occurring in France I have left my list
 as it stood, adding a few facts from M. Carrière and others. Any one
 who wishes to study the subject fully should refer to M. Carrière’s
 Essay.

 [2] ‘Gardener’s Chronicle,’ 1854, p. 821.

 [3] Lindley’s ‘Guide to Orchard,’ as quoted in ‘Gardener’s Chronicle,’
 1852, p. 821. For the _Early mignonne peach, see_ ‘Gardener’s
 Chronicle,’ 1864, p. 1251.

 [4] ‘Transact. Hort. Soc.,’ vol. ii. p. 160.

 [5] _See also_ ‘Gardener’s Chronicle,’ 1863, p. 27.

 [6] ‘Gardener’s Chronicle,’ 1852, p. 821.

 [7] ‘Gardener’s Chronicle,’ 1852, p. 629; 1856, p. 648; 1864, p. 986.
 Other cases are given by Braun ‘Rejuvenescence,’ in ‘Ray Soc. Bot.
 Mem.,’ 1853, p. 314.

 [8] ‘Ampélographie,’ etc., 1849, p. 71.

 [9] ‘Gardener’s Chronicle,’ 1866, p. 970.

 [10] ‘Gardener’s Chronicle,’ 1855, pp. 597, 612.

 [11] ‘Gardener’s Chronicle,’ 1842, p. 873; 1855, p. 646. In the
 ‘Chronicle,’ p. 876, Mr. P. Mackenzie states that the bush still
 continues to bear the three kinds of fruit, “although they have not
 been every year alike.”

 [12] ‘Revue Horticole,’ quoted in ‘Gardener’s Chronicle,’ 1844, p. 87.

 [13] ‘Rejuvenescence in Nature,’ ‘Bot. Memoirs Ray Soc.,’ 1853, p.
 314.

 [14] ‘Comptes Rendus,’ tom. xli. 1855, p. 804. The second case is
 given on the authority of Gaudichaud, ibid., tom. xxxiv. 1852, p. 748.

 [15] This case is given in the ‘Gardener’s Chronicle,’ 1867, p. 403.

 [16] ‘Journal of Proc. Linn. Soc.,’ vol ii. Botany, p. 131.

 [17] ‘Gardener’s Chronicle,’ 1847, p. 207.

 [18] Herbert, ‘Amaryllidaceæ,’ 1838, p. 369.

 [19] ‘Gardener’s Chronicle,’ 1843, p. 391.

 [20] Exhibited at Hort. Soc. London. Report in ‘Gardener’s Chronicle,’
 1844, p. 337.

 [21] Mr. W. Bell ‘Bot. Soc. of Edinburgh,’ May, 1863.

 [22] ‘Revue Horticole,’ quoted in ‘Gardener’s Chronicle,’ 1845, p.
 475.

 [23] ‘Bastarderzeugung,’ 1849, s. 76.

 [24] ‘Journal of Horticulture,’ 1861, p. 336.

 [25] W. P. Ayres, in ‘Gardener’s Chronicle,’ 1842, p. 791.

 [26] W. P. Ayres, ibid.

 [27] Dr. Maxwell Masters, ‘Pop. Science Review,’ July, 1872, p. 250.

 [28] ‘Gardener’s Chronicle,’ 1861, p. 968.

 [29] Ibid., 1861 p. 945.

 [30] W. Paul, in ‘Gardener’s Chronicle,’ 1861, p. 968.

 [31] Ibid., p. 945.

 [32] For other cases of bud-variation in this same variety, _ see_
 ‘Gardener’s Chronicle,’ 1861, pp. 578, 600, 925. For other distinct
 cases of bud-variation in the genus Pelargonium _see_ ‘Cottage
 Gardener,’ 1860, p. 194.

 [33] Dr. Maxwell Masters, ‘Pop. Science Review,’ July, 1872, p. 254.

 [34] Rev. W. T. Bree, in Loudon’s ‘Gardener’s Mag.,’ vol. viii. 1832,
 p. 93.

 [35] ‘The Chrysanthemum: its History and Culture,’ by J. Salter, 1865,
 p. 41, etc.

 [36] Bree, in Loudon’s ‘Gardener’s Mag.,’ vol. viii. 1832, p. 93.

 [37] Bronn ‘Geschichte der Natur,’ B. ii. s. 123.

 [38] T. Rivers, ‘Rose Amateur’s Guide ‘ 1837 p. 4.

 [39] Mr. Shailer, quoted in ‘Gardener’s Chronicle,’ 1848 p. 759.

 [40] ‘Transact. Hort. Soc.,’ vol. iv. 1822, p. 137; ‘Gardener’s
 Chronicle,’ 1842, p. 422.

 [41] _See also_ Loudon’s ‘Arboretum,’ vol. ii. p. 780.

 [42] All these statements on the origin of the several varieties of
 the moss-rose are given on the authority of Mr. Shailer, who, together
 with his father, was concerned in their original propagation. _See_
 ‘Gardener’s Chronicle,’ 1852, p. 759.

 [43] ‘Gardener’s Chronicle,’ 1845, p. 564.

 [44] ‘Transact. Hort. Soc.,’ vol. ii. p. 242.

 [45] ‘Shriften der Phys. Oekon. Gesell. zu Königsberg,’ Feb. 3rd,
 1865, s. 4. _See also_ Dr. Caspary’s paper in ‘Transactions of the
 Hort. Congress of Amsterdam,’ 1865.

 [46] ‘Gardener’s Chronicle,’ 1852, p. 759.

 [47] ‘Transact. Hort. Soc.,’ vol. ii. p. 242.

 [48] Sir R. Schomburgk, ‘Proc. Linn. Soc. Bot.,’ vol. ii. p. 132.

 [49] ‘Gardener’s Chronicle,’ 1862, p. 619.

 [50] Hopkirk’s ‘Flora Anomala,’ 167.

 [51] ‘Sur La Production et la Fixation des Variétés,’ 1865, p. 4.

 [52] ‘Journal of Horticulture,’ March, 1865, p. 233.

 [53] ‘Gardener’s Chronicle,’ 1843, p. 135.

 [54] Ibid., 1842, p. 55.

 [55] ‘Gardener’s Chronicle,’ 1867, p. 235.

 [56] Gärtner ‘Bastarderzeugung,’ s. 305.

 [57] Mr. D. Beaton, in ‘Cottage Gardener,’ 1860, p. 250.

 [58] ‘Gardener’s Chronicle,’ 1850, p. 536.

 [59] Braun, ‘Ray Soc. Bot. Mem.,’ 1853, p. 315; Hopkirk’s ‘Flora
 Anomala,’ p. 164; Lecoq ‘Géograph. Bot. de l’Europe,’ tom. iii. 1854,
 p. 405; and ‘De la Fécondation,’ 1862, p. 303.

 [60] ‘Des Variétés,’ 1865, p. 5.

 [61] W. Mason, in ‘Gardener’s Chronicle,’ 1843, p. 878.

 [62] Alex. Braun, ‘Ray Soc. Bot. Mem.,’ 1853, p. 315; ‘Gardener’s
 Chronicle,’ 1841, p. 329.

 [63] Dr. M. T. Masters, ‘Royal Institution Lecture,’ March 16th, 1860.

 [64] _See_ Mr. W. K. Bridgeman’s curious paper in ‘Annals and Mag. of
 Nat. Hist.,’ Dec. 1861; also Mr. J. Scott, ‘Bot. Soc. Edinburgh,’ June
 12th, 1862.

 [65] ‘Journal of Horticulture,’ 1861, p. 336; Verlot, ‘Des Variétés,’
 p. 76.

 [66] _See also_ Verlot, ‘Des Variétés,’ p. 74.

 [67] ‘Gardener’s Chronicle,’ 1844, p. 86.

 [68] Ibid., 1861, p. 963.

 [69] Ibid., 1861, p. 433; ‘Cottage Gardener,’ 1860, p. 2.

 [70] M. Lemoine (quoted in ‘Gardener’s Chronicle,’ 1867, p. 74) has
 lately observed that the Symphytum with variegated leaves cannot be
 propagated by division of the roots. He also found that out of 500
 plants of a Phlox with striped flowers, which had been propagated by
 root-division, only seven or eight produced striped flowers. _See
 also_ on striped Pelargoniums, ‘Gardener’s Chronicle,’ 1867, p. 1000.

 [71] Anderson’s ‘Recreations in Agriculture,’ vol. v. p. 152.

 [72] For wheat, _see_ ‘Improvement of the Cereals,’ by P. Shirreff,
 1873, p. 47. For maize and sugar-cane, Carrière, ibid., pp. 40, 42.
 With respect to the sugar-cane Mr. J. Caldwell of Mauritius, says
 (‘Gardener’s Chronicle,’ 1874, p. 316) the Ribbon cane has here
 “sported into a perfectly green cane and a perfectly red cane from the
 same head. I verified this myself, and saw at least 200 instances in
 the same plantation, and the fact has completely upset all our
 preconceived ideas of the difference of colour being permanent. The
 conversion of a striped cane into a green cane was not uncommon, but
 the change into a red cane universally disbelieved, and that both
 events should occur in the same plant incredible. I find, however, in
 Fleischman’s ‘Report on Sugar Cultivation in Louisiana for 1848,’ by
 the American Patent Office, the circumstance is mentioned, but he says
 he never saw it himself.”

 [73] ‘Gardener’s Chronicle,’ 1857, p. 662.

 [74] ‘Gardener’s Chronicle,’ 1841, p. 814.

 [75] Ibid., 1857, p. 613.

 [76] Ibid., 1857, p. 679. _See also_ Philips ‘Hist. of Vegetables,’
 vol. ii. p. 91, for other and similar accounts.)

 [77] ‘Journal of Proc. Linn. Soc.,’ vol. ii. Botany, p. 132.

 [78] Loudon’s ‘Gardener’s Mag.,’ vol. viii. 1832, p. 94.

 [79] ‘Gardener’s Chronicle,’ 1850, p. 536; and 1842, p. 729.

 [80] ‘Des Jacinthes,’ etc., Amsterdam, 1768, p. 122.

 [81] ‘Gardener’s Chronicle.’ 1845. p. 212.

 [82] Loudon’s ‘Encyclopædia of Gardening,’ p. 1024.

 [83] ‘Production des Variétés,’ 1865, p. 63.

 [84] ‘Gardener’s Chronicle,’ 1841, p. 782; 1842, p. 55.

 [85] ‘Gardener’s Chronicle,’ 1849. p. 565.

 [86] ‘Transact. Lin. Soc.,’ vol. ii. p. 354.

 [87] Godron, ‘De l’Espèce,’ tom. ii. p. 84.

 [88] M. Carrière has lately described in the ‘Revue Horticole,’ (Dec.
 1st, 1866, p. 457,) an extraordinary case. He twice inserted grafts of
 the _Aria vestita_ on thorn-trees (_épines_) growing in pots; and the
 grafts, as they grew, produced shoots with bark, buds, leaves,
 petioles, petals, and flower-stalks, all widely different from those
 of the Aria. The grafted shoots were also much hardier, and flowered
 earlier, than those on the ungrafted Aria.

 [89] ‘Transact. Hort. Soc.,’ vol. ii. p. 160.

 [90] For the cases of oaks _see_ Alph. De Candolle in ‘Bibl.
 Univers.,’ Geneva, Nov. 1862; for limes, etc., Loudon’s ‘Gard. Mag.,’
 vol. xi. 1835, p. 503.

 [91] For analogous facts, _see_ Braun ‘Rejuvenescence,’ in ‘Ray Soc.
 Bot. Mem.,’ 1853, p. 320; and ‘Gardener’s Chronicle,’ 1842, p. 397;
 also Braun in ‘Sitzungsberichte der Ges. naturforschender Freunde,’
 June, 1873, p. 63.

 [92] ‘Journal of Hort. Soc.,’ vol. ii. 1847, p. 100.

 [93] _See_ ‘Transact. of Hort. Congress of Amsterdam,’ 1865; but I owe
 most of the following information to Prof. Caspary’s letters.

 [94] ‘Nouvelles Archives du Muséum,’ tom. i. p. 143.

 [95] _See_ on this head, Naudin, ibid., p. 141.

 [96] Braun, in ‘Bot. Mem. Ray. Soc.,’ 1853, p. 23.

 [97] This hybrid has never been described. It is exactly intermediate
 in foliage, time of flowering, dark striæ at the base of the standard
 petal, hairiness of the ovarium, and in almost every other character,
 between _C. laburnum_ and _ alpinus_; but it approaches the former
 species more nearly in colour, and exceeds it in the length of the
 racemes. We have before seen that 20·3 per cent of its pollen-grains
 are ill-formed and worthless. My plant, though growing not above
 thirty or forty yards from both parent-species, during some seasons
 yielded no good seeds; but in 1866 it was unusually fertile, and its
 long racemes produced from one to occasionally even four pods. Many of
 the pods contained no good seeds, but generally they contained a
 single apparently good seed, sometimes two, and in one case three
 seeds. Some of these seeds germinated, and I raised two trees from
 them; one resembles the present form; the other has a remarkable dwarf
 character with small leaves, but has not yet flowered.

 [98] ‘Annales de la Soc. de l’Hort. de Paris,’ tom. vii. 1830, p. 93.

 [99] An account was given in the ‘Gardener’s Chronicle’ (1857, pp.
 382, 400) of a common laburnum on which grafts of _C. purpureus_ had
 been inserted, and which gradually assumed the character of _C.
 adami_; but I have little doubt that _C. adami_ had been sold to the
 purchaser, who was not a botanist, in the place of _C. purpureus._ I
 have ascertained that this occurred in another instance.

 [100] Gallesio, ‘Gli Agrumi dei Giard. Bot. Agrar. di. Firenze,’ 1839,
 p. 11. In his ‘Traité du Citrus,’ 1811, p. 146, he speaks as if the
 compound fruit consisted in part of a lemon, but this apparently was a
 mistake.

 [101] ‘Gardener’s Chronicle,’ 1855, p. 628. _See also_ Prof. Caspary
 in ‘Transact. Hort. Congress of Amsterdam,’ 1865.

 [102] Gärtner (‘Bastarderzeugung,’ s. 611) gives many references on
 this subject.

 [103] A nearly similar account was given by Brabley, in 1724, in his
 ‘Treatise on Husbandry,’ vol. i. p. 199.

 [104] Morren, ‘Bull. de l’Acad. R. des Sciences de Belgique,’ 2de
 séries, tom. xxviii. 1869, p. 434. Also Magnus ‘Gesellschaft
 naturforschender Freunde, Berlin,’ Feb. 21st, 1871, p. 13; ibid., June
 21st, 1870, and Oct. 17th, 1871. Also ‘Bot. Zeitung,’ Feb. 24th, 1871.

 [105] Loudon’s ‘Arboretum,’ vol. iv. p. 2595.

 [106] ‘Bastarderzeugung,’ s. 619.

 [107] Amsterdam, 1768, p. 124.

 [108] ‘Gardener’s Chronicle,’ 1860, p. 672, with a woodcut.

 [109] _See_ ‘Gardener’s Chronicle,’ 1869, p. 220.

 [110] ‘Gardener’s Chronicle,’ 1869, p. 335.

 [111] ‘Gardener’s Chronicle,’ 1869, p. 1018, with remarks by Dr.
 Masters on the adhesion of the united wedges. _See also_ ibid., 1870,
 pp. 1277, 1283.

 [112] ‘Gardener’s Chronicle,’ 1871, p. 837.

 [113] ‘Gardener’s Chronicle,’ 1870, p. 1506.

 [114] ‘Sitzungsberichte der Gesellschaft naturforschender Freunde zu
 Berlin,’ Oct. 17th, 1871.

 [115] Ibid., Nov. 17th, 1874. _See also_ excellent remarks by Herr
 Magnus.

 [116] ‘Bastarderzeugung,’ s. 549. It is, however, doubtful whether
 these plants should be ranked as species or varieties.

 [117] Gärtner, ibid., s. 550.

 [118] ‘Journal de Physique,’ tom. xxiii. 1873, p. 100. ‘Act. Acad. St.
 Petersburgh,’ 1781, part i. p. 249.

 [119] ‘Nouvelles Archives du Muséum,’ tom. i. p. 49.

 [120] L’Hermès, Jan. 14th, 1837, quoted in Loudon’s ‘Gardener’s Mag.,’
 vol. xiii. p. 230.

 [121] ‘Comptes Rendus,’ tom. xxxiv. 1852, p. 746.

 [122] ‘Géograph. Bot. de l’Europe,’ tom. iii. 1854, p. 405; and ‘De la
 Fécondation,’ 1862, p. 302.

 [123] ‘Traité du Citrus,’ 1811, p. 45.

 [124] ‘Transact. Linn. Soc.,’ vol. ix. p. 268.

 [125] ‘Annals and Mag. of Nat. Hist.,’ March, 1848.

 [126] ‘Pomologie Physiolog.,’ 1830, p. 126.

 [127] ‘Philosophical Transact.,’ vol. xliii. 1744-45, p. 525.

 [128] Mr. Goss, ‘Transact. Hort. Soc.,’ vol. v. p. 234: and Gärtner,
 ‘Bastarderzeugung,’ 1849, ss. 81 and 499.

 [129] ‘Gardener’s Chronicle,’ 1854, p. 404.

 [130] Ibid., 1866, p. 900.

 [131] _See also_ a paper by this observer read before the
 International Hort. and Bot. Congress of London, 1866.

 [132] ‘Traité du Citrus,’ p. 40.

 [133] ‘Transact. Hort. Soc.,’ vol. iii. p. 318. _See also_ vol. v. p.
 65.

 [134] Prof. Asa Gray, ‘Proc. Acad. Sc.,’ Boston, vol. iv. 1860, p. 21.
 I have received statements to the same effect from other persons in
 the United States.

 [135] For the French case _see_ ‘Journ. Hort. Soc.,’ vol. i. new
 series, 1866, p. 50. For Germany, _see_ M. Jack quoted in Henfrey’s
 ‘Botanical Gazette,’ vol. i. p. 277. A case in England has recently
 been alluded to by the Rev. J. M. Berkeley before the Hort. Soc. of
 London.

 [136] ‘Philosophical Transactions,’ vol. xlvii. 1751-52, p. 206.

 [137] Gallesio, ‘Teoria della Riproduzione,’ 1816, p. 95.

 [138] ‘Bot. Zeitung,’ May, 1868, p. 326.

 [139] _See_ Dr. J. Stockton-Hough, in ‘American Naturalist,’ Jan.
 1874, p. 29.

 [140] ‘Transact. Hort. Soc.,’ vol. v. p. 69.

 [141] ‘Bull. de l’Acad. Imp. de St. Petersburg,’ tom. xvii. p. 275,
 1872. The author gives references to those cases in the Solanaceæ of
 fruit affected by foreign pollen, but as it does not appear that the
 mother-plant was artificially fertilised, I have not entered into
 details.

 [142] ‘Bot. Zeitung,’ Sept. 1868, p. 631. For Maximowicz’s judgment,
 _see_ the paper last referred to.

 [143] ‘Journal of Horticulture,’ Jan. 20th, 1863, p. 46.

 [144] _See_ on this head the high authority of Prof. Decaisne, in a
 paper translated in ‘Journ. Hort. Soc.,’ vol. i., new series, 1866, p.
 48.

 [145] Vol. xliii., 1744-45, p. 525; vol. xlv., 1747-48, p. 602.

 [146] ‘Transact. Hort. Soc.,’ vol. v. pp. 65 and 68. _See also_ Prof.
 Hildebrand, with a coloured figure, in ‘Bot. Zeitung,’ May 15th, 1868,
 p. 327. Puvis also has collected, ‘De La Dégénération,’ 1837, p.
 36)several other instances; but it is not in all cases possible to
 distinguish between the direct action of foreign pollen and
 bud-variations.

 [147] T. de Clermont-Tonnerre, in ‘Mém. de la Soc. Linn. de Paris,’
 tom. iii. 1825, p. 164.

 [148] ‘Transact. of Hort. Soc.,’ vol. v. p. 68.

 [149] ‘Beiträge zur Kenntniss der Befruchtung,’ 1844, s. 347-351.

 [150] ‘Die Fruchtbildung der Orchideen, ein Beweis für die doppelte
 Wirkung des Pollens,’ ‘Botanische Zeitung,’ No. 44 et seq., Oct. 30th,
 1865; and Aug. 4th, 1865, s. 249.

 [151] ‘Philos. Transact.,’ 1821, p. 20.

 [152] Dr. Alex. Harvey on ‘A remarkable Effect of Cross-breeding,’
 1851. On the ‘Physiology of Breeding,’ by Mr. Reginald Orton, 1855.
 ‘Intermarriage,’ by Alex. Walker, 1837. ‘L’Hérédité Naturelle,’ by Dr.
 Prosper Lucas, tom. ii. p. 58. Mr. W. Sedgwick, in ‘British and
 Foreign Medico-Chirurgical Review,’ 1863, July, p. 183. Bronn, in his
 ‘Geschichte der Natur,’ 1843, B. ii. s. 127, has collected several
 cases with respect to mares, sows, and dogs. Mr. W. C. L. Martin
 (‘History of the Dog,’ 1845, p. 104) says he can personally vouch for
 the influence of the male parent on subsequent litters by other dogs.
 A French poet, Jacques Savary, who wrote in 1665 on dogs, was aware of
 this singular fact. Dr. Bowerbank has given us the following striking
 case:—A black, hairless Barbary bitch was first accidentally
 impregnated by a mongrel spaniel with long brown hair, and she
 produced five puppies, three of which were hairless and two covered
 with _ short_ brown hair. The next time she was put to a black,
 hairless Barbary dog; “but the mischief had been implanted in the
 mother, and again about half the litter looked like pure Barbarys, and
 the other half like the _short_-haired progeny of the first father.” I
 have given in the text one case with pigs; an equally striking one has
 been recently published in Germany, ‘Illust. Landwirth. Zeitung,’
 1868, Nov. 17th, p. 143. It is worth notice that farmers in S. Brazil
 (as I hear from Fritz Müller), and at the C. of Good Hope (as I have
 heard from two trustworthy persons) are convinced that mares which
 have once borne mules, when subsequently put to horses, are extremely
 liable to produce colts, striped like a mule. Dr. Wilckens, of
 Pogarth, gives (‘Jahrbuch Landwirthschaft,’ ii. 1869, p. 325) a
 striking and analogous case. A merino ram, having two small lappets or
 flaps of skin on the neck, was in the winter of 1861-62 put to several
 Merino ewes, all of whom bore lambs with similar flaps on their necks.
 The ram was killed in the spring of 1862 and subsequently to his death
 the ewes were put to other Merino rams, and in 1863 to Southdown rams,
 none of whom ever have neck lappets: nevertheless, even as long
 afterwards as 1867, several of these ewes produced lambs bearing these
 appendages.

 [153] ‘Le Pigeon Voyageur Belge,’ 1865, p. 59.

 [154] It may be worth while to call attention to the several means by
 which flowers and fruit become striped or mottled. Firstly, by the
 direct action of the pollen of another variety or species, as in the
 cases given of oranges and maize. Secondly, in crosses of the first
 generation, when the colours of the two parents do not readily unite,
 as with Mirabilis and Dianthus. Thirdly, in crossed plants of a
 subsequent generation by reversion, through either bud or seminal
 generation. Fourthly, by reversion to a character not originally
 gained by a cross, but which had long been lost, as with
 white-flowered varieties, which we shall hereafter see often become
 striped with some other colour. Lastly, there are cases, as when
 peaches are produced with a half or quarter of the fruit like a
 nectarine, in which the change is apparently due to mere variation,
 through either bud or seminal generation.

 [155] ‘Production des Variétés,’ p. 37.

 [156] ‘Flora Anomala,’ p. 164.

 [157] ‘Schriften der physisch-okon. Gesell. zu Königsberg,’ B. vi.
 Feb. 3rd, 1865, s. 4.

 [158] ‘Production des Variétés,’ pp. 58, 70.

 [159] Carrière, ‘Production des Variétés,’ p. 39.




CHAPTER XII. INHERITANCE.

WONDERFUL NATURE OF INHERITANCE—PEDIGREES OF OUR DOMESTICATED
ANIMALS—INHERITANCE NOT DUE TO CHANCE—TRIFLING CHARACTERS
INHERITED—DISEASES INHERITED—PECULIARITIES IN THE EYE
INHERITED—DISEASES IN THE HORSE—LONGEVITY AND VIGOUR—ASYMMETRICAL
DEVIATIONS OF STRUCTURE—POLYDACTYLISM AND REGROWTH OF SUPERNUMERARY
DIGITS AFTER AMPUTATION—CASES OF SEVERAL CHILDREN SIMILARLY AFFECTED
FROM NON-AFFECTED PARENTS—WEAK AND FLUCTUATING INHERITANCE: IN WEEPING
TREES, IN DWARFNESS, COLOUR OF FRUIT AND FLOWERS—COLOUR OF
HORSES—NON-INHERITANCE IN CERTAIN CASES—INHERITANCE OF STRUCTURE AND
HABITS OVERBORNE BY HOSTILE CONDITIONS OF LIFE, BY INCESSANTLY
RECURRING VARIABILITY, AND BY REVERSION—CONCLUSION.


The subject of inheritance is an immense one, and has been treated by
many authors. One work alone, ‘De l’Hérédité Naturelle’ by Dr. Prosper
Lucas, runs to the length of 1562 pages. We must confine ourselves to
certain points which have an important bearing on the general subject
of variation, both with domestic and natural productions. It is obvious
that a variation which is not inherited throws no light on the
derivation of species, nor is of any service to man, except in the case
of perennial plants, which can be propagated by buds.

If animals and plants had never been domesticated, and wild ones alone
had been observed, we should probably never have heard the saying, that
“like begets like.” The proposition would have been as self-evident as
that all the buds on the same tree are alike, though neither
proposition is strictly true. For, as has often been remarked, probably
no two individuals are identically the same. All wild animals recognise
each other, which shows that there is some difference between them; and
when the eye is well practised, the shepherd knows each sheep, and man
can distinguish a fellow-man out of millions on millions of other men.
Some authors have gone so far as to maintain that the production of
slight differences is as much a necessary function of the powers of
generation, as the production of offspring like their parents. This
view, as we shall see in a future chapter, is not theoretically
probable, though practically it holds good. The saying that “like
begets like” has, in fact, arisen from the perfect confidence felt by
breeders, that a superior or inferior animal will generally reproduce
its kind; but this very superiority or inferiority shows that the
individual in question has departed slightly from its type.

The whole subject of inheritance is wonderful. When a new character
arises, whatever its nature may be, it generally tends to be inherited,
at least in a temporary and sometimes in a most persistent manner. What
can be more wonderful than that some trifling peculiarity, not
primordially attached to the species, should be transmitted through the
male or female sexual cells, which are so minute as not to be visible
to the naked eye, and afterwards through the incessant changes of a
long course of development, undergone either in the womb or in the egg,
and ultimately appear in the offspring when mature, or even when quite
old, as in the case of certain diseases? Or again, what can be more
wonderful than the well-ascertained fact that the minute ovule of a
good milking cow will produce a male, from whom a cell, in union with
an ovule, will produce a female, and she, when mature, will have large
mammary glands, yielding an abundant supply of milk, and even milk of a
particular quality? Nevertheless, the real subject of surprise is, as
Sir H. Holland has well remarked,[1] not that a character should be
inherited, but that any should ever fail to be inherited. In a future
chapter, devoted to an hypothesis which I have termed pangenesis, an
attempt will be made to show the means by which characters of all kinds
are transmitted from generation to generation.

Some writers,[2] who have not attended to natural history, have
attempted to show that the force of inheritance has been much
exaggerated. The breeders of animals would smile at such simplicity;
and if they condescended to make any answer, might ask what would be
the chance of winning a prize if two inferior animals were paired
together? They might ask whether the half-wild Arabs were led by
theoretical notions to keep pedigrees of their horses? Why have
pedigrees been scrupulously kept and published of the Shorthorn cattle,
and more recently of the Hereford breed? Is it an illusion that these
recently improved animals safely transmit their excellent qualities
even when crossed with other breeds? have the Shorthorns, without good
reason, been purchased at immense prices and exported to almost every
quarter of the globe, a thousand guineas having been given for a bull?
With greyhounds pedigrees have likewise been kept, and the names of
such dogs, as Snowball, Major, etc., are as well known to coursers as
those of Eclipse and Herod on the turf. Even with the Gamecock,
pedigrees of famous strains were formerly kept, and extended back for a
century. With pigs, the Yorkshire and Cumberland breeders “preserve and
print pedigrees;” and to show how such highly-bred animals are valued,
I may mention that Mr. Brown, who won all the first prizes for small
breeds at Birmingham in 1850, sold a young sow and boar of his breed to
Lord Ducie for 43 guineas; the sow alone was afterwards sold to the
Rev. F. Thursby for 65 guineas; who writes, “She paid me very well,
having sold her produce for 300 pounds, and having now four breeding
sows from her.”[3] Hard cash paid down, over and over again, is an
excellent test of inherited superiority. In fact, the whole art of
breeding, from which such great results have been attained during the
present century, depends on the inheritance of each small detail of
structure. But inheritance is not certain; for if it were, the
breeder’s art[4] would be reduced to a certainty, and there would be
little scope left for that wonderful skill and perseverance shown by
the men who have left an enduring monument of their success in the
present state of our domesticated animals.

It is hardly possible, within a moderate compass, to impress on the
mind of those who have not attended to the subject, the full conviction
of the force of inheritance which is slowly acquired by rearing
animals, by studying the many treatises which have been published on
the various domestic animals, and by conversing with breeders. I will
select a few facts of the kind, which, as far as I can judge, have most
influenced my own mind. With man and the domestic animals, certain
peculiarities have appeared in an individual, at rare intervals, or
only once or twice in the history of the world, but have reappeared in
several of the children and grandchildren. Thus Lambert, “the
porcupine-man,” whose skin was thickly covered with warty projections,
which were periodically moulted, had all his six children and two
grandsons similarly affected.[5] The face and body being covered with
long hair, accompanied by deficient teeth (to which I shall hereafter
refer), occurred in three successive generations in a Siamese family;
but this case is not unique, as a woman[6] with a completely hairy face
who was exhibited in London in 1663, and another instance has recently
occurred. Colonel Hallam[7] has described a race of two-legged pigs,
“the hinder extremities being entirely wanting;” and this deficiency
was transmitted through three generations. In fact, all races
presenting any remarkable peculiarity, such as solid-hoofed swine,
Mauchamp sheep, niata cattle, etc., are instances of the long-continued
inheritance of rare deviations of structure.

When we reflect that certain extraordinary peculiarities have thus
appeared in a single individual out of many millions, all exposed in
the same country to the same general conditions of life, and, again,
that the same extraordinary peculiarity has sometimes appeared in
individuals living under widely different conditions of life, we are
driven to conclude that such peculiarities are not directly due to the
action of the surrounding conditions, but to unknown laws acting on the
organisation or constitution of the individual;—that their production
stands in hardly closer relation to the conditions of life than does
life itself. If this be so, and the occurrence of the same unusual
character in the child and parent cannot be attributed to both having
been exposed to the same unusual conditions, then the following problem
is worth consideration, as showing that the result cannot be due, as
some authors have supposed, to mere coincidence, but must be consequent
on the members of the same family inheriting something in common in
their constitution. Let it be assumed that, in a large population, a
particular affection occurs on an average in one out of a million, so
that the _à priori_ chance that an individual taken at random will be
so affected is only one in a million. Let the population consist of
sixty millions, composed, we will assume, of ten million families, each
containing six members. On these data, Professor Stokes has calculated
for me that the odds will be no less than 8333 millions to 1 that in
the ten million families there will not be even a single family in
which one parent and two children will be affected by the peculiarity
in question. But numerous instances could be given, in which several
children have been affected by the same rare peculiarity with one of
their parents; and in this case, more especially if the grandchildren
be included in the calculation, the odds against mere coincidence
become something prodigious, almost beyond enumeration.

In some respects the evidence of inheritance is more striking when we
consider the reappearance of trifling peculiarities. Dr. Hodgkin
formerly told me of an English family in which, for many generations,
some members had a single lock differently coloured from the rest of
the hair. I knew an Irish gentleman, who, on the right side of his
head, had a small white lock in the midst of his dark hair: he assured
me that his grandmother had a similar lock on the same side, and his
mother on the opposite side. But it is superfluous to give instances;
every shade of expression, which may often be seen alike in parents and
children, tells the same story. On what a curious combination of
corporeal structure, mental character, and training, handwriting
depends! yet every one must have noted the occasional close similarity
of the handwriting in father and son, although the father had not
taught his son. A great collector of autographs assured me that in his
collection there were several signatures of father and son hardly
distinguishable except by their dates. Hofacker, in Germany, remarks on
the inheritance of handwriting; and it has even been asserted that
English boys when taught to write in France naturally cling to their
English manner of writing; but for so extraordinary a statement more
evidence is requisite.[8] Gait, gestures, voice, and general bearing
are all inherited, as the illustrious Hunter and Sir A. Carlisle have
insisted.[9] My father communicated to me some striking instances, in
one of which a man died during the early infancy of his son, and my
father, who did not see this son until grown up and out of health,
declared that it seemed to him as if his old friend had risen from the
grave, with all his highly peculiar habits and manners. Peculiar
manners pass into tricks, and several instances could be given of their
inheritance; as in the case, often quoted, of the father who generally
slept on his back, with his right leg crossed over the left, and whose
daughter, whilst an infant in the cradle, followed exactly the same
habit, though an attempt was made to cure her.[10] I will give one
instance which has fallen under my own observation, and which is
curious from being a trick associated with a peculiar state of mind,
namely, pleasureable emotion. A boy had the singular habit, when
pleased, of rapidly moving his fingers parallel to each other, and,
when much excited, of raising both hands, with the fingers still
moving, to the sides of his face on a level with the eyes; when this
boy was almost an old man, he could still hardly resist this trick when
much pleased, but from its absurdity concealed it. He had eight
children. Of these, a girl, when pleased, at the age of four and a half
years, moved her fingers in exactly the same way, and what is still
odder, when much excited, she raised both her hands, with her fingers
still moving, to the sides of her face, in exactly the same manner as
her father had done, and sometimes even still continued to do so when
alone. I never heard of any one, excepting this one man and his little
daughter, who had this strange habit; and certainly imitation was in
this instance out of the question.

Some writers have doubted whether those complex mental attributes, on
which genius and talent depend, are inherited, even when both parents
are thus endowed. But he who will study Mr. Galton’s able work on
‘Hereditary Genius’ will have its doubts allayed.

Unfortunately it matters not, as far as inheritance is concerned, how
injurious a quality or structure may be if compatible with life. No one
can read the many treatises[11] on hereditary disease and doubt this.
The ancients were strongly of this opinion, or, as Ranchin expresses
it, _Omnes Grœci, Arabes, et Latini in eo consentiunt._ A long
catalogue could be given of all sorts of inherited malformations and of
predisposition to various diseases. With gout, fifty per cent of the
cases observed in hospital practice are, according to Dr. Garrod,
inherited, and a greater percentage in private practice. Every one
knows how often insanity runs in families, and some of the cases given
by Mr. Sedgwick are awful,—as of a surgeon, whose brother, father, and
four paternal uncles were all insane, the latter dying by suicide; of a
Jew, whose father, mother, and six brothers and sisters were all mad;
and in some other cases several members of the same family, during
three or four successive generations, have committed suicide. Striking
instances have been recorded of epilepsy, consumption, asthma, stone in
the bladder, cancer, profuse bleeding from the slightest injuries, of
the mother not giving milk, and of bad parturition being inherited. In
this latter respect I may mention an odd case given by a good
observer,[12] in which the fault lay in the offspring, and not in the
mother: in a part of Yorkshire the farmers continued to select cattle
with large hind-quarters, until they made a strain called
“Dutch-buttocked,” and “the monstrous size of the buttocks of the calf
was frequently fatal to the cow, and numbers of cows were annually lost
in calving.”

Instead of giving numerous details on various inherited malformations
and diseases, I will confine myself to one organ, that which is the
most complex, delicate, and probably best-known in the human frame,
namely, the eye, with its accessory parts.[13] To begin with the
latter: I have received an account of a family in which one parent and
the children are affected by drooping eyelids, in so peculiar a manner,
that they cannot see without throwing their heads backwards. Mr. Wade,
of Wakefield, has given me an analogous case of a man who had not his
eyelids thus affected at birth, nor owed their state, as far as was
known, to inheritance, but they began to droop whilst he was an infant
after suffering from fits, and he has transmitted the affection to two
out of his three children, as was evident in the photographs of the
whole family sent to me together with this account. Sir A. Carlisle[14]
specifies a pendulous fold to the eyelids, as inherited. “In a family,”
says Sir H. Holland,[15] “where the father had a singular elongation of
the upper eyelid, seven or eight children were born with the same
deformity; two or three other children having it not.” Many persons, as
I hear from Sir J. Paget, have two or three hairs in their eyebrows
much longer than the others; and even so trifling a peculiarity as this
certainly runs in families.

With respect to the eye itself, the highest authority in England, Mr.
Bowman, has been so kind as to give me the following remarks on certain
inherited imperfections. First, hypermetropia, or morbidly long sight:
in this affection, the organ, instead of being spherical, is too flat
from front to back, and is often altogether too small, so that the
retina is brought too forward for the focus of the humours;
consequently a convex glass is required for clear vision of near
objects, and frequently even of distant ones. This state occurs
congenitally, or at a very early age, often in several children of the
same family, where one of the parents has presented it.[16] Secondly,
myopia, or short-sight, in which the eye is egg-shaped and too long
from front to back; the retina in this case lies behind the focus, and
is therefore fitted to see distinctly only very near objects. This
condition is not commonly congenital, but comes on in youth, the
liability to it being well known to be transmissible from parent to
child. The change from the spherical to the ovoidal shape seems the
immediate consequence of something like inflammation of the coats,
under which they yield, and there is ground for believing that it may
often originate in causes acting on the individual affected,[17] and
may thenceforward become transmissible. When both parents are myopic
Mr. Bowman has observed the hereditary tendency in this direction to be
heightened, and some of the children to be myopic at an earlier age or
in a higher degree than their parents. Thirdly, squinting is a familiar
example of hereditary transmission: it is frequently a result of such
optical defects as have been above mentioned; but the more primary and
uncomplicated forms of it are also sometimes in a marked degree
transmitted in a family. Fourthly, _Cataract,_ or opacity of the
crystalline lens, is commonly observed in persons whose parents have
been similarly affected, and often at an earlier age in the children
than in the parents. Occasionally more than one child in a family is
thus afflicted, one of whose parents or other relations, presents the
senile form of the complaint. When cataract affects several members of
a family in the same generation, it is often seen to commence at about
the same age in each: _e.g.,_ in one family several infants or young
persons may suffer from it; in another, several persons of middle age.
Mr. Bowman also informs me that he has occasionally seen, in several
members of the same family, various defects in either the right or left
eye; and Mr. White Cooper has often seen peculiarities of vision
confined to one eye reappearing in the same eye in the offspring.[18]

The following cases are taken from an able paper by Mr. W. Sedgwick,
and from Dr. Prosper Lucas.[19] Amaurosis, either congenital or coming
on late in life, and causing total blindness, is often inherited; it
has been observed in three successive generations. Congenital absence
of the iris has likewise been transmitted for three generations, a
cleft-iris for four generations, being limited in this latter case to
the males of the family. Opacity of the cornea and congenital smallness
of the eyes have been inherited. Portal records a curious case, in
which a father and two sons were rendered blind, whenever the head was
bent downwards, apparently owing to the crystalline lens, with its
capsule, slipping through an unusually large pupil into the anterior
chamber of the eye. Day-blindness, or imperfect vision under a bright
light, is inherited, as is night-blindness, or an incapacity to see
except under a strong light: a case has been recorded, by M. Cunier, of
this latter defect having affected eighty-five members of the same
family during six generations. The singular incapacity of
distinguishing colours, which has been called _Daltonism,_ is
notoriously hereditary, and has been traced through five generations,
in which it was confined to the female sex.

With respect to the colour of the iris: deficiency of colouring matter
is well known to be hereditary in albinoes. The iris of one eye being
of different colour from that of the other, and the iris being spotted,
are cases which have been inherited. Mr. Sedgwick gives, in addition,
on the authority of Dr. Osborne,[20] the following curious instance of
strong inheritance: a family of sixteen sons and five daughters all had
eyes “resembling in miniature the markings on the back of a
tortoiseshell cat.” The mother of this large family had three sisters
and a brother all similarly marked, and they derived this peculiarity
from their mother, who belonged to a family notorious for transmitting
it to their posterity.

Finally, Dr. Lucas emphatically remarks that there is not one single
faculty of the eye which is not subject to anomalies; and not one which
is not subjected to the principle of inheritance. Mr. Bowman agrees
with the general truth of this proposition; which of course does not
imply that all malformations are necessarily inherited; this would not
even follow if both parents were affected by an anomaly which in most
cases was transmissible.

Even if no single fact had been known with respect to the inheritance
of disease and malformations by man, the evidence would have been ample
in the case of the horse. And this might have been expected, as horses
breed much quicker than man, are matched with care, and are highly
valued. I have consulted many works, and the unanimity of the belief by
veterinaries of all nations in the transmission of various morbid
tendencies is surprising. Authors who have had wide experience give in
detail many singular cases, and assert that contracted feet, with the
numerous contingent evils, of ring-bones, curbs, splints, spavin,
founder and weakness of the front legs, roaring or broken and thick
wind, melanosis, specific ophthalmia, and blindness (the great French
veterinary Huzard going so far as to say that a blind race could soon
be formed), crib-biting, jibbing and ill-temper, are all plainly
hereditary. Youatt sums up by saying “there is scarcely a malady to
which the horse is subject which is not hereditary;” and M. Bernard
adds that the doctrine “that there is scarcely a disease which does not
run in the stock, is gaining new advocates every day.”[21] So it is in
regard to cattle, with consumption, good and bad teeth, fine skin, etc.
etc. But enough, and more than enough, has been said on disease. Andrew
Knight, from his own experience, asserts that disease is hereditary
with plants; and this assertion is endorsed by Lindley.[22]

Seeing how hereditary evil qualities are, it is fortunate that good
health, vigour, and longevity are equally inherited. It was formerly a
well-known practice, when annuities were purchased to be received
during the life-time of a nominee, to search out a person belonging to
a family of which many members had lived to extreme old age. As to the
inheritance of vigour and endurance, the English race-horse offers an
excellent instance. Eclipse begot 334, and King Herod 497 winners. A
“cock-tail” is a horse not purely bred, but with only one-eighth, or
one-sixteenth impure blood in his veins, yet very few instances have
ever occurred of such horses having won a great race. They are
sometimes as fleet for short distances as thoroughbreds, but as Mr.
Robson, the great trainer, asserts, they are deficient in wind, and
cannot keep up the pace. Mr. Lawrence also remarks, “perhaps no
instance has ever occurred of a three-part-bred horse saving his _
‘distance’_ in running two miles with thoroughbred racers.” It has been
stated by Cecil, that when unknown horses, whose parents were not
celebrated, have unexpectedly won great races, as in the case of Priam,
they can always be proved to be descended, on both sides, through many
generations, from first-rate ancestors. On the Continent, Baron
Cameronn challenges, in a German veterinary periodical, the opponents
of the English race-horse to name one good horse on the Continent,
which has not some English race-blood in his veins.[23]

With respect to the transmission of the many slight, but infinitely
diversified characters, by which the domestic races of animals and
plants are distinguished, nothing need be said; for the very existence
of persistent races proclaims the power of inheritance.

A few special cases, however, deserve some consideration. It might have
been anticipated, that deviations from the law of symmetry would not
have been inherited. But Anderson[24] states that a rabbit produced in
a litter a young animal having only one ear; and from this animal a
breed was formed which steadily produced one-eared rabbits. He also
mentions a bitch with a single leg deficient, and she produced several
puppies with the same deficiency. From Hofacker’s account,[25] it
appears that a one-horned stag was seen in 1781 in a forest in Germany,
in 1788 two, and afterwards, from year to year, many were observed with
only one horn on the right side of the head. A cow lost a horn by
suppuration,[26] and she produced three calves which had on the same
side of the head, instead of a horn, a small bony lump attached merely
to the skin; but we here encroach on the subject of inherited
mutilations. A man who is left-handed, and a shell in which the spire
turns in the wrong directions, are departures from the normal
asymmetrical condition, and they are well-known to be inherited.

_Polydactylism._—Supernumerary fingers and toes are eminently liable,
as various authors have insisted, to be inherited. Polydactylism
graduates[27] by multifarious steps from a mere cutaneous appendage,
not including any bone, to a double hand. But an additional digit,
supported on a metacarpal bone, and furnished with all the proper
muscles, nerves, and vessels, is sometimes so perfect, that it escapes
detection, unless the fingers are actually counted. Occasionally there
are several supernumerary digits; but usually only one, making the
total number six. This one may be attached to the inner or outer margin
of the hand, representing either a thumb or little finger, the latter
being the more frequent. Generally, through the law of correlation,
both hands and both feet are similarly affected. Dr. Burt Wilder has
tabulated[28] a large number of cases, and finds that supernumerary
digits are more common on the hands than on the feet, and that men are
affected oftener than women. Both these facts can be explained on two
principles which seem generally to hold good; firstly, that of two
parts, the more specialised one is the more variable, and the arm is
more highly specialised than the leg; and secondly that male animals
are more variable than females.

The presence of a greater number of digits than five is a great
anomaly, for this number is not normally exceeded by any existing
mammal, bird, or reptile. Nevertheless, supernumerary digits are
strongly inherited; they have been transmitted through five
generations; and in some cases, after disappearing for one, two, or
even three generations, have reappeared through reversion. These facts
are rendered, as Professor Huxley has observed, more remarkable from
its being known in most cases that the affected person has not married
one similarly affected. In such cases the child of the fifth generation
would have only 1-32nd part of the blood of his first sedigitated
ancestor. Other cases are rendered remarkable by the affection
gathering force, as Dr. Struthers has shown, in each generation, though
in each the affected person married one not affected; moreover, such
additional digits are often amputated soon after birth, and can seldom
have been strengthened by use. Dr. Struthers gives the following
instance: in the first generation an additional digit appeared on one
hand; in the second, on both hands; in the third, three brothers had
both hands, and one of the brothers a foot affected; and in the fourth
generation all four limbs were affected. Yet we must not over-estimate
the force of inheritance. Dr. Struthers asserts that cases of
non-inheritance and of the first appearance of additional digits in
unaffected families are much more frequent than cases of inheritance.
Many other deviations of structure, of a nature almost as anomalous as
supernumerary digits, such as deficient phalanges,[29] thickened
joints, crooked fingers, etc., are, in like manner, strongly inherited,
and are equally subject to intermission, together with reversion,
though in such cases there is no reason to suppose that both parents
had been similarly affected.[30]

Additional digits have been observed in negroes as well as in other
races of man, and in several of the lower animals, and have been
inherited. Six toes have been described on the hind feet of the newt
(_Salamandra cristata_), and are said to have occurred with the frog.
It deserves notice, that the six-toed newt, though adult, preserved
some of its larval characters; for part of the hyoidal apparatus, which
is properly absorbed during the act of metamorphosis, was retained. It
is also remarkable that in the case of man various structures in an
embryonic or arrested state of development, such as a cleft-palate,
bifid uterus, etc., are often accompanied by polydactylism.[31] Six
toes on the hinder feet are known to have been inherited for three
generations of cats. In several breeds of the fowl the hinder toe is
double, and is generally transmitted truly, as is well shown when
Dorkings are crossed with common four-toed breeds.[32] With animals
which have properly less than five digits, the number is sometimes
increased to five, especially on the front legs, though rarely carried
beyond that number; but this is due to the development of a digit
already existing in a more or less rudimentary state. Thus, the dog has
properly four toes behind, but in the larger breeds a fifth toe is
commonly, though not perfectly, developed. Horses, which properly have
one toe alone fully developed with rudiments of the others, have been
described with each foot bearing two or three small separate hoofs:
analogous facts have been noticed with cows, sheep, goats, and
pigs.[33]

There is a famous case described by Mr. White of a child, three years
old, with a thumb double from the first joint. He removed the lesser
thumb, which was furnished with a nail; but to his astonishment it grew
again and reproduced a nail. The child was then taken to an eminent
London surgeon, and the newly-grown thumb was removed by its
socket-joint, but again it grew and reproduced a nail. Dr. Struthers
mentions a case of the partial regrowth of an additional thumb,
amputated when a child was three months old; and the late Dr. Falconer
communicated to me an analogous instance. In the last edition of this
work I also gave a case of the regrowth of a supernumerary
little-finger after amputation; but having been informed by Dr.
Bachmaier that several eminent surgeons expressed, at a meeting of the
Anthropological Society of Munich, great doubt about my statements, I
have made more particular inquiries. The full information thus gained,
together with a tracing of the hand in its present state, has been laid
before Sir J. Paget, and he has come to the conclusion that the degree
of regrowth in this case is not greater than sometimes occurs with
normal bones, especially with the humerus, when amputated at an early
age. He further does not feel fully satisfied about the facts recorded
by Mr. White. This being so, it is necessary for me to withdraw the
view which I formerly advanced, with much hesitation, chiefly on the
ground of the supposed regrowth of additional digits, namely, that
their occasional development in man is a case of reversion to a lowly,
organised progenitor provided with more than five digits.

I may here allude to a class of facts closely allied to, but somewhat
different from, ordinary cases of inheritance. Sir H. Holland[34]
states that brothers and sisters of the same family are frequently
affected, often at about the same age, by the same peculiar disease,
not known to have previously occurred in the family. He specifies the
occurrence of diabetes in three brothers under ten years old; he also
remarks that children of the same family often exhibit in common
infantile diseases, the same peculiar symptoms. My father mentioned to
me the case of four brothers who died between the ages of sixty and
seventy, in the same highly peculiar comatose state. An instance has
already been given of supernumerary digits appearing in four children
out of six in a previously unaffected family. Dr. Devay states[35] that
two brothers married two sisters, their first-cousins, none of the four
nor any relation being an albino; but the seven children produced from
this double marriage were all perfect albinoes. Some of these cases, as
Mr. Sedgwick[36] has shown, are probably the result of reversion to a
remote ancestor, of whom no record had been preserved; and all these
cases are so far directly connected with inheritance that no doubt the
children inherited a similar constitution from their parents, and, from
being exposed to nearly similar conditions of life, it is not
surprising that they should be affected in the same manner and at the
same period of life.

Most of the facts hitherto given have served to illustrate the force of
inheritance, but we must now consider cases grouped as well as the
subject allows into classes, showing how feeble, capricious, or
deficient the power of inheritance sometimes is. When a new peculiarity
first appears, we can never predict whether it will be inherited. If
both parents from their birth present the same peculiarity, the
probability is strong that it will be transmitted to at least some of
their offspring. We have seen that variegation is transmitted much more
feebly by seed, taken from a branch which had become variegated through
bud-variation, than from plants which were variegated as seedlings.
With most plants the power of transmission notoriously depends on some
innate capacity in the individual: thus Vilmorin[37] raised from a
peculiarly coloured balsam some seedlings, which all resembled their
parent; but of these seedlings some failed to transmit the new
character, whilst others transmitted it to all their descendants during
several successive generations. So again with a variety of the rose,
two plants alone out of six were found by Vilmorin to be capable of
transmitting the desired character; numerous analogous cases could be
given.

The weeping or pendulous growth of trees is strongly inherited in some
cases, and, without any assignable reason, feebly in other cases. I
have selected this character as an instance of capricious inheritance,
because it is certainly not proper to the parent-species, and because,
both sexes being borne on the same tree, both tend to transmit the same
character. Even supposing that there may have been in some instances
crossing with adjoining trees of the same species, it is not probable
that all the seedlings would have been thus affected. At Moccas Court
there is a famous weeping oak; many of its branches “are 30 feet long,
and no thicker in any part of this length than a common rope:” this
tree transmits its weeping character, in a greater or less degree, to
all its seedlings; some of the young oaks being so flexible that they
have to be supported by props; others not showing the weeping tendency
till about twenty years old.[38] Mr. Rivers fertilised, as he informs
me, the flowers of a new Belgian weeping thorn (_Cratægus oxyacantha_)
with pollen from a crimson not-weeping variety, and three young trees,
“now six or seven years old, show a decided tendency to be pendulous,
but as yet are not so much so as the mother-plant.” According to Mr.
MacNab,[39] seedlings from a magnificent weeping birch (_Betula alba_),
in the Botanic Garden at Edinburgh, grew for the first ten or fifteen
years upright, but then all became weepers like their parent. A peach
with pendulous branches, like those of the weeping willow, has been
found capable of propagation by seed.[40] Lastly, a weeping or rather a
prostrate yew (_Taxus baccata_) was found in a hedge in Shropshire; it
was a male, but one branch bore female flowers, and produced berries;
these, being sown, produced seventeen trees all of which had exactly
the same peculiar habit with the parent-tree.[41]

These facts, it might have been thought, would have been sufficient to
render it probable that a pendulous habit would in all cases be
strictly inherited. But let us look to the other side. Mr. MacNab[42]
sowed seeds of the weeping beech (_Fagus sylvatica_), but succeeded in
raising only common beeches. Mr. Rivers, at my request, raised a number
of seedlings from three distinct varieties of weeping elm; and at least
one of the parent-trees was so situated that it could not have been
crossed by any other elm; but none of the young trees, now about a foot
or two in height, show the least signs of weeping. Mr. Rivers formerly
sowed above twenty thousand seeds of the weeping ash (_Fraxinus
excelsior_), and not a single seedling was in the least degree
pendulous: in Germany, M. Borchmeyer raised a thousand seedlings, with
the same result. Nevertheless, Mr. Anderson, of the Chelsea Botanic
Garden, by sowing seed from a weeping ash, which was found before the
year 1780, in Cambridgeshire, raised several pendulous trees.[43]
Professor Henslow also informs me that some seedlings from a female
weeping ash in the Botanic Garden at Cambridge were at first a little
pendulous, but afterwards became quite upright: it is probable that
this latter tree, which transmits to a certain extent its pendulous
habit, was derived by a bud from the same original Cambridgeshire
stock; whilst other weeping ashes may have had a distinct origin. But
the crowning case, communicated to me by Mr. Rivers, which shows how
capricious is the inheritance of a pendulous habit, is that a variety
of another species of ash (_F. lentiscifolia_), now about twenty years
old, which was formerly pendulous, “has long lost this habit, every
shoot being remarkably erect; but seedlings formerly raised from it
were perfectly prostrate, the stems not rising more than two inches
above the ground.” Thus the weeping variety of the common ash, which
has been extensively propagated by buds during a long period, did not
with Mr. Rivers, transmit its character to one seedling out of above
twenty thousand; whereas the weeping variety of a second species of
ash, which could not, whilst grown in the same garden, retain its own
weeping character, transmitted to its character the pendulous habit in
excess!

Many analogous facts could be given, showing how apparently capricious
is the principle of inheritance. All the seedlings from a variety of
the Barberry (_B. vulgaris_) with red leaves inherited the same
character; only about one-third of the seedlings of the copper Beech
(_Fagus sylvatica_) had purple leaves. Not one out of a hundred
seedlings of a variety of the _Cerasus padus,_ with yellow fruit, bore
yellow fruit: one-twelfth of the seedlings of the variety of _Cornus
mascula,_ with yellow fruit, came true:[44] and lastly, all the trees
raised by my father from a yellow-berried holly (_Ilex aquifolium_),
found wild, produced yellow berries. Vilmorin[45] observed in a bed of
_Saponaria calabrica_ an extremely dwarf variety, and raised from it a
large number of seedlings; some of these partially resembled their
parent, and he selected their seed; but the grandchildren were not in
the least dwarfed: on the other hand, he observed a stunted and bushy
variety of _Tagetes signata_ growing in the midst of the common
varieties by which it was probably crossed; for most of the seedlings
raised from this plant were intermediate in character, only two
perfectly resembling their parent; but seed saved from these two plants
reproduced the new variety so truly, that hardly any selection has
since been necessary.

Flowers transmit their colour truly, or most capriciously. Many annuals
come true: thus I purchased German seeds of thirty-four named
sub-varieties of one _race_ of ten-week stocks (_Matthiola annua_), and
raised a hundred and forty plants, all of which, with the exception of
a single plant, came true. In saying this, however, it must be
understood that I could distinguish only twenty kinds out of the
thirty-four named sub-varieties; nor did the colour of the flower
always correspond with the name affixed to the packet; but I say that
they came true, because in each of the thirty-six short rows every
plant was absolutely alike, with the one single exception. Again, I
procured packets of German seed of twenty-five named varieties of
common and quilled asters, and raised a hundred and twenty-four plants;
of these, all except ten were true in the above limited sense; and I
considered even a wrong shade of colour as false.

It is a singular circumstance that white varieties generally transmit
their colour much more truly than any other variety. This fact probably
stands in close relation with one observed by Verlot,[46] namely, that
flowers which are normally white rarely vary into any other colour. I
have found that the white varieties of _Delphinium consolida_ and of
the Stock are the truest. It is, indeed, sufficient to look through a
nurseryman’s seed-list, to see the large number of white varieties
which can be propagated by seed. The several coloured varieties of the
sweet-pea (_Lathyrus odoratus_) are very true; but I hear from Mr.
Masters, of Canterbury, who has particularly attended to this plant,
that the white variety is the truest. The hyacinth, when propagated by
seed, is extremely inconstant in colour, but “white hyacinths almost
always give by seed white-flowered plants;”[47] and Mr. Masters informs
me that the yellow varieties also reproduce their colour, but of
different shades. On the other hand, pink and blue varieties, the
latter being the natural colour, are not nearly so true: hence, as Mr.
Masters has remarked to me, “we see that a garden variety may acquire a
more permanent habit than a natural species;” but it should have been
added, that this occurs under cultivation, and therefore under changed
conditions.

With many flowers, especially perennials, nothing can be more
fluctuating than the colour of the seedlings, as is notoriously the
case with verbenas, carnations, dahlias, cinerarias, and others.[48] I
sowed seed of twelve named varieties of Snapdragon (_Antirrhinum
majus_), and utter confusion was the result. In most cases the
extremely fluctuating colour of seedling plants is probably in chief
part due to crosses between differently-coloured varieties during
previous generations. It is almost certain that this is the case with
the polyanthus and coloured primrose (_Primula veris_ and _vulgaris_),
from their reciprocally dimorphic structure;[49] and these are plants
which florists speak of as never coming true by seed: but if care be
taken to prevent crossing, neither species is by any means very
inconstant, in colour; thus I raised twenty-three plants from a purple
primrose, fertilised by Mr. J. Scott with its pollen, and eighteen came
up purple of different shades, and only five reverted to the ordinary
yellow colour: again, I raised twenty plants from a bright-red cowslip,
similarly treated by Mr. Scott, and every one perfectly resembled its
parent in colour, as likewise did, with the exception of a single
plant, 72 grandchildren. Even with the most variable flowers, it is
probable that each delicate shade of colour might be permanently fixed
so as to be transmitted by seed, by cultivation in the same soil, by
long-continued selection, and especially by the prevention of crosses.
I infer this from certain annual larkspurs (_Delphinium consolida_ and
_ajacis_), of which common seedlings present a greater diversity of
colour than any other plant known to me; yet on procuring seed of five
named German varieties of _D. consolida,_ only nine plants out of
ninety-four were false; and the seedlings of six varieties of _D.
ajacis_ were true in the same manner and degree as with the stocks
above described. A distinguished botanist maintains that the annual
species of Delphinium are always self-fertilised; therefore I may
mention that thirty-two flowers on a branch of _ D. consolida,_
enclosed in a net, yielded twenty-seven capsules, with an average of
17·2 seed in each; whilst five flowers, under the same net, which were
artificially fertilised, in the same manner as must be effected by bees
during their incessant visits, yielded five capsules with an average of
35·2 fine seed; and this shows that the agency of insects is necessary
for the full fertility of this plant. Analogous facts could be given
with respect to the crossing of many other flowers, such as carnations,
etc., of which the varieties fluctuate much in colour.

As with flowers, so with our domesticated animals, no character is more
variable than colour, and probably in no animal more so than with the
horse. Yet, with a little care in breeding, it appears that races of
any colour might soon be formed. Hofacker gives the result of matching
two hundred and sixteen mares of four different colours with
like-coloured stallions, without regard to the colour of their
ancestors; and of the two hundred and sixteen colts born, eleven alone
failed to inherit the colour of their parents: Autenrieth and Ammon
assert that, after two generations, colts of a uniform colour are
produced with certainty.[50]

In a few rare cases peculiarities fail to be inherited, apparently from
the force of inheritance being too strong. I have been assured by
breeders of the canary-bird that to get a good jonquil-coloured bird it
does not answer to pair two jonquils, as the colour then comes out too
strong, or is even brown; but this statement is disputed by other
breeders. So again, if two crested canaries are paired, the young birds
rarely inherit this character:[51] for in crested birds a narrow space
of bare skin is left on the back of the head, where the feathers are
up-turned to form the crest, and, when both parents are thus
characterised, the bareness becomes excessive, and the crest itself
fails to be developed. Mr. Hewitt, speaking of Laced Sebright Bantams,
says[52] that, “why this should be so I know not, but I am confident
that those that are best laced frequently produce offspring very far
from perfect in their markings, whilst those exhibited by myself, which
have so often proved successful, were bred from the union of
heavily-laced birds with those that were scarcely sufficiently laced.”

It is a singular fact that, although several deaf-mutes often occur in
the same family, and though their cousins and other relations are often
in the same condition, yet their parents are rarely deaf-mutes. To give
a single instance: not one scholar out of 148, who were at the same
time in the London Institution, was the child of parents similarly
affected. So again, when a male or female deaf-mute marries a sound
person, their children are most rarely affected: in Ireland, out of 203
children thus produced one alone was mute. Even when both parents have
been deaf-mutes, as in the case of forty-one marriages in the United
States and of six in Ireland, only two deaf and dumb children were
produced. Mr. Sedgwick,[53] in commenting on this remarkable and
fortunate failure in the power of transmission in the direct line,
remarks that it may possibly be owing to “excess having reversed the
action of some natural law in development.” But it is safer in the
present state of our knowledge to look at the whole case as simply
unintelligible.

Although many congenital monstrosities are inherited, of which examples
have already been given, and to which may be added the lately recorded
case of the transmission during a century of hare-lip with a
cleft-palate in the writer’s own family,[54] yet other malformations
are rarely or never inherited. Of these latter cases, many are probably
due to injuries in the womb or egg, and would come under the head of
non-inherited injuries or mutilations. With plants, a long catalogue of
inherited monstrosities of the most serious and diversified nature
could easily be given; and with plants, there is no reason to suppose
that monstrosities are caused by direct injuries to the seed or embryo.

With respect to the inheritance of structures mutilated by injuries or
altered by disease, it was until lately difficult to come to any
definite conclusion. Some mutilations have been practised for a vast
number of generations without any inherited result. Godron remarks[55]
that different races of man have from time immemorial knocked out their
upper incisors, cut off joints of their fingers, made holes of immense
size through the lobes of their ears or through their nostrils, tatooed
themselves, made deep gashes in various parts of their bodies, and
there is no reason to suppose that these mutilations have ever been
inherited.[56] Adhesions due to inflammation and pits from the
small-pox (and formerly many consecutive generations must have been
thus pitted) are not inherited. With respect to Jews, I have been
assured by three medical men of the Jewish faith that circumcision,
which has been practised for so many ages, has produced no inherited
effect. Blumenbach, however, asserts[57] that Jews are often born in
Germany in a condition rendering circumcision difficult, so that a name
is given them signifying “born circumcised;” and Professor Preyer
informs me that this is the case in Bonn, such children being
considered the special favourites of Jehovah. I have also heard from
Dr. A. Newman, of Guy’s Hospital, of the grandson of a circumcised Jew,
the father not having been circumcised, in a similar condition. But it
is possible that all these cases may be accidental coincidence, for Sir
J. Paget has seen five sons of a lady and one son of her sister with
adherent prepuces; and one of these boys was affected in a manner
“which might be considered like that commonly produced by
circumcision;” yet there was no suspicion of Jewish blood in the family
of these two sisters. Circumcision is practised by Mahomedans, but at a
much later age than by Jews; and Dr. Riedel, Assistant Resident in
North Celebes, writes to me that the boys there go naked until from six
to ten years old; and he has observed that many of them, though not
all, have their prepuces much reduced in length, and this he attributes
to the inherited effects of the operation. In the vegetable kingdom
oaks and other trees have borne galls from primeval times, yet they do
not produce inherited excrescences; and many other such facts could be
adduced.

Notwithstanding the above several negative cases, we now possess
conclusive evidence that the effects of operations are sometimes
inherited. Dr. Brown-Séquard[58] gives the following summary of his
observations on guinea-pigs; and this summary is so important that I
will quote the whole:—

“1st. Appearance of epilepsy in animals born of parents having been
rendered epileptic by an injury to the spinal cord.

“2nd. Appearance of epilepsy also in animals born of parents having
been rendered epileptic by the section of the sciatic nerve.

“3rd. A change in the shape of the ear in animals born of parents in
which such a change was the effect of a division of the cervical
sympathetic nerve.

“4th. Partial closure of the eyelids in animals born of parents in
which that state of the eyelids had been caused either by the section
of the cervical sympathetic nerve or the removal of the superior
cervical ganglion.

“5th. Exophthalmia in animals born of parents in which an injury to the
restiform body had produced that protrusion of the eyeball. This
interesting fact I have witnessed a good many times, and I have seen
the transmission of the morbid state of the eye continue through four
generations. In these animals, modified by heredity, the two eyes
generally protruded, although in the parents usually only one showed
exophthalmia, the lesion having been made in most cases only on one of
the corpora restiformia.

“6th. Hæmatoma and dry gangrene of the ears in animals born of parents
in which these ear-alterations had been caused by an injury to the
restiform body near the nib of the calamus.

“7th. Absence of two toes out of the three of the hind leg, and
sometimes of the three, in animals whose parents had eaten up their
hind-leg toes which had become anæsthetic from a section of the sciatic
nerve alone, or of that nerve and also of the crural. Sometimes,
instead of complete absence of the toes, only a part of one or two or
three was missing in the young, although in the parent not only the
toes but the whole foot was absent (partly eaten off, partly destroyed
by inflammation, ulceration, or gangrene).

“8th. Appearance of various morbid states of the skin and hair of the
neck and face in animals born of parents having had similar alterations
in the same parts, as effects of an injury to the sciatic nerve.”

It should be especially observed that Brown-Séquard has bred during
thirty years many thousand guinea-pigs from animals which had not been
operated upon, and not one of these manifested the epileptic tendency.
Nor has he ever seen a guinea-pig born without toes, which was not the
offspring of parents which had gnawed off their own toes owing to the
sciatic nerve having been divided. Of this latter fact thirteen
instances were carefully recorded, and a greater number were seen; yet
Brown-Séquard speaks of such cases as one of the rarer forms of
inheritance. It is a still more interesting fact—

“That the sciatic nerve in the congenitally toeless animal has
inherited the power of passing through all the different morbid states
which have occurred in one of its parents from the time of the division
till after its reunion with the peripheric end. It is not therefore
simply the power of performing an action which is inherited, but the
power of performing a whole series of actions, in a certain order.”

In most of the cases of inheritance recorded by Brown-Séquard only one
of the two parents had been operated upon and was affected. He
concludes by expressing his belief that “what is transmitted is the
morbid state of the nervous system,” due to the operation performed on
the parents.

With the lower animals Dr. Prosper Lucas has collected a long list of
inherited injuries. A few instances will suffice. A cow lost a horn
from an accident with consequent suppuration, and she produced three
calves which were hornless on the same side of the head. With the
horse, there seems hardly a doubt that exostoses on the legs, caused by
too much travelling on hard roads, are inherited. Blumenbach records
the case of a man who had his little finger on the right hand almost
cut off, and which in consequence grew crooked, and his sons had the
same finger on the same hand similarly crooked. A soldier, fifteen
years before his marriage, lost his left eye from purulent ophthalmia,
and his two sons were microphthalmic on the same side.[59] In all cases
in which a parent has had an organ injured on one side, and two or more
of the offspring are born with the same organ affected on the same
side, the chances against mere coincidence are almost infinitely great.
Even when only a single child is born having exactly the same part of
the body affected as that of his injured parent, the chances against
coincidence are great; and Professor Rolleston has given me two such
cases which have fallen under his own observation,—namely of two men,
one of whom had his knee and the other his cheek severely cut, and both
had children born with exactly the same spot marked or scarred. Many
instances have been recorded of cats, dogs, and horses, which have had
their tails, legs, etc., amputated or injured, producing offspring with
the same parts ill-formed; but as it is not very rare for similar
malformations to appear spontaneously, all such cases may be due to
coincidence. It is, however, an argument on the other side that “under
the old excise laws the shepherd-dog was only exempt from tax when
without a tail, and for this reason it was always removed;”[60] and
there still exist breeds of the shepherd-dog which are always born
destitute of a tail. Finally, it must be admitted, more especially
since the publication of Brown-Séquard’s observations, that the effects
of injuries, especially when followed by disease, or perhaps
exclusively when thus followed, are occasionally inherited.[61]

      _Causes of Non-inheritance._

A large number of cases of non-inheritance are intelligible on the
principle, that a strong tendency to inheritance does exist, but that
it is overborne by hostile or unfavourable conditions of life. No one
would expect that our improved pigs, if forced during several
generations to travel about and root in the ground for their own
subsistence, would transmit, as truly as they now do their short
muzzles and legs, and their tendency to fatten. Dray-horses assuredly
would not long transmit their great size and massive limbs, if
compelled to live on a cold, damp mountainous region; we have indeed
evidence of such deterioration in the horses which have run wild on the
Falkland Islands. European dogs in India often fail to transmit their
true character. Our sheep in tropical countries lose their wool in a
few generations. There seems also to be a close relation between
certain peculiar pastures and the inheritance of an enlarged tail in
fat-tailed sheep, which form one of the most ancient breeds in the
world. With plants, we have seen that tropical varieties of maize lose
their proper character in the course of two or three generations, when
cultivated in Europe; and conversely so it is with European varieties
cultivated in Brazil. Our cabbages, which here come so true by seed,
cannot form heads in hot countries. According to Carrière,[62] the
purple-leafed beech and barberry transmit their character by seed far
less truly in certain districts than in others. Under changed
circumstances, periodical habits of life soon fail to be transmitted,
as the period of maturity in summer and winter wheat, barley, and
vetches. So it is with animals: for instance, a person, whose statement
I can trust, procured eggs of Aylesbury ducks from that town, where
they are kept in houses and are reared as early as possible for the
London market; the ducks bred from these eggs in a distant part of
England, hatched their first brood on January 24th, whilst common
ducks, kept in the same yard and treated in the same manner, did not
hatch till the end of March; and this shows that the period of hatching
was inherited. But the grandchildren of these Aylesbury ducks
completely lost their habit of early incubation, and hatched their eggs
at the same time with the common ducks of the same place.

Many cases of non-inheritance apparently result from the conditions of
life continually inducing fresh variability. We have seen that when the
seeds of pears, plums, apples, etc., are sown, the seedlings generally
inherit some degree of family likeness. Mingled with these seedlings, a
few, and sometimes many, worthless, wild-looking plants commonly
appear, and their appearance may be attributed to the principle of
reversion. But scarcely a single seedling will be found perfectly to
resemble the parent-form; and thus may be accounted for by constantly
recurring variability induced by the conditions of life. I believe in
this, because it has been observed that certain fruit-trees truly
propagate their kind whilst growing on their own roots; but when
grafted on other stocks, and by this process their natural state is
manifestly affected, they produce seedlings which vary greatly,
departing from the parental type in many characters.[63] Metzger, as
stated in the ninth chapter, found that certain kinds of wheat brought
from Spain and cultivated in Germany, failed during many years to
reproduce themselves truly; but at last, when accustomed to their new
conditions, they ceased to be variable,—that is, they became amenable
to the power of inheritance. Nearly all the plants which cannot be
propagated with any approach to certainty by seed, are kinds which have
been long propagated by buds, cuttings, offsets, tubers, etc., and have
in consequence been frequently exposed during what may be called their
individual lives to widely diversified conditions of life. Plants thus
propagated become so variable, that they are subject, as we have seen
in the last chapter, even to bud-variation. Our domesticated animals,
on the other hand, are not commonly exposed during the life of the
individual to such extremely diversified conditions, and are not liable
to such extreme variability; therefore they do not lose the power of
transmitting most of their characteristic features. In the foregoing
remarks on non-inheritance, crossed breeds are of course excluded, as
their diversity mainly depends on the unequal development of character
derived from either parent or their ancestors.

      _Conclusion._

It has been shown in the early part of this chapter how commonly new
characters of the most diversified nature, whether normal or abnormal,
injurious or beneficial, whether affecting organs of the highest or
most trifling importance, are inherited. It is often sufficient for the
inheritance of some peculiar character, that one parent alone should
possess it, as in most cases in which the rarer anomalies have been
transmitted. But the power of transmission is extremely variable. In a
number of individuals descended from the same parents, and treated in
the same manner, some display this power in a perfect manner, and in
some it is quite deficient; and for this difference no reason can be
assigned. The effects of injuries or mutilations are occasionally
inherited; and we shall see in a future chapter that the long-continued
use and disuse of parts produces an inherited effect. Even those
characters which are considered the most fluctuating, such as colour,
are with rare exceptions transmitted much more forcibly than is
generally supposed. The wonder, indeed, in all cases is not that any
character should be transmitted, but that the power of inheritance
should ever fail. The checks to inheritance, as far as we know them,
are, firstly, circumstances hostile to the particular character in
question; secondly, conditions of life incessantly inducing fresh
variability; and lastly, the crossing of distinct varieties during some
previous generation, together with reversion or atavism-that is, the
tendency in the child to resemble its grand-parents or more remote
ancestors instead of its immediate parents. This latter subject will be
discussed in the following chapter.

REFERENCES

 [1] ‘Medical Notes and Reflections,’ 3rd edit., 1855, p. 267.

 [2] Mr. Buckle, in his ‘History of Civilisation,’ expresses doubts on
 the subject, owing to the want of statistics. _See also_ Mr. Bowen,
 Professor of Moral Philosophy, in ‘Proc. American Acad. of Sciences,’
 vol. v. p. 102.

 [3] For greyhounds, _see_ Low’s ‘Domestic Animals of the British
 Islands,’ 1845, p. 721. For game-fowls, _see_ ‘The Poultry Book,’ by
 Mr. Tegetmeier, 1866, p. 123. For pigs, _ see_ Mr. Sidney’s edition of
 ‘Youatt on the Pig,’ 1860, pp. 11, 22.

 [4] ‘The Stud Farm,’ by Cecil, p. 39.

 [5] ‘Philosophical Transactions,’ 1755, p. 23. I have seen only
 second-hand accounts of the two grandsons. Mr. Sedgwick, in a paper to
 which I shall hereafter often refer, states that _ four_ generations
 were affected, and in each the males alone.

 [6] Barbara Van Beck, figured, as I am informed by the Rev. W.D. Fox,
 in Woodburn’s ‘Gallery of Rare Portraits,’ 1816, vol. ii.

 [7] ‘Proc. Zoolog. Soc.,’ 1833, p. 16.

 [8] Hofacker ‘Ueber die Eigenschaften,’ etc., 1828, s. 34. With
 respect to France, Report by Pariset in ‘Comptes Rendus,’ 1847, p.
 592.

 [9] Hunter, as quoted in Harlan’s ‘Med. Researches,’ p. 530. Sir A.
 Carlisle, ‘Phil. Transact.,’ 1814, p. 94.

 [10] Girou de Buzareingues, ‘De la Génération,’ p. 282. I have given
 an analogous case in my book on ‘The Expression of the Emotions.’

 [11] The works which I have read and found most useful are Dr. Prosper
 Lucas’s great work, ‘Traité de l’Hérédité Naturelle,’ 1847; Mr. W.
 Sedgwick, in ‘British and Foreign Medico-Chirurg. Review,’ April and
 July, 1861, and April and July, 1863: Dr. Garrod on Gout is quoted in
 these articles. Sir Henry Holland, ‘Medical Notes and Reflections,’
 3rd edit., 1855. Piorry, ‘De l’Hérédité dans les Maladies,’ 1840.
 Adams, ‘A Philosophical Treatise on Hereditary Peculiarities,’ 2nd
 edit., 1815. Essay on ‘Hereditary Diseases,’ by Dr. J. Steinan, 1843.
 _See_ Paget in ‘Medical Times,’ 1857, p. 192, on the Inheritance of
 Cancer; Dr. Gould, in ‘Proc. of American Acad. of Sciences,’ Nov. 8th,
 1853, gives a curious case of hereditary bleeding in four generations.
 Harlan, ‘Medical Researches,’ p. 593.

 [12] Marshall, quoted by Youatt in his work on Cattle, p. 284.

 [13] Almost any other organ might have been selected. For instance Mr.
 J. Tomes, ‘System of Dental Surgery,’ 2nd edit., 1873, p. 114, gives
 many instances with teeth, and others have been communicated to me.

 [14] ‘Philosoph. Transact.,’ 1814, p. 94.

 [15] ‘Medical Notes and Reflections,’ 3rd edit., p. 33.

 [16] This affection, as I hear from Mr. Bowman, has been ably
 described and spoken of as hereditary by Dr. Donders of Utrecht, whose
 work was published in English by the Sydenham Society in 1864.

 [17] M. Giraud-Teulon has recently collected abundant statistical
 evidence, ‘Revue des Cours Scientifiques,’ Sept., 1870, p. 625,
 showing that short sight is due to the habit of viewing objects from a
 short distance, _c’est le travail assidu, de près._

 [18] Quoted by Mr. Herbert Spencer, ‘Principles of Biology,’ vol. i.
 p. 244.

 [19] ‘British and Foreign Medico-Chirurg. Review,’ April, 1861, pp.
 482-6; ‘L’Héréd. Nat.,’ tom. i. pp. 391-408.

 [20] Dr. Osborne, Pres. of Royal College of Phys. in Ireland,
 published this case in the ‘Dublin Medical Journal,’ for 1835.

 [21] These various statements are taken from the following works and
 papers:—Youatt on ‘The Horse,’ pp. 35, 220. Lawrence, ‘The Horse,’ p.
 30. Karkeek, in an excellent paper in ‘Gard. Chronicle,’ 1853, p. 92.
 Mr. Burke, in ‘Journal of R. Agricul. Soc. of England,’ vol. v. p.
 511. ‘Encyclop. of Rural Sports,’ p. 279. Girou de Buzareingues,
 ‘Philosoph. Phys.,’ p. 215. _ See_ following papers in ‘The
 Veterinary;’ Roberts in vol. ii. p. 144; M. Marrimpoey vol. ii. p.
 387; Mr. Karkeek, vol. iv. p. 5; Youatt on Goitre in Dogs, vol. v. p.
 483: Youatt in vol. vi. pp. 66, 348, 412; M. Bernard, vol. xi. p. 539;
 Dr. Samesreuther, on Cattle, in vol. xii. p. 181; Percivall, in vol.
 xiii. p. 47. With respect to blindness in horses _see also_ a whole
 row of authorities in Dr. P. Lucas’s great work, tom. i. p. 399. Mr.
 Baker in ‘The Veterinary,’ vol. xiii. p. 721, gives a strong case of
 hereditary imperfect vision and of jibbing.

 [22] Knight on ‘The Culture of the Apple and Pear,’ p. 34. Lindley’s
 ‘Horticulture,’ p. 180.

 [23] These statements are taken from the following works in
 order:—Youatt on ‘The Horse,’ p. 48; Mr. Darvill, in ‘The Veterinary,’
 vol. viii. p. 50. With respect to Robson, _see_ ‘The Veterinary,’ vol.
 iii. p. 580; Mr. Lawrence on ‘The Horse,’ 1829, p. 9; ‘The Stud Farm,’
 by Cecil, 1851; Baron Cameronn, quoted in ‘The Veterinary,’ vol. x. p.
 500.

 [24] ‘Recreations in Agriculture and Nat. Hist.,’ vol. i. p. 68.

 [25] ‘Ueber die Eigenschaften,’ etc., 1828, s. 107.

 [26] Bronn’s ‘Geschichte der Natur,’ Band ii. 2 s. 132.

 [27] Vrolik has discussed this point at full length in a work
 published in Dutch, from which Sir J. Paget has kindly translated for
 me passages. _See, also,_ Isidore Geoffroy St. Hilaire’s ‘Hist. des
 Anomalies,’ 1832, tom. i. p. 684.

 [28] ‘Massachusetts Medical Society,’ vol. ii. No. 3; and ‘Proc.
 Boston Soc. of Nat. Hist.,’ vol. xiv. 1871, p. 154.

 [29] Dr. J. W. Ogle gives a case of the inheritance of deficient
 phalanges during four generations. He adds references to various
 recent papers on inheritance, ‘Brit. and For. Med.-Chirurg. Review,’
 April 1872.

 [30] For these several statements, _see_ Dr. Struthers ‘Edinburgh New
 Phil. Journal,’ July, 1863, especially on intermissions in the line of
 descent. Prof. Huxley, ‘Lectures on our Knowledge of Organic Nature,’
 1863, p. 97. With respect to inheritance, _see_ Dr. Prosper Lucas,
 ‘L’Hérédité Nat.,’ tom. i. p. 325. Isid. Geoffroy, ‘Anom.,’ tom. i. p.
 701. Sir A. Carlisle, in ‘Phil. Transact.,’ 1814, p. 94. A. Walker, on
 ‘Intermarriage,’ 1838, p. 140, gives a case of five generations; as
 does Mr. Sedgwick in ‘Brit. and Foreign Medico-Chirurg. Review,’
 April, 1863, p. 462. On the inheritance of other anomalies in the
 extremities _see_ Dr. H. Dobell, in vol. xlvi. of ‘Medico-Chirurg.
 Transactions,’ 1863; also Mr. Sedgwick in op. cit., April, 1863, p.
 460. With respect to additional digits in the negro _see_ Prichard,
 ‘Physical History of Mankind.’ Dr. Dieffenbach (‘Jour. Royal Geograph.
 Soc.,’ 1841, p. 208) says this anomaly is not uncommon with the
 Polynesians of the Chatham Islands; and I have heard of several cases
 with Hindus and Arabs.

 [31] Meckel and Isid G. St. Hilaire insist on this fact. _See also_ M.
 A. Roujou, ‘Sur quelques Analogies du Type Humain,’ p. 61; published,
 I believe, in the ‘Journal of the Anthropolog. Soc. of Paris,’ Jan.
 1872.

 [32] ‘The Poultry Chronicle,’ 1854, p. 559.

 [33] The statements in this paragraph are taken from Isidore Geoffroy
 St. Hilaire, ‘Hist. des Anomalies,’ tom. i. pp. 688-693. Mr. Goodman
 gives, ‘Phil. Soc. of Cambridge,’ Nov. 25th, 1872, the case of a cow
 with three well developed toes on each hind limb, besides the ordinary
 rudiments; and her calf by an ordinary bull had extra digits. This
 calf also bore two calves having extra digits.

 [34] ‘Medical Notes and Reflections,’ 1839, pp. 24, 34. _See also_ Dr.
 P. Lucas, ‘L’Héréd. Nat.,’ tom. ii. p. 33.

 [35] ‘Du Danger des Mariages Consanguins,’ 2nd edit., 1862, p. 103.

 [36] ‘British and Foreign Medico-Chirurg. Review,’ July, 1863, pp.
 183, 189.

 [37] Verlot ‘La Product. des Variétés,’ 1865, p. 32.

 [38] Loudon’s ‘Gardener’s Mag.,’ vol. xii. 1836, p. 368.

 [39] Verlot, ‘La Product. des Variétés,’ 1865, p. 94.

 [40] Bronn’s ‘Geschichte der Natur,’ B. ii. s. 121. Mr. Meehan makes a
 similar statement in ‘Proc. Nat. of Philadelphia,’ 1872, p. 235.

 [41] Rev. W. A. Leighton, ‘Flora of Shropshire,’ p. 497; and
 Charlesworth, ‘Mag. of Nat. Hist.,’ vol. i. 1837, p. 30. I possess
 prostrate trees produced from these seeds.

 [42] Verlot, op. cit., p. 93.

 [43] For these several statements, _see_ Loudon’s ‘Gard. Magazine,’
 vol. x. 1834, pp. 408, 180; and vol. ix. 1833, p. 597.

 [44] These statements are taken from Alph. De Candolle, ‘Bot.
 Géograph.,’ p. 1083.

 [45] Verlot, op. cit., p. 38.

 [46] Op. cit., p. 59.

 [47] Alph. De Candolle, ‘Géograph. Bot.,’ p. 1082.

 [48] _See_ ‘Cottage Gardener,’ April 10th, 1860, p. 18, and Sept.
 10th, 1861, p. 456; ‘Gardener’s Chronicle,’ 1845, p. 102.

 [49] Darwin in ‘Journal of Proc. Linn. Soc. Bot.,’ 1862, p. 94.

 [50] Hofacker, ‘Ueber die Eigenschaften,’ etc., s. 10.

 [51] Bechstein, ‘Naturgesch. Deutschlands,’ B. iv. s. 462. Mr. Brent,
 a great breeder of canaries, informs me that he believes that these
 statements are correct.

 [52] ‘The Poultry Book,’ by W. B. Tegetmeier, 1866, p. 245.

 [53] ‘British and Foreign Med.-Chirurg. Review,’ July, 1861, pp.
 200-204. Mr. Sedgwick has given such full details on this subject,
 with ample references, that I need refer to no other authorities.

 [54] Mr. Sproule, in ‘British Medical Journal,’ April 18th, 1863.

 [55] ‘De l’Espèce,’ tom. ii. 1859, p. 299.

 [56] Nevertheless Mr. Wetherell states, ‘Nature,’ Dec. 1870, p. 168,
 that when he visited fifteen years ago the Sioux Indians, he was
 informed “by a physician, who has passed much of his time with these
 tribes, that sometimes a child was born with these marks. This was
 confirmed by the U.S. Government Indian Agent.”

 [57] ‘Philosoph. Mag.,’ vol. iv. 1799, p. 5.

 [58] ‘Proc. Royal Soc.,’ vol. x. p. 297. ‘Communication to the Brit.
 Assoc.,’ 1870. ‘The Lancet,’ Jan. 1875, p. 7. The extracts are from
 this last paper. It appears that Obersteiner, ‘Stricker’s Med.
 Jahrbücher,’ 1875, No. 2, has confirmed Brown-Séquard’s observations.

 [59] This last case is quoted by Mr. Sedgwick in ‘British and Foreign
 Medico-Chirurg. Review,’ April, 1861, p. 484. For Blumenbach, _see_
 above-cited paper. _See also_ Dr. P. Lucas, ‘Traité de l’Héréd. Nat.,’
 tom. ii. p. 492. Also, ‘Transact. Linn. Soc.,’ vol. ix. p. 323. Some
 curious cases are given by Mr. Baker in the ‘Veterinary,’ vol. xiii.
 p. 723. Another curious case is given in the ‘Annales des Scienc.
 Nat.,’ 1st series, tom. xi. p. 324.

 [60] ‘The Dog,’ by Stonehenge, 1867, p. 118.

 [61] The Mot-mot habitually bites the barbs off the middle part of the
 two central tail-feathers, and as the barbs are congenitally somewhat
 reduced on the same part of these feathers, it seems extremely
 probable, as Mr. Salvin remarks (‘Proc. Zoolog. Soc.’ 1873, p. 429),
 that this is due to the inherited effects of long-continued
 mutilation.

 [62] ‘Production et Fixation des Variétés,’ 1865, p. 72.

 [63] Downing, ‘Fruits of America,’ p. 5: Sageret, ‘Pom. Phys.,’ pp.
 43, 72.




CHAPTER XIII. INHERITANCE _continued_—REVERSION OF ATAVISM.

DIFFERENT FORMS OF REVERSION—IN PURE OR UNCROSSED BREEDS, AS IN
PIGEONS, FOWLS, HORNLESS CATTLE AND SHEEP, IN CULTIVATED
PLANTS—REVERSION IN FERAL ANIMALS AND PLANTS—REVERSION IN CROSSED
VARIETIES AND SPECIES—REVERSION THROUGH BUD-PROPAGATION, AND BY
SEGMENTS IN THE SAME FLOWER OR FRUIT—IN DIFFERENT PARTS OF THE BODY IN
THE SAME ANIMAL—THE ACT OF CROSSING A DIRECT CAUSE OF REVERSION,
VARIOUS CASES OF, WITH INSTINCTS—OTHER PROXIMATE CAUSES OF
REVERSION—LATENT CHARACTERS—SECONDARY SEXUAL CHARACTERS—UNEQUAL
DEVELOPMENT OF THE TWO SIDES OF THE BODY—APPEARANCE WITH ADVANCING AGE
OF CHARACTERS DERIVED FROM A CROSS—THE GERM, WITH ALL ITS LATENT
CHARACTERS, A WONDERFUL OBJECT—MONSTROSITIES—PELORIC FLOWERS DUE IN
SOME CASES TO REVERSION.


The great principle of inheritance to be discussed in this chapter has
been recognised by agriculturists and authors of various nations, as
shown by the scientific term _ Atavism,_ derived from atavus, an
ancestor; by the English terms of _Reversion,_ or _Throwing-back_; by
the French _ Pas-en-Arrière_; and by the German _Rückschlag,_ or
_Rückschritt._ When the child resembles either grandparent more closely
than its immediate parents, our attention is not much arrested, though
in truth the fact is highly remarkable; but when the child resembles
some remote ancestor or some distant member in a collateral line,—and
in the last case we must attribute this to the descent of all the
members from a common progenitor,—we feel a just degree of
astonishment. When one parent alone displays some newly-acquired and
generally inheritable character, and the offspring do not inherit it,
the cause may lie in the other parent having the power of prepotent
transmission. But when both parents are similarly characterised, and
the child does not, whatever the cause may be, inherit the character in
question, but resembles its grandparents, we have one of the simplest
cases of reversion. We continually see another and even more simple
case of atavism, though not generally included under this head, namely,
when the son more closely resembles his maternal than his paternal
grand-sire in some male attribute, as in any peculiarity in the beard
of man, the horns of the bull, the hackles or comb of the cock, or, as
in certain diseases necessarily confined to the male sex; for as the
mother cannot possess or exhibit such male attributes, the child must
inherit them, through her blood, from his maternal grandsire.

 The cases of reversion may be divided into two main classes which,
 however, in some instances, blend into one another; namely, first,
 those occurring in a variety or race which has not been crossed, but
 has lost by variation some character that it formerly possessed, and
 which afterwards reappears. The second class includes all cases in
 which an individual with some distinguishable character, a race, or
 species, has at some former period been crossed, and a character
 derived from this cross, after having disappeared during one or
 several generations, suddenly reappears. A third class, differing only
 in the manner of reproduction, might be formed to include all cases of
 reversion effected by means of buds, and therefore independent of true
 or seminal generation. Perhaps even a fourth class might be
 instituted, to include reversions by segments in the same individual
 flower or fruit, and in different parts of the body in the same
 individual animal as it grows old. But the two first main classes will
 be sufficient for our purpose.

_Reversion to lost Characters by pure or uncrossed forms._—Striking
instances of this first class of cases were given in the sixth chapter,
namely, of the occasional reappearance, in variously-coloured breeds of
the pigeon, of blue birds with all the marks characteristic of the wild
_Columba livia._ Similar cases were given in the case of the fowl. With
the common ass, as the legs of the wild progenitor are almost always
striped, we may feel assured that the occasional appearance of such
stripes in the domestic animal is a case of simple reversion. But I
shall be compelled to refer again to these cases, and therefore here
pass them over.

The aboriginal species from which our domesticated cattle and sheep are
descended, no doubt possessed horns; but several hornless breeds are
now well established. Yet in these—for instance, in Southdown sheep—“it
is not unusual to find among the male lambs some with small horns.” The
horns, which thus occasionally reappear in other polled breeds, either
“grow to the full size,” or are curiously attached to the skin alone
and hang “loosely down, or drop off.”[1] The Galloways and Suffolk
cattle have been hornless for the last 100 or 150 years, but a horned
calf, with the horn often loosely attached, is occasionally
produced.[2]

There is reason to believe that sheep in their early domesticated
condition were “brown or dingy black;” but even in the time of David
certain flocks were spoken of as white as snow. During the classical
period the sheep of Spain are described by several ancient authors as
being black, red, or tawny.[3] At the present day, notwithstanding the
great care which is taken to prevent it, particoloured lambs and some
entirely black are occasionally, or even frequently, dropped by our
most highly improved and valued breeds, such as the Southdowns. Since
the time of the famous Bakewell, during the last century, the Leicester
sheep have been bred with the most scrupulous care; yet occasionally
grey-faced, or black-spotted, or wholly black lambs appear.[4] This
occurs still more frequently with the less improved breeds, such as the
Norfolks.[5] As bearing on this tendency in sheep to revert to dark
colours, I may state (though in doing so I trench on the reversion of
crossed breeds, and likewise on the subject of prepotency) that the
Rev. W. D. Fox was informed that seven white Southdown ewes were put to
a so-called Spanish ram, which had two small black spots on his sides,
and they produced thirteen lambs, all perfectly black. Mr. Fox believes
that this ram belonged to a breed which he has himself kept, and which
is always spotted with black and white; and he finds that Leicester
sheep crossed by rams of this breed always produce black lambs: he has
gone on recrossing these crossed sheep with pure white Leicesters
during three successive generations, but always with the same result.
Mr. Fox was also told by the friend from whom the spotted breed was
procured, that he likewise had gone on for six or seven generations
crossing with white sheep, but still black lambs were invariably
produced.

Similar facts could be given with respect to tailless breeds of various
animals. For instance, Mr. Hewitt[6] states that chickens bred from
some rumpless fowls, which were reckoned so good that they won a prize
at an exhibition, “in a considerable number of instances were furnished
with fully developed tail-feathers.” On inquiry, the original breeder
of these fowls stated that, from the time when he had first kept them,
they had often produced fowls furnished with tails; but that these
latter would again reproduce rumpless chickens.

Analogous cases of reversion occur in the vegetable kingdom; thus “from
seeds gathered from the finest cultivated varieties of Heartsease
(_Viola tricolor_), plants perfectly wild both in their foliage and
their flowers are frequently produced;”[7] but the reversion in this
instance is not to a very ancient period, for the best existing
varieties of the heartsease are of comparatively modern origin. With
most of our cultivated vegetables there is some tendency to reversion
to what is known to be, or may be presumed to be, their aboriginal
state; and this would be more evident if gardeners did not generally
look over their beds of seedlings, and pull up the false plants or
“rogues” as they are called. It has already been remarked, that some
few seedling apples and pears generally resemble, but apparently are
not identical with, the wild trees from which they are descended. In
our turnip[8] and carrot-beds a few plants often “break ”—that is,
flower too soon; and their roots are generally hard and stringy, as in
the parent-species. By the aid of a little selection, carried on during
a few generations, most of our cultivated plants could probably be
brought back, without any great change in their conditions of life, to
a wild or nearly wild condition: Mr. Buckman has effected this with the
parsnip;[9] and Mr. Hewett C. Watson, as he informs me, selected,
during three generations, “the most diverging plants of Scotch kail,
perhaps one of the least modified varieties of the cabbage; and in the
third generation some of the plants came very close to the forms now
established in England about old castle-walls, and called indigenous.”

_Reversion in Animals and Plants which have run wild._—In the cases
hitherto considered, the reverting animals and plants have not been
exposed to any great or abrupt change in their conditions of life which
could have induced this tendency; but it is very different with animals
and plants which have become feral or run wild. It has been repeatedly
asserted in the most positive manner by various authors, that feral
animals and plants invariably return to their primitive specific type.
It is curious on what little evidence this belief rests. Many of our
domesticated animals could not subsist in a wild state; thus, the more
highly improved breeds of the pigeon will not “field” or search for
their own food. Sheep have never become feral, and would be destroyed
by almost every beast of prey.[10] In several cases we do not know the
aboriginal parent-species, and cannot possibly tell whether or not
there has been any close degree of reversion. It is not known in any
instance what variety was first turned out; several varieties have
probably in some cases run wild, and their crossing alone would tend to
obliterate their proper character. Our domesticated animals and plants,
when they run wild, must always be exposed to new conditions of life,
for, as Mr. Wallace[11] has well remarked, they have to obtain their
own food, and are exposed to competition with the native productions.
Under these circumstances, if our domesticated animals did not undergo
change of some kind, the result would be quite opposed to the
conclusions arrived at in this work. Nevertheless, I do not doubt that
the simple fact of animals and plants becoming feral, does cause some
tendency to reversion to the primitive state; though this tendency has
been much exaggerated by some authors.

I will briefly run through the recorded cases. With neither horses nor
cattle is the primitive stock known; and it has been shown in former
chapters that they have assumed different colours in different
countries. Thus the horses which have run wild in South America are
generally brownish-bay, and in the East dun-coloured; their heads have
become larger and coarser, and this may be due to reversion. No careful
description has been given of the feral goat. Dogs which have run wild
in various countries have hardly anywhere assumed a uniform character;
but they are probably descended from several domestic races, and
aboriginally from several distinct species. Feral cats, both in Europe
and La Plata, are regularly striped; in some cases they have grown to
an unusually large size, but do not differ from the domestic animal in
any other character. When variously-coloured tame rabbits are turned
out in Europe, they generally reacquire the colouring of the wild
animal; there can be no doubt that this does really occur, but we
should remember that oddly-coloured and conspicuous animals would
suffer much from beasts of prey and from being easily shot; this at
least was the opinion of a gentleman who tried to stock his woods with
a nearly white variety; if thus destroyed, they would be supplanted by,
instead of being transformed into, the common rabbit. We have seen that
the feral rabbits of Jamaica, and especially of Porto Santo, have
assumed new colours and other new characters. The best known case of
reversion, and that on which the widely spread belief in its
universality apparently rests, is that of pigs. These animals have run
wild in the West Indies, South America, and the Falkland Islands, and
have everywhere acquired the dark colour, the thick bristles, and great
tusks of the wild boar; and the young have reacquired longitudinal
stripes. But even in the case of the pig, Roulin describes the
half-wild animals in different parts of South America as differing in
several respects. In Louisiana the pig[12] has run wild, and is said to
differ a little in form, and much in colour, from the domestic animal,
yet does not closely resemble the wild boar of Europe. With pigeons and
fowls,[13] it is not known what variety was first turned out, nor what
character the feral birds have assumed. The guinea-fowl in the West
Indies, when feral, seems to vary more than in the domesticated state.

With respect to plants run wild, Dr. Hooker[14] has strongly insisted
on what slight evidence the common belief in their reversion to a
primitive state rests. Godron[15] describes wild turnips, carrots, and
celery; but these plants in their cultivated state hardly differ from
their wild prototypes, except in the succulency and enlargement of
certain parts,— characters which would certainly be lost by plants
growing in poor soil and struggling with other plants. No cultivated
plant has run wild on so enormous a scale as the cardoon (_Cynara
cardunculus_) in La Plata. Every botanist who has seen it growing
there, in vast beds, as high as a horse’s back, has been struck with
its peculiar appearance; but whether it differs in any important point
from the cultivated Spanish form, which is said not to be prickly like
its American descendant, or whether it differs from the wild
Mediterranean species, which is said not to be social (though this may
be due merely to the nature of the conditions), I do not know.

_Reversion to Characters derived from a Cross, in the case of
Sub-varieties, Races, and Species._—When an individual having some
recognisable peculiarity unites with another of the same sub-variety,
not having the peculiarity in question, it often reappears in the
descendants after an interval of several generations. Every one must
have noticed, or heard from old people of children closely resembling
in appearance or mental disposition, or in so small and complex a
character as expression, one of their grandparents, or some more
distant collateral relation. Very many anomalies of structure and
diseases[16] of which instances have been given in the last chapter,
have come into a family from one parent, and have reappeared in the
progeny after passing over two or three generations. The following case
has been communicated to me on good authority, and may, I believe, be
fully trusted: a pointer-bitch produced seven puppies; four were marked
with blue and white, which is so unusual a colour with pointers that
she was thought to have played false with one of the greyhounds, and
the whole litter was condemned; but the gamekeeper was permitted to
save one as a curiosity. Two years afterwards a friend of the owner saw
the young dog, and declared that he was the image of his old
pointer-bitch Sappho, the only blue and white pointer of pure descent
which he had ever seen. This led to close inquiry, and it was proved
that he was the great-great-grandson of Sappho; so that, according to
the common expression, he had only 1/16th of her blood in his veins. I
may give one other instance, on the authority of Mr. R. Walker, a large
cattle-breeder in Kincardineshire. He bought a black bull, the son of a
black cow with white legs, white belly and part of the tail white; and
in 1870 a calf the gr.-gr.-gr.-gr.-grandchild of this cow was born
coloured in the same very peculiar manner; all the intermediate
offspring having been black. In these cases there can hardly be a doubt
that a character derived from a cross with an individual of the same
variety reappeared after passing over three generations in the one
case, and five in the other.

When two distinct races are crossed, it is notorious that the tendency
in the offspring to revert to one or both parent-forms is strong, and
endures for many generations. I have myself seen the clearest evidence
of this in crossed pigeons and with various plants. Mr. Sidney[17]
states that, in a litter of Essex pigs, two young ones appeared which
were the image of the Berkshire boar that had been used twenty-eight
years before in giving size and constitution to the breed. I observed
in the farmyard at Betley Hall some fowls showing a strong likeness to
the Malay breed, and was told by Mr. Tollet that he had forty years
before crossed his birds with Malays; and that, though he had at first
attempted to get rid of this strain, he had subsequently given up the
attempt in despair, as the Malay character would reappear.

This strong tendency in crossed breeds to revert has given rise to
endless discussions in how many generations after a single cross,
either with a distinct breed or merely with an inferior animal, the
breed may be considered as pure, and free from all danger of reversion.
No one supposes that less than three generations suffices, and most
breeders think that six, seven, or eight are necessary, and some go to
still greater lengths.[18] But neither in the case of a breed which has
been contaminated by a single cross, nor when, in the attempt to form
an intermediate breed, half-bred animals have been matched together
during many generations, can any rule be laid down how soon the
tendency to reversion will be obliterated. It depends on the difference
in the strength or prepotency of transmission in the two parent-forms,
on their actual amount of difference, and on the nature of the
conditions of life to which the crossed offspring are exposed. But we
must be careful not to confound these cases of reversion to characters
which were gained by a cross, with those under the first class, in
which characters originally common to BOTH parents, but lost at some
former period, reappear; for such characters may recur after an almost
indefinite number of generations.

The law of reversion is as powerful with hybrids, when they are
sufficiently fertile to breed together, or when they are repeatedly
crossed with either pure parent-form, as in the case of mongrels. It is
not necessary to give instances. With plants almost every one who has
worked on this subject, from the time of Kölreuter to the present day,
has insisted on this tendency. Gärtner has recorded some good
instances; but no one has given more striking ones than Naudin.[19] The
tendency differs in degree or strength in different groups, and partly
depends, as we shall presently see, on whether the parent-plants have
been long cultivated. Although the tendency to reversion is extremely
general with nearly all mongrels and hybrids, it cannot be considered
as invariably characteristic of them; it may also be mastered by
long-continued selection; but these subjects will more properly be
discussed in a future chapter on Crossing. From what we see of the
power and scope of reversion, both in pure races, and when varieties or
species are crossed, we may infer that characters of almost every kind
are capable of reappearing after having been lost for a great length of
time. But it does not follow from this that in each particular case
certain characters will reappear; for instance, this will not occur
when a race is crossed with another endowed with prepotency of
transmission. Sometimes the power of reversion wholly fails, without
our being able to assign any cause for the failure: thus it has been
stated that in a French family in which 85 out of above 600 members,
during six generations, had been subject to night-blindness, “there has
not been a single example of this affection in the children of parents
who were themselves free from it.”[20]

_Reversion through Bud-propagation—Partial Reversion, by segments in
the same flower or fruit, or in different parts of the body in the same
individual animal._—In the eleventh chapter many cases of reversion by
buds, independently of seminal generation, were given—as when a
leaf-bud on a variegated, a curled, or laciniated variety suddenly
reassumes its proper character; or as when a Provence-rose appears on a
moss-rose, or a peach on a nectarine-tree. In some of these cases only
half the flower or fruit, or a smaller segment, or mere stripes,
reassume their former character; and here we have reversion by
segments. Vilmorin[21] has also recorded several cases with plants
derived from seed, of flowers reverting by stripes or blotches to their
primitive colours: he states that in all such cases a white or
pale-coloured variety must first be formed, and, when this is
propagated for a length of time by seed, striped seedlings occasionally
make their appearance; and these can afterwards by care be multiplied
by seed.

The stripes and segments just referred to are not due, as far as is
known, to reversion to characters derived from a cross, but to
characters lost by variation. These cases, however, as Naudin[22]
insists in his discussion on disjunction of character, are closely
analogous with those given in the eleventh chapter, in which crossed
plants have been known to produce half-and-half or striped flowers and
fruit, or distinct kinds of flowers on the same root resembling the two
parent-forms. Many piebald animals probably come under this same head.
Such cases, as we shall see in the chapter on Crossing, apparently
result from certain characters not readily blending together, and, as a
consequence of this incapacity for fusion, the offspring either
perfectly resemble one of their two parents, or resemble one parent in
one part, and the other parent in another part; or whilst young are
intermediate in character, but with advancing age revert wholly or by
segments to either parent-form, or to both. Thus, young trees of the
_Cytisus_ adami are intermediate in foliage and flowers between the two
parent-forms; but when older the buds continually revert either
partially or wholly to both forms. The cases given in the eleventh
chapter on the changes which occurred during growth in crossed plants
of Tropæolum, Cereus, Datura, and Lathyrus are all analogous. As,
however, these plants are hybrids of the first generation, and as their
buds after a time come to resemble their parents and not their
grandparents, these cases do not at first appear to come under the law
of reversion in the ordinary sense of the word; nevertheless, as the
change is effected through a succession of bud-generations on the same
plant, they may be thus included.

Analogous facts have been observed in the animal kingdom, and are more
remarkable, as they occur in the same individual in the strictest
sense, and not as with plants through a succession of bud-generations.
With animals the act of reversion, if it can be so designated, does not
pass over a true generation, but merely over the early stages of growth
in the same individual. For instance, I crossed several white hens with
a black cock, and many of the chickens were, during the first year,
perfectly white, but acquired during the second year black feathers; on
the other hand, some of the chickens which were at first black, became
during the second year piebald with white. A great breeder[23] says,
that a Pencilled Brahma hen which has any of the blood of the Light
Brahma in her, will “occasionally produce a pullet well pencilled
during the first year, but she will most likely moult brown on the
shoulders and become quite unlike her original colours in the second
year.” The same thing occurs with light Brahmas if of impure blood. I
have observed exactly similar cases with the crossed offspring from
differently coloured pigeons. But here is a more remarkable fact: I
crossed a turbit, which has a frill formed by the feathers being
reversed on its breast, with a trumpeter; and one of the young pigeons
thus raised at first showed not a trace of the frill, but, after
moulting thrice, a small yet unmistakably distinct frill appeared on
its breast. According to Girou[24] calves produced from a red cow by a
black bull, or from a black cow by a red bull, are not rarely born red,
and subsequently become black. I possess a dog, the daughter of a white
terrier by a fox-coloured bulldog; as a puppy she was quite white, but
when about six months old a black spot appeared on her nose, and brown
spots on her ears. When a little older she was badly wounded on the
back, and the hair which grew on the cicatrix was of a brown colour,
apparently derived from her father. This is the more remarkable, as
with most animals having coloured hair, that which grows on a wounded
surface is white.

In the foregoing cases, the characters which with advancing age
reappeared, were present in the immediately preceding generations; but
characters sometimes reappear in the same manner after a much longer
interval of time. Thus the calves of a hornless race of cattle which
originated in Corrientes, though at first quite hornless, as they
become adult sometimes acquire small, crooked, and loose horns; and
these in succeeding years occasionally become attached to the
skull.[25] White and black Bantams, both of which generally breed true,
sometimes assume as they grow old a saffron or red plumage. For
instance, a first-rate black bantam has been described, which during
three seasons was perfectly black, but then annually became more and
more red; and it deserves notice that this tendency to change, whenever
it occurs in a bantam, “is almost certain to prove hereditary.”[26] The
cuckoo or blue-mottled Dorking cock, when old, is liable to acquire
yellow or orange hackles in place of his proper bluish-grey
hackles.[27] Now as _Gallus bankiva_ is coloured red and orange, and as
Dorking fowls and bantams are descended from this species, we can
hardly doubt that the change which occasionally occurs in the plumage
of these birds as their age advances, results from a tendency in the
individual to revert to the primitive type.

_Crossing as a direct cause of Reversion._—It has long been notorious
that hybrids and mongrels often revert to both or to one of their
parent-forms, after an interval of from two to seven or eight, or,
according to some authorities, even a greater number of generations.
But that the act of crossing in itself gives an impulse towards
reversion, as shown by the reappearance of long-lost characters, has
never, I believe, been hitherto proved. The proof lies in certain
peculiarities, which do not characterise the immediate parents, and
therefore cannot have been derived from them, frequently appearing in
the offspring of two breeds when crossed, which peculiarities never
appear, or appear with extreme rarity, in these same breeds, as long as
they are precluded from crossing. As this conclusion seems to me highly
curious and novel, I will give the evidence in detail.

My attention was first called to this subject, and I was led to make
numerous experiments, by MM. Boitard and Corbie having stated that,
when they crossed certain breeds of pigeons, birds coloured like the
wild _C. livia,_ or the common dovecote—namely, slaty-blue, with double
black wing-bars, sometimes chequered with black, white loins, the tail
barred with black, with the outer feathers edged with white,—were
almost invariably produced. The breeds which I crossed, and the
remarkable results attained, have been fully described in the sixth
chapter. I selected pigeons belonging to true and ancient breeds, which
had not a trace of blue or any of the above specified marks; but when
crossed, and their mongrels recrossed, young birds were often produced,
more or less plainly coloured slaty-blue, with some or all of the
proper characteristic marks. I may recall to the reader’s memory one
case, namely, that of a pigeon, hardly distinguishable from the wild
Shetland species, the grandchild of a red-spot, white fantail, and two
black barbs, from any of which, when purely-bred, the production of a
pigeon coloured like the wild _C. livia_ would have been almost a
prodigy.

I was thus led to make the experiments, recorded in the seventh
chapter, on fowls. I selected long-established pure breeds, in which
there was not a trace of red, yet in several of the mongrels feathers
of this colour appeared; and one magnificent bird, the offspring of a
black Spanish cock and white Silk hen, was coloured almost exactly like
the wild _Gallus bankiva._ All who know anything of the breeding of
poultry will admit that tens of thousands of pure Spanish and of pure
white Silk fowls might have been reared without the appearance of a red
feather. The fact, given on the authority of Mr. Tegetmeier, of the
frequent appearance, in mongrel fowls, of pencilled or
transversely-barred feathers, like those common to many gallinaceous
birds, is likewise apparently a case of reversion to a character
formerly possessed by some ancient progenitor of the family. I owe to
the kindness of this excellent observer the opportunity of inspecting
some neck-hackles and tail-feathers from a hybrid between the common
fowl and a very distinct species, the Gallus varius; and these feathers
are transversely striped in a conspicuous manner with dark metallic
blue and grey, a character which could not have been derived from
either immediate parent.

I have been informed by Mr. B. P. Brent, that he crossed a white
Aylesbury drake and a black so-called Labrador duck, both of which are
true breeds, and he obtained a young drake closely like the mallard
(_A. boschas_). Of the musk-duck (_Cairina moschata,_ Linn.) there are
two sub-breeds, namely, white and slate-coloured; and these I am
informed breed true, or nearly true. But the Rev. W. D. Fox tells me
that, by putting a white drake to a slate-coloured duck, black birds,
pied with white, like the wild musk-duck, were always produced. I hear
from Mr. Blyth that hybrids from the canary and gold-finch almost
always have streaked feathers on their backs; and this streaking must
be derived from the original wild canary.

We have seen in the fourth chapter, that the so-called Himalayan
rabbit, with its snow-white body, black ears, nose, tail, and feet,
breeds perfectly true. This race is known to have been formed by the
union of two varieties of silver-grey rabbits. Now, when a Himalayan
doe was crossed by a sandy-coloured buck, a silver-grey rabbit was
produced; and this is evidently a case of reversion to one of the
parent varieties. The young of the Himalayan rabbit are born
snow-white, and the dark marks do not appear until some time
subsequently; but occasionally young Himalayan rabbits are born of a
light silver-grey, which colour soon disappears; so that here we have a
trace of reversion, during an early period of life, to the parent
varieties, independently of any recent cross.

In the third chapter it was shown that at an ancient period some breeds
of cattle in the wilder parts of Britain were white with dark ears, and
that the cattle now kept half wild in certain parks, and those which
have run quite wild in two distant parts of the world, are likewise
thus coloured. Now, an experienced breeder, Mr. J. Beasley, of
Northamptonshire,[28] crossed some carefully selected West Highland
cows with purely-bred shorthorn bulls. The bulls were red, red and
white, or dark roan; and the Highland cows were all of a red colour,
inclining to a light or yellow shade. But a considerable number of the
offspring—and Mr. Beasley calls attention to this as a remarkable
fact—were white, or white with red ears. Bearing in mind that none of
the parents were white, and that they were purely-bred animals, it is
highly probable that here the offspring reverted, in consequence of the
cross, to the colour of some ancient and half-wild parent-breed. The
following case, perhaps, comes under the same head: cows in their
natural state have their udders but little developed, and do not yield
nearly so much milk as our domesticated animals. Now there is some
reason to believe[29] that cross-bred animals between two kinds, both
of which are good milkers, such as Alderneys and Shorthorns, often turn
out worthless in this respect.

In the chapter on the Horse reasons were assigned for believing that
the primitive stock was striped and dun-coloured; and details were
given, showing that in all parts of the world stripes of a dark colour
frequently appear along the spine, across the legs, and on the
shoulders, where they are occasionally double or treble, and even
sometimes on the face and body of horses of all breeds and of all
colours. But the stripes appear most frequently on the various kinds of
duns. In foals they are sometimes plainly seen, and subsequently
disappear. The dun-colour and the stripes are strongly transmitted when
a horse thus characterised is crossed with any other; but I was not
able to prove that striped duns are generally produced from the
crossing of two distinct breeds, neither of which are duns, though this
does sometimes occur.

The legs of the ass are often striped, and this may be considered as a
reversion to the wild parent form, the _Equus tæniopus_ of
Abyssinia,[30] which is generally thus striped. In the domestic animal
the stripes on the shoulder are occasionally double, or forked at the
extremity, as in certain zebrine species. There is reason to believe
that the foal is more frequently striped on the legs than the adult
animal. As with the horse, I have not acquired any distinct evidence
that the crossing of differently-coloured varieties of the ass brings
out the stripes.

But now let us turn to the result of crossing the horse and ass.
Although mules are not nearly so numerous in England as asses, I have
seen a much greater number with striped legs, and with the stripes far
more conspicuous than in either parent-form. Such mules are generally
light-coloured, and might be called fallow-duns. The shoulder-stripe in
one instance was deeply forked at the extremity, and in another
instance was double, though united in the middle. Mr. Martin gives a
figure of a Spanish mule with strong zebra-like marks on its legs,[31]
and remarks that mules are particularly liable to be thus striped on
their legs. In South America, according to Roulin,[32] such stripes are
more frequent and conspicuous in the mule than in the ass. In the
United States, Mr. Gosse,[33] speaking of these animals, says, “that in
a great number, perhaps in nine out of every ten, the legs are banded
with transverse dark stripes.”

Many years ago I saw in the Zoological Gardens a curious triple hybrid,
from a bay mare, by a hybrid from a male ass and female zebra. This
animal when old had hardly any stripes; but I was assured by the
superintendent, that when young it had shoulder-stripes, and faint
stripes on its flanks and legs. I mention this case more especially as
an instance of the stripes being much plainer during youth than in old
age.

As the zebra has such a conspicuously striped body and legs, it might
have been expected that the hybrids from this animal and the common ass
would have had their legs in some degree striped; but it appears from
the figures given in Dr. Gray’s ‘Knowsley Gleanings’ and still more
plainly from that given by Geoffroy and F. Cuvier,[34] that the legs
are much more conspicuously striped than the rest of the body; and this
fact is intelligible only on the belief that the ass aids in giving,
through the power of reversion, this character to its hybrid offspring.

The quagga is banded over the whole front part of its body like a
zebra, but has no stripes on its legs, or mere traces of them. But in
the famous hybrid bred by Lord Morton[35] from a chestnut, nearly
purely-bred, Arabian mare, by a male quagga, the stripes were more
strongly defined and darker than those on the legs of “the quagga.” The
mare was subsequently put to a black Arabian horse, and bore two colts,
both of which, as formerly stated, were plainly striped on the legs,
and one of them likewise had stripes on the neck and body.

The _Equus indicus_[36] is characterised by a spinal stripe, without
shoulder or leg stripes; but traces of these latter stripes may
occasionally be seen even in the adult[37] and Colonel S. Poole, who
has had ample opportunities for observation, informs me that in the
foal, when first born, the head and legs are often striped, but the
shoulder-stripe is not so distinct as in the domestic ass; all these
stripes, excepting that along the spine, soon disappear. Now a hybrid,
raised at Knowsley[38] from a female of this species by a male domestic
ass, had all four legs transversely and conspicuously striped, had
three short stripes on each shoulder and had even some zebra-like
stripes on its face! Dr. Gray informs me that he has seen a second
hybrid of the same parentage, similarly striped.

From these facts we see that the crossing of the several equine species
tends in a marked manner to cause stripes to appear on various parts of
the body, especially on the legs. As we do not know whether the
parent-form of the genus was striped, the appearance of the stripes can
only hypothetically be attributed to reversion. But most persons, after
considering the many undoubted cases of variously coloured marks
reappearing by reversion in my experiments on crossed pigeons and
fowls, will come to the same conclusion with respect to the
horse-genus; and if so, we must admit that the progenitor of the group
was striped on the legs, shoulders, face, and probably over the whole
body, like a zebra.

Lastly, Professor Jaeger has given[39] a good case with pigs. He
crossed the Japanese or masked breed with the common German breed, and
the offspring were intermediate in character. He then re-crossed one of
these mongrels with the pure Japanese, and in the litter thus produced
one of the young resembled in all its characters a wild pig; it had a
long snout and upright ears, and was striped on the back. It should be
borne in mind that the young of the Japanese breed are not striped, and
that they have a short muzzle and ears remarkably dependent.

A similar tendency to the recovery of long lost characters holds good
even with the instincts of crossed animals. There are some breeds of
fowls which are called “everlasting layers,” because they have lost the
instinct of incubation; and so rare is it for them to incubate that I
have seen notices published in works on poultry, when hens of such
breeds have taken to sit.[40] Yet the aboriginal species was of course
a good incubator; and with birds in a state of nature hardly any
instinct is so strong as this. Now, so many cases have been recorded of
the crossed offspring from two races, neither of which are incubators,
becoming first-rate sitters, that the reappearance of this instinct
must be attributed to reversion from crossing. One author goes so far
as to say, “that a cross between two non-sitting varieties almost
invariably produces a mongrel that becomes broody, and sits with
remarkable steadiness.”[41] Another author, after giving a striking
example, remarks that the fact can be explained only on the principle
that “two negatives make a positive.” It cannot, however, be maintained
that hens produced from a cross between two non-sitting breeds
invariably recover their lost instinct, any more than that crossed
fowls or pigeons invariably recover the red or blue plumage of their
prototypes. Thus I raised several chickens from a Polish hen by a
Spanish cock,—breeds which do not incubate,—and none of the young hens
at first showed any tendency to sit; but one of them—the only one which
was preserved—in the third year sat well on her eggs and reared a brood
of chickens. So that here we have the reappearance with advancing age
of a primitive instinct, in the same manner as we have seen that the
red plumage of the _Gallus bankiva_ is sometimes reacquired both by
crossed and purely-bred fowls of various kinds as they grow old.

The parents of all our domesticated animals were of course aboriginally
wild in disposition; and when a domesticated species is crossed with a
distinct species, whether this is a domesticated or only a tamed
animal, the hybrids are often wild to such a degree, that the fact is
intelligible only on the principle that the cross has caused a partial
return to a primitive disposition. Thus, the Earl of Powis formerly
imported some thoroughly domesticated humped cattle from India, and
crossed them with English breeds, which belong to a distinct species;
and his agent remarked to me, without any question having been asked,
how oddly wild the cross-bred animals were. The European wild boar and
the Chinese domesticated pig are almost certainly specifically
distinct: Sir F. Darwin crossed a sow of the latter breed with a wild
Alpine boar which had become extremely tame, but the young, though
having half-domesticated blood in their veins, were “extremely wild in
confinement, and would not eat swill like common English pigs.” Captain
Hutton, in India, crossed a tame goat with a wild one from the
Himalaya, and he remarked to me how surprisingly wild the offspring
were. Mr. Hewitt, who has had great experience in crossing tame
cock-pheasants with fowls belonging to five breeds, gives as the
character of all “extraordinary wildness”;[42] but I have myself seen
one exception to this rule. Mr. S. J. Salter[43] who raised a large
number of hybrids from a bantam-hen by _Gallus sonneratii,_ states that
“all were exceedingly wild.” Mr. Waterton[44] bred some wild ducks from
eggs hatched under a common duck, and the young were allowed to cross
freely both amongst themselves and with the tame ducks; they were “half
wild and half tame; they came to the windows to be fed, but still they
had a wariness about them quite remarkable.”

On the other hand, mules from the horse and ass are certainly not in
the least wild, though notorious for obstinacy and vice. Mr. Brent, who
has crossed canary-birds with many kinds of finches, has not observed,
as he informs me, that the hybrids were in any way remarkably wild: but
Mr. Jenner Weir who has had still greater experience, is of a directly
opposite opinion. He remarks that the siskin is the tamest of finches,
but its mules are as wild, when young, as newly caught birds, and are
often lost through their continued efforts to escape. Hybrids are often
raised between the common and musk duck, and I have been assured by
three persons, who have kept these crossed birds, that they were not
wild; but Mr. Garnett[45] observed that his hybrids were wild, and
exhibited “migratory propensities” of which there is not a vestige in
the common or musk duck. No case is known of this latter bird having
escaped and become wild in Europe or Asia, except, according to Pallas,
on the Caspian Sea; and the common domestic duck only occasionally
becomes wild in districts where large lakes and fens abound.
Nevertheless, a large number of cases have been recorded[46] of hybrids
from these two ducks having been shot in a completely wild state,
although so few are reared in comparison with purely-bred birds of
either species. It is improbable that any of these hybrids could have
acquired their wildness from the musk-duck having paired with a truly
wild duck; and this is known not to be the case in North America; hence
we must infer that they have reacquired, through reversion, their
wildness, as well as renewed powers of flight.

These latter facts remind us of the statements, so frequently made by
travellers in all parts of the world, on the degraded state and savage
disposition of crossed races of man. That many excellent and
kind-hearted mulattos have existed no one will dispute; and a more mild
and gentle set of men could hardly be found than the inhabitants of the
island of Chiloe, who consist of Indians commingled with Spaniards in
various proportions. On the other hand, many years ago, long before I
had thought of the present subject, I was struck with the fact that, in
South America, men of complicated descent between Negroes, Indians, and
Spaniards, seldom had, whatever the cause might be, a good
expression.[47] Livingstone—and a more unimpeachable authority cannot
be quoted,—after speaking of a half-caste man on the Zambesi, described
by the Portuguese as a rare monster of inhumanity, remarks, “It is
unaccountable why half-castes, such as he, are so much more cruel than
the Portuguese, but such is undoubtedly the case.” An inhabitant
remarked to Livingstone, “God made white men, and God made black men,
but the Devil made halfcastes.”[48] When two races, both low in the
scale, are crossed the progeny seems to be eminently bad. Thus the
noble-hearted Humboldt, who felt no prejudice against the inferior
races, speaks in strong terms of the bad and savage disposition of
Zambos, or half-castes between Indians and Negroes; and this conclusion
has been arrived at by various observers.[49] From these facts we may
perhaps infer that the degraded state of so many half-castes is in part
due to reversion to a primitive and savage condition, induced by the
act of crossing, even if mainly due to the unfavourable moral
conditions under which they are generally reared.

_Summary on the proximate causes leading to Reversion._—When
purely-bred animals or plants reassume long-lost characters,—when the
common ass, for instance, is born with striped legs, when a pure race
of black or white pigeons throws a slaty-blue bird, or when a
cultivated heartsease with large and rounded flowers produces a
seedling with small and elongated flowers,—we are quite unable to
assign any proximate cause. When animals run wild, the tendency to
reversion, which, though it has been greatly exaggerated, no doubt
exists, is sometimes to a certain extent intelligible. Thus, with feral
pigs, exposure to the weather will probably favour the growth of the
bristles, as is known to be the case with the hair of other
domesticated animals, and through correlation the tusks will tend to be
redeveloped. But the reappearance of coloured longitudinal stripes on
young feral pigs cannot be attributed to the direct action of external
conditions. In this case, and in many others, we can only say that any
change in the habits of life apparently favour a tendency, inherent or
latent in the species, to return to the primitive state.

It will be shown in a future chapter that the position of flowers on
the summit of the axis, and the position of seeds within the capsule,
sometimes determine a tendency towards reversion; and this apparently
depends on the amount of sap or nutriment which the flower-buds and
seeds receive. The position, also, of buds, either on branches or on
roots, sometimes determines, as was formerly shown, the transmission of
the character proper to the variety, or its reversion to a former
state.

We have seen in the last section that when two races or species are
crossed there is the strongest tendency to the reappearance in the
offspring of long-lost characters, possessed by neither parent nor
immediate progenitor. When two white, or red, or black pigeons, of
well-established breeds, are united, the offspring are almost sure to
inherit the same colours; but when differently-coloured birds are
crossed, the opposed forces of inheritance apparently counteract each
other, and the tendency which is inherent in both parents to produce
slaty-blue offspring becomes predominant. So it is in several other
cases. But when, for instance, the ass is crossed with _E. indicus_ or
with the horse—animals which have not striped legs—and the hybrids have
conspicuous stripes on their legs and even on their faces, all that can
be said is, that an inherent tendency to reversion is evolved through
some disturbance in the organisation caused by the act of crossing.

Another form of reversion is far commoner, indeed is almost universal
with the offspring from a cross, namely, to the characters proper to
either pure parent-form. As a general rule, crossed offspring in the
first generation are nearly intermediate between their parents, but the
grandchildren and succeeding generations continually revert, in a
greater or lesser degree, to one or both of their progenitors. Several
authors have maintained that hybrids and mongrels include all the
characters of both parents, not fused together, but merely mingled in
different proportions in different parts of the body; or, as Naudin[50]
has expressed it, a hybrid is a living mosaic-work, in which the eye
cannot distinguish the discordant elements, so completely are they
intermingled. We can hardly doubt that, in a certain sense, this is
true, as when we behold in a hybrid the elements of both species
segregating themselves into segments in the same flower or fruit, by a
process of self-attraction or self-affinity; this segregation taking
place either by seminal or bud-propagation. Naudin further believes
that the segregation of the two specific elements or essences is
eminently liable to occur in the male and female reproductive matter;
and he thus explains the almost universal tendency to reversion in
successive hybrid generations. For this would be the natural result of
the union of pollen and ovules, in both of which the elements of the
same species had been segregated by self-affinity. If, on the other
hand, pollen which included the elements of one species happened to
unite with ovules including the elements of the other species, the
intermediate or hybrid state would still be retained, and there would
be no reversion. But it would, as I suspect, be more correct to say
that the elements of both parent-species exist in every hybrid in a
double state, namely, blended together and completely separate. How
this is possible, and what the term specific essence or element may be
supposed to express, I shall attempt to show in the chapter on the
hypothesis of pangenesis.

But Naudin’s view, as propounded by him, is not applicable to the
reappearance of characters lost long ago by variation; and it is hardly
applicable to races or species which, after having been crossed at some
former period with a distinct form, and having since lost all traces of
the cross, nevertheless occasionally yield an individual which reverts
(as in the case of the great-great-grandchild of the pointer Sappho) to
the crossing form. The most simple case of reversion, namely, of a
hybrid or mongrel to its grandparents, is connected by an almost
perfect series with the extreme case of a purely-bred race recovering
characters which had been lost during many ages; and we are thus led to
infer that all the cases must be related by some common bond.

Gärtner believed that only highly sterile hybrid plants exhibit any
tendency to reversion to their parent-forms. This erroneous belief may
perhaps be accounted for by the nature of the genera crossed by him,
for he admits that the tendency differs in different genera. The
statement is also directly contradicted by Naudin’s observations, and
by the notorious fact that perfectly fertile mongrels exhibit the
tendency in a high degree,—even in a higher degree, according to
Gärtner himself, than hybrids.[51]

Gärtner further states that reversions rarely occur with hybrid plants
raised from species which have not been cultivated, whilst, with those
which have been long cultivated, they are of frequent occurrence. This
conclusion explains a curious discrepancy: Max Wichura[52] who worked
exclusively on willows which had not been subjected to culture, never
saw an instance of reversion; and he goes so far as to suspect that the
careful Gartner had not sufficiently protected his hybrids from the
pollen of the parent-species: Naudin, on the other hand, who chiefly
experimented on cucurbitaceous and other cultivated plants, insists
more strenuously than any other author on the tendency to reversion in
all hybrids. The conclusion that the condition of the parent-species,
as affected by culture, is one of the proximate causes leading to
reversion, agrees well with the converse case of domesticated animals
and cultivated plants being liable to reversion when they become feral;
for in both cases the organisation or constitution must be disturbed,
though in a very different way.[53]

Finally, we have seen that characters often reappear in purely-bred
races without our being able to assign any proximate cause; but when
they become feral this is either indirectly or directly induced by the
change in their conditions of life. With crossed breeds, the act of
crossing in itself certainly leads to the recovery of long-lost
characters, as well as of those derived from either parent-form.
Changed conditions, consequent on cultivation, and the relative
position of buds, flowers, and seeds on the plant, all apparently aid
in giving this same tendency. Reversion may occur either through
seminal or bud generation, generally at birth, but sometimes only with
an advance of age. Segments or portions of the individual may alone be
thus affected. That a being should be born resembling in certain
characters an ancestor removed by two or three, and in some cases by
hundreds or even thousands of generations, is assuredly a wonderful
fact. In these cases the child is commonly said to inherit such
characters directly from its grandparent, or more remote ancestors. But
this view is hardly conceivable. If, however, we suppose that every
character is derived exclusively from the father or mother, but that
many characters lie latent or dormant in both parents during a long
succession of generations, the foregoing facts are intelligible. In
what manner characters may be conceived to lie latent, will be
considered in a future chapter to which I have lately alluded.

_Latent Characters._—But I must explain what is meant by characters
lying latent. The most obvious illustration is afforded by secondary
sexual characters. In every female all the secondary male characters,
and in every male all the secondary female characters, apparently exist
in a latent state, ready to be evolved under certain conditions. It is
well known that a large number of female birds, such as fowls, various
pheasants, partridges, peahens, ducks, etc., when old or diseased, or
when operated on, assume many or all of the secondary male characters
of their species. In the case of the hen-pheasant this has been
observed to occur far more frequently during certain years than during
others.[54] A duck ten years old has been known to assume both the
perfect winter and summer plumage of the drake.[55] Waterton,[56] gives
a curious case of a hen which had ceased laying, and had assumed the
plumage, voice, spurs, and warlike disposition of the cock; when
opposed to an enemy she would erect her hackles and show fight. Thus
every character, even to the instinct and manner of fighting, must have
lain dormant in this hen as long as her ovaria continued to act. The
females of two kinds of deer, when old, have been known to acquire
horns; and, as Hunter has remarked, we see something of an analogous
nature in the human species.

On the other hand, with male animals, it is notorious that the
secondary sexual characters are more or less completely lost when they
are subjected to castration. Thus, if the operation be performed on a
young cock, he never, as Yarrell states, crows again; the comb,
wattles, and spurs do not grow to their full size, and the hackles
assume an intermediate appearance between true hackles and the feathers
of the hen. Cases are recorded of confinement, which often affects the
reproductive system, causing analogous results. But characters properly
confined to the female are likewise acquired by the male; the capon
takes to sitting on eggs, and will bring up chickens; and what is more
curious, the utterly sterile male hybrids from the pheasant and the
fowl act in the same manner, “their delight being to watch when the
hens leave their nests, and to take on themselves the office of a
sitter.”[57] That admirable observer Reaumur[58] asserts that a cock,
by being long confined in solitude and darkness, can be taught to take
charge of young chickens; he then utters a peculiar cry, and retains
during his whole life this newly acquired maternal instinct. The many
well-ascertained cases of various male mammals giving milk shows that
their rudimentary mammary glands retain this capacity in a latent
condition.

We thus see that in many, probably in all cases, the secondary
characters of each sex lie dormant or latent in the opposite sex, ready
to be evolved under peculiar circumstances. We can thus understand how,
for instance, it is possible for a good milking cow to transmit her
good qualities through her male offspring to future generations; for we
may confidently believe that these qualities are present, though
latent, in the males of each generation. So it is with the game-cock,
who can transmit his superiority in courage and vigour through his
female to his male offspring; and with man it is known[59] that
diseases, such as hydrocele, necessarily confined to the male sex, can
be transmitted through the female to the grandson. Such cases as these
offer, as was remarked at the commencement of this chapter, the
simplest possible examples of reversion; and they are intelligible on
the belief that characters common to the grandparent and grandchild of
the same sex are present, though latent, in the intermediate parent of
the opposite sex.

The subject of latent characters is so important, as we shall see in a
future chapter, that I will give another illustration. Many animals
have the right and left sides of their body unequally developed: this
is well known to be the case with flat-fish, in which the one side
differs in thickness and colour and in the shape of the fins, from the
other, and during the growth of the young fish one eye is gradually
twisted from the lower to the upper surface.[60] In most flat-fishes
the left is the blind side, but in some it is the right; though in both
cases reversed or “wrong fishes,” are occasionally developed; and in
_Platessa flesus_ the right or left side is indifferently the upper
one. With gasteropods or shell-fish, the right and left sides are
extremely unlike; the far greater number of species are dextral, with
rare and occasional reversals of development; and some few are normally
sinistral; but certain species of Bulimus, and many Achatinellæ[61] are
as often sinistral as dextral. I will give an analogous case in the
great articulate kingdom: the two sides of Verruca[62] are so
wonderfully unlike, that without careful dissection it is extremely
difficult to recognise the corresponding parts on the opposite sides of
the body; yet it is apparently a mere matter of chance whether it be
the right or the left side that undergoes so singular amount of change.
One plant is known to me[63] in which the flower, according as it
stands on the one or other side of the spike, is unequally developed.
In all the foregoing cases the two sides are perfectly symmetrical at
an early period of growth. Now, whenever a species is as liable to be
unequally developed on the one as on the other side, we may infer that
the capacity for such development is present, though latent, in the
undeveloped side. And as a reversal of development occasionally occurs
in animals of many kinds, this latent capacity is probably very common.

The best yet simplest cases of characters lying dormant are, perhaps,
those previously given, in which chickens and young pigeons, raised
from a cross between differently coloured birds, are at first of one
colour, but in a year or two acquire feathers of the colour of the
other parent; for in this case the tendency to a change of plumage is
clearly latent in the young bird. So it is with hornless breeds of
cattle, some of which acquire small horns as they grow old. Purely bred
black and white bantams, and some other fowls, occasionally assume,
with advancing years, the red feathers of the parent-species. I will
here add a somewhat different case, as it connects in a striking manner
latent characters of two classes. Mr. Hewitt[64] possessed an excellent
Sebright gold-laced bantam hen, which, as she became old, grew diseased
in her ovaria, and assumed male characters. In this breed the males
resemble the females in all respects except in their combs, wattles,
spurs, and instincts; hence it might have been expected that the
diseased hen would have assumed only those masculine characters which
are proper to the breed, but she acquired, in addition, well-arched
tail sickle-feathers quite a foot in length, saddle-feathers on the
loins, and hackles on the neck,—ornaments which, as Mr. Hewitt remarks,
“would be held as abominable in this breed.” The Sebright bantam is
known[65] to have originated about the year 1800 from a cross between a
common bantam and a Polish fowl, recrossed by a hen-tailed bantam, and
carefully selected; hence there can hardly be a doubt that the
sickle-feathers and hackles which appeared in the old hen were derived
from the Polish fowl or common bantam; and we thus see that not only
certain masculine characters proper to the Sebright bantam, but other
masculine characters derived from the first progenitors of the breed,
removed by a period of above sixty years, were lying latent in this
henbird, ready to be evolved as soon as her ovaria became diseased.

From these several facts it must be admitted that certain characters,
capacities, and instincts, may lie latent in an individual, and even in
a succession of individuals, without our being able to detect the least
sign of their presence. When fowls, pigeons, or cattle of different
colours are crossed, and their offspring change colour as they grow
old, or when the crossed turbit acquired the characteristic frill after
its third moult, or when rarely-bred bantams partially assume the red
plumage of their prototype, we cannot doubt that these qualities were
from the first present, though latent, in the individual animal, like
the characters of a moth in the caterpillar. Now, if these animals had
produced offspring before they had acquired with advancing age their
new characters, nothing is more probable than that they would have
transmitted them to some of their offspring, who in this case would in
appearance have received such characters from their grand-parents or
more distant progenitors. We should then have had a case of reversion,
that is, of the reappearance in the child of an ancestral character,
actually present, though during youth completely latent, in the parent;
and this we may safely conclude is what occurs in all reversions to
progenitors, however remote.

This view of the latency in each generation of all the characters which
appear through reversion, is also supported by their actual presence in
some cases during early youth alone, or by their more frequent
appearance and greater distinctness at this age than during maturity.
We have seen that this is often the case with the stripes on the legs
and faces of the several species of the horse genus. The Himalayan
rabbit, when crossed, sometimes produces offspring which revert to the
parent silver-grey breed, and we have seen that in purely bred animals
pale-grey fur occasionally reappears during early youth. Black cats, we
may feel assured, would occasionally produce by reversion tabbies; and
on young black kittens, with a pedigree[66] known to have been long
pure, faint traces of stripes may almost always be seen which
afterwards disappear. Hornless Suffolk cattle occasionally produce by
reversion horned animals; and Youatt[67] asserts that even in hornless
individuals “the rudiment of a horn may be often felt at an early age.”

No doubt it appears at first sight in the highest degree improbable
that in every horse of every generation there should be a latent
capacity and tendency to produce stripes, though these may not appear
once in a thousand generations; that in every white, black, or other
coloured pigeon, which may have transmitted its proper colour during
centuries, there should be a latent capacity in the plumage to become
blue and to be marked with certain characteristic bars; that in every
child in a six-fingered family there should be the capacity for the
production of an additional digit; and so in other cases. Nevertheless,
there is no more inherent improbability in this being the case than in
a useless and rudimentary organ, or even in only a tendency to the
production of a rudimentary organ, being inherited during millions of
generations, as is well known to occur with a multitude of organic
beings. There is no more inherent improbability in each domestic pig,
during a thousand generations, retaining the capacity and tendency to
develop great tusks under fitting conditions, than in the young calf
having retained, for an indefinite number of generations rudimentary
incisor teeth, which never protrude through the gums.

I shall give at the end of the next chapter a summary of the three
preceding chapters; but as isolated and striking cases of reversion
have here been chiefly insisted on, I wish to guard the reader against
supposing that reversion is due to some rare or accidental combination
of circumstances. When a character, lost during hundreds of
generations, suddenly reappears, no doubt some such combination must
occur; but reversions, to the immediately preceding generations may be
constantly observed, at least, in the offspring of most unions. This
has been universally recognised in the case of hybrids and mongrels,
but it has been recognised simply from the difference between the
united forms rendering the resemblance of the offspring to their
grandparents or more remote progenitors of easy detection. Reversion is
likewise almost invariably the rule, as Mr. Sedgwick has shown, with
certain diseases. Hence we must conclude that a tendency to this
peculiar form of transmission is an integral part of the general law of
inheritance.

_Monstrosities._—A large number of monstrous growths and of lesser
anomalies are admitted by every one to be due to an arrest of
development, that is, to the persistence of an embryonic condition. But
many monstrosities cannot be thus explained; for parts of which no
trace can be detected in the embryo, but which occur in other members
of the same class of animals occasionally appear, and these may
probably with truth be attributed to reversion. As, however, I have
treated this subject as fully as I could in my ‘Descent of Man’ (ch. 1
2nd edition), I will not here recur to it.

When flowers which have normally an irregular structure become regular
or peloric, the change is generally looked at by botanists as a return
to the primitive state. But Dr. Maxwell Masters,[68] who has ably
discussed this subject, remarks that when, for instance, all the sepals
of a Tropæolum become green and of the same shape, instead of being
coloured with one prolonged into a spur, or when all the petals of a
Linaria become simple and regular, such cases may be due merely to an
arrest of development; for in these flowers all the organs during their
earliest condition are symmetrical, and, if arrested at this stage of
growth, they would not become irregular. If, moreover, the arrest were
to take place at a still earlier period of development, the result
would be a simple tuft of green leaves; and no one probably would call
this a case of reversion. Dr. Masters designates the cases first
alluded to as regular peloria; and others, in which all the
corresponding parts assume a similar form of irregularity, as when all
the petals in a Linaria become spurred, as irregular peloria. We have
no right to attribute these latter cases to reversion, until it can be
shown that the parent-form, for instance, of the genus Linaria had had
all its petals spurred; for a chance of this nature might result from
the spreading of an anomalous structure, in accordance with the law, to
be discussed in a future chapter, of homologous parts tending to vary
in the same manner. But as both forms of peloria frequently occur on
the same individual plant of the Linaria,[69] they probably stand in
some close relation to one another. On the doctrine that peloria is
simply the result of an arrest of development, it is difficult to
understand how an organ arrested at a very early period of growth
should acquire its full functional perfection;—how a petal, supposed to
be thus arrested, should acquire its brilliant colours, and serve as an
envelope to the flower, or a stamen produce efficient pollen; yet this
occurs with many peloric flowers. That pelorism is not due to mere
chance variability, but either to an arrest of development or to
reversion, we may infer from an observation made by Ch. Morren[70]
namely, that families which have irregular flowers often “return by
these monstrous growths to their regular form; whilst we never see a
regular flower realise the structure of an irregular one.”

Some flowers have almost certainly become more or less completely
peloric through reversion, as the following interesting case shows.
_Corydalis tuberosa_ properly has one of its two nectaries colourless,
destitute of nectar, only half the size of the other, and therefore, to
a certain extent, in a rudimentary state; the pistil is curved towards
the perfect nectary, and the hood, formed of the inner petals, slips
off the pistil and stamen in one direction alone, so that, when a bee
sucks the perfect nectary, the stigma and stamens are exposed and
rubbed against the insect’s body. In several closely allied genera, as
in Dielytra, etc., there are two perfect nectaries, the pistil is
straight, and the hood slips off on either side, according as the bee
sucks either nectary. Now, I have examined several flowers of
_Corydalis tuberosa,_ in which both nectaries were equally developed
and contained nectar; in this we see only the redevelopment of a
partially aborted organ; but with this redevelopment the pistil becomes
straight, and the hood slips off in either direction, so that these
flowers have acquired the perfect structure, so well adapted for insect
agency, of Dielytra and its allies. We cannot attribute these coadapted
modifications to chance, or to correlated variability; we must
attribute them to reversion to a primordial condition of the species.

The peloric flowers of Pelargonium have their five petals in all
respects alike, and there is no nectary so that they resemble the
symmetrical flowers of the closely allied genus Geranium; but the
alternate stamens are also sometimes destitute of anthers, the
shortened filaments being left as rudiments, and in this respect they
resemble the symmetrical flowers of the closely allied genus Erodium.
Hence we may look at the peloric flowers of Pelargonium as having
reverted to the state of some primordial form, the progenitor of the
three closely related genera of Pelargonium, Geranium, and Erodium.

In the peloric form of _Antirrhinum majus,_ appropriately called the
“_Wonder,_” the tubular and elongated flowers differ wonderfully from
those of the common snapdragon; the calyx and the mouth of the corolla
consist of six equal lobes, and include six equal instead of four
unequal stamens. One of the two additional stamens is manifestly formed
by the development of a microscopically minute papilla, which may be
found at the base of the upper lip of the flower of the common
snapdragons in the nineteen plants examined by me. That this papilla is
a rudiment of a stamen was well shown by its various degrees of
development in crossed plants between the common and the peloric
Antirrhinum. Again, a peloric _Galeobdolon luteum,_ growing in my
garden, had five equal petals, all striped like the ordinary lower lip,
and included five equal instead of four unequal stamens; but Mr. R.
Keeley, who sent me this plant, informs me that the flowers vary
greatly, having from four to six lobes to the corolla, and from three
to six stamens.[71] Now, as the members of the two great families to
which the Antirrhinum and Galeobdolon belong are properly pentamerous,
with some of the parts confluent and others suppressed, we ought not to
look at the sixth stamen and the sixth lobe to the corolla in either
case as due to reversion, any more than the additional petals in double
flowers in these same two families. But the case is different with the
fifth stamen in the peloric Antirrhinum, which is produced by the
redevelopment of a rudiment always present, and which probably reveals
to us the state of the flower, as far as the stamens are concerned, at
some ancient epoch. It is also difficult to believe that the other four
stamens and the petals, after an arrest of development at a very early
embryonic age, would have come to full perfection in colour, structure,
and function, unless these organs had at some former period normally
passed through a similar course of growth. Hence it appears to me
probable that the progenitor of the genus Antirrhinum must at some
remote epoch have included five stamens and borne flowers in some
degree resembling those now produced by the peloric form. The
conclusion that peloria is not a mere monstrosity, irrespective of any
former state of the species, is supported by the fact that this
structure is often strongly inherited, as in the case of the peloric
Antirrhinum and Gloxinia and sometimes in that of the peloric
_Corydalis solida_.[72]

Lastly I may add that many instances have been recorded of flowers, not
generally considered as peloric, in which certain organs are abnormally
augmented in number. As an increase of parts cannot be looked at as an
arrest of development, nor as due to the redevelopment of rudiments,
for no rudiments are present, and as these additional parts bring the
plant into closer relationship with its natural allies, they ought
probably to be viewed as reversions to a primordial condition.

These several facts show us in an interesting manner how intimately
certain abnormal states are connected together; namely, arrests of
development causing parts to become rudimentary or to be wholly
suppressed,—the redevelopment of parts now in a more or less
rudimentary condition,—the reappearance of organs of which not a
vestige can be detected,—and to these may be added, in the case of
animals, the presence during youth, and subsequent disappearance, of
certain characters which occasionally are retained throughout life.
Some naturalists look at all such abnormal structures as a return to
the ideal state of the group to which the affected being belongs; but
it is difficult to conceive what is meant to be conveyed by this
expression. Other naturalists maintain, with greater probability and
distinctness of view, that the common bond of connection between the
several foregoing cases is an actual, though partial, return to the
structure of the ancient progenitor of the group. If this view be
correct, we must believe that a vast number of characters, capable of
evolution, lie hidden in every organic being. But it would be a mistake
to suppose that the number is equally great in all beings. We know, for
instance, that plants of many orders occasionally become peloric; but
many more cases have been observed in the Labiatæ and Scrophulariaceæ
than in any other order; and in one genus of the Scrophulariaceæ,
namely Linaria, no less than thirteen species have been described in
this condition.[73] On this view of the nature of peloric flowers, and
bearing in mind certain monstrosities in the animal kingdom, we must
conclude that the progenitors of most plants and animals have left an
impression, capable of redevelopment, on the germs of their
descendants, although these have since been profoundly modified.

The fertilised germ of one of the higher animals, subjected as it is to
so vast a series of changes from the germinal cell to old
age,—incessantly agitated by what Quatrefages well calls the
_tourbillon vital,_—is perhaps the most wonderful object in nature. It
is probable that hardly a change of any kind affects either parent,
without some mark being left on the germ. But on the doctrine of
reversion, as given in this chapter, the germ becomes a far more
marvellous object, for, besides the visible changes which it undergoes,
we must believe that it is crowded with invisible characters, proper to
both sexes, to both the right and left side of the body, and to a long
line of male and female ancestors separated by hundreds or even
thousands of generations from the present time: and these characters,
like those written on paper with invisible ink, lie ready to be evolved
whenever the organisation is disturbed by certain known or unknown
conditions.

REFERENCES

 [1] Youatt on Sheep, pp. 20, 234. The same fact of loose horns
 occasionally appearing in hornless breeds has been observed in
 Germany; Bechstein, ‘Naturgesch. Deutschlands.’ b. 1 s. 362.

 [2] Youatt on Cattle, pp. 155, 174.

 [3] Youatt on Sheep, 1838, pp. 17, 145.

 [4] I have been informed of this fact through the Rev. W. D. Fox on
 the excellent authority of Mr. Wilmot: _see also_ remarks on this
 subject in an article in the ‘Quarterly Review,’ 1849, p. 395.

 [5] Youatt, pp. 19, 234.

 [6] ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 231.

 [7] Loudon’s ‘Gardener’s Mag.,’ vol. x., 1834, p. 396: a nurseryman,
 with much experience on this subject, has likewise assured me that
 this sometimes occurs.

 [8] ‘Gardener’s Chronicle,’ 1855, p. 777.

 [9] Ibid., 1862, p. 721.

 [10] Mr. Boner speaks (‘Chamois-hunting,’ 2nd edit., 1860, p. 92) of
 sheep often running wild in the Bavarian Alps; but, on making further
 inquiries at my request, he found that they are not able to establish
 themselves; they generally perish from the frozen snow clinging to
 their wool, and they have lost the skill necessary to pass over steep
 icy slopes. On one occasion two ewes survived the winter, but their
 lambs perished.

 [11] _See_ some excellent remarks on this subject by Mr. Wallace
 ‘Journal Proc. Linn. Soc.,’ 1858, vol. iii. p. 60.

 [12] Dureau de la Malle ‘Comptes Rendus,’ tom. xli., 1855, p. 807.
 From the statements above given, the author concludes that the wild
 pigs of Louisiana are not descended from the European _Sus scrofa._

 [13] Capt. W. Allen, in his ‘Expedition to the Niger,’ states that
 fowls have run wild on the island of Annobon, and have become modified
 in form and voice. The account is so meagre and vague that it did not
 appear to me worth copying; but I now find that Dureau de la Malle
 (‘Comptes Rendus,’ tom. xli., 1855, p. 690) advances this as a good
 instance of reversion to the primitive stock, and as confirmatory of a
 still more vague statement in classical times by Varro.

 [14] ‘Flora of Australia,’ 1859, Introduct., p. ix.

 [15] ‘De l’Espèce,’ tom. ii. pp. 54, 58, 60.

 [16] Mr. Sedgwick gives many instances in the ‘British and Foreign
 Med.-Chirurg. Review,’ April and July, 1863, pp. 448, 188.

 [17] In his edit. of ‘Youatt on the Pig,’ 1860, p. 27.

 [18] Dr. P. Lucas, ‘Héréd. Nat.,’ tom. ii. pp. 314, 892: _see_ a good
 practical article on the subject in ‘Gard. Chronicle,’ 1856, p. 620. I
 could add a vast number of references, but they would be superfluous.

 [19] Kölreuter gives curious cases in his ‘Dritte Fortsetzung,’ 1766,
 ss. 53, 59; and in his well-known ‘Memoirs on Lavatera and Jalapa.’
 Gärtner, ‘Bastarderzeugung,’ ss. 437, 441, etc. Naudin in his
 “Recherches sur l’Hybridité,” ‘Nouvelles Archives du Muséum,’ tom. i.
 p. 25.

 [20] Quoted by Mr. Sedgwick in ‘Med.-Chirurg. Review,’ April, 1861, p.
 485. Dr. H. Dobell in ‘Med.-Chirurg. Transactions,’ vol. xlvi., gives
 an analogous case in which, in a large family, fingers with thickened
 joints were transmitted to several members during five generations;
 but when the blemish once disappeared it never reappeared.

 [21] Verlot ‘Des Variétés,’ 1865, p. 63.

 [22] ‘Nouvelles Archives du Muséum,’ tom. i. p. 25. Alex. Braun (in
 his ‘Rejuvenescence,’ Ray Soc., 1853, p. 315) apparently holds a
 similar opinion.

 [23] Mr. Teebay in ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 72.

 [24] Quoted by Hofacker ‘Ueber die Eigenschaften,’ etc., s. 98.

 [25] Azara, ‘Essais Hist. Nat. de Paraguay,’ tom. ii. 1801, p. 372.

 [26] These facts are given on the high authority of Mr. Hewitt, in
 ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 248.

 [27] ‘The Poultry Book,’ by Tegetmeier, 1866, p. 97.

 [28] ‘Gardener’s Chron. and Agricultural Gazette,’ 1866, p. 528.

 [29] Ibid., 1860, p. 343. I am glad to find that so experienced a
 breeder of cattle as Mr. Willoughby Wood, (‘Gard. Chron.’ 1869, p.
 1216), admits my principle of a cross giving a tendency to reversion.

 [30] Sclater in ‘Proc. Zoolog. Soc.,’ 1862, p. 163.

 [31] ‘History of the Horse,’ p. 212.

 [32] ‘Mém. présentés par divers Savans à l’Acad. Royale,’ tom. vi.
 1835, p. 338.

 [33] ‘Letters from Alabama,’ 1859, p. 280.

 [34] ‘Hist. Nat. des Mammiferes,’ 1820, tom. i.

 [35] ‘Philosoph. Transact.,’ 1821, p. 20.

 [36] Sclater, in ‘Proc. Zoolog. Soc.,’ 1862, p. 163: this species is
 the Ghor-Khur of N.W. India, and has often been called the Hemionus of
 Pallas. _See also_ Mr. Blyth’s excellent paper in ‘Journal of Asiatic
 Soc. of Bengal,’ vol. xviii., 1860, p. 229.

 [37] Another species of wild ass, the true _E. hemionus_ or _Kiang,_
 which ordinarily has no shoulder-stripes, is said occasionally to have
 them; and these, as with the horse and ass, are sometimes double:
 _see_ Mr. Blyth in the paper just quoted and in ‘Indian Sporting
 Review,’ 1856, p. 320: and Col. Hamilton Smith in ‘Nat. Library,
 Horses,’ p. 318; and ‘Dict. Class. d’Hist. Nat.,’ tom. iii. p. 563.

 [38] Figured in the ‘Gleanings from the Knowsley Menageries,’ by Dr.
 J. E. Gray.

 [39] ‘Darwin’sche Theorie und ihre Stellung zu Moral und Religion,’ p.
 85.

 [40] Cases of both Spanish and Polish hens sitting are given in the
 ‘Poultry Chronicle,’ 1855, vol. iii. p. 477.

 [41] ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, pp. 119, 163. The
 author, who remarks on the two negatives (‘Journ. of Hort.,’ 1862, p.
 325), states that two broods were raised from a Spanish cock and
 Silver-pencilled Hamburgh hen, neither of which are incubators, and no
 less than seven out of eight hens in these two broods “showed a
 perfect obstinacy in sitting.” The Rev. E. S. Dixon (‘Ornamental
 Poultry,’ 1848, p. 200) says that chickens reared from a cross between
 Golden and Black Polish fowls, are “good and steady birds to sit.” Mr.
 B. P. Brent informs me that he raised some good sitting hens by
 crossing Pencilled Hamburgh and Polish breeds. A cross-bred bird from
 a Spanish non-incubating cock and Cochin incubating hen is mentioned
 in the ‘Poultry Chronicle,’ vol. iii. p. 13, as an “exemplary mother.”
 On the other hand, an exceptional case is given in the ‘Cottage
 Gardener,’ 1860, p. 388, of a hen raised from a Spanish cock and black
 Polish hen which did not incubate.

 [42] ‘The Poultry Book,’ by Tegetmeier, 1866, pp. 165, 167.

 [43] ‘Natural History Review,’ 1863, April, p. 277.

 [44] ‘Essays on Natural History,’ p. 917.

 [45] As stated by Mr. Orton, in his ‘Physiology of Breeding,’ p. 12.

 [46] M. E. de Selys-Longchamps refers (‘Bulletin Acad. Roy. de
 Bruxelles,’ tom. xii. No. 10) to more than seven of these hybrids shot
 in Switzerland and France. M. Deby asserts (‘Zoologist,’ vol. v.,
 1845-46, p. 1254) that several have been shot in various parts of
 Belgium and Northern France. Audubon (‘Ornitholog. Biography,’ vol.
 iii. p. 168), speaking of these hybrids, says that, in North America,
 they “now and then wander off and become quite wild.”

 [47] ‘Journal of Researches,’ 1845, p. 71.

 [48] ‘Expedition to the Zambesi,’ 1865, pp. 25, 150.

 [49] Dr. P. Broca, on ‘Hybridity in the Genus Homo,’ Eng. translat.,
 1864, p. 39.

 [50] ‘Nouvelles Archives du Muséum,’ tom. i. p. 151.

 [51] ‘Bastarderzeugung,’ s. 582, 438, etc.

 [52] ‘Die Bastardbefruchtung . . . der Weiden,’ 1865, s. 23. For
 Gärtner’s remarks on this head, _see_ ‘Bastarderzeugung,’ s. 474, 582.

 [53] Prof. Weismann, in his very curious essay on the different forms
 produced by the same species of butterfly at different seasons
 (‘Saison-Dimorphismus der Schmetterlinge,’ pp. 27, 28), has come to a
 similar conclusion, namely, that any cause which disturbs the
 organisation, such as the exposure of the cocoons to heat or even to
 much shaking, gives a tendency to reversion.

 [54] Yarrell, ‘Phil. Transact.,’ 1827, p. 268; Dr. Hamilton, in ‘Proc.
 Zoolog. Soc.,’ 1862, p. 23.

 [55] ‘Archiv. Skand. Beiträge zur Naturgesch.’ viii. s. 397-413.

 [56] In his ‘Essays on Nat. Hist.,’ 1838, Mr. Hewitt gives analogous
 cases with hen-pheasants in ‘Journal of Horticulture,’ July 12, 1864,
 p. 37. Isidore Geoffroy Saint-Hilaire, in his ‘Essais de Zoolog. Gen.’
 (‘suites a Buffon,’ 1842, pp. 496-513), has collected such cases in
 ten different kinds of birds. It appears that Aristotle was well aware
 of the change in mental disposition in old hens. The case of the
 female deer acquiring horns is given at p. 513.

 [57] ‘Cottage Gardener,’ 1860, p. 379.

 [58] ‘Art de faire Eclore,’ etc., 1749, tom. ii. p. 8.

 [59] Sir H. Holland, ‘Medical Notes and Reflections,’ 3rd edit., 1855,
 p. 31.

 [60] _See_ Steenstrup on the ‘Obliquity of Flounders’: in ‘Annals and
 Mag. of Nat. Hist.’ May, 1865, p. 361. I have given an abstract of
 Malm’s explanation of this wonderful phenomenon in the ‘Origin of
 Species’ 6th Edit. p. 186.

 [61] Dr. E. von Martens, in ‘Annals and Mag. of Nat. Hist.’ March,
 1866, p. 209.

 [62] Darwin, ‘Balanidæ,’ Ray Soc., 1854, p. 499: _see also_ the
 appended remarks on the apparently capricious development of the
 thoracic limbs on the right and left sides in the higher crustaceans.

 [63] Mormodes ignea: Darwin, ‘Fertilisation of Orchids,’ 1862, p. 251.

 [64] ‘Journal of Horticulture,’ July, 1864, p. 38. I have had the
 opportunity of examining these remarkable feathers through the
 kindness of Mr. Tegetmeier.

 [65] ‘The Poultry Book,’ by Mr. Tegetmeier, 1866, p. 241.

 [66] Carl Vogt, ‘Lectures on Man,’ Eng. translat., 1864, p. 411.

 [67] ‘On Cattle,’ p. 174.

 [68] ‘Natural Hist. Review,’ April, 1863, p. 258. _See also_ his
 Lecture, Royal Institution, March 16, 1860. On same subject see
 Moquin-Tandon, ‘Eléments de Tératologie,’ 1841, pp. 184, 352. Dr.
 Peyritsch has collected a large number of very interesting cases,
 Sitzb. d. k. Akad. d. Wissensch.: Wien. b. LX. and especially b.
 LXVI., 1872, p. 125.

 [69] Verlot, ‘Des Variétés,’ 1865, p. 89; Naudin, ‘Nouvelles Archives
 du Museum,’ tom. i. p. 137.

 [70] In his discussion on some curious peloric Calceolarias, quoted in
 ‘Journal of Horticulture,’ Feb. 24, 1863, p. 152.

 [71] For other cases of six divisions in peloric flowers of the
 Labiatæ and Scrophulariaceæ, _see_ Moquin-Tandon, ‘Tératologie,’ p.
 192.

 [72] Godron, reprinted from the ‘Mémoires de l’Acad. de Stanislas,’
 1868.

 [73] Moquin-Tandon, ‘Tératologie,’ p. 186.




CHAPTER XIV. INHERITANCE _continued_—FIXEDNESS OF
CHARACTER—PREPOTENCY—SEXUAL LIMITATION—CORRESPONDENCE OF AGE.

FIXEDNESS OF CHARACTER APPARENTLY NOT DUE TO ANTIQUITY OF
INITANCE—PREPOTENCY OF TRANSMISSION IN INDIVIDUALS OF THE SAME FAMILY,
IN CROSSED BREEDS AND SPECIES; OFTEN STRONGER IN ONE SEX THAN THE
OTHER; SOMETIMES DUE TO THE SAME CHARACTER BEING PRESENT AND VISIBLE IN
ONE BREED AND LATENT IN THE OTHER—INHERITANCE AS LIMITED BY
SEX—NEWLY-ACQUIRED CHARACTERS IN OUR DOMESTICATED ANIMALS OFTEN
TRANSMITTED BY ONE SEX ALONE, SOMETIMES LOST BY ONE SEX
ALONE—INHERITANCE AT CORRESPONDING PERIODS OF LIFE—THE IMPORTANCE OF
THE PRINCIPLE WITH RESPECT TO EMBRYOLOGY; AS EXHIBITED IN DOMESTICATED
ANIMALS: AS EXHIBITED IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED
DISEASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN IN THE
PARENT—SUMMARY OF THE THREE PRECEDING CHAPTERS.


In the last two chapters the nature and force of Inheritance, the
circumstances which interfere with its power, and the tendency to
Reversion, with its many remarkable contingencies, were discussed. In
the present chapter some other related phenomena will be treated of, as
fully as my materials permit.

      _Fixedness of Character._

It is a general belief amongst breeders that the longer any character
has been transmitted by a breed, the more fully it will continue to be
transmitted. I do not wish to dispute the truth of the proposition that
inheritance gains strength simply through long continuance, but I doubt
whether it can be proved. In one sense the proposition is little better
than a truism; if any character has remained constant during many
generations, it will be likely to continue so, if the conditions of
life remain the same. So, again, in improving a breed, if care be taken
for a length of time to exclude all inferior individuals, the breed
will obviously tend to become truer, as it will not have been crossed
during many generations by an inferior animal. We have previously seen,
but without being able to assign any cause, that, when a new character
appears, it is occasionally from the first constant, or fluctuates
much, or wholly fails to be transmitted. So it is with the aggregate of
slight differences which characterise a new variety, for some propagate
their kind from the first much truer than others. Even with plants
multiplied by bulbs, layers, etc., which may in one sense be said to
form parts of the same individual, it is well known that certain
varieties retain and transmit through successive bud-generations their
newly-acquired characters more truly than others. In none of these, nor
in the following cases, does there appear to be any relation between
the force with which a character is transmitted and the length of time
during which it has been transmitted. Some varieties, such as white and
yellow hyacinths and white sweet-peas, transmit their colours more
faithfully than do the varieties which have retained their natural
colour. In the Irish family, mentioned in the twelfth chapter, the
peculiar tortoiseshell-like colouring of the eyes was transmitted far
more faithfully than any ordinary colour. Ancon and Mauchamp sheep and
niata cattle, which are all comparatively modern breeds, exhibit
remarkably strong powers of inheritance. Many similar cases could be
adduced.

As all domesticated animals and cultivated plants have varied, and yet
are descended from aboriginally wild forms, which no doubt had retained
the same character from an immensely remote epoch, we see that scarcely
any degree of antiquity ensures a character being transmitted perfectly
true. In this case, however, it may be said that changed conditions of
life induce certain modifications, and not that the power of
inheritance fails; but in every case of failure, some cause, either
internal or external, must interfere. It will generally be found that
the organs or parts which in our domesticated productions have varied,
or which still continue to vary,—that is, which fail to retain their
former state,—are the same with the parts which differ in the natural
species of the same genus. As, on the theory of descent with
modification, the species of the same genus have been modified since
they branched off from a common progenitor, it follows that the
characters by which they differ from one another have varied, whilst
other parts of the organisation have remained unchanged; and it might
be argued that these same characters now vary under domestication, or
fail to be inherited, from their lesser antiquity. But variation in a
state of nature seems to stand in some close relation with changed
conditions of life, and characters which have already varied under such
conditions would be apt to vary under the still greater changes
consequent on domestication, independently of their greater or less
antiquity.

Fixedness of character, or the strength of inheritance, has often been
judged of by the preponderance of certain characters in the crossed
offspring between distinct races; but prepotency of transmission here
comes into play, and this, as we shall immediately see, is a very
different consideration from the strength or weakness of
inheritance.[1] It has often been observed that breeds of animals
inhabiting wild and mountainous countries cannot be permanently
modified by our improved breeds; and as these latter are of modern
origin, it has been thought that the greater antiquity of the wilder
breeds has been the cause of their resistance to improvement by
crossing; but it is more probably due to their structure and
constitution being better adapted to the surrounding conditions. When
plants are first subjected to culture, it has been found that, during
several generations, they transmit their characters truly, that is, do
not vary, and this has been attributed to ancient characters being
strongly inherited: but it may with equal or greater probability be
consequent on changed conditions of life requiring a long time for
their cumulative action. Notwithstanding these considerations, it would
perhaps be rash to deny that characters become more strongly fixed the
longer they are transmitted; but I believe that the proposition
resolves itself into this,—that characters of all kinds, whether new or
old, tend to be inherited, and that those which have already withstood
all counteracting influences and been truly transmitted, will, as a
general rule, continue to withstand them, and consequently be
faithfully inherited.

_Prepotency in the Transmission of Character._

When individuals, belonging to the same family, but distinct enough to
be recognised, or when two well-marked races, or two species, are
crossed, the usual result, as stated in the previous chapter, is, that
the offspring in the first generation are intermediate between their
parents, or resemble one parent in one part and the other parent in
another part. But this is by no means the invariable rule; for in many
cases it is found that certain individuals, races, and species, are
prepotent in transmitting their likeness. This subject has been ably
discussed by Prosper Lucas,[2] but is rendered extremely complex by the
prepotency sometimes running equally in both sexes, and sometimes more
strongly in one sex than in the other; it is likewise complicated by
the presence of secondary sexual characters, which render the
comparison of crossed breeds with their parents difficult.

It would appear that in certain families some one ancestor, and after
him others in the same family, have had great power in transmitting
their likeness through the male line; for we cannot otherwise
understand how the same features should so often be transmitted after
marriages with many females, as in the case of the Austrian Emperors;
and so it was, according to Niebuhr, with the mental qualities of
certain Roman families.[3] The famous bull Favourite is believed[4] to
have had a prepotent influence on the shorthorn race. It has also been
observed[5] with English racehorses that certain mares have generally
transmitted their own character, whilst other mares of equally pure
blood have allowed the character of the sire to prevail. A famous black
greyhound, Bedlamite, as I hear from Mr. C. M. Brown “invariably got
all his puppies black, no matter what was the colour of the bitch;” but
then Bedlamite “had a preponderance of black in his blood, both on the
sire and dam side.”

The truth of the principle of prepotency comes out more clearly when
distinct races are crossed. The improved Shorthorns, notwithstanding
that the breed is comparatively modern, are generally acknowledged to
possess great power in impressing their likeness on all other breeds;
and it is chiefly in consequence of this power that they are so highly
valued for exportation.[6] Godine has given a curious case of a ram of
a goat-like breed of sheep from the Cape of Good Hope, which produced
offspring hardly to be distinguished from himself, when crossed with
ewes of twelve other breeds. But two of these half-bred ewes, when put
to a merino ram, produced lambs closely resembling the merino breed.
Girou de Buzareingues[7] found that of two races of French sheep the
ewes of one, when crossed during successive generations with merino
rams, yielded up their character far sooner than the ewes of the other
race. Sturm and Girou have given analogous cases with other breeds of
sheep and with cattle, the prepotency running in these cases through
the male side; but I was assured on good authority in South America,
that when niata cattle are crossed with common cattle, though the niata
breed is prepotent whether males or females are used, yet that the
prepotency is strongest through the female line. The Manx cat is
tailless and has long hind legs; Dr. Wilson crossed a male Manx with
common cats, and, out of twenty-three kittens, seventeen were destitute
of tails; but when the female Manx was crossed by common male cats all
the kittens had tails, though they were generally short and
imperfect.[8]

In making reciprocal crosses between pouter and fantail pigeons, the
pouter-race seemed to be prepotent through both sexes over the fantail.
But this is probably due to weak power in the fantail rather than to
any unusually strong power in the pouter, for I have observed that
barbs also preponderate over fantails. This weakness of transmission in
the fantail, though the breed is an ancient one, is said[9] to be
general; but I have observed one exception to the rule, namely, in a
cross between a fantail and laugher. The most curious instance known to
me of weak power in both sexes is in the trumpeter pigeon. This breed
has been well known for at least 130 years: it breeds perfectly true,
as I have been assured by those who have long kept many birds: it is
characterised by a peculiar tuft of feathers over the beak, by a crest
on the head, by a singular coo quite unlike that of any other breed,
and by much-feathered feet. I have crossed both sexes with turbits of
two sub-breeds, with almond tumblers, spots, and runts, and reared many
mongrels and recrossed them; and though the crest on the head and
feathered feet were inherited (as is generally the case with most
breeds), I have never seen a vestige of the tuft over the beak or heard
the peculiar coo. Boitard and Corbié[10] assert that this is the
invariable result of crossing trumpeters with other breeds:
Neumeister,[11] however, states that in Germany mongrels have been
obtained, though very rarely, which were furnished with the tuft and
would trumpet: but a pair of these mongrels with a tuft, which I
imported, never trumpeted. Mr. Brent states[12] that the crossed
offspring of a trumpeter were crossed with trumpeters for three
generations, by which time the mongrels had 7/8ths of this blood in
their veins, yet the tuft over the beak did not appear. At the fourth
generation the tuft appeared, but the birds though now having 15-16ths
trumpeter’s blood still did not trumpet. This case well shows the wide
difference between inheritance and prepotency; for here we have a
well-established old race which transmits its characters faithfully,
but which, when crossed with any other race, has the feeblest power of
transmitting its two chief characteristic qualities.

I will give one other instance with fowls and pigeons of weakness and
strength in the transmission of the same character to their crossed
offspring. The Silk fowl breeds true, and there is reason to believe is
a very ancient race; but when I reared a large number of mongrels from
a Silk hen by a Spanish cock, not one exhibited even a trace of the
so-called silkiness. Mr. Hewitt also asserts that in no instance are
the silky feathers transmitted by this breed when crossed with any
other variety. But three birds out of many raised by Mr. Orton from a
cross between a silk cock and a bantam hen had silky feathers.[13] So
that it is certain that this breed very seldom has the power of
transmitting its peculiar plumage to its crossed progeny. On the other
hand, there is a silk sub-variety of the fantail pigeon, which has its
feathers in nearly the same state as in the Silk fowl: now we have
already seen that fantails, when crossed, possess singularly weak power
in transmitting their general qualities; but the silk sub-variety when
crossed with any other small-sized race invariably transmits its silky
feathers![14]

The well-known horticulturist, Mr. Paul, informs me that he fertilised
the Black Prince hollyhock with pollen of the White Globe and the
Lemonade and Black Prince hollyhocks reciprocally; but not one seedling
from these three crosses inherited the black colour of the Black
Prince. So, again, Mr. Laxton, who has had such great experience in
crossing peas, writes to me that “whenever a cross has been effected
between a white-blossomed and a purple-blossomed pea, or between a
white-seeded and a purple-spotted, brown or maple-seeded pea, the
offspring seems to lose nearly all the characteristics of the
white-flowered and white-seeded varieties; and this result follows
whether these varieties have been used as the pollen-bearing or
seed-producing parents.”

The law of prepotency comes into action when species are crossed, as
with races and individuals. Gärtner has unequivocally shown[15] that
this is the case with plants. To give one instance: when _Nicotiana
paniculata_ and _ vincæflora_ are crossed, the character of _N.
paniculata_ is almost completely lost in the hybrid; but if _ N.
quadrivalvis_ be crossed with _N. vincæflora,_ this latter species,
which was before so prepotent, now in its turn almost disappears under
the power of _N. quadrivalvis._ It is remarkable that the prepotency of
one species over another in transmission is quite independent, as shown
by Gärtner, of the greater or less facility with which the one
fertilises the other.

With animals, the jackal is prepotent over the dog, as is stated by
Flourens, who made many crosses between these animals; and this was
likewise the case with a hybrid which I once saw between a jackal and a
terrier. I cannot doubt, from the observations of Colin and others,
that the ass is prepotent over the horse; the prepotency in this
instance running more strongly through the male than through the female
ass; so that the mule resembles the ass more closely than does the
hinny.[16] The male pheasant, judging from Mr. Hewitt’s
descriptions,[17] and from the hybrids which I have seen, preponderates
over the domestic fowl; but the latter, as far as colour is concerned,
has considerable power of transmission, for hybrids raised from five
differently coloured hens differed greatly in plumage. I formerly
examined some curious hybrids in the Zoological Gardens, between the
Penguin variety of the common duck and the Egyptian goose (_Anser
ægyptiacus_); and although I will not assert that the domesticated
variety preponderated over the natural species, yet it had strongly
impressed its unnatural upright figure on these hybrids.

I am aware that such cases as the foregoing have been ascribed by
various authors, not to one species, race, or individual being
prepotent over the other in impressing its character on its crossed
offspring, but to such rules as that the father influences the external
characters and the mother the internal or vital organs. But the great
diversity of the rules given by various authors almost proves their
falseness. Dr. Prosper Lucas has fully discussed this point, and has
shown[18] that none of the rules (and I could add others to those
quoted by him) apply to all animals. Similar rules have been announced
for plants, and have been proved by Gärtner[19] to be all erroneous. If
we confine our view to the domesticated races of a single species, or
perhaps even to the species of the same genus, some such rules may hold
good; for instance, it seems that in reciprocally crossing various
breeds of fowls the male generally gives colour;[20] but conspicuous
exceptions have passed under my own eyes. It seems that the ram usually
gives its peculiar horns and fleece to its crossed offspring, and the
bull the presence or absence of horns.

In the following chapter on Crossing I shall have occasion to show that
certain characters are rarely or never blended by crossing, but are
transmitted in an unmodified state from either parent-form; I refer to
this fact here because it is sometimes accompanied on the one side by
prepotency, which thus acquires the false appearance of unusual
strength. In the same chapter I shall show that the rate at which a
species or breed absorbs and obliterates another by repeated crosses,
depends in chief part on prepotency in transmission.

In conclusion, some of the cases above given,—for instance, that of the
trumpeter pigeon,—prove that there is a wide difference between mere
inheritance and prepotency. This latter power seems to us, in our
ignorance, to act in most cases quite capriciously. The very same
character, even though it be an abnormal or monstrous one, such as
silky feathers, may be transmitted by different species, when crossed,
either with prepotent force or singular feebleness. It is obvious, that
a purely-bred form of either sex, in all cases in which prepotency does
not run more strongly in one sex than the other, will transmit its
character with prepotent force over a mongrelised and already variable
form.[21] From several of the above-given cases we may conclude that
mere antiquity of character does not by any means necessarily make it
prepotent. In some cases prepotency apparently depends on the same
character being present and visible in one of the two breeds which are
crossed, and latent or invisible in the other breed; and in this case
it is natural that the character which is potentially present in both
breeds should be prepotent. Thus, we have reason to believe that there
is a latent tendency in all horses to be dun-coloured and striped; and
when a horse of this kind is crossed with one of any other colour, it
is said that the offspring are almost sure to be striped. Sheep have a
similar latent tendency to become dark-coloured, and we have seen with
what prepotent force a ram with a few black spots, when crossed with
white sheep of various breeds, coloured its offspring. All pigeons have
a latent tendency to become slaty-blue, with certain characteristic
marks, and it is known that, when a bird thus coloured is crossed with
one of any other colour, it is most difficult afterwards to eradicate
the blue tint. A nearly parallel case is offered by those black bantams
which, as they grow old, develop a latent tendency to acquire red
feathers. But there are exceptions to the rule: hornless breeds of
cattle possess a latent capacity to reproduce horns, yet when crossed
with horned breeds they do not invariably produce offspring bearing
horns.

We meet with analogous cases with plants. Striped flowers, though they
can be propagated truly by seed, have a latent tendency to become
uniformly coloured, but when once crossed by a uniformly coloured
variety, they ever afterwards fail to produce striped seedlings.[22]
Another case is in some respects more curious: plants bearing peloric
flowers have so strong a latent tendency to reproduce their normally
irregular flowers, that this often occurs by buds when a plant is
transplanted into poorer or richer soil.[23] Now I crossed the peloric
snapdragon (_Antirrhinum majus_), described in the last chapter, with
pollen of the common form; and the latter, reciprocally, with peloric
pollen. I thus raised two great beds of seedlings, and not one was
peloric. Naudin[24] obtained the same result from crossing a peloric
Linaria with the common form. I carefully examined the flowers of
ninety plants of the crossed Antirrhinum in the two beds, and their
structure had not been in the least affected by the cross, except that
in a few instances the minute rudiment of the fifth stamen, which is
always present, was more fully or even completely developed. It must
not be supposed that this entire obliteration of the peloric structure
in the crossed plants can be accounted for by any incapacity of
transmission; for I raised a large bed of plants from the peloric
Antirrhinum, artificially fertilised by its own pollen, and sixteen
plants, which alone survived the winter, were all as perfectly peloric
as the parent-plant. Here we have a good instance of the wide
difference between the inheritance of a character and the power of
transmitting it to crossed offspring. The crossed plants, which
perfectly resembled the common snapdragon, were allowed to sow
themselves, and out of a hundred and twenty-seven seedlings,
eighty-eight proved to be common snapdragons, two were in an
intermediate condition between the peloric and normal state, and
thirty-seven were perfectly peloric, having reverted to the structure
of their one grand-parent. This case seems at first sight to offer an
exception to the rule just given, namely, that a character which is
present in one form and latent in the other is generally transmitted
with prepotent force when the two forms are crossed. For in all the
Scrophulariaceæ, and especially in the genera Antirrhinum and Linaria,
there is, as was shown in the last chapter, a strong latent tendency to
become peloric; but there is also, as we have seen, a still stronger
tendency in all peloric plants to reacquire their normal irregular
structure. So that we have two opposed latent tendencies in the same
plants. Now, with the crossed Antirrhinums the tendency to produce
normal or irregular flowers, like those of the common Snapdragon,
prevailed in the first generation; whilst the tendency to pelorism,
appearing to gain strength by the intermission of a generation,
prevailed to a large extent in the second set of seedlings. How it is
possible for a character to gain strength by the intermission of a
generation, will be considered in the chapter on pangenesis.

On the whole, the subject of prepotency is extremely intricate,—from
its varying so much in strength, even in regard to the same character,
in different animals,—from its running either equally in both sexes,
or, as frequently is the case with animals, but not with plants, much
stronger in one sex than the other,—from the existence of secondary
sexual characters,—from the transmission of certain characters being
limited, as we shall immediately see, by sex,—from certain characters
not blending together,—and, perhaps, occasionally from the effects of a
previous fertilisation on the mother. It is therefore not surprising
that no one has hitherto succeeded in drawing up general rules on the
subject of prepotency.

      _Inheritance as limited by Sex._

New characters often appear in one sex, and are afterwards transmitted
to the same sex, either exclusively or in a much greater degree than to
the other. This subject is important, because with animals of many
kinds in a state of nature, both high and low in the scale, secondary
sexual characters, not directly connected with the organs of
reproduction, are conspicuously present. With our domesticated animals,
characters of this kind often differ widely from those distinguishing
the two sexes of the parent species; and the principle of inheritance,
as limited by sex, explains how this is possible.

Dr. P. Lucas has shown[25] that when a peculiarity, in no manner
connected with the reproductive organs, appears in either parent, it is
often transmitted exclusively to the offspring of the same sex, or to a
much greater number of them than of the opposite sex. Thus, in the
family of Lambert, the horn-like projections on the skin were
transmitted from the father to his sons and grandsons alone; so it has
been with other cases of ichthyosis, with supernumerary digits, with a
deficiency of digits and phalanges, and in a lesser degree with various
diseases, especially with colour-blindness and the hæmorrhagic
diathesis, that is, an extreme liability to profuse and uncontrollable
bleeding from trifling wounds. On the other hand, mothers have
transmitted, during several generations, to their daughters alone,
supernumerary and deficient digits, colour-blindness and other
peculiarities. So that the very same peculiarity may become attached to
either sex, and be long inherited by that sex alone; but the attachment
in certain cases is much more frequent to one than the other sex. The
same peculiarities also may be promiscuously transmitted to either sex.
Dr. Lucas gives other cases, showing that the male occasionally
transmits his peculiarities to his daughters alone, and the mother to
her sons alone; but even in this case we see that inheritance is to a
certain extent, though inversely, regulated by sex. Dr. Lucas, after
weighing the whole evidence, comes to the conclusion that every
peculiarity tends to be transmitted in a greater or lesser degree to
that sex in which it first appears. But a more definite rule, as I have
elsewhere shown[26] generally holds good, namely, that variations which
first appear in either sex at a late period of life, when the
reproductive functions are active, tend to be developed in that sex
alone; whilst variations which first appear early in life in either sex
are commonly transmitted to both sexes. I am, however, far from
supposing that this is the sole determining cause.

A few details from the many cases collected by Mr. Sedgwick,[27] may be
here given. Colour-blindness, from some unknown cause, shows itself
much oftener in males than in females; in upwards of two hundred cases
collected by Mr. Sedgwick, nine-tenths related to men; but it is
eminently liable to be transmitted through women. In the case given by
Dr. Earle, members of eight related families were affected during five
generations: these families consisted of sixty-one individuals, namely,
of thirty-two males, of whom nine-sixteenths were incapable of
distinguishing colour, and of twenty-nine females, of whom only
one-fifteenth were thus affected. Although colour-blindness thus
generally clings to the male sex, nevertheless, in one instance in
which it first appeared in a female, it was transmitted during five
generations to thirteen individuals, all of whom were females. The
hæmorrhagic diathesis, often accompanied by rheumatism, has been known
to affect the males alone during five generations, being transmitted,
however, through the females. It is said that deficient phalanges in
the fingers have been inherited by the females alone during ten
generations. In another case, a man thus deficient in both hands and
feet, transmitted the peculiarity to his two sons and one daughter; but
in the third generation,—out of nineteen grandchildren, twelve sons had
the family defect, whilst the seven daughters were free. In ordinary
cases of sexual limitation, the sons or daughters inherit the
peculiarity, whatever it may be, from their father or mother, and
transmit it to their children of the same sex; but generally with the
hæmorrhagic diathesis, and often with colour-blindness, and in some
other cases, the sons never inherit the peculiarity directly from their
fathers, but the daughters alone transmit the latent tendency, so that
the sons of the daughters alone exhibit it. Thus the father, grandson,
and great-great-grandson will exhibit a peculiarity,—the grandmother,
daughter, and great-grand-daughter having transmitted it in a latent
state. Hence we have, as Mr. Sedgwick remarks, a double kind of atavism
or reversion; each grandson apparently receiving and developing the
peculiarity from his grandfather, and each daughter apparently
receiving the latent tendency from her grandmother.

From the various facts recorded by Dr. Prosper Lucas, Mr. Sedgwick, and
others, there can be no doubt that peculiarities first appearing in
either sex, though not in any way necessarily or invariably connected
with that sex, strongly tend to be inherited by the offspring of the
same sex, but are often transmitted in a latent state through the
opposite sex.

Turning now to domesticated animals, we find that certain characters
not proper to the parent species are often confined to, and inherited
by, one sex alone; but we do not know the history of the first
appearance of such characters. In the chapter on Sheep, we have seen
that the males of certain races differ greatly from the females in the
shape of their horns, these being absent in the ewes of some breeds;
they differ also in the development of fat in the tail and in the
outline of the forehead. These differences, judging from the character
of the allied wild species, cannot be accounted for by supposing that
they have been derived from distinct parent forms. There is, also, a
great difference between the horns of the two sexes in one Indian breed
of goats. The bull zebu is said to have a larger hump than the cow. In
the Scotch deer-hound the two sexes differ in size more than in any
other variety of the dog[28] and, judging from analogy, more than in
the aboriginal parent-species. The peculiar colour called
tortoise-shell is very rarely seen in a male cat; the males of this
variety being of a rusty tint.

In various breeds of the fowl the males and females often differ
greatly; and these differences are far from being the same with those
which distinguish the two sexes of the parent-species, the _Gallus
bankiva_; and consequently have originated under domestication. In
certain sub-varieties of the Game race we have the unusual case of the
hens differing from each other more than the cocks. In an Indian breed
of a white colour shaded with black, the hens invariably have black
skins, and their bones are covered by a black periosteum, whilst the
cocks are never or most rarely thus characterised. Pigeons offer a more
interesting case; for throughout the whole great family the two sexes
do not often differ much; and the males and females of the parent-form,
the _C. livia,_ are undistinguishable: yet we have seen that with
pouters the male has the characteristic quality of pouting more
strongly developed than the female; and in certain sub-varieties the
males alone are spotted or striated with black, or otherwise differ in
colour. When male and female English carrier-pigeons are exhibited in
separate pens, the difference in the development of the wattle over the
beak and round the eyes is conspicuous. So that here we have instances
of the appearance of secondary sexual characters in the domesticated
races of a species in which such differences are naturally quite
absent.

On the other hand, secondary sexual characters which belong to the
species in a state of nature are sometimes quite lost, or greatly
diminished, under domestication. We see this in the small size of the
tusks in our improved breeds of the pig, in comparison with those of
the wild boar. There are sub-breeds of fowls, in which the males have
lost the fine-flowing tail-feathers and hackles; and others in which
there is no difference in colour between the two sexes. In some cases
the barred plumage, which in gallinaceous birds is commonly the
attribute of the hen, has been transferred to the cock, as in the
cuckoo sub-breeds. In other cases masculine characters have been partly
transferred to the female, as with the splendid plumage of the
golden-spangled Hamburgh hen, the enlarged comb of the Spanish hen, the
pugnacious disposition of the Game hen, and as in the well-developed
spurs which occasionally appear in the hens of various breeds. In
Polish fowls both sexes are ornamented with a topknot, that of the male
being formed of hackle-like feathers, and this is a new male character
in the genus Gallus. On the whole, as far as I can judge, new
characters are more apt to appear in the males of our domesticated
animals than in the females,[29] and afterwards to be inherited
exclusively or more strongly by the males. Finally, in accordance with
the principle of inheritance as limited by sex, the preservation and
augmentation of secondary sexual characters in natural species offers
no especial difficulty, as this would follow through that form of
selection which I have called sexual selection.

      _Inheritance at corresponding periods of Life._

This is an important subject. Since the publication of my ‘Origin of
Species’ I have seen no reason to doubt the truth of the explanation
there given of one of the most remarkable facts in biology, namely, the
difference between the embryo and the adult animal. The explanation is,
that variations do not necessarily or generally occur at a very early
period of embryonic growth, and that such variations are inherited at a
corresponding age. As a consequence of this the embryo, even after the
parent-form has undergone great modification, is left only slightly
modified; and the embryos of widely-different animals which are
descended from a common progenitor remain in many important respects
like one another and probably like their common progenitor. We can thus
understand why embryology throws a flood of light on the natural system
of classification, as this ought to be as far as possible genealogical.
When the embryo leads an independent life, that is, becomes a larva, it
has to be adapted to the surrounding conditions in its structure and
instincts, independently of those of its parents; and the principle of
inheritance at corresponding periods of life renders this possible.

This principle is, indeed, in one way so obvious that it escapes
attention. We possess a number of races of animals and plants, which,
when compared with one another and with their parent-forms, present
conspicuous differences, both in their immature and mature states. Look
at the seeds of the several kinds of peas, beans, maize, which can be
propagated truly, and see how they differ in size, colour, and shape,
whilst the full-grown plants differ but little. Cabbages, on the other
hand, differ greatly in foliage and manner of growth, but hardly at all
in their seeds; and generally it will be found that the differences
between cultivated plants at different periods of growth are not
necessarily closely connected together, for plants may differ much in
their seeds and little when full-grown, and conversely may yield seeds
hardly distinguishable, yet differ much when full-grown. In the several
breeds of poultry, descended from a single species, differences in the
eggs and chickens whilst covered with down, in the plumage at the first
and subsequent moults, as well as in the comb and wattles, are all
inherited. With man peculiarities in the milk and second teeth (of
which I have received the details) are inheritable, and longevity is
often transmitted. So again with our improved breeds of cattle and
sheep, early maturity, including the early development of the teeth,
and with certain breeds of fowl the early appearance of secondary
sexual characters, all come under the same head of inheritance at
corresponding periods.

Numerous analogous facts could be given. The silk-moth, perhaps, offers
the best instance; for in the breeds which transmit their characters
truly, the eggs differ in size, colour, and shape: the caterpillars
differ, in moulting three or four times, in colour, even in having a
dark-coloured mark like an eyebrow, and in the loss of certain
instincts;—the cocoons differ in size, shape, and in the colour and
quality of the silk; these several differences being followed by slight
or barely distinguishable differences in the mature moth.

But it may be said that, if in the above cases a new peculiarity is
inherited, it must be at the corresponding stage of development; for an
egg or seed can resemble only an egg or seed, and the horn in a
full-grown ox can resemble only a horn. The following cases show
inheritance at corresponding periods more plainly, because they refer
to peculiarities which might have supervened, as far as we can see,
earlier or later in life, yet are inherited at the same period at which
they first appeared.

In the Lambert family the porcupine-like excrescences appeared in the
father and sons at the same age, namely, about nine weeks after
birth.[30] In the extraordinary hairy family described by Mr.
Crawfurd,[31] children were produced during three generations with
hairy ears; in the father the hair began to grow over his body at six
years old; in his daughter somewhat earlier, namely, at one year; and
in both generations the milk teeth appeared late in life, the permanent
teeth being afterwards singularly deficient. Greyness of hair at an
unusually early age has been transmitted in some families. These cases
border on diseases inherited at corresponding periods of life, to which
I shall immediately refer.

It is a well-known peculiarity with almond-tumbler pigeons, that the
full beauty and peculiar character of the plumage does not appear until
the bird has moulted two or three times. Neumeister describes and
figures a brace of pigeons in which the whole body is white except the
breast, neck, and head; but in their first plumage all the white
feathers have coloured edges. Another breed is more remarkable: its
first plumage is black, with rusty-red wing-bars and a crescent-shaped
mark on the breast; these marks then become white, and remain so during
three or four moults; but after this period the white spreads over the
body, and the bird loses its beauty.[32] Prize canary-birds have their
wings and tail black: “this colour, however, is only retained until the
first moult, so that they must be exhibited ere the change takes place.
Once moulted, the peculiarity has ceased. Of course all the birds
emanating from this stock have black wings and tails the first
year.”[33] A curious and somewhat analogous account has been given[34]
of a family of wild pied rooks which were first observed in 1798, near
Chalfont, and which every year from that date up to the period of the
published notice, viz., 1837 “have several of their brood
particoloured, black and white. This variegation of the plumage,
however, disappears with the first moult; but among the next young
families there are always a few pied ones.” These changes of plumage,
which are inherited at various corresponding periods of life in the
pigeon, canary-bird, and rook, are remarkable, because the
parent-species passes through no such change.

Inherited diseases afford evidence in some respects of less value than
the foregoing cases, because diseases are not necessarily connected
with any change in structure; but in other respects of more value,
because the periods have been more carefully observed. Certain diseases
are communicated to the child apparently by a process like inoculation,
and the child is from the first affected; such cases may be here passed
over. Large classes of diseases usually appear at certain ages, such as
St. Vitus’s dance in youth, consumption in early mid-life, gout later,
and apoplexy still later; and these are naturally inherited at the same
period. But even in diseases of this class, instances have been
recorded, as with St. Vitus’s dance, showing that an unusually early or
late tendency to the disease is inheritable.[35] In most cases the
appearance of any inherited disease is largely determined by certain
critical periods in each person’s life, as well as by unfavourable
conditions. There are many other diseases, which are not attached to
any particular period, but which certainly tend to appear in the child
at about the same age at which the parent was first attacked. An array
of high authorities, ancient and modern, could be given in support of
this proposition. The illustrious Hunter believed in it; and Piorry[36]
cautions the physician to look closely to the child at the period when
any grave inheritable disease attacked the parent. Dr. Prosper
Lucas,[37] after collecting facts from every source, asserts that
affections of all kinds, though not related to any particular period of
life, tend to reappear in the offspring at whatever period of life they
first appeared in the progenitor.

As the subject is important, it may be well to give a few instances,
simply as illustrations, not as proof; for proof, recourse must be had
to the authorities above quoted. Some of the following cases have been
selected for the sake of showing that, when a slight departure from the
rule occurs, the child is affected somewhat earlier in life than the
parent. In the family of Le Compte blindness was inherited through
three generations, and no less than twenty-seven children and
grandchildren were all affected at about the same age; their blindness
in general began to advance about the fifteenth or sixteenth year, and
ended in total deprivation of sight at the age of about twenty-two.[38]
In another case a father and his four children all became blind at
twenty-one years old; in another, a grandmother grew blind at
thirty-five, her daughter at nineteen, and three grandchildren at the
ages of thirteen and eleven.[39] So with deafness, two brothers, their
father and paternal grandfather, all became deaf at the age of
forty.[40]

Esquirol gives several striking instances of insanity coming on at the
same age, as that of a grandfather, father, and son, who all committed
suicide near their fiftieth year. Many other cases could be given, as
of a whole family who became insane at the age of forty.[41] Other
cerebral affections sometimes follow the same rule,—for instance,
epilepsy and apoplexy. A woman died of the latter disease when
sixty-three years old; one of her daughters at forty-three, and the
other at sixty-seven: the latter had twelve children, who all died from
tubercular meningitis.[42] I mention this latter case because it
illustrates a frequent occurrence, namely, a change in the precise
nature of an inherited disease, though still affecting the same organ.

Asthma has attacked several members of the same family when forty years
old, and other families during infancy. The most different diseases,
such as angina pectoris, stone in the bladder, and various affections
of the skin, have appeared in successive generations at nearly the same
age. The little finger of a man began from some unknown cause to grow
inwards, and the same finger in his two sons began at the same age to
bend inwards in a similar manner. Strange and inexplicable neuralgic
affections have caused parents and children to suffer agonies at about
the same period of life.[43]

I will give only two other cases, which are interesting as illustrating
the disappearance as well as the appearance of disease at the same age.
Two brothers, their father, their paternal uncles, seven cousins, and
their paternal grandfather, were all similarly affected by a
skin-disease, called pityriasis versicolor; “the disease, strictly
limited to the males of the family (though transmitted through the
females), usually appeared at puberty, and disappeared at about the age
of forty or forty-five years.” The second case is that of four
brothers, who when about twelve years old suffered almost every week
from severe headaches, which were relieved only by a recumbent position
in a dark room. Their father, paternal uncles, paternal grandfather,
and granduncles all suffered in the same way from headaches, which
ceased at the age of fifty-four or fifty-five in all those who lived so
long. None of the females of the family were affected.[44]

It is impossible to read the foregoing accounts, and the many others
which have been recorded, of diseases coming on during three or even
more generations in several members of the same family at the same age,
especially in the case of rare affections in which the coincidence
cannot be attributed to chance, and to doubt that there is a strong
tendency to inheritance in disease at corresponding periods of life.
When the rule fails, the disease is apt to come on earlier in the child
than in the parent; the exceptions in the other direction being very
much rarer. Dr. Lucas[45] alludes to several cases of inherited
diseases coming on at an earlier period. I have already given one
striking instance with blindness during three generations; and Mr.
Bowman remarks that this frequently occurs with cataract. With cancer
there seems to be a peculiar liability to earlier inheritance: Sir J.
Paget, who has particularly attended to this subject, and tabulated a
large number of cases, informs me that he believes that in nine cases
out of ten the later generation suffers from the disease at an earlier
period than the previous generation. He adds, “In the instances in
which the opposite relation holds, and the members of later generations
have cancer at a later age than their predecessors, I think it will be
found that the non-cancerous parents have lived to extreme old ages.”
So that the longevity of a non-affected parent seems to have the power
of influencing the fatal period in the offspring; and we thus
apparently get another element of complexity in inheritance.

The facts, showing that with certain diseases the period of inheritance
occasionally or even frequently advances, are important with respect to
the general descent-theory, for they render it probable that the same
thing would occur with ordinary modifications of structure. The final
result of a long series of such advances would be the gradual
obliteration of characters proper to the embryo and larva, which would
thus come to resemble more and more closely the mature parent-form. But
any structure which was of service to the embryo or larva would be
preserved by the destruction at this stage of growth of each individual
which manifested any tendency to lose its proper character at too early
an age.

Finally, from the numerous races of cultivated plants and domestic
animals, in which the seeds or eggs, the young or old, differ from one
another and from those of the parent-species;—from the cases in which
new characters have appeared at a particular period, and afterwards
been inherited at the same period;—and from what we know with respect
to disease, we must believe in the truth of the great principle of
inheritance at corresponding periods of life.

_Summary of the three preceding Chapters._—Strong as is the force of
inheritance, it allows the incessant appearance of new characters.
These, whether beneficial or injurious,—of the most trifling
importance, such as a shade of colour in a flower, a coloured lock of
hair, or a mere gesture,—or of the highest importance, as when
affecting the brain, or an organ so perfect and complex as the eye,—or
of so grave a nature as to deserve to be called a monstrosity,—or so
peculiar as not to occur normally in any member of the same natural
class,—often inherited by man, by the lower animals, and plants. In
numberless cases it suffices for the inheritance of a peculiarity that
one parent alone should be thus characterised. Inequalities in the two
sides of the body, though opposed to the law of symmetry, may be
transmitted. There is ample evidence that the effects of mutilations
and of accidents, especially or perhaps exclusively when followed by
disease, are occasionally inherited. There can be no doubt that the
evil effects of the long-continued exposure of the parent to injurious
conditions are sometimes transmitted to the offspring. So it is, as we
shall see in a future chapter, with the effects of the use and disuse
of parts, and of mental habits. Periodical habits are likewise
transmitted, but generally, as it would appear, with little force.

Hence we are led to look at inheritance as the rule, and
non-inheritance as the anomaly. But this power often appears to us in
our ignorance to act capriciously, transmitting a character with
inexplicable strength or feebleness. The very same peculiarity, as the
weeping habit of trees, silky feathers, etc., may be inherited either
firmly or not at all by different members of the same group, and even
by different individuals of the same species, though treated in the
same manner. In this latter case we see that the power of transmission
is a quality which is merely individual in its attachment. As with
single characters, so it is with the several concurrent slight
differences which distinguish sub-varieties or races; for of these,
some can be propagated almost as truly as species, whilst others cannot
be relied on. The same rule holds good with plants, when propagated by
bulbs, offsets, etc., which in one sense still form parts of the same
individual, for some varieties retain or inherit through successive
bud-generations their character far more truly than others.

Some characters not proper to the parent-species have certainly been
inherited from an extremely remote epoch, and may therefore be
considered as firmly fixed. But it is doubtful whether length of
inheritance in itself gives fixedness of character; though the chances
are obviously in favour of any character which has long been
transmitted true or unaltered still being transmitted true as long as
the conditions of life remain the same. We know that many species,
after having retained the same character for countless ages, whilst
living under their natural conditions, when domesticated have varied in
the most diversified manner, that is, have failed to transmit their
original form; so that no character appears to be absolutely fixed. We
can sometimes account for the failure of inheritance by the conditions
of life being opposed to the development of certain characters; and
still oftener, as with plants cultivated by grafts and buds, by the
conditions causing new and slight modifications incessantly to appear.
In this latter case it is not that inheritance wholly fails, but that
new characters are continually superadded. In some few cases, in which
both parents are similarly characterised, inheritance seems to gain so
much force by the combined action of the two parents, that it
counteracts its own power, and a new modification is the result.

In many cases the failure of the parents to transmit their likeness is
due to the breed having been at some former period crossed; and the
child takes after his grandparent or more remote ancestor of foreign
blood. In other cases, in which the breed has not been crossed, but
some ancient character has been lost through variation, it occasionally
reappears through reversion, so that the parents apparently fail to
transmit their own likeness. In all cases, however, we may safely
conclude that the child inherits all its characters from its parents,
in whom certain characters are latent, like the secondary sexual
characters of one sex in the other. When, after a long succession of
bud-generations, a flower or fruit becomes separated into distinct
segments, having the colours or other attributes of both parent-forms,
we cannot doubt that these characters were latent in the earlier buds,
though they could not then be detected, or could be detected only in an
intimately commingled state. So it is with animals of crossed
parentage, which with advancing years occasionally exhibit characters
derived from one of their two parents, of which not a trace could at
first be perceived. Certain monstrosities, which resemble what
naturalists call the typical form of the group in question, apparently
come under the same law of reversion. It is assuredly an astonishing
fact that the male and female sexual elements, that buds, and even
full-grown animals, should retain characters, during several
generations in the case of crossed breeds, and during thousands of
generations in the case of pure breeds, written as it were in invisible
ink, yet ready at any time to be evolved under certain conditions.

What these conditions precisely are, we do not know. But any cause
which disturbs the organisation or constitution seems to be sufficient.
A cross certainly gives a strong tendency to the reappearance of
long-lost characters, both corporeal and mental. In the case of plants,
this tendency is much stronger with those species which have been
crossed after long cultivation and which therefore have had their
constitutions disturbed by this cause as well as by crossing, than with
species which have always lived under their natural conditions and have
then been crossed. A return, also, of domesticated animals and
cultivated plants to a wild state favours reversion; but the tendency
under these circumstances has been much exaggerated.

When individuals of the same family which differ somewhat, and when
races or species are crossed, the one is often prepotent over the other
in transmitting its character. A race may possess a strong power of
inheritance, and yet when crossed, as we have seen with
trumpeter-pigeons, yield to the prepotency of every other race.
Prepotency of transmission may be equal in the two sexes of the same
species, but often runs more strongly in one sex. It plays an important
part in determining the rate at which one race can be modified or
wholly absorbed by repeated crosses with another. We can seldom tell
what makes one race or species prepotent over another; but it sometimes
depends on the same character being present and visible in one parent,
and latent or potentially present in the other.

Characters may first appear in either sex, but oftener in the male than
in the female, and afterwards be transmitted to the offspring of the
same sex. In this case we may feel confident that the peculiarity in
question is really present though latent in the opposite sex! hence the
father may transmit through his daughter any character to his grandson;
and the mother conversely to her granddaughter. We thus learn, and the
fact is an important one, that transmission and development are
distinct powers. Occasionally these two powers seem to be antagonistic,
or incapable of combination in the same individual; for several cases
have been recorded in which the son has not directly inherited a
character from his father, or directly transmitted it to his son, but
has received it by transmission through his non-affected mother, and
transmitted it through his non-affected daughter. Owing to inheritance
being limited by sex, we see how secondary sexual characters may have
arisen under nature; their preservation and accumulation being
dependent on their service to either sex.

At whatever period of life a new character first appears, it generally
remains latent in the offspring until a corresponding age is attained,
and then is developed. When this rule fails, the child generally
exhibits the character at an earlier period than the parent. On this
principle of inheritance at corresponding periods, we can understand
how it is that most animals display from the germ to maturity such a
marvellous succession of characters.

Finally, though much remains obscure with respect to Inheritance, we
may look at the following laws as fairly well established. Firstly, a
tendency in every character, new and old, to be transmitted by seminal
and bud generation, though often counteracted by various known and
unknown causes. Secondly, reversion or atavism, which depends on
transmission and development being distinct powers: it acts in various
degrees and manners through both seminal and bud generation. Thirdly,
prepotency of transmission, which may be confined to one sex, or be
common to both sexes. Fourthly, transmission, as limited by sex,
generally to the same sex in which the inherited character first
appeared; and this in many, probably most cases, depends on the new
character having first appeared at a rather late period of life.
Fifthly, inheritance at corresponding periods of life, with some
tendency to the earlier development of the inherited character. In
these laws of Inheritance, as displayed under domestication, we see an
ample provision for the production, through variability and natural
selection, of new specific forms.

REFERENCES

 [1] _See_ Youatt on Cattle, pp. 92, 69, 78, 88, 163; and Youatt on
 Sheep, p. 325. Also Dr. Lucas ‘L’Héréd. Nat.,’ tom. ii. p. 310.

 [2] ‘Héréd. Nat.,’ tom. ii. pp. 112-120.

 [3] Sir H. Holland, ‘Chapters on Mental Physiology,’ 1852, p. 234.

 [4] ‘Gardener’s Chronicle,’ 1860, p. 270.

 [5] Mr. N. H. Smith, ‘Observations on Breeding,’ quoted in ‘Encyclop.
 of Rural Sports,’ p. 278.

 [6] Quoted by Bronn, ‘Geshichte der Natur,’ b. ii. s. 170. _ See_
 Sturm, ‘Ueber Racen,’ 1825, s. 104-107. For the niata cattle, _see_ my
 ‘Journal of Researches,’ 1845, p. 146.

 [7] Lucas, ‘L’Hérédite Nat.,’ tom. ii. p. 112.

 [8] Mr. Orton, ‘Physiology of Breeding,’ 1855, p. 9.

 [9] Boitard and Corbié, ‘Les Pigeons,’ 1824, p. 224.

 [10] ‘Les Pigeons,’ pp. 168, 198.

 [11] ‘Das Ganze,’ etc., 1837, s. 39.

 [12] ‘The Pigeon Book,’ p. 46.

 [13] ‘Physiology of Breeding,’ p. 22; Mr. Hewitt, in ‘The Poultry
 Book,’ by Tegetmeier, 1866, p. 224.

 [14] Boitard and Corbié, ‘Les Pigeons,’ 1824, p. 226.

 [15] ‘Bastarderzeugung,’ s. 256, 290, etc. Naudin (‘Nouvelles Archives
 du Muséum,’ tom. i. p. 149) gives a striking instance of prepotency in
 _Datura stramonium_ when crossed with two other species.

 [16] Flourens, ‘Longévité Humaine,’ p. 144, on crossed jackals. With
 respect to the difference between the mule and the hinny I am aware
 that this has generally been attributed to the sire and dam
 transmitting their characters differently; but Colin, who has given in
 his ‘Traité Phys. Comp.,’ tom. ii. pp. 537-539, the fullest
 description which I have met with of these reciprocal hybrids, is
 strongly of opinion that the ass preponderates in both crosses, but in
 an unequal degree. This is likewise the conclusion of Flourens, and of
 Bechstein in his ‘Naturgeschichte Deutschlands,’ b. i. s. 294. The
 tail of the hinny is much more like that of the horse than is the tail
 of the mule, and this is generally accounted for by the males of both
 species transmitting with greater power this part of their structure;
 but a compound hybrid which I saw in the Zoological Gardens, from a
 mare by a hybrid ass-zebra, closely resembled its mother in its tail.

 [17] Mr. Hewitt, who has had such great experience in raising these
 hybrids says (‘Poultry Book,’ by Mr. Tegetmeier, 1866, pp. 165-167)
 that in all, the head was destitute of wattles, comb, and ear-lappets;
 and all closely resembled the pheasant in the shape of the tail and
 general contour of the body. These hybrids were raised from hens of
 several breeds by a cock-pheasant; but another hybrid, described by
 Mr. Hewitt, was raised from a hen-pheasant, by a silver-laced Bantam
 cock, and this possessed a rudimental comb and wattles.

 [18] ‘L’Héréd. Nat.’ tom. ii. 2 book ii. ch. i.

 [19] ‘Bastarderzeugung,’ s. 264-266. Naudin (‘Nouvelles Archives du
 Muséum,’ tom. i. p. 148) has arrived at a similar conclusion.

 [20] ‘Cottage Gardener,’ 1856, pp. 101, 137.

 [21] _See_ some remarks on this head with respect to sheep by Mr.
 Wilson, in ‘Gardener’s Chronicle,’ 1863, p. 15. Many striking
 instances of this result are given by M. Malingié-Nouel (‘Journ. R.
 Agricult. Soc.,’ vol. xiv. 1853, p. 220) with respect to crosses
 between English and French sheep. He found that he obtained the
 desired influence of the English breeds by crossing intentionally
 mongrelised French breeds with pure English breeds.

 [22] Verlot, ‘Des Variétés,’ 1865, p. 66.

 [23] Moquin-Tandon, ‘Tératologie,’ p. 191.

 [24] ‘Nouvelles Archives du Muséum,’ tom. i. p. 137.

 [25] ‘L’Héréd. Nat.,’ tom. ii. pp. 137-165. _See also_ Mr. Sedgwick’s
 four memoirs, immediately to be referred to.

 [26] ‘Descent of Man,’ 2nd edit., p. 32.

 [27] On Sexual Limitation in Hereditary Diseases, ‘Brit. and For.
 Med.-Chirurg. Review,’ April 1861, p. 477; July, p. 198; April 1863,
 p. 445; and July, p. 159. Also in 1867, ‘On the influence of Age in
 Hereditary Disease.’

 [28] W. Scrope, ‘Art of Deer Stalking,’ p. 354.

 [29] I have given in my ‘Descent of Man’ (2nd edit. p. 223) sufficient
 evidence that male animals are usually more variable than the females.

 [30] Prichard, ‘Phys. Hist. of Mankind,’ 1851, vol. i. p. 349.

 [31] ‘Embassy to the Court of Ava,’ vol. i. p. 320. The third
 generation is described by Capt. Yule in his ‘Narrative of the Mission
 to the Court of Ava,’ 1855, p. 94.

 [32] ‘Das Ganze der Taubenzucht,’ 1837, s. 24, tab. iv., fig. 2; s.
 21, tab. i., fig. 4.

 [33] Kidd’s ‘Treatise on the Canary,’ p. 18.

 [34] Charlesworth, ‘Mag. of Nat. Hist.,’ vol. i. 1837, p. 167.

 [35] Dr. Prosper Lucas, ‘Héréd. Nat.,’ tom. ii. p. 713.

 [36] ‘L’Héréd. dans les Maladies,’ 1840, p. 135. For Hunter, _see_
 Harlan’s ‘Med. Researches,’ p. 530.

 [37] ‘L’Héréd. Nat.,’ tom. ii. p. 850.

 [38] Sedgwick, ‘Brit. and For. Med.-Chirurg. Review,’ April, 1861, p.
 485. In some accounts the number of children and grandchildren is
 given as 37; but this seems to be an error judging from the paper
 first published in the ‘Baltimore Med. and Phys. Reg.’ 1809, of which
 Mr. Sedgwick has been so kind as to send me a copy.

 [39] Prosper Lucas, ‘Héréd. Nat.,’ tom. i. p. 400.

 [40] Sedgwick, ibid., July, 1861, p. 202.

 [41] Piorry, p. 109; Prosper Lucas, tom. ii. p. 759.

 [42] Prosper Lucas, tom. ii. p. 748.

 [43] Prosper Lucas, tom. iii. pp. 678, 700, 702; Sedgwick, ibid.,
 April, 1863, p. 449, and July, 1863, p. 162. Dr. J. Steinan ‘Essay on
 Hereditary Disease,’ 1843, pp. 27, 34.

 [44] These cases are given by Mr. Sedgwick on the authority of Dr. H.
 Stewart, in ‘Med.-Chirurg. Review,’ April, 1863, pp. 449, 477.

 [45] ‘Héréd. Nat.,’ tom. ii. p. 852.




CHAPTER XV. ON CROSSING.

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED
BREEDS—WHEN THE NUMBERS OF TWO COMMINGLING BREEDS ARE UNEQUAL, ONE
ABSORBS THE OTHER—THE RATE OF ABSORPTION DETERMINED BY PREPOTENCY OF
TRANSMISSION, BY THE CONDITIONS OF LIFE, AND BY NATURAL SELECTION—ALL
ORGANIC BEINGS OCCASIONALLY INTERCROSS; APPARENT EXCEPTIONS—ON CERTAIN
CHARACTERS INCAPABLE OF FUSION; CHIEFLY OR EXCLUSIVELY THOSE WHICH HAVE
SUDDENLY APPEARED IN THE INDIVIDUAL—ON THE MODIFICATION OF OLD RACES,
AND THE FORMATION OF NEW RACES BY CROSSING—SOME CROSSED RACES HAVE BRED
TRUE FROM THEIR FIRST PRODUCTION—ON THE CROSSING OF DISTINCT SPECIES IN
RELATION TO THE FORMATION OF DOMESTIC RACES.


In the two previous chapters, when discussing reversion and prepotency,
I was necessarily led to give many facts on crossing. In the present
chapter I shall consider the part which crossing plays in two opposed
directions,—firstly, in obliterating characters, and consequently in
preventing the formation of new races; and secondly, in the
modification of old races, or in the formation of new and intermediate
races, by a combination of characters. I shall also show that certain
characters are incapable of fusion.

The effects of free or uncontrolled breeding between the members of the
same variety or of closely allied varieties are important; but are so
obvious that they need not be discussed at much length. It is free
intercrossing which chiefly gives uniformity, both under nature and
under domestication, to the individuals of the same species or variety,
when they live mingled together and are not exposed to any cause
inducing excessive variability. The prevention of free crossing, and
the intentional matching of individual animals, are the corner-stones
of the breeder’s art. No man in his senses would expect to improve or
modify a breed in any particular manner, or keep an old breed true and
distinct, unless he separated his animals. The killing of inferior
animals in each generation comes to the same thing as their separation.
In savage and semi-civilised countries, where the inhabitants have not
the means of separating their animals, more than a single breed of the
same species rarely or never exists. In former times, even in the
United States, there were no distinct races of sheep, for all had been
mingled together.[1] The celebrated agriculturist Marshall[2] remarks
that “sheep that are kept within fences, as well as shepherded flocks
in open countries, have generally a similarity, if not a uniformity, of
character in the individuals of each flock;” for they breed freely
together, and are prevented from crossing with other kinds; whereas in
the unenclosed parts of England the unshepherded sheep, even of the
same flock, are far from true or uniform, owing to various breeds
having mingled and crossed. We have seen that the half-wild cattle in
each of the several British parks are nearly uniform in character; but
in the different parks, from not having mingled and crossed during many
generations, they differ to a certain small extent.

We cannot doubt that the extraordinary number of varieties and
sub-varieties of the pigeon, amounting to at least one hundred and
fifty, is partly due to their remaining, differently from other
domesticated birds, paired for life once matched. On the other hand,
breeds of cats imported into this country soon disappear, for their
nocturnal and rambling habits render it hardly possible to prevent free
crossing. Rengger[3] gives an interesting case with respect to the cat
in Paraguay: in all the distant parts of the kingdom it has assumed,
apparently from the effects of the climate, a peculiar character, but
near the capital this change has been prevented, owing, as he asserts,
to the native animal frequently crossing with cats imported from
Europe. In all cases like the foregoing, the effects of an occasional
cross will be augmented by the increased vigour and fertility of the
crossed offspring, of which fact evidence will hereafter be given; for
this will lead to the mongrels increasing more rapidly than the pure
parent-breeds.

When distinct breeds are allowed to cross freely, the result will be a
heterogeneous body; for instance, the dogs in Paraguay are far from
uniform, and can no longer be affiliated to their parent-races.[4] The
character which a crossed body of animals will ultimately assume must
depend on several contingencies,—namely, on the relative members of the
individuals belonging to the two or more races which are allowed to
mingle; on the prepotency of one race over the other in the
transmission of character; and on the conditions of life to which they
are exposed. When two commingled breeds exist at first in nearly equal
numbers, the whole will sooner or later become intimately blended, but
not so soon, both breeds being equally favoured in all respects, as
might have been expected. The following calculation[5] shows that this
is the case: if a colony with an equal number of black and white men
were founded, and we assume that they marry indiscriminately, are
equally prolific, and that one in thirty annually dies and is born;
then “in 65 years the number of blacks, whites, and mulattoes would be
equal. In 91 years the whites would be 1-10th, the blacks 1-10th, and
the mulattoes, or people of intermediate degrees of colour, 8-10ths of
the whole number. In three centuries not 1-100th part of the whites
would exist.”

When one of two mingled races exceed the other greatly in number, the
latter will soon be wholly, or almost wholly, absorbed and lost.[6]
Thus European pigs and dogs have been largely introduced in the islands
of the Pacific Ocean, and the native races have been absorbed and lost
in the course of about fifty or sixty years;[7] but the imported races
no doubt were favoured. Rats may be considered as semi-domesticated
animals. Some snake-rats (_Mus alexandrinus_) escaped in the Zoological
Gardens of London “and for a long time afterwards the keepers
frequently caught cross-bred rats, at first half-breds, afterwards with
less of the character of the snake-rat, till at length all traces of it
disappeared.”[8] On the other hand, in some parts of London, especially
near the docks, where fresh rats are frequently imported, an endless
variety of intermediate forms may be found between the brown, black,
and snake rat, which are all three usually ranked as distinct species.

How many generations are necessary for one species or race to absorb
another by repeated crosses has often been discussed;[9] and the
requisite number has probably been much exaggerated. Some writers have
maintained that a dozen or score, or even more generations, are
necessary; but this in itself is improbable, for in the tenth
generation there would be only 1-1024th part of foreign blood in the
offspring. Gärtner found,[10] that with plants, one species could be
made to absorb another in from three to five generations, and he
believes that this could always be effected in from six to seven
generations. In one instance, however, Kolreuter[11] speaks of the
offspring of _Mirabilis vulgaris,_ crossed during eight successive
generations by _M. longiflora,_ as resembling this latter species so
closely, that the most scrupulous observer could detect “vix aliquam
notabilem differentiam” or, as he says, he succeeded, “ad plenariam
fere transmutationem.” But this expression shows that the act of
absorption was not even then absolutely complete, though these crossed
plants contained only the 1-256th part of _M. vulgaris._ The
conclusions of such accurate observers as Gärtner and Kölreuter are of
far higher worth than those made without scientific aim by breeders.
The most precise account which I have met with is given by
Stonehenge[12] and is illustrated by photographs. Mr. Hanley crossed a
greyhound bitch with a bulldog; the offspring in each succeeding
generation being recrossed with first-rate greyhounds. As Stonehenge
remarks, it might naturally be supposed that it would take several
crosses to get rid of the heavy form of the bulldog; but Hysterics, the
gr-gr-granddaughter of a bulldog, showed no trace whatever of this
breed in external form. She and all of the same litter, however, were
“remarkably deficient in stoutness, though fast as well as clever.” I
believe clever refers to skill in turning. Hysterics was put to a son
of Bedlamite, “but the result of the fifth cross is not as yet, I
believe, more satisfactory than that of the fourth.” On the other hand,
with sheep, Fleischmann[13] shows how persistent the effects of a
single cross may be: he says “that the original coarse sheep (of
Germany) have 5500 fibres of wool on a square inch; grades of the third
or fourth Merino cross produced about 8000, the twentieth cross 27,000,
the perfect pure Merino blood 40,000 to 48,000.” So that common German
sheep crossed twenty times successively with Merino did not by any
means acquire wool as fine as that of the pure breed. But in all cases,
the rate of absorption will depend largely on the conditions of life
being favourable to any particular character; and we may suspect that
there would be a constant tendency to degeneration in the wool of
Merinos under the climate of Germany, unless prevented by careful
selection; and thus perhaps the foregoing remarkable case may be
explained. The rate of absorption must also depend on the amount of
distinguishable difference between the two forms which are crossed, and
especially, as Gärtner insists, on prepotency of transmission in the
one form over the other. We have seen in the last chapter that one of
two French breeds of sheep yielded up its character, when crossed with
Merinos, very much more slowly than the other; and the common German
sheep referred to by Fleischmann may be in this respect analogous. In
all cases there will be more or less liability to reversion during many
subsequent generations, and it is this fact which has probably led
authors to maintain that a score or more of generations are requisite
for one race to absorb another. In considering the final result of the
commingling of two or more breeds, we must not forget that the act of
crossing in itself tends to bring back long-lost characters not proper
to the immediate parent-forms.

With respect to the influence of the conditions of life on any two
breeds which are allowed to cross freely, unless both are indigenous
and have long been accustomed to the country where they live, they
will, in all probability, be unequally affected by the conditions, and
this will modify the result. Even with indigenous breeds, it will
rarely or never occur that both are equally well adapted to the
surrounding circumstances; more especially when permitted to roam
freely, and not carefully tended, as is generally the case with breeds
allowed to cross. As a consequence of this, natural selection will to a
certain extent come into action, and the best fitted will survive, and
this will aid in determining the ultimate character of the commingled
body.

How long a time it would require before such a crossed body of animals
would assume a uniform character within a limited area, no one can say;
that they would ultimately become uniform from free intercrossing, and
from the survival of the fittest, we may feel assured; but the
characters thus acquired would rarely or never, as may be inferred from
the previous considerations, be exactly intermediate between those of
the two parent-breeds. With respect to the very slight differences by
which the individuals of the same sub-variety, or even of allied
varieties, are characterised, it is obvious that free crossing would
soon obliterate such small distinctions. The formation of new
varieties, independently of selection, would also thus be prevented;
except when the same variation continually recurred from the action of
some strongly predisposing cause. We may therefore conclude that free
crossing has in all cases played an important part in giving uniformity
of character to all the members of the same domestic race and of the
same natural species, though largely governed by natural selection and
by the direct action of the surrounding conditions.

_On the possibility of all organic beings occasionally
intercrossing._—But it may be asked, can free crossing occur with
hermaphrodite animals and plants? All the higher animals, and the few
insects which have been domesticated, have separate sexes, and must
inevitably unite for each birth. With respect to the crossing of
hermaphrodites, the subject is too large for the present volume, but in
the ‘Origin of Species’ I have given a short abstract of the reasons
which induce me to believe that all organic beings occasionally cross,
though perhaps in some cases only at long intervals of time.[14] I will
merely recall the fact that many plants, though hermaphrodite in
structure, are unisexual in function;—such as those called by C.K.
Sprengel _dichogamous,_ in which the pollen and stigma of the same
flower are matured at different periods; or those called by me
_reciprocally dimorphic,_ in which the flower’s own pollen is not
fitted to fertilise its own stigma; or again, the many kinds in which
curious mechanical contrivances exist, effectually preventing
self-fertilisation. There are, however, many hermaphrodite plants which
are not in any way specially constructed to favour intercrossing, but
which nevertheless commingle almost as freely as animals with separated
sexes. This is the case with cabbages, radishes, and onions, as I know
from having experimented on them: even the peasants of Liguria say that
cabbages must be prevented “from falling in love” with each other. In
the orange tribe, Gallesio[15] remarks that the amelioration of the
various kinds is checked by their continual and almost regular
crossing. So it is with numerous other plants.

On the other hand, some cultivated plants rarely or never intercross,
for instance, the common pea and sweet-pea (_Lathyrus odoratus_); yet
their flowers are certainly adapted for cross fertilisation. The
varieties of the tomato and aubergine (_Solanum_) and the pimenta
(_Pimenta vulgaris?_) are said[16] never to cross, even when growing
alongside one another. But it should be observed that these are all
exotic plants, and we do not know how they would behave in their native
country when visited by the proper insects. With respect to the common
pea, I have ascertained that it is rarely crossed in this country owing
to premature fertilisation. There exist, however, some plants which
under their natural conditions appear to be always self-fertilised,
such as the Bee Ophrys (_Ophrys apifera_) and a few other Orchids; yet
these plants exhibit the plainest adaptations for cross-fertilisation.
Again, some few plants are believed to produce only closed flowers,
called cleistogene, which cannot possibly be crossed. This was long
thought to be the case with the _Leersia oryzoides,_[17] but this grass
is now known occasionally to produce perfect flowers, which set seed.

Although some plants, both indigenous and naturalised, rarely or never
produce flowers, or if they flower never produce seeds, yet no one
doubts that phanerogamic plants are adapted to produce flowers, and the
flowers to produce seed. When they fail, we believe that such plants
under different conditions would perform their proper function, or that
they formerly did so, and will do so again. On analogous grounds, I
believe that the flowers in the above specified anomalous cases which
do not now intercross, either would do so occasionally under different
conditions, or that they formerly did so—the means for affecting this
being generally still retained—and will again intercross at some future
period, unless indeed they become extinct. On this view alone, many
points in the structure and action of the reproductive organs in
hermaphrodite plants and animals are intelligible,—for instance, the
fact of the male and female organs never being so completely enclosed
as to render access from without impossible. Hence we may conclude that
the most important of all the means for giving uniformity to the
individuals of the same species, namely, the capacity of occasionally
intercrossing, is present, or has been formerly present, with all
organic beings, except, perhaps, some of the lowest.

_On certain Characters not blending._—When two breeds are crossed their
characters usually become intimately fused together; but some
characters refuse to blend, and are transmitted in an unmodified state
either from both parents or from one. When grey and white mice are
paired, the young are piebald, or pure white or grey, but not of an
intermediate tint; so it is when white and common collared turtle-doves
are paired. In breeding Game fowls, a great authority, Mr. J. Douglas,
remarks, “I may here state a strange fact: if you cross a black with a
white game, you get birds of both breeds of the clearest colour.” Sir
R. Heron crossed during many years white, black, brown, and
fawn-coloured Angora rabbits, and never once got these colours mingled
in the same animal, but often all four colours in the same litter.[18]
From cases like these, in which the colours of the two parents are
transmitted quite separately to the offspring, we have all sorts of
gradations, leading to complete fusion. I will give an instance: a
gentleman with a fair complexion, light hair but dark eyes, married a
lady with dark hair and complexion: their three children have very
light hair, but on careful search about a dozen black hairs were found
scattered in the midst of the light hair on the heads of all three.

When turnspit dogs and ancon sheep, both of which have dwarfed limbs,
are crossed with common breeds, the offspring are not intermediate in
structure, but take after either parent. When tailless or hornless
animals are crossed with perfect animals, it frequently, but by no
means invariably, happens that the offspring are either furnished with
these organs in a perfect state, or are quite destitute of them.
According to Rengger, the hairless condition of the Paraguay dog is
either perfectly or not at all transmitted to its mongrel offspring;
but I have seen one partial exception in a dog of this parentage which
had part of its skin hairy, and part naked, the parts being distinctly
separated as in a piebald animal. When Dorking fowls with five toes are
crossed with other breeds, the chickens often have five toes on one
foot and four on the other. Some crossed pigs raised by Sir R. Heron
between the solid-hoofed and common pig had not all four feet in an
intermediate condition, but two feet were furnished with properly
divided, and two with united hoofs.

Analogous facts have been observed with plants: Major Trevor Clarke
crossed the little, glabrous-leaved, annual stock (Matthiola), with
pollen of a large, red-flowered, rough-leaved, biennial stock, called
_cocardeau_ by the French, and the result was that half the seedlings
had glabrous and the other half rough leaves, but none had leaves in an
intermediate state. That the glabrous seedlings were the product of the
rough-leaved variety, and not accidentally of the mother-plant’s own
pollen, was shown by their tall and strong habit of growth.[19] in the
succeeding generations raised from the rough-leaved crossed seedlings,
some glabrous plants appeared, showing that the glabrous character,
though incapable of blending with and modifying the rough leaves, was
all the time latent in this family of plants. The numerous plants
formerly referred to, which I raised from reciprocal crosses between
the peloric and common Antirrhinum, offer a nearly parallel case; for
in the first generation all the plants resembled the common form, and
in the next generation, out of one hundred and thirty-seven plants, two
alone were in an intermediate condition, the others perfectly
resembling either the peloric or common form. Major Trevor Clarke also
fertilised the above-mentioned red-flowered stock with pollen from the
purple Queen stock, and about half the seedlings scarcely differed in
habit, and not at all in the red colour of the flower, from the
mother-plant, the other half bearing blossoms of a rich purple, closely
like those of the paternal plant. Gärtner crossed many white and
yellow-flowered species and varieties of Verbascum; and these colours
were never blended, but the offspring bore either pure white or pure
yellow blossoms; the former in the larger proportion.[20] Dr. Herbert
raised many seedlings, as he informed me, from Swedish turnips crossed
by two other varieties, and these never produced flowers of an
intermediate tint, but always like one of their parents. I fertilised
the purple sweet-pea (_Lathyrus odoratus_), which has a dark
reddish-purple standard-petal and violet-coloured wings and keel, with
pollen of the painted lady sweet-pea, which has a pale cherry-coloured
standard, and almost white wings and keel; and from the same pod I
twice raised plants perfectly resembling both sorts; the greater number
resembling the father. So perfect was the resemblance, that I should
have thought there had been some mistake, if the plants which were at
first identical with the paternal variety, namely, the painted-lady,
had not later in the season produced, as mentioned in a former chapter,
flowers blotched and streaked with dark purple. I raised grandchildren
and great-grandchildren from these crossed plants, and they continued
to resemble the painted-lady, but during later generations became
rather more blotched with purple, yet none reverted completely to the
original mother-plant, the purple sweet-pea. The following case is
slightly different, but still shows the same principle: Naudin[21]
raised numerous hybrids between the yellow _Linaria vulgaris_ and the
purple _L. purpurea,_ and during three successive generations the
colours kept distinct in different parts of the same flower.

From cases such as the foregoing, in which the offspring of the first
generation perfectly resemble either parent, we come by a small step to
those cases in which differently coloured flowers borne on the same
root resemble both parents, and by another step to those in which the
same flower or fruit is striped or blotched with the two parental
colours, or bears a single stripe of the colour or other characteristic
quality of one of the parent-forms. With hybrids and mongrels it
frequently or even generally happens that one part of the body
resembles more or less closely one parent and another part the other
parent; and here again some resistence to fusion, or, what comes to the
same thing, some mutual affinity between the organic atoms of the same
nature, apparently comes into play, for otherwise all parts of the body
would be equally intermediate in character. So again, when the
offspring of hybrids or mongrels, which are themselves nearly
intermediate in character, revert either wholly or by segments to their
ancestors, the principle of the affinity of similar, or the repulsion
of dissimilar atoms, must come into action. To this principle, which
seems to be extremely general, we shall recur in the chapter on
pangenesis.

It is remarkable, as has been strongly insisted upon by Isidore
Geoffroy St. Hilaire in regard to animals, that the transmission of
characters without fusion occurs very rarely when species are crossed;
I know of one exception alone, namely, with the hybrids naturally
produced between the common and hooded crow (_Corvus corone_ and
_cornix_), which, however, are closely allied species, differing in
nothing except colour. Nor have I met with any well-ascertained cases
of transmission of this kind, even when one form is strongly prepotent
over another, when two races are crossed which have been slowly formed
by man’s selection, and therefore resemble to a certain extent natural
species. Such cases as puppies in the same litter closely resembling
two distinct breeds, are probably due to superfoetation,—that is, to
the influence of two fathers. All the characters above enumerated,
which are transmitted in a perfect state to some of the offspring and
not to others,— such as distinct colours, nakedness of skin, smoothness
of leaves, absence of horns or tail, additional toes, pelorism, dwarfed
structure, etc.,—have all been known to appear suddenly in individual
animals and plants. From this fact, and from the several slight,
aggregated differences which distinguish domestic races and species
from one another, not being liable to this peculiar form of
transmission, we may conclude that it is in some way connected with the
sudden appearance of the characters in question.

_On the Modification of old Races and the Formation of new Races by
Crossing._—We have hitherto chiefly considered the effects of crossing
in giving uniformity of character; we must now look to an opposite
result. There can be no doubt that crossing, with the aid of rigorous
selection during several generations, has been a potent means in
modifying old races, and in forming new ones. Lord Orford crossed his
famous stud of greyhounds once with the bulldog, in order to give them
courage and perseverance. Certain pointers have been crossed, as I hear
from the Rev. W. D. Fox, with the foxhound, to give them dash and
speed. Certain strains of Dorking fowls have had a slight infusion of
Game blood; and I have known a great fancier who on a single occasion
crossed his turbit-pigeons with barbs, for the sake of gaining greater
breadth of beak.

In the foregoing cases breeds have been crossed once, for the sake of
modifying some particular character; but with most of the improved
races of the pig, which now breed true, there have been repeated
crosses,—for instance, the improved Essex owes its excellence to
repeated crosses with the Neapolitan, together probably with some
infusion of Chinese blood.[22] So with our British sheep: almost all
the races, except the Southdown, have been largely crossed; “this, in
fact, has been the history of our principal breeds.”[23] To give an
example, the “Oxfordshire Downs” now rank as an established breed.[24]
They were produced about the year 1830 by crossing “Hampshire and in
some instances Southdown ewes with Cotswold rams:” now the Hampshire
ram was itself produced by repeated crosses between the native
Hampshire sheep and Southdowns; and the long-woolled Cotswold were
improved by crosses with the Leicester, which latter again is believed
to have been a cross between several long-woolled sheep. Mr. Spooner,
after considering the various cases which have been carefully recorded,
concludes, “that from a judicious pairing of cross-bred animals it is
practicable to establish a new breed.” On the continent the history of
several crossed races of cattle and of other animals has been well
ascertained. To give one instance: the King of Wurtemburg, after
twenty-five years’ careful breeding, that is, after six or seven
generations, made a new breed of cattle from a cross between a Dutch
and a Swiss breed, combined with other breeds.[25] The Sebright bantam,
which breeds as true as any other kind of fowl, was formed about sixty
years ago by a complicated cross.[26] Dark Brahmas, which are believed
by some fanciers to constitute a distinct species, were undoubtedly
formed[27] in the United States, within a recent period, by a cross
between Chittagongs and Cochins. With plants there is little doubt that
the Swede-turnip originated from a cross; and the history of a variety
of wheat, raised from two very distinct varieties, and which after six
years’ culture presented an even sample, has been recorded on good
authority.[28]

Until lately, cautious and experienced breeders, though not averse to a
single infusion of foreign blood, were almost universally convinced
that the attempt to establish a new race, intermediate between two
widely distinct races, was hopeless “they clung with superstitious
tenacity to the doctrine of purity of blood, believing it to be the ark
in which alone true safety could be found.”[29] Nor was this conviction
unreasonable: when two distinct races are crossed, the offspring of the
first generation are generally nearly uniform in character; but even
this sometimes fails to be the case, especially with crossed dogs and
fowls, the young of which from the first are sometimes much
diversified. As cross-bred animals are generally of large size and
vigorous, they have been raised in great numbers for immediate
consumption. But for breeding they are found utterly useless; for
though they may themselves be uniform in character, they yield during
many generations astonishingly diversified offspring. The breeder is
driven to despair, and concludes that he will never form an
intermediate race. But from the cases already given, and from others
which have been recorded, it appears that patience alone is necessary;
as Mr. Spooner remarks, “nature opposes no barrier to successful
admixture; in the course of time, by the aid of selection and careful
weeding, it is practicable to establish a new breed.” After six or
seven generations the hoped-for result will in most cases be obtained;
but even then an occasional reversion, or failure to keep true, may be
expected. The attempt, however, will assuredly fail if the conditions
of life be decidedly unfavourable to the characters of either
parent-breed.[30]

Although the grandchildren and succeeding generations of cross-bred
animals are generally variable in an extreme degree, some curious
exceptions to the rule have been observed both with crossed races and
species. Thus Boitard and Corbié[31] assert that from a Pouter and a
Runt “a Cavalier will appear, which we have classed amongst pigeons of
pure race, because it transmits all its qualities to its posterity.”
The editor of the ‘Poultry Chronicle’[32] bred some bluish fowls from a
black Spanish cock and a Malay hen; and these remained true to colour
“generation after generation.” The Himalayan breed of rabbits was
certainly formed by crossing two sub-varieties of the silver-grey
rabbit; although it suddenly assumed its present character, which
differs much from that of either parent-breed, yet it has ever since
been easily and truly propagated. I crossed some Labrador and Penguin
ducks, and recrossed the mongrels with Penguins; afterwards most of the
ducks reared during three generations were nearly uniform in character,
being brown with a white crescentic mark on the lower part of the
breast, and with some white spots at the base of the beak; so that by
the aid of a little selection a new breed might easily have been
formed. With regard to crossed varieties of plants, Mr. Beaton[33]
remarks that “Melville’s extraordinary cross between the Scotch kale
and an early cabbage is as true and genuine as any on record;” but in
this case no doubt selection was practised. Gärtner[34] has given five
cases of hybrids, in which the progeny kept constant; and hybrids
between _Dianthus armeria_ and _deltoides_ remained true and uniform to
the tenth generation. Dr. Herbert likewise showed me a hybrid from two
species of Loasa which from its first production had kept constant
during several generations.

We have seen in the first chapter, that the several kinds of dogs are
almost certainly descended from more than one species, and so it is
with cattle, pigs and some other domesticated animals. Hence the
crossing of aboriginally distinct species probably came into play at an
early period in the formation of our present races. From Rutimeyer’s
observations there can be little doubt that this occurred with cattle;
but in most cases one form will probably have absorbed and obliterated
the other, for it is not likely that semi-civilised men would have
taken the necessary pains to modify by selection their commingled,
crossed, and fluctuating stock. Nevertheless, those animals which were
best adapted to their conditions of life would have survived through
natural selection; and by this means crossing will often have
indirectly aided in the formation of primeval domesticated breeds.
Within recent times, as far as animals are concerned, the crossing of
distinct species has done little or nothing towards the formation or
modification of our races. It is not yet known whether the several
species of silk-moth which have been recently crossed in France will
yield permanent races. With plants which can be multiplied by buds and
cuttings, hybridisation has done wonders, as with many kinds of Roses,
Rhododendrons, Pelargoniums, Calceolarias, and Petunias. Nearly all
these plants can be propagated by seed, most of them freely; but
extremely few or none come true by seed.

Some authors believe that crossing is the chief cause of
variability,—that is, of the appearance of absolutely new characters.
Some have gone so far as to look at it as the sole cause; but this
conclusion is disproved by the facts given in the chapter on
Bud-variation. The belief that characters not present in either parent
or in their ancestors frequently originate from crossing is doubtful;
that they occasionally do so is probable; but this subject will be more
conveniently discussed in a future chapter on the causes of
Variability.

A condensed summary of this and of the three following chapters,
together with some remarks on Hybridism, will be given in the
nineteenth chapter.

REFERENCES

 [1] ‘Communications to the Board of Agriculture,’ vol. i. p. 367.

 [2] ‘Review of Reports, North of England,’ 1808, p. 200.

 [3] ‘Säugethiere von Paraguay,’ 1830, s. 212.

 [4] Rengger, ‘Säugethiere,’ etc., s. 154.

 [5] White, ‘Regular Gradation in Man,’ p. 146.

 [6] Dr. W. F. Edwards, in his ‘Caractères Physiolog. des Races
 Humaines,’ p. 24, first called attention to this subject, and ably
 discussed it.

 [7] Rev. D. Tyerman and Bennett, ‘Journal of Voyages,’ 1821-1829, vol.
 i. p. 300.

 [8] Mr. S. J. Salter, ‘Journal Linn. Soc.,’ vol. vi., 1862, p. 71.

 [9] Sturm, ‘Ueber Racen, etc.,’ 1825, s. 107. Bronn, ‘Geschichte der
 Natur,’ b. ii. s. 170, gives a table of the proportions of blood after
 successive crosses. Dr. P. Lucas, ‘L’Hérédité Nat.,’ tom. ii. p. 308.

 [10] ‘Bastarderzeugung,’ s. 463, 470.

 [11] ‘Nova Acta Petrop.,’ 1794, p. 393: _see also_ previous volume.

 [12] ‘The Dog,’ 1867, pp. 179-184.

 [13] As quoted in the ‘True Principles of Breeding,’ by C. H.
 Macknight and Dr. H. Madden, 1865, p. 11.

 [14] With respect to plants, an admirable essay on this subject (Die
 Geschlechter-Vertheilung bei den Pflanzen: 1867) has been published by
 Dr. Hildebrand, who arrives at the same general conclusions as I have
 done. Various other treatises have since appeared on the same subject,
 more especially by Hermann Müller and Delpino.

 [15] ‘Teoria della Riproduzione Vegetal,’ 1816, p. 12.

 [16] Verlot ‘Des Variétés,’ 1865, p. 72.

 [17] Duval Jouve, ‘Bull. Soc. Bot. de France,’ tom. x., 1863, p. 194.
 With respect to the perfect flowers setting seed, _see_ Dr. Ascherson
 in ‘Bot. Zeitung,’ 1864, p. 350.

 [18] Extract of a letter from Sir R. Heron, 1838, given me by Mr.
 Yarrell. With respect to mice, _see_ ‘Annal. des Sc. Nat.,’ tom. i. p.
 180; and I have heard of other similar cases. For turtle-doves Boitard
 and Corbié, ‘Les Pigeons,’ etc., p. 238. For the Game fowl, ‘The
 Poultry Book,’ 1866, p. 128. For crosses of tailless fowls _see_
 Bechstein, ‘Naturges. Deutsch.’ b. iii. s. 403. Bronn, ‘Geschichte der
 Natur,’ b. ii. s. 170, gives analogous facts with horses. On the
 hairless condition of crossed South American dogs, _see_ Rengger,
 ‘Säugethiere von Paraguay,’ s. 152; but I saw in the Zoological
 Gardens mongrels, from a similar cross, which were hairless, quite
 hairy, or hairy in patches, that is, piebald with hair. For crosses of
 Dorking and other fowls, _see_ ‘Poultry Chronicle,’ vol. ii. p. 355.
 About the crossed pigs, extract of letter from Sir R. Heron to Mr.
 Yarrell. For other cases, _ see_ P. Lucas ‘L’Héréd. Nat.’ tom. i. p.
 212.

 [19] ‘Internat. Hort. and Bot. Congress of London,’ 1866.

 [20] ‘Bastarderzeugung,’ s. 307. Kölreuter (‘Dritte Fortsetszung,’ s.
 34, 39), however, obtained intermediate tints from similar crosses in
 the genus Verbascum. With respect to the turnips, _see_ Herbert’s
 ‘Amaryllidaceæ,’ 1837, p. 370.

 [21] ‘Nouvelles Archives du Muséum,’ tom. i. p. 100.

 [22] Richardson, ‘Pigs,’ 1847, pp. 37, 42; S. Sidney’s edition of
 ‘Youatt on the Pig,’ 1860, p. 3.

 23[] _See_ Mr. W. C. Spooner’s excellent paper on Cross-Breeding,
 ‘Journal Royal Agricult. Soc.,’ vol. xx., part ii.: _see also_ an
 equally good article by Mr. Ch. Howard, in ‘Gardener’s Chronicle,’
 1860, p. 320.

 [24] ‘Gardener’s Chronicle,’ 1857, pp. 649, 652.

 [25] ‘Bulletin de la Soc. d’Acclimat.,’ 1862, tom. ix. p. 463. _ See
 also_ for other cases MM. Moll and Gayot, ‘Du Bœuf,’ 1860, p. 32.

 [26] ‘Poultry Chronicle,’ vol. ii., 1854, p. 36.

 [27] ‘The Poultry Book,’ by W. B. Tegetmeier, 1866, p. 58.

 [28] ‘Gardener’s Chronicle,’ 1852, p. 765.

 [29] Spooner, in ‘Journal Royal Agricult. Soc.,’ vol. xx., part ii.

 [30] _See_ Colin’s ‘Traité de Phys. Comp. des Animaux Domestiques,’
 tom. ii. p. 536, where this subject is well treated.

 [31] ‘Les Pigeons,’ p. 37.

 [32] Vol. i., 1854, p. 101.

 [33] ‘Cottage Gardener,’ 1856, p. 110.

 [34] ‘Bastarderzeugung,’ s. 553.




CHAPTER XVI. CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF
VARIETIES—INFLUENCE OF DOMESTICATION ON FERTILITY.

DIFFICULTIES IN JUDGING OF THE FERTILITY OF VARIETIES WHEN CROSSED.
VARIOUS CAUSES WHICH KEEP VARIETIES DISTINCT, AS THE PERIOD OF BREEDING
AND SEXUAL PREFERENCE—VARIETIES OF WHEAT SAID TO BE STERILE WHEN
CROSSED—VARIETIES OF MAIZE, VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND
TOBACCO, RENDERED IN SOME DEGREE MUTUALLY STERILE—DOMESTICATION
ELIMINATES THE TENDENCY TO STERILITY NATURAL TO SPECIES WHEN CROSSED—ON
THE INCREASED FERTILITY OF UNCROSSED ANIMALS AND PLANTS FROM
DOMESTICATION AND CULTIVATION.


The domesticated races of both animals and plants, when crossed, are,
with extremely few exceptions, quite prolific,—in some cases even more
so than the purely-bred parent-races. The offspring, also, raised from
such crosses are likewise, as we shall see in the following chapter,
generally more vigorous and fertile than their parents. On the other
hand, species when crossed, and their hybrid offspring, are almost
invariably in some degree sterile; and here there seems to exist a
broad and insuperable distinction between races and species. The
importance of this subject as bearing on the origin of species is
obvious; and we shall hereafter recur to it.

It is unfortunate how few precise observations have been made on the
fertility of mongrel animals and plants during several successive
generations. Dr. Broca[1] has remarked that no one has observed
whether, for instance, mongrel dogs, bred inter se, are indefinitely
fertile; yet, if a shade of infertility be detected by careful
observation in the offspring of natural forms when crossed, it is
thought that their specific distinction is proved. But so many breeds
of sheep, cattle, pigs, dogs, and poultry, have been crossed and
recrossed in various ways, that any sterility, if it had existed, would
from being injurious almost certainly have been observed. In
investigating the fertility of crossed varieties many sources of doubt
occur. Whenever the least trace of sterility between two plants,
however closely allied, was observed by Kolreuter, and more especially
by Gärtner, who counted the exact number of seed in each capsule, the
two forms were at once ranked as distinct species; and if this rule be
followed, assuredly it will never be proved that varieties when crossed
are in any degree sterile. We have formerly seen that certain breeds of
dogs do not readily pair together; but no observations have been made
whether, when paired, they produce the full number of young, and
whether the latter are perfectly fertile _inter se_; but, supposing
that some degree of sterility were found to exist, naturalists would
simply infer that these breeds were descended from aboriginally
distinct species; and it would be scarcely possible to ascertain
whether or not this explanation was the true one.

The Sebright Bantam is much less prolific than any other breed of
fowls, and is descended from a cross between two very distinct breeds,
recrossed by a third sub-variety. But it would be extremely rash to
infer that the loss of fertility was in any manner connected with its
crossed origin, for it may with more probability be attributed either
to long-continued close interbreeding, or to an innate tendency to
sterility correlated with the absence of hackles and sickle
tail-feathers.

Before giving the few recorded cases of forms, which must be ranked as
varieties, being in some degree sterile when crossed, I may remark that
other causes sometimes interfere with varieties freely intercrossing.
Thus they may differ too greatly in size, as with some kinds of dogs
and fowls: for instance, the editor of the ‘Journal of Horticulture,
etc.’[2] says that he can keep Bantams with the larger breeds without
much danger of their crossing, but not with the smaller breeds, such as
Games, Hamburghs, etc. With plants a difference in the period of
flowering serves to keep varieties distinct, as with the various kinds
of maize and wheat: thus Colonel Le Couteur[3] remarks, “the Talavera
wheat, from flowering much earlier than any other kind, is sure to
continue pure.” In different parts of the Falkland Islands the cattle
are breaking up into herds of different colours; and those on the
higher ground, which are generally white, usually breed, as I am
informed by Sir J. Sulivan, three months earlier than those on the
lowland; and this would manifestly tend to keep the herds from
blending.

Certain domestic races seem to prefer breeding with their own kind; and
this is a fact of some importance, for it is a step towards that
instinctive feeling which helps to keep closely allied species in a
state of nature distinct. We have now abundant evidence that, if it
were not for this feeling, many more hybrids would be naturally
produced than in this case. We have seen in the first chapter that the
alco dog of Mexico dislikes dogs of other breeds; and the hairless dog
of Paraguay mixes less readily with the European races, than the latter
do with each other. In Germany the female Spitz-dog is said to receive
the fox more readily than will other dogs; a female Australian Dingo in
England attracted the wild male foxes. But these differences in the
sexual instinct and attractive power of the various breeds may be
wholly due to their descent from distinct species. In Paraguay the
horses have much freedom, and an excellent observer[4] believes that
the native horses of the same colour and size prefer associating with
each other, and that the horses which have been imported from Entre
Rios and Banda Oriental into Paraguay likewise prefer associating
together. In Circassia six sub-races of the horse have received
distinct names; and a native proprietor of rank[5] asserts that horses
of three of these races, whilst living a free life, almost always
refuse to mingle and cross, and will even attack one another.

It has been observed, in a district stocked with heavy Lincolnshire and
light Norfolk sheep, that both kinds; though bred together, when turned
out, “in a short time separate to a sheep;” the Lincolnshires drawing
off to the rich soil, and the Norfolks to their own dry light soil; and
as long as there is plenty of grass, “the two breeds keep themselves as
distinct as rooks and pigeons.” In this case different habits of life
tend to keep the races distinct. On one of the Faroe islands, not more
than half a mile in diameter, the half-wild native black sheep are said
not to have readily mixed with the imported white sheep. It is a more
curious fact that the semi-monstrous ancon sheep of modern origin “have
been observed to keep together, separating themselves from the rest of
the flock, when put into enclosures with other sheep.”[6] With respect
to fallow-deer, which live in a semi-domesticated condition, Mr.
Bennett[7] states that the dark and pale coloured herds, which have
long been kept together in the Forest of Dean, in High Meadow Woods,
and in the New Forest, have never been known to mingle: the
dark-coloured deer, it may be added, are believed to have been first
brought by James I. from Norway, on account of their greater hardiness.
I imported from the island of Porto Santo two of the feral rabbits,
which differ, as described in the fourth chapter, from common rabbits;
both proved to be males, and, though they lived during some years in
the Zoological Gardens, the superintendent, Mr. Bartlett, in vain
endeavoured to make them breed with various tame kinds; but whether
this refusal to breed was due to any change in the instinct, or simply
to their extreme wildness, or whether confinement had rendered them
sterile, as often occurs, cannot be determined.

Whilst matching for the sake of experiment many of the most distinct
breeds of pigeons, it frequently appeared to me that the birds, though
faithful to their marriage vow, retained some desire after their own
kind. Accordingly I asked Mr. Wicking, who has kept a larger stock of
various breeds together than any man in England, whether he thought
that they would prefer pairing with their own kind, supposing that
there were males and females enough of each; and he without hesitation
answered that he was convinced that this was the case. It has often
been noticed that the dovecote pigeon seems to have an actual aversion
towards the several fancy breeds[8] yet all have certainly sprung from
a common progenitor. The Rev. W. D. Fox informs me that his flocks of
white and common Chinese geese kept distinct.

These facts and statements, though some of them are incapable of proof,
resting only on the opinion of experienced observers, show that some
domestic races are led by different habits of life to keep to a certain
extent separate, and that others prefer coupling with their own kind,
in the same manner as species in a state of nature, though in a much
less degree.

With respect to sterility from the crossing of domestic races, I know
of no well-ascertained case with animals. This fact, seeing the great
difference in structure between some breeds of pigeons, fowls, pigs,
dogs, etc., is extraordinary, in contrast with the sterility of many
closely allied natural species when crossed; but we shall hereafter
attempt to show that it is not so extraordinary as it at first appears.
And it may be well here to recall to mind that the amount of external
difference between two species is not a safe guide for predicting
whether or not they will breed together,—some closely allied species
when crossed being utterly sterile, and others which are extremely
unlike being moderately fertile. I have said that no case of sterility
in crossed races rests on satisfactory evidence; but here is one which
at first seems trustworthy. Mr. Youatt[9] and a better authority cannot
be quoted, states, that formerly in Lancashire crosses were frequently
made between longhorn and shorthorn cattle; the first cross was
excellent, but the produce was uncertain; in the third or fourth
generation the cows were bad milkers; “in addition to which, there was
much uncertainty whether the cows would conceive; and full one-third of
the cows among some of these half-breds failed to be in calf.” This at
first seems a good case: but Mr. Wilkinson states,[10] that a breed
derived from this same cross was actually established in another part
of England; and if it had failed in fertility, the fact would surely
have been noticed. Moreover, supposing that Mr. Youatt had proved his
case, it might be argued that the sterility was wholly due to the two
parent-breeds being descended from primordially distinct species.

In the case of plants Gärtner states that he fertilised thirteen heads
(and subsequently nine others) on a dwarf maize bearing yellow seed[11]
with pollen of a tall maize having red seed; and one head alone
produced good seed, but only five in number. Though these plants are
monœcious, and therefore do not require castration, yet I should have
suspected some accident in the manipulation, had not Gärtner expressly
stated that he had during many years grown these two varieties
together, and they did not spontaneously cross; and this, considering
that the plants are monoecious and abound with pollen, and are well
known generally to cross freely, seems explicable only on the belief
that these two varieties are in some degree mutually infertile. The
hybrid plants raised from the above five seeds were intermediate in
structure, extremely variable, and perfectly fertile.[12] In like
manner Prof. Hildebrand[13] could not succeed in fertilising the female
flowers of a plant bearing brown grains with pollen from a certain kind
bearing yellow grains; although other flowers on the same plant, which
were fertilised with their own pollen, yielded good seed. No one, I
believe, even suspects that these varieties of maize are distinct
species; but had the hybrids been in the least sterile, no doubt
Gärtner would at once have so classed them. I may here remark, that
with undoubted species there is not necessarily any close relation
between the sterility of a first cross and that of the hybrid
offspring. Some species can be crossed with facility, but produce
utterly sterile hybrids; others can be crossed with extreme difficulty,
but the hybrids when produced are moderately fertile. I am not aware,
however, of any instance quite like this of the maize, namely, of a
first cross made with difficulty, but yielding perfectly fertile
hybrids.[14]

The following case is much more remarkable, and evidently perplexed
Gärtner, whose strong wish it was to draw a broad line of distinction
between species and varieties. In the genus Verbascum, he made, during
eighteen years, a vast number of experiments, and crossed no less than
1085 flowers and counted their seeds. Many of these experiments
consisted in crossing white and yellow varieties of both _V. lychnitis_
and _V. blattaria_ with nine other species and their hybrids. That the
white and yellow flowered plants of these two species are really
varieties, no one has doubted; and Gärtner actually raised in the case
of both species one variety from the seed of the other. Now in two of
his works[15] he distinctly asserts that crosses between
similarly-coloured flowers yield more seed than between
dissimilarly-coloured; so that the yellow-flowered variety of either
species (and conversely with the white-flowered variety), when crossed
with pollen of its own kind, yields more seed than when crossed with
that of the white variety; and so it is when differently coloured
species are crossed. The general results may be seen in the Table at
the end of his volume. In one instance he gives[16] the following
details; but I must premise that Gärtner, to avoid exaggerating the
degree of sterility in his crosses, always compares the _maximum_
number obtained from a cross with the _average_ number naturally given
by the pure mother-plant. The white variety of _V. lychnitis,_
naturally fertilised by its own pollen, gave from an _average_ of
twelve capsules ninety-six good seeds in each; whilst twenty flowers
fertilised with pollen from the yellow variety of this same species,
gave as the _maximum_ only eighty-nine good seeds; so that we have the
proportion of 1000 to 908, according to Gärtner’s usual scale. I should
have thought it possible that so small a difference in fertility might
have been accounted for by the evil effects of the necessary
castration; but Gärtner shows that the white variety of _V. lychnitis,_
when fertilised first by the white variety of _V. blattaria,_ and then
by the yellow variety of this species, yielded seed in the proportion
of 622 to 438; and in both these cases castration was performed. Now
the sterility which results from the crossing of the differently
coloured varieties of the same species, is fully as great as that which
occurs in many cases when distinct species are crossed. Unfortunately
Gärtner compared the results of the first unions alone, and not the
sterility of the two sets of hybrids produced from the white variety of
_V. lychnitis_ when fertilised by the white and yellow varieties of _V.
blattaria,_ for it is probable that they would have differed in this
respect.

Mr. J. Scott has given me the results of a series of experiments on
Verbascum, made by him in the Botanic Gardens of Edinburgh.[17] He
repeated some of Gärtner’s experiments on distinct species, but
obtained only fluctuating results, some confirmatory, the greater
number contradictory; nevertheless these seem hardly sufficient to
overthrow the conclusion arrived at by Gärtner from experiments tried
on a larger scale. Mr. Scott also experimented on the relative
fertility of unions between similarly and dissimilarly-coloured
varieties of the same species. Thus he fertilised six flowers of the
yellow variety of _V. lychnitis_ by its own pollen, and obtained six
capsules; and calling, for the sake of comparison, the average number
of good seed in each of their capsules one hundred, he found that this
same yellow variety, when fertilised by the white variety, yielded from
seven capsules an average of ninety-four seed. On the same principle,
the white variety of _V. lychnitis_ by its own pollen (from six
capsules), and by the pollen of the yellow variety (eight capsules),
yielded seed in the proportion of 100 to 82. The yellow variety of _V.
thapsus_ by its own pollen (eight capsules), and by that of the white
variety (only two capsules), yielded seed in the proportion of 100 to
94. Lastly, the white variety of _V. blattaria_ by its own pollen
(eight capsules), and by that of the yellow variety (five capsules),
yielded seed in the proportion of 100 to 79. So that in every case the
unions of similarly-coloured varieties of the same species were more
fertile than the unions of dissimilarly-coloured varieties; when all
the cases are grouped together, the difference of fertility is as 100
to 86. Some additional trials were made, and altogether thirty-six
similarly-coloured unions yielded thirty-five good capsules; whilst
thirty-five dissimilarly-coloured unions yielded only twenty-six good
capsules. Besides the foregoing experiments, the purple _V. phœniceum_
was crossed by a rose-coloured and a white variety of the same species;
these two varieties were also crossed together, and these several
unions yielded less seed than _V. phœniceum_ by its own pollen. Hence
it follows from Mr. Scott’s experiments, that in the genus Verbascum
the similarly and dissimilarly-coloured varieties of the same species
behave, when crossed, like closely allied but distinct species.[18]

This remarkable fact of the sexual affinity of similarly-coloured
varieties, as observed by Gärtner and Mr. Scott, may not be of very
rare occurrence; for the subject has not been attended to by others.
The following case is worth giving, partly to show how difficult it is
to avoid error. Dr. Herbert[19] has remarked that variously-coloured
double varieties of the Hollyhock (_Althea rosea_) may be raised with
certainty by seed from plants growing close together. I have been
informed that nurserymen who raise seed for sale do not separate their
plants; accordingly I procured seed of eighteen named varieties; of
these, eleven varieties produced sixty-two plants all perfectly true to
their kind; and seven produced forty-nine plants, half of which were
true and half false. Mr. Masters of Canterbury has given me a more
striking case; he saved seed from a great bed of twenty-four named
varieties planted in closely adjoining rows, and each variety
reproduced itself truly with only sometimes a shade of difference in
tint. Now in the hollyhock the pollen, which is abundant, is matured
and nearly all shed before the stigma of the same flower is ready to
receive it;[20] and as bees covered with pollen incessantly fly from
plant to plant, it would appear that adjoining varieties could not
escape being crossed. As, however, this does not occur, it appeared to
me probable that the pollen of each variety was prepotent on its own
stigma over that of all other varieties, but I have no evidence on this
point. Mr. C. Turner of Slough, well known for his success in the
cultivation of this plant, informs me that it is the doubleness of the
flowers which prevents the bees gaining access to the pollen and
stigma; and he finds that it is difficult even to cross them
artificially. Whether this explanation will fully account for varieties
in close proximity propagating themselves so truly by seed, I do not
know.

The following cases are worth giving, as they relate to monoecious
forms, which do not require, and consequently cannot have been injured
by, castration. Girou de Buzareingues crossed what he designates three
varieties of gourd,[21] and asserts that their mutual fertilisation is
less easy in proportion to the difference which they present. I am
aware how imperfectly the forms in this group were until recently
known; but Sageret,[22] who ranked them according to their mutual
fertility, considers the three forms above alluded to as varieties, as
does a far higher authority, namely, M. Naudin.[23] Sageret[24] has
observed that certain melons have a greater tendency, whatever the
cause may be, to keep true than others; and M. Naudin, who has had such
immense experience in this group, informs me that he believes that
certain varieties intercross more readily than others of the same
species; but he has not proved the truth of this conclusion; the
frequent abortion of the pollen near Paris being one great difficulty.
Nevertheless, he has grown close together, during seven years, certain
forms of Citrullus, which, as they could be artificially crossed with
perfect facility and produced fertile offspring, are ranked as
varieties; but these forms when not artificially crossed kept true.
Many other varieties, on the other hand, in the same group cross with
such facility, as M. Naudin repeatedly insists, that without being
grown far apart they cannot be kept in the least true.

Another case, though somewhat different, may be here given, as it is
highly remarkable, and is established on excellent evidence. Kolreuter
minutely describes five varieties of the common tobacco[25] which were
reciprocally crossed, and the offspring were intermediate in character
and as fertile as their parents: from this fact Kolreuter inferred that
they are really varieties; and no one, as far as I can discover, seems
to have doubted that such is the case. He also crossed reciprocally
these five varieties with _N. glutinosa,_ and they yielded very sterile
hybrids; but those raised from the _var. perennis,_ whether used as the
father or mother plant, were not so sterile as the hybrids from the
four other varieties.[26] So that the sexual capacity of this one
variety has certainly been in some degree modified, so as to approach
in nature that of _N. glutinosa._[27]

These facts with respect to plants show that in some few cases certain
varieties have had their sexual powers so far modified, that they cross
together less readily and yield less seed than other varieties of the
same species. We shall presently see that the sexual functions of most
animals and plants are eminently liable to be affected by the
conditions of life to which they are exposed; and hereafter we shall
briefly discuss the conjoint bearing of this fact, and others, on the
difference in fertility between crossed varieties and crossed species.

      _Domestication eliminates the tendency to Sterility which is
      general with Species when crossed._

This hypothesis was first propounded by Pallas,[28] and has been
adopted by several authors. I can find hardly any direct facts in its
support; but unfortunately no one has compared, in the case of either
animals or plants, the fertility of anciently domesticated varieties,
when crossed with a distinct species, with that of the wild
parent-species when similarly crossed. No one has compared, for
instance, the fertility of _Gallus bankiva_ and of the domesticated
fowl, when crossed with a distinct species of Gallus or Phasianus; and
the experiment would in all cases be surrounded by many difficulties.
Dureau de la Malle, who has so closely studied classical literature,
states[29] that in the time of the Romans the common mule was produced
with more difficulty than at the present day; but whether this
statement may be trusted I know not. A much more important, though
somewhat different, case is given by M. Groenland,[30] namely, that
plants, known from their intermediate character and sterility to be
hybrids between Ægilops and wheat, have perpetuated themselves under
culture since 1857, _with a rapid but varying increase of fertility in
each generation._ In the fourth generation the plants, still retaining
their intermediate character, had become as fertile as common
cultivated wheat.

The indirect evidence in favour of the Pallasian doctrine appears to me
to be extremely strong. In the earlier chapters I have shown that our
various breeds of the dog are descended from several wild species; and
this probably is the case with sheep. There can be no doubt that the
Zebu or humped Indian ox belongs to a distinct species from European
cattle: the latter, moreover, are descended from two forms, which may
be called either species or races. We have good evidence that our
domesticated pigs belong to at least two specific types, _S. scrofa_
and _ indicus._ Now a widely extended analogy leads to the belief that
if these several allied species, when first reclaimed, had been
crossed, they would have exhibited, both in their first unions and in
their hybrid offspring, some degree of sterility. Nevertheless, the
several domesticated races descended from them are now all, as far as
can be ascertained, perfectly fertile together. If this reasoning be
trustworthy, and it is apparently sound, we must admit the Pallasian
doctrine that long-continued domestication tends to eliminate that
sterility which is natural to species when crossed in their aboriginal
state.

      _On increased Fertility from Domestication and Cultivation._

Increased fertility from domestication, without any reference to
crossing, may be here briefly considered. This subject bears indirectly
on two or three points connected with the modification of organic
beings. As Buffon long ago remarked,[31] domestic animals breed oftener
in the year and produce more young at a birth than wild animals of the
same species; they, also, sometimes breed at an earlier age. The case
would hardly have deserved further notice, had not some authors lately
attempted to show that fertility increases and decreases in an inverse
ratio with the amount of food. This strange doctrine has apparently
arisen from individual animals when supplied with an inordinate
quantity of food, and from plants of many kinds when grown on
excessively rich soil, as on a dunghill, becoming sterile: but to this
latter point I shall have occasion presently to return. With hardly an
exception, our domesticated animals, which have been long habituated to
a regular and copious supply of food, without the labour of searching
for it, are more fertile than the corresponding wild animals. It is
notorious how frequently cats and dogs breed, and how many young they
produce at a birth. The wild rabbit is said generally to breed four
times yearly, and to produce each time at most six young; the tame
rabbit breeds six or seven times yearly, producing each time from four
to eleven young; and Mr. Harrison Weir tells me of a case of eighteen
young having been produced at a birth, all of which survived. The
ferret, though generally so closely confined, is more prolific than its
supposed wild prototype. The wild sow is remarkably prolific; she often
breeds twice in the year, and bears from four to eight and sometimes
even twelve young; but the domestic sow regularly breeds twice a year,
and would breed oftener if permitted; and a sow that produces less than
eight at a birth “is worth little, and the sooner she is fattened for
the butcher the better.” The amount of food affects the fertility of
the same individual: thus sheep, which on mountains never produce more
than one lamb at a birth, when brought down to lowland pastures
frequently bear twins. This difference apparently is not due to the
cold of the higher land, for sheep and other domestic animals are said
to be extremely prolific in Lapland. Hard living, also, retards the
period at which animals conceive; for it has been found disadvantageous
in the northern islands of Scotland to allow cows to bear calves before
they are four years old.[32]

Birds offer still better evidence of increased fertility from
domestication: the hen of the wild _ Gallus bankiva_ lays from six to
ten eggs, a number which would be thought nothing of with the domestic
hen. The wild duck lays from five to ten eggs; the tame one in the
course of the year from eighty to one hundred. The wild grey-lag goose
lays from five to eight eggs; the tame from thirteen to eighteen, and
she lays a second time; as Mr. Dixon has remarked, “high-feeding, care,
and moderate warmth induce a habit of prolificacy which becomes in some
measure hereditary.” Whether the semi-domesticated dovecote pigeon is
more fertile than the wild rock-pigeon, C. livia, I know not; but the
more thoroughly domesticated breeds are nearly twice as fertile as
dovecotes: the latter, however, when caged and highly fed, become
equally fertile with house pigeons. I hear from Judge Caton that the
wild turkey in the United States does not breed when a year old, as the
domesticated turkeys there invariably do. The peahen alone of
domesticated birds is rather more fertile, according to some accounts,
when wild in its native Indian home, than in Europe when exposed to our
much colder climate.[33]

With respect to plants, no one would expect wheat to tiller more, and
each ear to produce more grain, in poor than in rich soil; or to get in
poor soil a heavy crop of peas or beans. Seeds vary so much in number
that it is difficult to estimate them; but on comparing beds of carrots
in a nursery garden with wild plants, the former seemed to produce
about twice as much seed. Cultivated cabbages yielded thrice as many
pods by measure as wild cabbages from the rocks of South Wales. The
excess of berries produced by the cultivated asparagus in comparison
with the wild plant is enormous. No doubt many highly cultivated
plants, such as pears, pineapples, bananas, sugar-cane, etc., are
nearly or quite sterile; and I am inclined to attribute this sterility
to excess of food and to other unnatural conditions; but to this
subject I shall recur.

In some cases, as with the pig, rabbit, etc., and with those plants
which are valued for their seed, the direct selection of the more
fertile individuals has probably much increased their fertility; and in
all cases this may have occurred indirectly, from the better chance of
some of the numerous offspring from the more fertile individuals having
been preserved. But with cats, ferrets, and dogs, and with plants like
carrots, cabbages, and asparagus, which are not valued for their
prolificacy, selection can have played only a subordinate part; and
their increased fertility must be attributed to the more favourable
conditions of life under which they have long existed.

REFERENCES

 [1] ‘Journal de Physiolog.,’ tom. ii., 1859, p. 385.

 [2] Dec. 1863, p. 484.

 [3] On ‘The Varieties of Wheat,’ p. 66.

 [4] Rengger, ‘Säugethiere von Paraguay,’ s. 336.

 [5] _See_ a memoir by MM. Lherbette and De Quatrefages, in ‘Bull. Soc.
 d’Acclimat.,’ tom. viii., July, 1861, p. 312.

 [6] For the Norfolk sheep, _see_ Marshall’s ‘Rural Economy of
 Norfolk,’ vol. ii. p. 136. _See_ Rev. L. Landt’s ‘Description of
 Faroe,’ p. 66. For the ancon sheep, _see_ ‘Phil. Transact.,’ 1813, p.
 90.

 [7] White’s ‘Nat. Hist. of Selbourne,’ edited by Bennett, p. 39. With
 respect to the origin of the dark-coloured deer, _see_ ‘Some Account
 of English Deer Parks,’ by E. P. Shirley, Esq.

 [8] ‘The Dovecote,’ by the Rev. E. S. Dixon, p. 155; Bechstein,
 ‘Naturgesch. Deutschlands,’ b. iv., 1795, s. 17.

 [9] ‘Cattle,’ p. 202.

 [10] Mr. J. Wilkinson, in ‘Remarks addressed to Sir J. Sebright,’
 1820, p. 38.

 [11] ‘Bastarderzeugung,’ s. 87, 169. _See also_ the Table at the end
 of volume.

 [12] ‘Bastarderzeugung,’ s. 87, 577.

 [13] ‘Bot. Zeitung,’ 1868, p. 327.

 [14] Mr. Shirreff formerly thought (‘Gard. Chron.,’ 1858, p. 771) that
 the offspring from a cross between certain varieties of wheat became
 sterile in the fourth generation; but he now admits (‘Improvement of
 the Cereals,’ 1873) that this was an error.

 [15] ‘Kenntniss der Befruchtung,’ s. 137; ‘Bastarderzeugung,’ s. 92,
 181. On raising the two varieties from seed, _see_ s. 307.

 [16] ‘Bastarderzeugung,’ s. 216.

 [17] The results have since been published in ‘Journ. Asiatic Soc. of
 Bengal,’ 1867, p. 145.

 [18] The following facts, given by Kölreuter in his ‘Dritte
 Fortsetzung,’ ss. 34, 39, appear at first sight strongly to confirm
 Mr. Scott’s and Gärtner’s statements; and to a certain limited extent
 they do so. Kölreuter asserts, from innumerable observations, that
 insects incessantly carry pollen from one species and variety of
 Verbascum to another; and I can confirm this assertion; yet he found
 that the white and yellow varieties of _Verbascum lychnitis_ often
 grew wild mingled together: moreover, he cultivated these two
 varieties in considerable numbers during four years in his garden, and
 they kept true by seed; but when he crossed them, they produced
 flowers of an intermediate tint. Hence it might have been thought that
 both varieties must have a stronger elective affinity for the pollen
 of their own variety than for that of the other; this elective
 affinity, I may add of each species for its own pollen (Kölreuter,
 ‘Dritte Forts.’ s. 39, and Gärtner, ‘Bastarderz.,’ _passim_) being a
 perfectly well-ascertained power. But the force of the foregoing facts
 is much lessened by Gärtner’s numerous experiments, for, differently
 from Kölreuter, he never once got (‘Bastarderz.,’ s. 307) an
 intermediate tint when he crossed the yellow and white flowered
 varieties of Verbascum. So that the fact of the white and yellow
 varieties keeping true to their colour by seed does not prove that
 they were not mutually fertilised by the pollen carried by insects
 from one to the other.

 [19] ‘Amaryllidaceæ,’ 1837, p. 366. Gärtner has made a similar
 observation.

 [20] Kölreuter first observed this fact, ‘Mém. de l’Acad. de St.
 Petersburg,’ vol. iii. p. 127. _See also_ C. K. Sprengel, ‘Das
 Entdeckte Geheimniss,’ s. 345.

 [21] Namely, Barbarines, Pastissons, Giraumous: ‘Annal. des Sc. Nat.’
 tom. xxx., 1833, pp. 398 and 405.

 [22] ‘Mémoire sur les Cucurbitaceæ,’ 1826, pp. 46, 55.

 [23] ‘Annales des Sc. Nat.,’ 4th series, tom. vi. M. Naudin considers
 these forms as undoubtedly varieties of _Cucurbita pepo._

 [24] ‘Mém. Cucurb.,’ p. 8.

 [25] ‘Zweite Forts.,’ s. 53, namely, _Nicotiana major vulgaris;_ (2)
 _perennis;_ (3) _transylvanica;_ (4) a sub-var. of the last; (5)
 _major latifol. fl. alb._

 [26] Kölreuter was so much struck with this fact that he suspected
 that a little pollen of _N. glutinosa_ in one of his experiments might
 have accidentally got mingled with that of _var. perennis,_ and thus
 aided its fertilising power. But we now know conclusively from Gärtner
 (‘Bastarderz.,’ s. 34, 43) that the pollen of two species never acts
 _conjointly_ on a third species; still less will the pollen of a
 distinct species, mingled with a plant’s own pollen, if the latter be
 present in sufficient quantity, have any effect. The sole effect of
 mingling two kinds of pollen is to produce in the same capsule seeds
 which yield plants, some taking after the one and some after the other
 parent.

 [27] Mr. Scott has made some observations on the absolute sterility of
 a purple and white primrose (_Primula vulgaris_) when fertilised by
 pollen from the common primrose (‘Journal of Proc. of Linn. Soc.,’
 vol. viii., 1864, p. 98); but these observations require confirmation.
 I raised a number of purple-flowered long-styled seedlings from seed
 kindly sent me by Mr. Scott, and, though they were all in some degree
 sterile, they were much more fertile with pollen taken from the common
 primrose than with their own pollen. Mr. Scott has likewise described
 a red equal-styled cowslip (_P. veris,_ ibid. p. 106), which was found
 by him to be highly sterile when crossed with the common cowslip; but
 this was not the case with several equal-styled red seedlings raised
 by me from his plant. This variety of the cowslip presents the
 remarkable peculiarity of combining male organs in every respect like
 those of the short-styled form, with female organs resembling in
 function and partly in structure those of the long-styled form; so
 that we have the singular anomaly of the two forms combined in the
 same flower. Hence it is not surprising that these flowers should be
 spontaneously self-fertile in a high degree.

 [28] ‘Act. Acad. St. Petersburg,’ 1780, part ii. pp. 84, 100.

 [29] ‘Annales des Sc. Nat.’ tom. xxi. (1st series), p. 61.

 [30] ‘Bull. Bot. Soc. de France,’ Dec. 27th, 1861, tom. viii. p. 612.

 [31] Quoted by Isid. Geoffroy St. Hilaire ‘Hist. Naturelle Générale,’
 tom. iii. p. 476. Since this MS. has been sent to press a full
 discussion on the present subject has appeared in Mr. Herbert
 Spencer’s ‘Principles of Biology,’ vol. ii., 1867, p. 457 _et seq._

 [32] For cats and dogs, etc., _see_ Bellingeri in ‘Annal. des Sc.
 Nat.,’ 2nd series, Zoolog. tom. xii. p. 155. For ferrets, Bechstein,
 ‘Naturgeschichte Deutschlands,’ b. i. 1801, s. 786, 795. For rabbits,
 ditto, s. 1123, 1131; and Bronn’s ‘Geschichte der Natur.,’ b. ii. s.
 99. For mountain sheep, ditto, s. 102. For the fertility of the wild
 sow, _see_ Bechstein ‘Naturgesch. Deutschlands,’ b. i., 1801, s. 534;
 for the domestic pig, Sidney’s edit. of Youatt on the Pig, 1860, p.
 62. With respect to Lapland, _see_ Acerbi’s ‘Travels to the North
 Cape,’ Eng. translat., vol. ii. p. 222. About the Highland cows, _see_
 Hogg on Sheep, p. 263.

 [33] For the eggs of _Gallus bankiva, see_ Blyth, in ‘Annals and Mag.
 of Nat. Hist.,’ 2nd series, vol. i., 1848, p. 456. For wild and tame
 ducks, Macgillivray, ‘British Birds,’ vol. v. p. 37; and ‘Die Enten,’
 s. 87. For wild geese, L. Lloyd, ‘Scandinavian Adventures,’ vol. ii.
 1854, p. 413; and for tame geese, ‘Ornamental Poultry,’ by Rev. E. S.
 Dixon, p. 139. On the breeding of Pigeons, Pistor, ‘Das Ganze der
 Taubenzucht,’ 1831, s. 46; and Boitard and Corbié ‘Les Pigeons,’ p.
 158. With respect to peacocks, according to Temminck (‘Hist. Nat. Gén.
 des Pigeons,’ etc., 1813, tom. ii. p. 41), the hen lays in India even
 as many as twenty eggs; but according to Jerdon and another writer
 (quoted in Tegetmeier’s ‘Poultry Book,’ 1866, pp. 280, 282), she there
 lays only from four to nine or ten eggs: in England she is said, in
 the ‘Poultry Book,’ to lay five or six, but another writer says from
 eight to twelve eggs.




CHAPTER XVII. ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL EFFECTS
OF CLOSE INTERBREEDING.

DEFINITION OF CLOSE INTERBREEDING—AUGMENTATION OF MORBID
TENDENCIES—GENERAL EVIDENCE OF THE GOOD EFFECTS DERIVED FROM CROSSING,
AND ON THE EVIL EFFECTS FROM CLOSE INTERBREEDING—CATTLE, CLOSELY
INTERBRED; HALF-WILD CATTLE LONG KEPT IN THE SAME
PARKS—SHEEP—FALLOW-DEER—DOGS, RABBITS, PIGS—MAN, ORIGIN OF HIS
ABHORRENCE OF INCESTUOUS MARRIAGES—FOWLS—PIGEONS—HIVE-BEES—PLANTS,
GENERAL CONSIDERATIONS ON THE BENEFITS DERIVED FROM CROSSING—MELONS,
FRUIT-TREES, PEAS, CABBAGES, WHEAT, AND FOREST-TREES—ON THE INCREASED
SIZE OF HYBRID PLANTS, NOT EXCLUSIVELY DUE TO THEIR STERILITY—ON
CERTAIN PLANTS WHICH EITHER NORMALLY OR ABNORMALLY ARE SELF-IMPOTENT,
BUT ARE FERTILE, BOTH ON THE MALE AND FEMALE SIDE, WHEN CROSSED WITH
DISTINCT INDIVIDUALS EITHER OF THE SAME OR ANOTHER SPECIES—CONCLUSION.


The gain in constitutional vigour, derived from an occasional cross
between individuals of the same variety, but belonging to distinct
families, or between distinct varieties, has not been so largely or so
frequently discussed, as have the evil effects of too close
interbreeding. But the former point is the more important of the two,
inasmuch as the evidence is more decisive. The evil results from close
interbreeding are difficult to detect, for they accumulate slowly, and
differ much in degree with different species; whilst the good effects
which almost invariably follow a cross are from the first manifest. It
should, however, be clearly understood that the advantage of close
interbreeding, as far as the retention of character is concerned, is
indisputable, and often outweighs the evil of a slight loss of
constitutional vigour. In relation to the subject of domestication, the
whole question is of some importance, as too close interbreeding
interferes with the improvement of old races. It is important as
indirectly bearing on Hybridism; and possibly on the extinction of
species, when any form has become so rare that only a few individuals
remain within a confined area. It bears in an important manner on the
influence of free intercrossing, in obliterating individual
differences, and thus giving uniformity of character to the individuals
of the same race or species; for if additional vigour and fertility be
thus gained, the crossed offspring will multiply and prevail, and the
ultimate result will be far greater than otherwise would have occurred.
Lastly, the question is of high interest, as bearing on mankind. I
shall therefore discuss this subject at full length. As the facts which
prove the evil effects of close interbreeding are more copious, though
less decisive, than those on the good effects of crossing, I shall,
under each group of beings, begin with the former.

There is no difficulty in defining what is meant by a cross; but this
is by no means easy in regard to “breeding in and in” or “too close
interbreeding,” because, as we shall see, different species of animals
are differently affected by the same degree of interbreeding. The
pairing of a father and daughter, or mother and son, or brothers and
sisters, if carried on during several generations, is the closest
possible form of interbreeding. But some good judges, for instance Sir
J. Sebright, believe that the pairing of a brother and sister is much
closer than that of parents and children; for when the father is
matched with his daughter he crosses, as is said, with only half his
own blood. The consequences of close interbreeding carried on for too
long a time, are, as is generally believed, loss of size,
constitutional vigour, and fertility, sometimes accompanied by a
tendency to malformation. Manifest evil does not usually follow from
pairing the nearest relations for two, three, or even four generations;
but several causes interfere with our detecting the evil—such as the
deterioration being very gradual, and the difficulty of distinguishing
between such direct evil and the inevitable augmentation of any morbid
tendencies which may be latent or apparent in the related parents. On
the other hand, the benefit from a cross, even when there has not been
any very close interbreeding, is almost invariably at once conspicuous.
There is good reason to believe, and this was the opinion of that most
experienced observer Sir J. Sebright,[1] that the evil effects of close
interbreeding may be checked or quite prevented by the related
individuals being separated for a few generations and exposed to
different conditions of life. This conclusion is now held by many
breeders; for instance Mr. Carr[2] remarks, it is a well-known “fact
that a change of soil and climate effects perhaps almost as great a
change in the constitution as would result from an infusion of fresh
blood.” I hope to show in a future work that consanguinity by itself
counts for nothing, but acts solely from related organisms generally
having a similar constitution, and having been exposed in most cases to
similar conditions.

That any evil directly follows from the closest interbreeding has been
denied by many persons; but rarely by any practical breeder; and never,
as far as I know, by one who has largely bred animals which propagate
their kind quickly. Many physiologists attribute the evil exclusively
to the combination and consequent increase of morbid tendencies common
to both parents; and that this is an active source of mischief there
can be no doubt. It is unfortunately too notorious that men and various
domestic animals endowed with a wretched constitution, and with a
strong hereditary disposition to disease, if not actually ill, are
fully capable of procreating their kind. Close interbreeding, on the
other hand, often induces sterility; and this indicates something quite
distinct from the augmentation of morbid tendencies common to both
parents. The evidence immediately to be given convinces me that it is a
great law of nature, that all organic beings profit from an occasional
cross with individuals not closely related to them in blood; and that,
on the other hand, long-continued close interbreeding is injurious.

Various general considerations have had much influence in leading me to
this conclusion; but the reader will probably rely more on special
facts and opinions. The authority of experienced observers, even when
they do not advance the grounds of their belief, is of some little
value. Now almost all men who have bred many kinds of animals and have
written on the subject, such as Sir J. Sebright, Andrew Knight,
etc.,[3] have expressed the strongest conviction on the impossibility
of long-continued close interbreeding. Those who have compiled works on
agriculture, and have associated much with breeders, such as the
sagacious Youatt, Low, etc., have strongly declared their opinion to
the same effect. Prosper Lucas, trusting largely to French authorities,
has come to a similar conclusion. The distinguished German
agriculturist Hermann von Nathusius, who has written the most able
treatise on this subject which I have met with, concurs; and as I shall
have to quote from this treatise, I may state that Nathusius is not
only intimately acquainted with works on agriculture in all languages,
and knows the pedigrees of our British breeds better than most
Englishmen, but has imported many of our improved animals, and is
himself an experienced breeder.

Evidence of the evil effects of close interbreeding can most readily be
acquired in the case of animals, such as fowls, pigeons, etc., which
propagate quickly, and, from being kept in the same place, are exposed
to the same conditions. Now I have inquired of very many breeders of
these birds, and I have hitherto not met with a single man who was not
thoroughly convinced that an occasional cross with another strain of
the same sub-variety was absolutely necessary. Most breeders of highly
improved or fancy birds value their own strain, and are most unwilling,
at the risk, in their opinion, of deterioration, to make a cross. The
purchase of a first-rate bird of another strain is expensive, and
exchanges are troublesome; yet all breeders, as far as I can hear,
excepting those who keep large stocks at different places for the sake
of crossing, are driven after a time to take this step.

Another general consideration which has had great influence on my mind
is, that with all hermaphrodite animals and plants, which it might have
been thought would have perpetually fertilised themselves and been thus
subjected for long ages to the closest interbreeding, there is not a
single species, as far as I can discover, in which the structure
ensures self-fertilisation. On the contrary, there are in a multitude
of cases, as briefly stated in the fifteenth chapter, manifest
adaptations which favour or inevitably lead to an occasional cross
between one hermaphrodite and another of the same species; and these
adaptive structures are utterly purposeless, as far as we can see, for
any other end.

With _Cattle_ there can be no doubt that extremely close interbreeding
may be long carried on advantageously with respect to external
characters, and with no manifest evil as far as constitution is
concerned. The case of Bakewell’s Longhorns, which were closely
interbred for a long period, has often been quoted; yet Youatt says[4]
the breed “had acquired a delicacy of constitution inconsistent with
common management,” and “the propagation of the species was not always
certain.” But the Shorthorns offer the most striking case of close
interbreeding; for instance, the famous bull Favourite (who was himself
the offspring of a half-brother and sister from Foljambe) was matched
with his own daughter, granddaughter, and great-granddaughter; so that
the produce of this last union, or the great-great-granddaughter, had
15-16ths, or 93·75 per cent of the blood of Favourite in her veins.
This cow was matched with the bull Wellington, having 62·5 per cent of
Favourite blood in his veins, and produced Clarissa; Clarissa was
matched with the bull Lancaster, having 68·75 of the same blood, and
she yielded valuable offspring.[5] Nevertheless Collings, who reared
these animals, and was a strong advocate for close breeding, once
crossed his stock with a Galloway, and the cows from this cross
realised the highest prices. Bates’s herd was esteemed the most
celebrated in the world. For thirteen years he bred most closely in and
in; but during the next seventeen years, though he had the most exalted
notion of the value of his own stock, he thrice infused fresh blood
into his herd: it is said that he did this, not to improve the form of
his animals, but on account of their lessened fertility. Mr. Bates’s
own view, as given by a celebrated breeder,[6] was, that “to breed
in-and-in from a bad stock was ruin and devastation; yet that the
practice may be safely followed within certain limits when the parents
so related are descended from first-rate animals.” We thus see that
there has been much close interbreeding with Shorthorns; but Nathusius,
after the most careful study of their pedigrees, says that he can find
no instance of a breeder who has strictly followed this practice during
his whole life. From this study and his own experience, he concludes
that close interbreeding is necessary to ennoble the stock; but that in
effecting this the greatest care is necessary, on account of the
tendency to infertility and weakness. It may be added, that another
high authority[7] asserts that many more calves are born cripples from
Shorthorns than from other and less closely interbred races of cattle.

Although by carefully selecting the best animals (as Nature effectually
does by the law of battle) close interbreeding may be long carried on
with cattle, yet the good effects of a cross between almost any two
breeds is at once shown by the greater size and vigour of the
offspring; as Mr. Spooner writes to me, “crossing distinct breeds
certainly improves cattle for the butcher.” Such crossed animals are of
course of no value to the breeder; but they have been raised during
many years in several parts of England to be slaughtered;[8] and their
merit is now so fully recognised, that at fat-cattle shows a separate
class has been formed for their reception. The best fat ox at the great
show at Islington in 1862 was a crossed animal.

The half-wild cattle, which have been kept in British parks probably
for 400 or 500 years, or even for a longer period, have been advanced
by Culley and others as a case of long-continued interbreeding within
the limits of the same herd without any consequent injury. With respect
to the cattle at Chillingham, the late Lord Tankerville owned that they
were bad breeders.[9] The agent, Mr. Hardy, estimates (in a letter to
me, dated May, 1861) that in the herd of about fifty the average number
annually slaughtered, killed by fighting, and dying, is about ten, or
one in five. As the herd is kept up to nearly the same average number,
the annual rate of increase must be likewise about one in five. The
bulls, I may add, engage in furious battles, of which battles the
present Lord Tankerville has given me a graphic description, so that
there will always be rigorous selection of the most vigorous males. I
procured in 1855 from Mr. D. Gardner, agent to the Duke of Hamilton,
the following account of the wild cattle kept in the Duke’s park in
Lanarkshire, which is about 200 acres in extent. The number of cattle
varies from sixty-five to eighty; and the number annually killed (I
presume by all causes) is from eight to ten; so that the annual rate of
increase can hardly be more than one in six. Now in South America,
where the herds are half-wild, and therefore offer a nearly fair
standard of comparison, according to Azara the natural increase of the
cattle on an estancia is from one-third to one-fourth of the total
number, or one in between three and four and this, no doubt, applies
exclusively to adult animals fit for consumption. Hence the half-wild
British cattle which have long interbred within the limits of the same
herd are relatively far less fertile. Although in an unenclosed country
like Paraguay there must be some crossing between the different herds,
yet even there the inhabitants believe that the occasional introduction
of animals from distant localities is necessary to prevent
“degeneration in size and diminution of fertility.”[10] The decrease in
size from ancient times in the Chillingham and Hamilton cattle must
have been prodigious, for Professor Rütimeyer has shown that they are
almost certainly the descendants of the gigantic _Bos primigenius._ No
doubt this decrease in size may be largely attributed to less
favourable conditions of life; yet animals roaming over large parks,
and fed during severe winters, can hardly be considered as placed under
very unfavourable conditions.

With _Sheep_ there has often been long-continued interbreeding within
the limits of the same flock; but whether the nearest relations have
been matched so frequently as in the case of Shorthorn cattle, I do not
know. The Messrs. Brown during fifty years have never infused fresh
blood into their excellent flock of Leicesters. Since 1810 Mr. Barford
has acted on the same principle with the Foscote flock. He asserts that
half a century of experience has convinced him that when two nearly
related animals are quite sound in constitution, in-and-in breeding
does not induce degeneracy; but he adds that he “does not pride himself
on breeding from the nearest affinities.” In France the Naz flock has
been bred for sixty years without the introduction of a single strange
ram.[11] Nevertheless, most great breeders of sheep have protested
against close interbreeding prolonged for too great a length of
time.[12] The most celebrated of recent breeders, Jonas Webb, kept five
separate families to work on, thus “retaining the requisite distance of
relationship between the sexes”;[13] and what is probably of greater
importance, the separate flocks will have been exposed to somewhat
different conditions.

Although by the aid of careful selection the near interbreeding of
sheep may be long continued without any manifest evil, yet it has often
been the practice with farmers to cross distinct breeds to obtain
animals for the butcher, which plainly shows that good of some kind is
derived from this practice. We have excellent evidence on this head
from Mr. S. Druce,[14] who gives in detail the comparative numbers of
four pure breeds and of a cross-breed which can be supported on the
same ground, and he gives their produce in fleece and carcase. A high
authority, Mr. Pusey, sums up the result in money value during an equal
length of time, namely (neglecting shillings), for Cotswolds 248_l_.,
for Leicesters 223_l_., for Southdowns 204_l_., for Hampshire Downs
264_l_., and for the crossbred 293_l_. A former celebrated breeder,
Lord Somerville, states that his half-breeds from Ryelands and Spanish
sheep were larger animals than either the pure Ryelands or pure Spanish
sheep. Mr. Spooner concludes his excellent Essay on Crossing by
asserting that there is a pecuniary advantage in judicious
cross-breeding, especially when the male is larger than the female.[15]

As some of our British parks are ancient, it occurred to me that there
must have been long-continued close interbreeding with the fallow-deer
(_Cervus dama_) kept in them; but on inquiry I find that it is a common
practice to infuse new blood by procuring bucks from other parks. Mr.
Shirley,[16] who has carefully studied the management of deer, admits
that in some parks there has been no admixture of foreign blood from a
time beyond the memory of man. But he concludes “that in the end the
constant breeding in-and-in is sure to tell to the disadvantage of the
whole herd, though it may take a very long time to prove it; moreover,
when we find, as is very constantly the case, that the introduction of
fresh blood has been of the very greatest use to deer, both by
improving their size and appearance, and particularly by being of
service in removing the taint of ‘rickback,’ if not of other diseases,
to which deer are sometimes subject when the blood has not been
changed, there can, I think, be no doubt but that a judicious cross
with a good stock is of the greatest consequence, and is indeed
essential, sooner or later, to the prosperity of every well-ordered
park.”

Mr. Meynell’s famous foxhounds have been adduced, as showing that no
ill effects follow from close interbreeding; and Sir J. Sebright
ascertained from him that he frequently bred from father and daughter,
mother and son, and sometimes even from brothers and sisters. With
greyhounds also there has been much close interbreeding, but the best
breeders agree that it may be carried too far.[17] But Sir J. Sebright
declares,[18] that by breeding in-and-in, by which he means matching
brothers and sisters, he has actually seen the offspring of strong
spaniels degenerate into weak and diminutive lapdogs. The Rev. W. D.
Fox has communicated to me the case of a small lot of bloodhounds, long
kept in the same family, which had become very bad breeders, and nearly
all had a bony enlargement in the tail. A single cross with a distinct
strain of bloodhounds restored their fertility, and drove away the
tendency to malformation in the tail. I have heard the particulars of
another case with bloodhounds, in which the female had to be held to
the male. Considering how rapid is the natural increase of the dog, it
is difficult to understand the large price of all highly improved
breeds, which almost implies long-continued close interbreeding, except
on the belief that this process lessens fertility and increases
liability to distemper and other diseases. A high authority, Mr.
Scrope, attributes the rarity and deterioration in size of the Scotch
deerhound (the few individuals formerly existing throughout the country
being all related) in large part to close interbreeding.

With all highly-bred animals there is more or less difficulty in
getting them to procreate quickly, and all suffer much from delicacy of
constitution. A great judge of rabbits[19] says, “the long-eared does
are often too highly bred or forced in their youth to be of much value
as breeders, often turning out barren or bad mothers.” They often
desert their young, so that it is necessary to have nurse-rabbits, but
I do not pretend to attribute all these evil results to close
interbreeding.[20]

With respect to _Pigs_ there is more unanimity amongst breeders on the
evil effects of close interbreeding than, perhaps, with any other large
animal. Mr. Druce, a great and successful breeder of the Improved
Oxfordshires (a crossed race), writes, “without a change of boars of a
different tribe, but of the same breed, constitution cannot be
preserved.” Mr. Fisher Hobbs, the raiser of the celebrated Improved
Essex breed, divided his stock into three separate families, by which
means he maintained the breed for more than twenty years, “by judicious
selection from the _three distinct families._”[21] Lord Western was the
first importer of a Neapolitan boar and sow. “From this pair he bred
in-and-in, until the breed was in danger of becoming extinct, a sure
result (as Mr. Sidney remarks) of in-and-in breeding.” Lord Western
then crossed his Neapolitan pigs with the old Essex, and made the first
great step towards the Improved Essex breed. Here is a more interesting
case. Mr. J. Wright, well known as a breeder, crossed[22] the same boar
with the daughter, granddaughter, and great-granddaughter, and so on
for seven generations. The result was, that in many instances the
offspring failed to breed; in others they produced few that lived; and
of the latter many were idiotic, without sense, even to suck, and when
attempting to move could not walk straight. Now it deserves especial
notice, that the two last sows produced by this long course of
interbreeding were sent to other boars, and they bore several litters
of healthy pigs. The best sow in external appearance produced during
the whole seven generations was one in the last stage of descent; but
the litter consisted of this one sow. She would not breed to her sire,
yet bred at the first trial to a stranger in blood. So that, in Mr.
Wright’s case, long-continued and extremely close interbreeding did not
affect the external form or merit of the young; but with many of them
the general constitution and mental powers, and especially the
reproductive functions, were seriously affected.

Nathusius gives[23] an analogous and even more striking case: he
imported from England a pregnant sow of the large Yorkshire breed, and
bred the product closely in-and-in for three generations: the result
was unfavourable, as the young were weak in constitution, with impaired
fertility. One of the latest sows, which he esteemed a good animal,
produced, when paired with her own uncle (who was known to be
productive with sows of other breeds), a litter of six, and a second
time a litter of only five weak young pigs. He then paired this sow
with a boar of a small black breed, which he had likewise imported from
England; this boar, when matched with sows of his own breed, produced
from seven to nine young. Now, the sow of the large breed, which was so
unproductive when paired with her own uncle, yielded to the small black
boar, in the first litter twenty-one, and in the second litter eighteen
young pigs; so that in one year she produced thirty-nine fine young
animals!

As in the case of several other animals already mentioned, even when no
injury is perceptible from moderately close interbreeding, yet, to
quote the words of Mr. Coate (who five times won the annual gold medal
of the Smithfield Club Show for the best pen of pigs), “Crosses answer
well for profit to the farmer, as you get more constitution and quicker
growth; but for me, who sell a great number of pigs for breeding
purposes, I find it will not do, as it requires many years to get
anything like purity of blood again.”[24]

Almost all the animals as yet mentioned are gregarious, and the males
must frequently pair with their own daughters, for they expel the young
males as well as all intruders, until forced by old age and loss of
strength to yield to some stronger male. It is therefore not improbable
that gregarious animals may have been rendered less susceptible than
non-social species to the evil consequences of close interbreeding, so
that they may be enabled to live in herds without injury to their
offspring. Unfortunately we do not know whether an animal like the cat,
which is not gregarious, would suffer from close interbreeding in a
greater degree than our other domesticated animals. But the pig is not,
as far as I can discover, strictly gregarious, and we have seen that it
appears eminently liable to the evil effects of close interbreeding.
Mr. Huth, in the case of the pig, attributes (Chapter XXIV) these
effects to their having been “cultivated most for their fat,” or to the
selected individuals having had a weak constitution; but we must
remember that it is great breeders who have brought forward the above
cases, and who are far more familiar than ordinary men can be, with the
causes which are likely to interfere with the fertility of their
animals.

The effects of close interbreeding in the case of man is a difficult
subject, on which I will say but little. It has been discussed by
various authors under many points of view.[25] Mr. Tylor[26] has shown
that with widely different races in the most distant quarters of the
world, marriages between relations—even between distant relations—have
been strictly prohibited. There are, however, many exceptions to the
rule, which are fully given by Mr. Huth.[27] It is a curious problem
how these prohibitions arose during early and barbarous times. Mr.
Tylor is inclined to attribute them to the evil effects of
consanguineous marriages having been observed; and he ingeniously
attempts to explain some apparent anomalies in the prohibition not
extending equally to the relations on the male and female side. He
admits, however, that other causes, such as the extension of friendly
alliances, may have come into play. Mr. W. Adam, on the other hand,
concludes that related marriages are prohibited and viewed with
repugnance, from the confusion which would thus arise in the descent of
property, and from other still more recondite reasons. But I cannot
accept these views, seeing that incest is held in abhorrence by savages
such as those of Australia and South America,[28] who have no property
to bequeath, or fine moral feelings to confuse, and who are not likely
to reflect on distant evils to their progeny. According to Mr. Huth the
feeling is the indirect result of exogamy, inasmuch as when this
practice ceased in any tribe and it became endogamous, so that
marriages were strictly confined to the same tribe, it is not unlikely
that a vestige of the former practice would still be retained, so that
closely-related marriages would be prohibited. With respect to exogamy
itself Mr. MacLennan believes that it arose from a scarcity of women,
owing to female infanticide, aided perhaps by other causes.

It has been clearly shown by Mr. Huth that there is no instinctive
feeling in man against incest any more than in gregarious animals. We
know also how readily any prejudice or feeling may rise to abhorrence,
as shown by Hindus in regard to objects causing defilement. Although
there seems to be no strong inherited feeling in mankind against
incest, it seems possible that men during primeval times may have been
more excited by strange females than by those with whom they habitually
lived; in the same manner as according to Mr. Cupples,[29] male
deerhounds are inclined towards strange females, while the females
prefer dogs with whom they have associated. If any such feeling
formerly existed in man, this would have led to a preference for
marriages beyond the nearest kin, and might have been strengthened by
the offspring of such marriages surviving in greater numbers, as
analogy would lead us to believe would have occurred.

Whether consanguineous marriages, such as are permitted in civilised
nations, and which would not be considered as close interbreeding in
the case of our domesticated animals, cause any injury will never be
known with certainty until a census is taken with this object in view.
My son, George Darwin, has done what is possible at present by a
statistical investigation,[30] and he has come to the conclusion, from
his own researches and those of Dr. Mitchell, that the evidence as to
any evil thus caused is conflicting, but on the whole points to the
evil being very small.

_Birds._—In the case of the _Fowl_ a whole array of authorities could
be given against too close interbreeding. Sir J. Sebright positively
asserts that he made many trials, and that his fowls, when thus
treated, became long in the legs, small in the body, and bad
breeders.[31] He produced the famous Sebright Bantams by complicated
crosses, and by breeding in-and-in; and since his time there has been
much close interbreeding with these animals; and they are now
notoriously bad breeders. I have seen Silver Bantams, directly
descended from his stock, which had become almost as barren as hybrids;
for not a single chicken had been that year hatched from two full nests
of eggs. Mr. Hewitt says that with these Bantams the sterility of the
male stands, with rare exceptions, in the closest relation with their
loss of certain secondary male characters: he adds, “I have noticed, as
a general rule, that even the slightest deviation from feminine
character in the tail of the male Sebright—say the elongation by only
half an inch of the two principal tail feathers—brings with it improved
probability of increased fertility.”[32]

Mr. Wright states[33] that Mr. Clark, “whose fighting-cocks were so
notorious, continued to breed from his own kind till they lost their
disposition to fight, but stood to be cut up without making any
resistance, and were so reduced in size as to be under those weights
required for the best prizes; but on obtaining a cross from Mr.
Leighton, they again resumed their former courage and weight.” It
should be borne in mind that game-cocks before they fought were always
weighed, so that nothing was left to the imagination about any
reduction or increase of weight. Mr. Clark does not seem to have bred
from brothers and sisters, which is the most injurious kind of union;
and he found, after repeated trials, that there was a greater reduction
in weight in the young from a father paired with his daughter, than
from a mother with her son. I may add that Mr. Eyton of Eyton, the
well-known ornithologist, who is a large breeder of Grey Dorkings,
informs me that they certainly diminish in size, and become less
prolific, unless a cross with another strain is occasionally obtained.
So it is with Malays, according to Mr. Hewitt, as far as size is
concerned.[34]

An experienced writer[35] remarks that the same amateur, as is well
known, seldom long maintains the superiority of his birds; and this, he
adds, undoubtedly is due to all his stock “being of the same blood;”
hence it is indispensable that he should occasionally procure a bird of
another strain. But this is not necessary with those who keep a stock
of fowls at different stations. Thus, Mr. Ballance, who has bred Malays
for thirty years, and has won more prizes with these birds than any
other fancier in England, says that breeding in-and-in does not
necessarily cause deterioration; “but all depends upon how this is
managed. My plan has been to keep about five or six distinct runs, and
to rear about two hundred or three hundred chickens each year, and
select the best birds from each run for crossing. I thus secure
sufficient crossing to prevent deterioration.”[36]

We thus see that there is almost complete unanimity with
poultry-breeders that, when fowls are kept at the same place, evil
quickly follows from interbreeding carried on to an extent which would
be disregarded in the case of most quadrupeds. Moreover, it is a
generally received opinion that cross-bred chickens are the hardiest
and most easily reared.[37] Mr. Tegetmeier, who has carefully attended
to poultry of all breeds, says[38] that Dorking hens, allowed to run
with Houdan or Crevecœur cocks, “produce in the early spring chickens
that for size, hardihood, early maturity, and fitness for the market,
surpass those of any pure breed that we have ever raised.” Mr. Hewitt
gives it as a general rule with fowls, that crossing the breed
increases their size. He makes this remark after stating that hybrids
from the pheasant and fowl are considerably larger than either
progenitor: so again, hybrids from the male golden pheasant and female
common pheasant “are of far larger size than either parent-bird.”[39]
To this subject of the increased size of hybrids I shall presently
return.

With _Pigeons,_ breeders are unanimous, as previously stated, that it
is absolutely indispensable, notwithstanding the trouble and expense
thus caused, occasionally to cross their much-prized birds with
individuals of another strain, but belonging, of course, to the same
variety. It deserves notice that, when size is one of the desired
characters, as with pouters[40] the evil effects of close interbreeding
are much sooner perceived than when small birds, such as short-faced
tumblers, are valued. The extreme delicacy of the high fancy breeds,
such as these tumblers and improved English carriers, is remarkable;
they are liable to many diseases, and often die in the egg or during
the first moult; and their eggs have generally to be hatched under
foster-mothers. Although these highly-prized birds have invariably been
subjected to much close interbreeding, yet their extreme delicacy of
constitution cannot perhaps be thus fully explained. Mr. Yarrell
informed me that Sir J. Sebright continued closely interbreeding some
owl-pigeons, until from their extreme sterility he as nearly as
possible lost the whole family. Mr. Brent[41] tried to raise a breed of
trumpeters, by crossing a common pigeon, and recrossing the daughter,
granddaughter, great-granddaughter, and great-great-granddaughter, with
the same male trumpeter, until he obtained a bird with 15/16 of
trumpeter’s blood; but then the experiment failed, for “breeding so
close stopped reproduction.” The experienced Neumeister[42] also
asserts that the offspring from dovecotes and various other breeds are
“generally very fertile and hardy birds:” so again MM. Boitard and
Corbié,[43] after forty-five years’ experience, recommend persons to
cross their breeds for amusement; for, if they fail to make interesting
birds, they will succeed under an economical point of view, “as it is
found that mongrels are more fertile than pigeons of pure race.”

I will refer only to one other animal, namely, the Hive-bee, because a
distinguished entomologist has advanced this as a case of inevitable
close interbreeding. As the hive is tenanted by a single female, it
might have been thought that her male and female offspring would always
have bred together, more especially as bees of different hives are
hostile to each other; a strange worker being almost always attacked
when trying to enter another hive. But Mr. Tegetmeier has shown[44]
that this instinct does not apply to drones, which are permitted to
enter any hive; so that there is no _à priori_ improbability of a queen
receiving a foreign drone. The fact of the union invariably and
necessarily taking place on the wing, during the queen’s nuptial
flight, seems to be a special provision against continued
interbreeding. However this may be, experience has shown, since the
introduction of the yellow-banded Ligurian race into Germany and
England, that bees freely cross: Mr. Woodbury, who introduced Ligurian
bees into Devonshire, found during a single season that three stocks,
at distances of from one to two miles from his hives, were crossed by
his drones. In one case the Ligurian drones must have flown over the
city of Exeter, and over several intermediate hives. On another
occasion several common black queens were crossed by Ligurian drones at
a distance of from one to three and a half miles.[45]

      _Plants._

When a single plant of a new species is introduced into any country, if
propagated by seed, many individuals will soon be raised, so that if
the proper insects be present there will be crossing. With
newly-introduced trees or other plants not propagated by seed we are
not here concerned. With old-established plants it is an almost
universal practice occasionally to make exchanges of seed, by which
means individuals which have been exposed to different conditions of
life,—and this, as we have seen with animals, diminishes the evil from
close interbreeding,—will occasionally be introduced into each
district.

With respect to individuals belonging to the same sub-variety, Gärtner,
whose accuracy and experience exceeded that of all other observers,
states[46] that he has many times observed good effects from this step,
especially with exotic genera, of which the fertility is somewhat
impaired, such as Passiflora, Lobelia, Fuchsia. Herbert also says,[47]
“I am inclined to think that I have derived advantage from impregnating
the flower from which I wished to obtain seed with pollen from another
individual of the same variety, or at least from another flower, rather
than with its own.” Again, Professor Lecoq ascertained that crossed
offspring are more vigorous and robust than their parents.[48]

General statements of this kind, however, can seldom be fully trusted:
I therefore began a long series of experiments, continued for about ten
years, which will I think conclusively show the good effects of
crossing two distinct plants of the same variety, and the evil effects
of long-continued self-fertilisation. A clear light will thus be thrown
on such questions, as why flowers are almost invariably constructed so
as to permit, or favour, or necessitate the union of two individuals.
We shall clearly understand why monœcious and dioecious,—why
dichogamous, dimorphic and trimorphic plants exist, and many other such
cases. I intend soon to publish an account of these experiments, and I
can here give only a few cases in illustration. The plan which I
followed was to grow plants in the same pot, or in pots of the same
size, or close together in the open ground; carefully to exclude
insects; and then to fertilise some of the flowers with pollen from the
same flower, and others on the same plant with pollen from a distinct
but adjoining plant. In many of these experiments, the crossed plants
yielded much more seed than the self-fertilised plants; and I have
never seen the reversed case. The self-fertilised and crossed seeds
thus obtained were allowed to germinate in the same glass vessel on
damp sand; and as the seeds germinated, they were planted in pairs on
opposite sides of the same pot, with a superficial partition between
them, and were placed so as to be equally exposed to the light. In
other cases the self-fertilised and crossed seeds were simply sown on
opposite sides of the same small pot. I have, in short, followed
different plans, but in every case have taken all the precautions which
I could think of, so that the two lots should be equally favoured. The
growth of the plants raised from the crossed and self-fertilised seed,
were carefully observed from their germination to maturity, in species
belonging to fifty-two genera; and the difference in their growth, and
in withstanding unfavourable conditions, was in most cases manifest and
strongly marked. It is of importance that the two lots of seed should
be sown or planted on opposite sides of the same pot, so that the
seedlings may struggle against each other; for if sown separately in
ample and good soil, there is often but little difference in their
growth.

I will briefly describe two of the first cases observed by me. Six
crossed and six self-fertilised seeds of _Ipomoea purpurea,_ from
plants treated in the manner above described, were planted as soon as
they had germinated, in pairs on opposite sides of two pots, and rods
of equal thickness were given them to twine up. Five of the crossed
plants grew from the first more quickly than the opposed
self-fertilised plants; the sixth, however, was weakly and was for a
time beaten, but at last its sounder constitution prevailed and it shot
ahead of its antagonist. As soon as each crossed plant reached the top
of its seven-foot rod its fellow was measured, and the result was that,
when the crossed plants were seven feet high the self-fertilised had
attained the average height of only five feet four and a half inches.
The crossed plants flowered a little before, and more profusely than
the self-fertilised plants. On opposite sides of another _ small_ pot a
large number of crossed and self-fertilised seeds were sown, so that
they had to struggle for bare existence; a single rod was given to each
lot: here again the crossed plants showed from the first their
advantage; they never quite reached the summit of the seven-foot rod,
but relatively to the self-fertilised plants their average height was
as seven feet to five feet two inches. The experiment was repeated
during several succeeding generations, treated in exactly the same
manner, and with nearly the same result. In the second generation, the
crossed plants, which were again crossed, produced 121 seed-capsules,
whilst the self-fertilised, again self-fertilised, produced only 84
capsules.

Some flowers of the _Mimulus luteus_ were fertilised with their own
pollen, and others were crossed with pollen from distinct plants
growing in the same pot. The seeds were thickly sown on opposite sides
of a pot. The seedlings were at first equal in height; but when the
young crossed plants were half an inch, the self-fertilised plants were
only a quarter of an inch high. But this degree of inequality did not
last, for, when the crossed plants were four and a half inches high,
the self-fertilised were three inches, and they retained the same
relative difference till their growth was complete. The crossed plants
looked far more vigorous than the uncrossed, and flowered before them;
they produced also a far greater number of capsules. As in the former
case, the experiment was repeated during several succeeding
generations. Had I not watched these plants of Mimulus and Ipomoea
during their whole growth, I could not have believed it possible, that
a difference apparently so slight as that of the pollen being taken
from the same flower, or from a distinct plant growing in the same pot,
could have made so wonderful a difference in the growth and vigour of
the plants thus produced. This, under a physiological point of view, is
a most remarkable phenomenon.

With respect to the benefit derived from crossing distinct varieties,
plenty of evidence has been published. Sageret[49] repeatedly speaks in
strong terms of the vigour of melons raised by crossing different
varieties, and adds that they are more easily fertilised than common
melons, and produce numerous good seed. Here follows the evidence of an
English gardener:[50] “I have this summer met with better success in my
cultivation of melons, in an unprotected state, from the seeds of
hybrids (_i.e._ mongrels) obtained by cross impregnation, than with old
varieties. The offspring of three different hybridisations (one more
especially, of which the parents were the two most dissimilar varieties
I could select) each yielded more ample and finer produce than any one
of between twenty and thirty established varieties.”

Andrew Knight[51] believed that his seedlings from crossed varieties of
the apple exhibited increased vigour and luxuriance; and M.
Chevreul[52] alludes to the extreme vigour of some of the crossed
fruit-trees raised by Sageret.

By crossing reciprocally the tallest and shortest peas, Knight[53]
says: “I had in this experiment a striking instance of the stimulative
effects of crossing the breeds; for the smallest variety, whose height
rarely exceeded two feet, was increased to six feet: whilst the height
of the large and luxuriant kind was very little diminished.” Mr. Laxton
gave me seed-peas produced from crosses between four distinct kinds;
and the plants thus raised were extraordinarily vigorous, being in each
case from one to two or three feet taller than the parent-forms growing
close alongside them.

Wiegmann[54] made many crosses between several varieties of cabbage;
and he speaks with astonishment of the vigour and height of the
mongrels, which excited the amazement of all the gardeners who beheld
them. Mr. Chaundy raised a great number of mongrels by planting
together six distinct varieties of cabbage. These mongrels displayed an
infinite diversity of character; “But the most remarkable circumstance
was, that, while all the other cabbages and borecoles in the nursery
were destroyed by a severe winter, these hybrids were little injured,
and supplied the kitchen when there was no other cabbage to be had.”

Mr. Maund exhibited before the Royal Agricultural Society[55] specimens
of crossed wheat, together with their parent varieties; and the editor
states that they were intermediate in character, “united with that
greater vigour of growth, which it appears, in the vegetable as in the
animal world, is the result of a first cross.” Knight also crossed
several varieties of wheat,[56] and he says “that in the years 1795 and
1796, when almost the whole crop of corn in the island was blighted,
the varieties thus obtained, and these only, escaped in this
neighbourhood, though sown in several different soils and situations.”

Here is a remarkable case: M. Clotzsch[57] crossed _Pinus sylvestris_
and _nigricans, Quercus robur_ and _pedunculata, Alnus glutinosa_ and
_incana, Ulmus campestris_ and _ effusa_; and the cross-fertilised
seeds, as well as seeds of the pure parent-trees, were all sown at the
same time and in the same place. The result was, that after an interval
of eight years, the hybrids were one-third taller than the pure trees!

The facts above given refer to undoubted varieties, excepting the trees
crossed by Clotzsch, which are ranked by various botanists as
strongly-marked races, sub-species, or species. That true hybrids
raised from entirely distinct species, though they lose in fertility,
often gain in size and constitutional vigour, is certain. It would be
superfluous to quote any facts; for all experimenters, Kolreuter,
Gärtner, Herbert, Sageret, Lecoq, and Naudin, have been struck with the
wonderful vigour, height, size, tenacity of life, precocity, and
hardiness of their hybrid productions. Gärtner[58] sums up his
conviction on this head in the strongest terms. Kölreuter[59] gives
numerous precise measurements of the weight and height of his hybrids
in his comparison with measurements of both parent-forms; and speaks
with astonishment of their “_statura portentosa,_” their “_ambitus
vastissimus ac altitudo valde conspicua._” Some exceptions to the rule
in the case of very sterile hybrids have, however, been noticed by
Gärtner and Herbert; but the most striking exceptions are given by Max
Wichura[60] who found that hybrid willows were generally tender in
constitution, dwarf, and short-lived.

Kolreuter explains the vast increase in the size of the roots, stems,
etc., of his hybrids, as the result of a sort of compensation due to
their sterility, in the same way as many emasculated animals are larger
than the perfect males. This view seems at first sight extremely
probable, and has been accepted by various authors;[61] but Gärtner[62]
has well remarked that there is much difficulty in fully admitting it;
for with many hybrids there is no parallelism between the degree of
their sterility and their increased size and vigour. The most striking
instances of luxuriant growth have been observed with hybrids which
were not sterile in any extreme degree. In the genus Mirabilis, certain
hybrids are unusually fertile, and their extraordinary luxuriance of
growth, together with their enormous roots[63] have been transmitted to
their progeny. The result in all cases is probably in part due to the
saving of nutriment and vital force through the sexual organs acting
imperfectly or not at all, but more especially to the general law of
good being derived from a cross. For it deserves especial attention
that mongrel animals and plants, which are so far from being sterile
that their fertility is often actually augmented, have, as previously
shown, their size, hardiness, and constitutional vigour generally
increased. It is not a little remarkable that an accession of vigour
and size should thus arise under the opposite contingencies of
increased and diminished fertility.

It is a perfectly well ascertained fact[64] that hybrids invariably
breed with either pure parent, and not rarely with a distinct species,
more readily than with one another. Herbert is inclined to explain even
this fact by the advantage derived from a cross; but Gärtner more
justly accounts for it by the pollen of the hybrid, and probably its
ovules, being in some degree vitiated, whereas the pollen and ovules of
both pure parents and of any third species are sound. Nevertheless,
there are some well-ascertained and remarkable facts, which, as we
shall presently see, show that a cross by itself undoubtedly tends to
increase or re-establish the fertility of hybrids.

The same law, namely, that the crossed offspring both of varieties and
species are larger than the parent-forms, holds good in the most
striking manner with hybrid animals as well as with mongrels. Mr.
Bartlett, who has had such large experience says, “Among all hybrids of
vertebrated animals there is a marked increase of size.” He then
enumerates many cases with mammals, including monkeys, and with various
families of birds.[65]

      _On certain Hermaphrodite Plants which, either normally or
      abnormally, require to be fertilised by pollen from a distinct
      individual or species._

The facts now to be given differ from the foregoing, as self-sterility
is not here the result of long-continued close interbreeding. These
facts are, however, connected with our present subject, because a cross
with a distinct individual is shown to be either necessary or
advantageous. Dimorphic and trimorphic plants, though they are
hermaphrodites, must be reciprocally crossed, one set of forms by the
other, in order to be fully fertile, and in some cases to be fertile in
any degree. But I should not have noticed these plants, had it not been
for the following cases given by Dr. Hildebrand:—[66]

_Primula sinensis_ is a reciprocally dimorphic species: Dr. Hildebrand
fertilised twenty-eight flowers of both forms, each by pollen of the
other form, and obtained the full number of capsules containing on an
average 42·7 seed per capsule; here we have complete and normal
fertility. He then fertilised forty-two flowers of both forms with
pollen of the same form, but taken from a distinct plant, and all
produced capsules containing on an average only 19·6 seed. Lastly, and
here we come to our more immediate point, he fertilised forty-eight
flowers of both forms with pollen of the same form and taken from the
same flower, and now he obtained only thirty-two capsules, and these
contained on an average 18·6 seed, or one less per capsule than in the
former case. So that, with these illegitimate unions, the act of
impregnation is less assured, and the fertility slightly less, when the
pollen and ovules belong to the same flower, than when belonging to two
distinct individuals of the same form. Dr. Hildebrand has recently made
analogous experiments on the long-styled form of _Oxalis rosea,_ with
the same result.[67]

It has recently been discovered that certain plants, whilst growing in
their native country under natural conditions, cannot be fertilised
with pollen from the same plant. They are sometimes so utterly
self-impotent, that, though they can readily be fertilised by the
pollen of a distinct species or even distinct genus, yet, wonderful as
is the fact, they never produce a single seed by their own pollen. In
some cases, moreover, the plant’s own pollen and stigma mutually act on
each other in a deleterious manner. Most of the facts to be given
relate to orchids, but I will commence with a plant belonging to a
widely different family.

Sixty-three flowers of _Corydalis cava,_ borne on distinct plants, were
fertilised by Dr. Hildebrand[68] with pollen from other plants of the
same species; and fifty-eight capsules were obtained, including on an
average 4.5 seed in each. He then fertilised sixteen flowers produced
by the same raceme, one with another, but obtained only three capsules,
one of which alone contained any good seeds, namely, two in number.
Lastly, he fertilised twenty-seven flowers, each with its own pollen;
he left also fifty-seven flowers to be spontaneously fertilised, and
this would certainly have ensued if it had been possible, for the
anthers not only touch the stigma, but the pollen-tubes were seen by
Dr. Hildebrand to penetrate it; nevertheless these eighty-four flowers
did not produce a single seed-capsule! This whole case is highly
instructive, as it shows how widely different the action of the same
pollen is, according as it is placed on the stigma of the same flower,
or on that of another flower on the same raceme, or on that of a
distinct plant.

With exotic Orchids several analogous cases have been observed, chiefly
by Mr. John Scott.[69] _Oncidium sphacelatum_ has effective pollen, for
Mr. Scott fertilised two distinct species with it; the ovules are
likewise capable of impregnation, for they were readily fertilised by
the pollen of _O. divaricatum_; nevertheless, between one and two
hundred flowers fertilised by their own pollen did not produce a single
capsule, though the stigmas were penetrated by the pollen-tubes. Mr.
Robertson Munro, of the Royal Botanic Gardens of Edinburgh, also
informs me (1864) that a hundred and twenty flowers of this same
species were fertilised by him with their own pollen, and did not
produce a capsule, but eight flowers, fertilised by the pollen of _O.
divaricatum,_ produced four fine capsules: again, between two and three
hundred flowers of _O. divaricatum,_ fertilised by their own pollen,
did not set a capsule, but twelve flowers fertilised by _O. flexuosum_
produced eight fine capsules: so that here we have three utterly
self-impotent species, with their male and female organs perfect, as
shown by their mutual fertilisation. In these cases fertilisation was
effected only by the aid of a distinct species. But, as we shall
presently see, distinct plants, raised from seed, of _Oncidium
flexuosum,_ and probably of the other species, would have been
perfectly capable of fertilising each other, for this is the natural
process. Again, Mr. Scott found that the pollen of a plant of _O.
microchilum_ was effective, for with it he fertilised two distinct
species; he found its ovules good, for they could be fertilised by the
pollen of one of these species, and by the pollen of a distinct plant
of _O. microchilum_; but they could not be fertilised by pollen of the
same plant, though the pollen-tubes penetrated the stigma. An analogous
case has been recorded by M. Rivière[70] with two plants of _O.
cavendishianum,_ which were both self-sterile, but reciprocally
fertilised each other. All these cases refer to the genus Oncidium, but
Mr. Scott found that _Maxillaria atro-rubens_ was “totally
insusceptible of fertilisation with its own pollen,” but fertilised,
and was fertilised by, a widely distinct species, viz. _M. squalens._

As these orchids had been grown under unnatural conditions in
hot-houses, I concluded that their self-sterility was due to this
cause. But Fritz Müller informs me that at Desterro, in Brazil, he
fertilised above one hundred flowers of the above-mentioned _Oncidium
flexuosum,_ which is there endemic, with its own pollen, and with that
taken from distinct plants: all the former were sterile, whilst those
fertilised by pollen from any _other plant_ of the same species were
fertile. During the first three days there was no difference in the
action of the two kinds of pollen: that placed on stigma of the same
plant separated in the usual manner into grains, and emitted tubes
which penetrated the column, and the stigmatic chamber shut itself; but
only those flowers which had been fertilised by pollen taken from a
distinct plant produced seed-capsules. On a subsequent occasion these
experiments were repeated on a large scale with the same result. Fritz
Müller found that four other endemic species of Oncidium were in like
manner utterly sterile with their own pollen, but fertile with that
from any other plant: some of them likewise produced seed-capsules when
impregnated with pollen of widely distinct genera, such as Cyrtopodium,
and Rodriguezia. _Oncidium crispum,_ however, differs from the
foregoing species in varying much in its self-sterility; some plants
producing fine pods with their own pollen, others failing to do so in
two or three instances, Fritz Müller observed that the pods produced by
pollen taken from a distinct flower on the same plant, were larger than
those produced by the flower’s own pollen. In _Epidendrum
cinnabarinum,_ an orchid belonging to another division of the family,
fine pods were produced by the plant’s own pollen, but they contained
by weight only about half as much seed as the capsules which had been
fertilised by pollen from a distinct plant, and in one instance from a
distinct species; moreover, a very large proportion, and in some cases
nearly all the seeds produced by the plant’s own pollen, were destitute
of an embryo. Some self-fertilised capsules of a Maxillaria were in a
similar state.

Another observation made by Fritz Müller is highly remarkable, namely,
that with various orchids the plant’s own pollen not only fails to
impregnate the flower, but acts on the stigma, and is acted on, in an
injurious or poisonous manner. This is shown by the surface of the
stigma in contact with the pollen, and by the pollen itself becoming in
from three to five days dark brown, and then decaying. The
discoloration and decay are not caused by parasitic cryptograms, which
were observed by Fritz Müller in only a single instance. These changes
are well shown by placing on the same stigma, at the same time, the
plant’s own pollen and that from a distinct plant of the same species,
or of another species, or even of another and widely remote genus.
Thus, on the stigma of _Oncidium flexuosum,_ the plant’s own pollen and
that from a distinct plant were placed side by side, and in five days’
time the latter was perfectly fresh, whilst the plant’s own pollen was
brown. On the other hand, when the pollen of a distinct plant of the
_Oncidium flexuosum_ and of the _ Epidendrum zebra (nov. spec.?)_ were
placed together on the same stigma, they behaved in exactly the same
manner, the grains separating, emitting tubes, and penetrating the
stigma, so that the two pollen-masses, after an interval of eleven
days, could not be distinguished except by the difference of their
caudicles, which, of course, undergo no change. Fritz Müller has,
moreover, made a large number of crosses between orchids belonging to
distinct species and genera, and he finds that in all cases when the
flowers are not fertilised their footstalks first begin to wither; and
the withering slowly spreads upwards until the germens fall off, after
an interval of one or two weeks, and in one instance of between six and
seven weeks; but even in this latter case, and in most other cases, the
pollen and stigma remained in appearance fresh. Occasionally, however,
the pollen becomes brownish, generally on the external surface, and not
in contact with the stigma, as is invariably the case when the plant’s
own pollen is applied.

Fritz Müller observed the poisonous action of the plant’s own pollen in
the above-mentioned _Oncidium flexuosum, O. unicorne, pubes (?),_ and
in two other unnamed species. Also in two species of Rodriguezia, in
two of Notylia, in one of Burlingtonia, and of a fourth genus in the
same group. In all these cases, except the last, it was proved that the
flowers were, as might have been expected, fertile with pollen from a
distinct plant of the same species. Numerous flowers of one species of
Notylia were fertilised with pollen from the same raceme; in two days’
time they all withered, the germens began to shrink, the pollen-masses
became dark brown, and not one pollen-grain emitted a tube. So that in
this orchid the injurious action of the plant’s own pollen is more
rapid than with _Oncidium flexuosum._ Eight other flowers on the same
raceme were fertilised with pollen from a distinct plant of the same
species: two of these were dissected, and their stigmas were found to
be penetrated by numberless pollen-tubes; and the germens of the other
six flowers became well developed. On a subsequent occasion many other
flowers were fertilised with their own pollen, and all fell off dead in
a few days; whilst some flowers on the same raceme which had been left
simply unfertilised adhered and long remained fresh. We have seen that
in cross-unions between extremely distinct orchids the pollen long
remains undecayed; but Notylia behaved in this respect differently; for
when its pollen was placed on the stigma of _ Oncidium flexuosum,_ both
the stigma and pollen quickly became dark brown, in the same manner as
if the plant’s own pollen had been applied.

Fritz Müller suggests that, as in all these cases the plant’s own
pollen is not only impotent (thus effectually preventing
self-fertilisation), but likewise prevents, as was ascertained in the
case of the Notylia and _Oncidium flexuosum,_ the action of
subsequently applied pollen from a distinct individual, it would be an
advantage to the plant to have its own pollen rendered more and more
deleterious; for the germens would thus quickly be killed, and dropping
off, there would be no further waste in nourishing a part which
ultimately could be of no avail.

The same naturalist found in Brazil three plants of a Bignonia growing
near together. He fertilised twenty-nine flowerets on one of them with
their own pollen, and they did not set a single capsule. Thirty flowers
were then fertilised with pollen from a distinct plant, one of the
three, and they yielded only two capsules. Lastly, five flowers were
fertilised with pollen from a fourth plant growing at a distance, and
all five produced capsules. Fritz Müller thinks that the three plants
which grew near one another were probably seedlings from the same
parent, and that from being closely related, they acted very feebly on
one another. This view is extremely probable, for he has since shown in
a remarkable paper,[71] that in the case of some Brazilian species of
Abutilon, which are self-sterile, and between which he raised some
complex hybrids, that these, if near relatives, were much less fertile
_inter se,_ than when not closely related.

We now come to cases closely analogous with those just given, but
different in so far that only certain individuals of the species are
self-sterile. This self-impotence does not depend on the pollen or
ovules being in an unfit state for fertilisation, for both have been
found effective in union with other plants of the same or of a distinct
species. The fact of plants having acquired so peculiar a constitution,
that they can be fertilised more readily by the pollen of a distinct
species than by their own, is exactly the reverse of what occurs with
all ordinary species. For in the latter the two sexual elements of the
same individual plant are of course capable of freely acting on each
other; but are so constituted that they are more or less impotent when
brought into union with the sexual elements of a distinct species, and
produce more or less sterile hybrids.

Gärtner experimented on two plants of _Lobelia fulgens,_ brought from
separate places, and found[72] that their pollen was good, for he
fertilised with it _L. cardinalis_ and _ syphilitica_; their ovules
were likewise good, for they were fertilised by the pollen of these
same two species; but these two plants of _L. fulgens_ could not be
fertilised by their own pollen, as can generally be effected with
perfect ease with this species. Again, the pollen of a plant of
_Verbascum nigrum_ grown in a pot was found by Gärtner[73] capable of
fertilising _V. lychnitis_ and _V. austriacum_; the ovules could be
fertilised by the pollen of _V. thapsus_; but the flowers could not be
fertilised by their own pollen. Kölreuter, also,[74] gives the case of
three garden plants of _Verbascum phœniceum,_ which bore during two
years many flowers; these he fertilised successfully with the pollen of
no less than four distinct species, but they produced not a seed with
their own apparently good pollen; subsequently these same plants, and
others raised from seed, assumed a strangely fluctuating condition,
being temporarily sterile on the male or female side, or on both sides,
and sometimes fertile on both sides; but two of the plants were
perfectly fertile throughout the summer.

With _Reseda odorata_ I have found certain individuals quite sterile
with their own pollen, and so it is with the indigenous _Reseda lutea._
The self-sterile plants of both species were perfectly fertile when
crossed with pollen from any other individual of the same species.
These observations will hereafter be published in another work, in
which I shall also show that seeds sent to me by Fritz Müller produced
by plants of _Eschscholtzia californica_ which were quite self-sterile
in Brazil, yielded in this country plants which were only slightly
self-sterile.

It appears[75] that certain flowers on certain plants of _Lilium
candidum_ can be fertilised more freely by pollen from a distinct
individual than by their own. So, again, with the varieties of the
potato. Tinzmann,[76] who made many trials with this plant, says that
pollen from another variety sometimes “exerts a powerful influence, and
I have found sorts of potatoes which would not bear seed from
impregnation with the pollen of their own flowers would bear it when
impregnated with other pollen.” It does not, however, appear to have
been proved that the pollen which failed to act on the flower’s own
stigma was in itself good.

In the genus Passiflora it has long been known that several species do
not produce fruit, unless fertilised by pollen taken from distinct
species: thus, Mr. Mowbray[77] found that he could not get fruit from
_P. alata_ and _racemosa_ except by reciprocally fertilising them with
each other’s pollen; and similar facts have been observed in Germany
and France.[78] I have received two accounts of _P. quadrangularis_
never producing fruit from its own pollen, but doing so freely when
fertilised in one case with the pollen of _ P. cœrulea,_ and in another
case with that of _P. edulis._ But in three other cases this species
fruited freely when fertilised with its own pollen; and the writer in
one case attributed the favourable result to the temperature of the
house having been raised from 5° to 10° Fahr. above the former
temperature, after the flowers were fertilised.[79] With respect to _P.
laurifolia,_ a cultivator of much experience has recently remarked[80]
that the flowers “must be fertilised with the pollen of _P. cœrulea,_
or of some other common kind, as their own pollen will not fertilise
them.” But the fullest details on this subject have been given by
Messrs. Scott and Robertson Munro:[81] plants of _ Passiflora racemosa,
cœrulea,_ and _alata_ flowered profusely during many years in the
Botanic Gardens of Edinburgh, and, though repeatedly fertilised with
their own pollen, never produced any seed; yet this occurred at once
with all three species when they were crossed together in various ways.
In the case of _ P. cœrulea_ three plants, two of which grew in the
Botanic Gardens, were all rendered fertile, merely by impregnating each
with pollen of one of the others. The same result was attained in the
same manner with _P. alata,_ but with only one plant out of three. As
so many self-sterile species of Passiflora have been mentioned, it
should be stated that the flowers of the annual _P. gracilis_ are
nearly as fertile with their own pollen as with that from a distinct
plant; thus sixteen flowers spontaneously self-fertilised produced
fruit, each containing on an average 21·3 seed, whilst fruit from
fourteen crossed flowers contained 24·1 seed.

Returning to _P. alata,_ I have received (1866) some interesting
details from Mr. Robertson Munro. Three plants, including one in
England, have already been mentioned which were inveterately
self-sterile, and Mr. Munro informs me of several others which, after
repeated trials during many years, have been found in the same
predicament. At some other places, however, this species fruits readily
when fertilised with its own pollen. At Taymouth Castle there is a
plant which was formerly grafted by Mr. Donaldson on a distinct
species, name unknown, and ever since the operation it has produced
fruit in abundance by its own pollen; so that this small and unnatural
change in the state of this plant has restored its self-fertility! Some
of the seedlings from the Taymouth Castle plant were found to be not
only sterile with their own pollen, but with each other’s pollen, and
with the pollen of distinct species. Pollen from the Taymouth plant
failed to fertilise certain plants of the same species, but was
successful on one plant in the Edinburgh Botanic Gardens. Seedlings
were raised from this latter union, and some of their flowers were
fertilised by Mr. Munro with their own pollen; but they were found to
be as self-impotent as the mother-plant had always proved, except when
fertilised by the grafted Taymouth plant, and except, as we shall see,
when fertilised by her own seedlings. For Mr. Munro fertilised eighteen
flowers on the self-impotent mother-plant with pollen from these her
own self-impotent seedlings, and obtained, remarkable as the fact is,
eighteen fine capsules full of excellent seed! I have met with no case
in regard to plants which shows so well as this of _P. alata,_ on what
small and mysterious causes complete fertility or complete sterility
depends.

The facts hitherto given relate to the much-lessened or completely
destroyed fertility of pure species when impregnated with their own
pollen, in comparison with their fertility when impregnated by distinct
individuals or distinct species; but closely analogous facts have been
observed with hybrids.

Herbert states[82] that having in flower at the same time nine hybrid
Hippeastrums, of complicated origin, descended from several species, he
found that “almost every flower touched with pollen from another cross
produced seed abundantly, and those which were touched with their own
pollen either failed entirely, or formed slowly a pod of inferior size,
with fewer seeds.” In the ‘Horticultural Journal’ he adds that “the
admission of the pollen of another cross-bred Hippeastrum (however
complicated the cross) to any one flower of the number, is almost sure
to check the fructification of the others.” In a letter written to me
in 1839, Dr. Herbert says that he had already tried these experiments
during five consecutive years, and he subsequently repeated them, with
the same invariable result. He was thus led to make an analogous trial
on a pure species, namely, on the _Hippeastrum aulicum,_ which he had
lately imported from Brazil: this bulb produced four flowers, three of
which were fertilised by their own pollen, and the fourth by the pollen
of a triple cross between _H. bulbulosum, reginæ,_ and _vittatum_; the
result was, that “the ovaries of the three first flowers soon ceased to
grow, and after a few days perished entirely: whereas the pod
impregnated by the hybrid made vigorous and rapid progress to maturity,
and bore good seed, which vegetated freely.” This is, indeed, as
Herbert remarks, “a strange truth,” but not so strange as it then
appeared.

As a confirmation of these statements, I may add that Mr. M. Mayes[83]
after much experience in crossing the species of Amaryllis
(Hippeastrum), says, “neither the species nor the hybrids will, we are
well aware, produce seed so abundantly from their own pollen as from
that of others.” So, again, Mr. Bidwell, in New South Wales[84] asserts
that _Amaryllis belladonna_ bears many more seeds when fertilised by
the pollen of _ Brunswigia_ (_Amaryllis_ of some authors) _ josephinæ_
or of _B. multiflora,_ than when fertilised by its own pollen. Mr.
Beaton dusted four flowers of a Cyrtanthus with their own pollen, and
four with the pollen of _Vallota (Amaryllis) purpurea_; on the seventh
day “those which received their own pollen slackened their growth, and
ultimately perished; those which were crossed with the Vallota held
on.”[85] These latter cases, however, relate to uncrossed species, like
those before given with respect to Passiflora, Orchids, etc., and are
here referred to only because the plants belong to the same group of
Amaryllidaceæ.

In the experiments on the hybrid Hippeastrums, if Herbert had found
that the pollen of two or three kinds alone had been more efficient on
certain kinds than their own pollen, it might have been argued that
these, from their mixed parentage, had a closer mutual affinity than
the others; but this explanation is inadmissible, for the trials were
made reciprocally backwards and forwards on nine different hybrids; and
a cross, whichever way taken, always proved highly beneficial. I can
add a striking and analogous case from experiments made by the Rev. A.
Rawson, of Bromley Common, with some complex hybrids of Gladiolus. This
skilful horticulturist possessed a number of French varieties,
differing from each other only in the colour and size of the flowers,
all descended from Gandavensis, a well-known old hybrid, said to be
descended from _G. natalensis_ by the pollen of _ G.
oppositiflorus._[86] Mr. Rawson, after repeated trials, found that none
of the varieties would set seed with their own pollen, although taken
from distinct plants of the same variety (which had, of course, been
propagated by bulbs), but that they all seeded freely with pollen from
any other variety. To give two examples: Ophir did not produce a
capsule with its own pollen, but when fertilised with that of Janire,
Brenchleyensis, Vulcain and Linné, it produced ten fine capsules; but
the pollen of Ophir was good, for when Linné was fertilised by it seven
capsules were produced. This latter variety, on the other hand, was
utterly barren with its own pollen, which we have seen was perfectly
efficient on Ophir. Altogether, Mr. Rawson, in the year 1861 fertilised
twenty-six flowers borne by four varieties with pollen taken from other
varieties, and every single flower produced a fine seed-capsule;
whereas fifty-two flowers on the same plants, fertilised at the same
time with their own pollen, did not yield a single seed-capsule. Mr.
Rawson fertilised, in some cases, the alternate flowers, and in other
cases all those down one side of the spike, with pollen of other
varieties, and the remaining flowers with their own pollen. I saw these
plants when the capsules were nearly mature, and their curious
arrangement at once brought full conviction to the mind that an immense
advantage had been derived from crossing these hybrids.

Lastly, I have heard from Dr. E. Bornet, of Antibes, who has made
numerous experiments in crossing the species of Cistus, but has not yet
published the results, that, when any of these hybrids are fertile,
they may be said to be, in regard to function, dioecious; “for the
flowers are always sterile when the pistil is fertilised by pollen
taken from the same flower or from flowers on the same plant. But they
are often fertile if pollen be employed from a distinct individual of
the same hybrid nature, or from a hybrid made by a reciprocal cross.”

_Conclusion._—That plants should be self-sterile, although both sexual
elements are in a fit state for reproduction, appears at first sight
opposed to all analogy. With respect to the species, all the
individuals of which are in this state, although living under their
natural conditions, we may conclude that their self-sterility has been
acquired for the sake of effectually preventing self-fertilisation. The
case is closely analogous with that of dimorphic and trimorphic or
heterostyled plants, which can be fully fertilised only by plants
belonging to a different form, and not, as in the foregoing cases,
indifferently by any other individual of the species. Some of these
hetero-styled plants are completely sterile with pollen taken from the
same plant or from the same form. With respect to species living under
their natural conditions, of which only certain individuals are
self-sterile (as with _Reseda lutea_), it is probable that these have
been rendered self-sterile to ensure occasional cross-fertilisation,
whilst other individuals have remained self-fertile to ensure the
propagation of the species. The case seems to be parallel with that of
plants which produce, as Hermann Müller has discovered, two forms—one
bearing more conspicuous flowers with their structure adapted for
cross-fertilisation by insects, and the other form with less
conspicuous flowers adapted for self-fertilisation. The self-sterility,
however, of some of the foregoing plants is incidental on the
conditions to which they have been subjected, as with the
Eschscholtzia, the _Verbascum phœniceum_ (the sterility of which varied
according to the season), and with the _Passiflora alata,_ which
recovered its self-fertility when grafted on a different stock.

It is interesting to observe in the above several cases the graduated
series from plants which, when fertilised by their own pollen, yield
the full number of seeds, but with the seedlings a little dwarfed in
stature—to plants which when self-fertilised yield few seeds—to those
which yield none, but have their ovaria somewhat developed—and, lastly,
to those in which the plant’s own pollen and stigma mutually act on one
another like poison. It is also interesting to observe on how slight a
difference in the nature of the pollen or of the ovules complete
self-sterility or complete self-fertility must depend in some of the
above cases. Every individual of the self-sterile species appears to be
capable of producing the full complement of seed when fertilised by the
pollen of any other individual (though judging from the facts given
with respect to Abutilon the nearest kin must be excepted); but not one
individual can be fertilised by its own pollen. As every organism
differs in some slight degree from every other individual of the same
species, so no doubt it is with their pollen and ovules; and in the
above cases we must believe that complete self-sterility and complete
self-fertility depend on such slight differences in the ovules and
pollen, and not their having been differentiated in some special manner
in relation to one another; for it is impossible that the sexual
elements of many thousand individuals should have been specialised in
relation to every other individual. In some, however, of the above
cases, as with certain Passifloras, an amount of differentiation
between the pollen and ovules sufficient for fertilisation is gained
only by employing pollen from a distinct species; but this is probably
the result of such plants having been rendered somewhat sterile from
the unnatural conditions to which they have been exposed.

Exotic animals confined in menageries are sometimes in nearly the same
state as the above-described self-impotent plants; for, as we shall see
in the following chapter, certain monkeys, the larger carnivora,
several finches, geese, and pheasants, cross together, quite as freely
as, or even more freely than the individuals of the same species breed
together. Cases will, also, be given of sexual incompatibility between
certain, male and female domesticated animals, which, nevertheless, are
fertile when matched with any other individual of the same kind.

In the early part of this chapter it was shown that the crossing of
individuals belonging to distinct families of the same race, or to
different races or species, gives increased size and constitutional
vigour to the offspring, and, except in the case of crossed species,
increased fertility. The evidence rests on the universal testimony of
breeders (for it should be observed that I am not here speaking of the
evil results of close interbreeding), and is practically exemplified in
the higher value of cross-bred animals for immediate consumption. The
good results of crossing have also been demonstrated with some animals
and with numerous plants, by actual weight and measurement. Although
animals of pure blood will obviously be deteriorated by crossing, as
far as their characteristic qualities are concerned, there seems to be
no exception to the rule that advantages of the kind just mentioned are
thus gained, even when there has not been any previous close
interbreeding; and the rule applies to such animals as cattle and
sheep, which can long resist breeding in-and-in between the nearest
blood-relations.

In the case of crossed species, although size, vigour, precocity, and
hardiness are, with rare exceptions, gained, fertility, in a greater or
less degree, is lost; but the gain in the above respects can hardly be
attributed to the principle of compensation; for there is no close
parallelism between the increased size and vigour of hybrid offspring
and their sterility. Moreover, it has been clearly proved that mongrels
which are perfectly fertile gain these same advantages as well as
sterile hybrids.

With the higher animals no special adaptations for ensuring occasional
crosses between distinct families seem to exist. The eagerness of the
males, leading to severe competition between them, is sufficient; for
even with gregarious animals, the old and dominant males will be
dispossessed after a time and it would be a mere chance if a closely
related member of the same family were to be the victorious successor.
The structure of many of the lower animals, when they are
hermaphrodites, is such as to prevent the ovules being fertilised by
the male element of the same individual; so that the concourse of two
individuals is necessary. In other cases the access of the male element
of a distinct individual is at least possible. With plants, which are
affixed to the ground and cannot wander from place to place like
animals, the numerous adaptations for cross-fertilisation are
wonderfully perfect, as has been admitted by every one who has studied
the subject.

The evil consequences of long-continued close interbreeding are not so
easily recognised as the good effects from crossing, for the
deterioration is gradual. Nevertheless, it is the general opinion of
those who have had most experience, especially with animals which
propagate quickly, that evil does inevitably follow sooner or later,
but at different rates with different animals. No doubt a false belief
may, like a superstition, prevail widely; yet it is difficult to
suppose that so many acute observers have all been deceived at the
expense of much cost and trouble. A male animal may sometimes be paired
with his daughter, granddaughter, and so on, even for seven
generations, without any manifest bad result: but the experiment has
never been tried of matching brothers and sisters, which is considered
the closest form of interbreeding, for an equal number of generations.
There is good reason to believe that by keeping the members of the same
family in distinct bodies, especially if exposed to somewhat different
conditions of life, and by occasionally crossing these families, the
evil results of interbreeding may be much diminished or quite
eliminated. These results are loss of constitutional vigour, size, and
fertility; but there is no necessary deterioration in the general form
of the body, or in other good qualities. We have seen that with pigs
first-rate animals have been produced after long-continued close
interbreeding, though they had become extremely infertile when paired
with their near relations. The loss of fertility, when it occurs, seems
never to be absolute, but only relative to animals of the same blood;
so that this sterility is to a certain extent analogous with that of
self-impotent plants which cannot be fertilised by their own pollen,
but are perfectly fertile with pollen of any other individual of the
same species. The fact of infertility of this peculiar nature being one
of the results of long-continued interbreeding, shows that
interbreeding does not act merely by combining and augmenting various
morbid tendencies common to both parents; for animals with such
tendencies, if not at the time actually ill, can generally propagate
their kind. Although offspring descended from the nearest
blood-relations are not necessarily deteriorated in structure, yet some
authors believe that they are eminently liable to malformations; and
this is not improbable, as everything which lessens the vital powers
acts in this manner. Instances of this kind have been recorded in the
case of pigs, bloodhounds, and some other animals.

Finally, when we consider the various facts now given which plainly
show that good follows from crossing, and less plainly that evil
follows from close interbreeding, and when we bear in mind that with
very many organisms elaborate provisions have been made for the
occasional union of distinct individuals, the existence of a great law
of nature is almost proved; namely, that the crossing of animals and
plants which are not closely related to each other is highly beneficial
or even necessary, and that interbreeding prolonged during many
generations is injurious.

REFERENCES

 [1] ‘The Art of Improving the Breed, etc.,’ 1809, p. 16.

 [2] ‘The History of the Rise and Progress of the Killerby, etc.
 Herds,’ p. 41.

 [3] For Andrew Knight, _see_ A. Walker, on ‘Intermarriage,’ 1838, p.
 227. Sir J. Sebright’s Treatise has just been quoted.

 [4] ‘Cattle,’ p. 199.

 [5] I give this on the authority of Nathusius, ‘Ueber Shorthorn
 Rindvieh,’ 1857, s. 71, (_see also_ ‘Gardener’s Chronicle,’ 1860, p.
 270). But Mr. J. Storer, a large breeder of cattle, informs me that
 the parentage of Clarissa is not well authenticated. In the first vol.
 of the ‘Herd Book,’ she was entered as having six descents from
 Favourite, “which was a palpable mistake,” and in all subsequent
 editions she was spoken of as having only four descents. Mr. Storer
 doubts even about the four, as no names of the dams are given.
 Moreover, Clarissa bore “only two bulls and one heifer, and in the
 next generation her progeny became extinct.” Analogous cases of close
 interbreeding are given in a pamphlet published by Mr. C. Macknight
 and Dr. H. Madden, ‘On the True Principles of Breeding;’ Melbourne,
 Australia, 1865.

 [6] Mr. Willoughby Wood, in ‘Gardener’s Chronicle,’ 1855, p. 411; and
 1860, p. 270. _See_ the very clear tables and pedigrees given in
 Nathusius’ ‘Rindvieh,’ s. 72-77.

 [7] Mr. Wright, ‘Journal of Royal Agricult. Soc.,’ vol. vii., 1846, p.
 204. Mr. J. Downing (a successful breeder of Shorthorns in Ireland)
 informs me that the raisers of the great families of Shorthorns
 carefully conceal their sterility and want of constitution. He adds
 that Mr. Bates, after he had bred his herd in-and-in for some years,
 “lost in one season twenty-eight calves solely from want of
 constitution.”

 [8] Youatt on Cattle, p. 202.

 [9] ‘Report British Assoc., Zoolog. Sect.,’ 1838.

 [10] Azara, ‘Quadrupèdes du Paraguay,’ tom. ii. pp. 354, 368.

 [11] For the case of the Messrs. Brown, _see_ ‘Gardener’s Chronicle,’
 1855, p. 26. For the Foscote flock, ‘Gardener’s Chronicle,’ 1860, p.
 416. For the Naz flock, ‘Bull. de la Soc. d’Acclimat.,’ 1860, p. 477.

 [12] Nathusius, ‘Rindvieh,’ s. 65; Youatt on Sheep, p. 495.

 [13] ‘Gardener’s Chronicle,’ 1861, p. 631.

 [14] ‘Journal R. Agricult. Soc.,’ vol. xiv., 1853, p. 212.

 [15] Lord Somerville, ‘Facts on Sheep and Husbandry,’ p. 6. Mr.
 Spooner in ‘Journal of Royal Agricult. Soc. of England,’ vol. xx. part
 ii. _See also_ an excellent paper on the same subject in ‘Gardener’s
 Chronicle,’ 1860, p. 321, by Mr. Charles Howard.

 [16] ‘Some Account of English Deer Parks,’ by Evelyn P. Shirley, 1867.

 [17] Stonehenge, ‘The Dog,’ 1867, pp. 175-178.

 [18] ‘The Art of Improving the Breed,’ etc., p. 13. With respect to
 Scotch deerhounds, _see_ Scrope’s ‘Art of Deer Stalking,’ pp. 350-353.

 [19] ‘Cottage Gardener,’ 1861, p. 327.

 [20] Mr. Huth gives (‘The Marriage of Near Kin,’ 1875, p. 302) from
 the ‘Bulletin de l’Acad. R. de Méd. de Belgique’ (vol. ix., 1866, pp.
 287, 305), several statements made by a M. Legrain with respect to
 crossing brother and sister rabbits for five or six successive
 generations with no consequent evil results. I was so much surprised
 at this account, and at M. Legrain’s invariable success in his
 experiments, that I wrote to a distinguished naturalist in Belgium to
 inquire whether M. Legrain was a trustworthy observer. In answer, I
 have heard that, as doubts were expressed about the authenticity of
 these experiments, a commission of inquiry was appointed, and that at
 a succeeding meeting of the Society (‘Bull. de l’Acad. R. de Méd. de
 Belgique,’ 1867, 3rd series, Tome 1, No. 1 to 5), Dr. Crocq reported
 “qu’il était matériellement impossible que M. Legrain ait fait les
 expériences qu’il annonce.” To this public accusation no satisfactory
 answer was made.

 [21] Sidney’s edit. of ‘Youatt on the Pig,’ 1860, p. 30; p. 33
 quotation from Mr. Druce; p. 29 on Lord Western’s case.

 [22] ‘Journal of Royal Agricult. Soc. of England,’ 1846, vol. vii. p.
 205.

 [23] ‘Ueber Rindvieh,’ etc., s. 78. Col. Le Couteur, who has done so
 much for the agriculture of Jersey, writes to me that from possessing
 a fine breed of pigs he bred them very closely, twice pairing brothers
 and sisters, but nearly all the young had fits and died suddenly.

 [24] Sidney on the Pig, p. 36. _See also_ note p. 34. Also Richardson
 on the Pig, 1847, p. 26.

 [25] Dr. Dally has published an excellent article (translated in the
 ‘Anthropolog. Review,’ May, 1864, p. 65), criticising all writers who
 have maintained that evil follows from consanguineous marriages. No
 doubt on this side of the question many advocates have injured their
 cause by inaccuracies: thus it has been stated (Devay, ‘Du Danger des
 Mariages,’ etc., 1862, p. 141) that the marriages of cousins have been
 prohibited by the legislature of Ohio; but I have been assured, in
 answer to inquiries made in the United States, that this statement is
 a mere fable.

 [26] _See_ his interesting work on the ‘Early History of Man,’ 1865,
 chap. x.

 [27] ‘The Marriage of Near Kin,’ 1875. The evidence given by Mr. Huth
 would, I think, have been even more valuable than it is on this and
 some other points, if he had referred solely to the works of men who
 had long resided in each country referred to, and who showed that they
 possessed judgment and caution. _See also_ Mr. W. Adam, ‘On
 Consanguinity in Marriage’ in the ‘Fortnightly Review,’ 1865, p. 710.
 Also Hofacker, ‘Ueber die Eigenschaften,’ etc., 1828.

 [28] Sir G. Grey’s ‘Journal of Expeditions into Australia,’ vol. ii.
 p. 243; and Dobrizhoffer, ‘On the Abipones of South America.’

 [29] ‘Descent of Man,’ 2nd. edit. p. 524.

 [30] ‘Journal of Statistical Soc.’ June, 1875, p. 153; and
 ‘Fortnightly Review,’ June, 1875.

 [31] ‘The Art of Improving the Breed,’ p. 13.

 [32] ‘The Poultry Book,’ by W. B. Tegetmeier, 1866, p. 245.

 [33] ‘Journal Royal Agricult. Soc.,’ 1846, vol. vii. p. 205; _ see
 also_ Ferguson on the Fowl, pp. 83, 317; _see also_ ‘The Poultry
 Book,’ by Tegetmeier, 1866, p. 135, with respect to the extent to
 which cock-fighters found that they could venture to breed in-and-in,
 viz., occasionally a hen with her own son; “but they were cautious not
 to repeat the in-and-in breeding.”

 [34] ‘The Poultry Book,’ by W. B. Tegetmeier, 1866, p. 79.

 [35] ‘The Poultry Chronicle,’ 1854, vol. i. p. 43.

 [36] ‘The Poultry Book,’ by W. B. Tegetmeier, 1866, p. 79.

 [37] ‘The Poultry Chronicle,’ vol. i. p. 89.

 [38] ‘The Poultry Book,’ 1866, p. 210.

 [39] Ibid. 1866, p. 167; and ‘Poultry Chronicle,’ vol. iii., 1855, p.
 15.

 [40] ‘A Treatise on Fancy Pigeons,’ by J. M. Eaton, p. 56.

 [41] ‘The Pigeon Book,’ p. 46.

 [42] ‘Das Ganze der Taubenzucht,’ 1837, s. 18.

 [43] ‘Les Pigeons,’ 1824, p. 35.

 [44] ‘Proc. Entomolog. Soc.,’ Aug. 6th, 1860, p. 126.

 [45] ‘Journal of Horticulture,’ 1861, pp. 39, 77, 158; and 1864, p.
 206.

 [46] ‘Beiträge zur Kenntniss der Befruchtung,’ 1844, s. 366.

 [47] ‘Amaryllidaceæ,’ p. 371.

 [48] ‘De la Fécondation,’ 2nd edit., 1862, p. 79.

 [49] ‘Mémoire sur les Cucurbitacées,’ pp. 36, 28, 30.

 [50] Loudon’s ‘Gard. Mag.,’ vol. viii., 1832, p. 52.

 [51] ‘Transact. Hort. Soc.,’ vol. i. p. 25.

 [52] ‘Annal. des Sc. Nat.,’ 3rd series, Bot., tom. vi. p. 189.

 [53] ‘Philosophical Transactions,’ 1799, p. 200.

 [54] ‘Ueber die Bastarderzeugung,’ 1828, s. 32, 33. For Mr. Chaundy’s
 case, _see_ Loudon’s ‘Gard. Mag.’ vol. vii. 1831, p. 696.

 [55] ‘Gardener’s Chron.,’ 1846, p. 601.

 [56] ‘Philosoph. Transact.,’ 1799, p. 201.

 [57] Quoted in ‘Bull. Bot. Soc. France,’ vol. ii., 1855, p. 327.

 [58] Gärtner, ‘Bastarderzeugung,’ s. 259, 518, 526 _et seq._

 [59] ‘Fortsetzung,’ 1763, s. 29; ‘Dritte Fortsetzung,’ s. 44, 96;
 ‘Act. Acad. St. Petersburg,’ 1782, part ii., p. 251; ‘Nova Acta,’
 1793, pp. 391, 394; ‘Nova Acta,’ 1795, pp. 316, 323.

 [60] ‘Die Bastardbefruchtung,’ etc., 1865, s. 31, 41, 42.

 [61] Max Wichura fully accepts this view (‘Bastardbefruchtung,’ s.
 43), as does the Rev. M. J. Berkeley, in ‘Journal of Hort. Soc.,’ Jan.
 1866, p. 70.

 [62] ‘Bastarderzeugung,’ s. 394, 526, 528.

 [63] Kölreuter, ‘Nova Acta,’ 1795, p. 316.

 [64] Gärtner, ‘Bastarderzeugung,’ s. 430.

 [65] Quoted by Dr. Murie, in ‘Proc. Zoolog. Soc.,’ 1870, p. 40.

 [66] ‘Botanische Zeitung,’ Jan. 1864, s. 3.

 [67] ‘Monatsbericht Akad. Wissen.’ Berlin, 1866, s. 372.

 [68] International Hort. Congress, London, 1866.

 [69] ‘Proc. Bot. Soc. of Edinburgh,’ May, 1863: these observations are
 given in abstract, and others are added, in the ‘Journal of Proc. of
 Linn. Soc.,’ vol. viii. Bot., 1864, p. 162.

 [70] Prof. Lecoq, ‘De la Fécondation,’ 2nd edit., 1862, p. 76.

 [71] ‘Jenaische Zeitschrift fur Naturwiss.’ B. vii. p. 22, 1872, and
 p. 441, 1873. A large part of this paper has been translated in the
 ‘American Naturalist,’ 1874, p. 223.

 [72] ‘Bastarderzeugung,’ s. 64, 357.

 [73] Ibid., s. 357.

 [74] ‘Zweite Fortsetzung,’ s. 10; ‘Dritte Forts.,’ s. 40. Mr. Scott
 likewise fertilised fifty-four flowers of _Verbascum phœniceum,_
 including two varieties, with their own pollen, and not a single
 capsule was produced. Many of the pollen-grains emitted their tubes,
 but only a few of them penetrated the stigmas; some slight effect
 however was produced, as many of the ovaries became somewhat
 developed: ‘Journal Asiatic Soc. Bengal,’ 1867, p. 150.

 [75] Duvernoy, quoted by Gärtner, ‘Bastarderzeugung,’ s. 334.

 [76] ‘Gardener’s Chronicle,’ 1846, p. 183.

 [77] ‘Transact. Hort. Soc.,’ vol. vii., 1830, p. 95.

 [78] Prof. Lecoq ‘De la Fécondation,’ 1845, p. 70; Gärtner,
 ‘Bastarderzeugung,’ s. 64.

 [79] ‘Gardener’s Chronicle,’ 1868, p. 1341.

 [80] ‘Gardener’s Chronicle,’ 1866, p. 1068.

 [81] ‘Journal of Proc. of Linn. Soc.,’ vol. viii., 1864, p. 1168. Mr.
 Robertson Munro, in ‘Trans. Bot. Soc.’ of Edinburgh, vol. ix. p. 399.

 [82] ‘Amaryllidaceæ,’ 1837, p. 371; ‘Journal of Hort. Soc.,’ vol. ii.,
 1847, p. 19.

 [83] Loudon’s ‘Gardener’s Magazine,’ vol. xi., 1835, p. 260.

 [84] ‘Gardener’s Chronicle,’ 1850, p. 470.

 [85] ‘Journal Hort. Soc.,’ vol. v. p. 135. The seedlings thus raised
 were given to the Hort. Soc.; but I find, on inquiry, that they
 unfortunately died the following winter.

 [86] Mr. D. Beaton, in ‘Journal of Hort.,’ 1861, p. 453. Lecoq however
 (‘De la Fécond.,’ 1862, p. 369), states that this hybrid is descended
 from _G. psittacinus_ and _ cardinalis_; but this is opposed to
 Herbert’s experience, who found that the former species could not be
 crossed.




CHAPTER XVIII. ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED
CONDITIONS OF LIFE: STERILITY FROM VARIOUS CAUSES.

ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE CONDITIONS OF
LIFE—STERILITY FROM CHANGED CONDITIONS, IN ANIMALS, IN THEIR NATIVE
COUNTRY AND IN MENAGERIES—MAMMALS, BIRDS, AND INSECTS—LOSS OF SECONDARY
SEXUAL CHARACTERS AND OF INSTINCTS—CAUSES OF STERILITY—STERILITY OF
DOMESTICATED ANIMALS FROM CHANGED CONDITIONS—SEXUAL INCOMPATIBILITY OF
INDIVIDUAL ANIMALS—STERILITY OF PLANTS FROM CHANGED CONDITIONS OF
LIFE—CONTABESCENCE OF THE ANTHERS—MONSTROSITIES AS A CAUSE OF
STERILITY—DOUBLE FLOWERS—SEEDLESS FRUIT—STERILITY FROM THE EXCESSIVE
DEVELOPMENT OF THE ORGANS OF VEGETATION—FROM LONG-CONTINUED PROPAGATION
BY BUDS—INCIPIENT STERILITY THE PRIMARY CAUSE OF DOUBLE FLOWERS AND
SEEDLESS FRUIT.


_On the Good derived from slight Changes in the Conditions of Life._—In
considering whether any facts were known which might throw light on the
conclusion arrived at in the last chapter, namely, that benefits ensue
from crossing, and that it is a law of nature that all organic beings
should occasionally cross, it appeared to me probable that the good
derived from slight changes in the conditions of life, from being an
analogous phenomenon, might serve this purpose. No two individuals, and
still less no two varieties, are absolutely alike in constitution and
structure; and when the germ of one is fertilised by the male element
of another, we may believe that it is acted on in a somewhat similar
manner as an individual when exposed to slightly changed conditions.
Now, every one must have observed the remarkable influence on
convalescents of a change of residence, and no medical man doubts the
truth of this fact. Small farmers who hold but little land are
convinced that their cattle derive great benefit from a change of
pasture. In the case of plants, the evidence is strong that a great
advantage is derived from exchanging seeds, tubers, bulbs, and cuttings
from one soil or place to another as different as possible.

The belief that plants are thus benefited, whether or not well founded,
has been firmly maintained from the time of Columella, who wrote
shortly after the Christian era, to the present day; and it now
prevails in England, France, and Germany.[1] A sagacious observer,
Bradley, writing in 1724,[2] says, “When we once become Masters of a
good Sort of Seed, we should at least put it into Two or Three Hands,
where the Soils and Situations are as different as possible; and every
Year the Parties should change with one another; by which Means, I find
the Goodness of the Seed will be maintained for several Years. For Want
of this Use many Farmers have failed in their Crops and been great
Losers.” He then gives his own practical experience on this head. A
modern writer[3] asserts, “Nothing can be more clearly established in
agriculture than that the continual growth of any one variety in the
same district makes it liable to deterioration either in quality or
quantity.” Another writer states that he sowed close together in the
same field two lots of wheat-seed, the product of the same original
stock, one of which had been grown on the same land and the other at a
distance, and the difference in favour of the crop from the latter seed
was remarkable. A gentleman in Surrey who has long made it his business
to raise wheat to sell for seed, and who has constantly realised in the
market higher prices than others, assures me that he finds it
indispensable continually to change his seed; and that for this purpose
he keeps two farms differing much in soil and elevation.

With respect to the tubers of the potato, I find that at the present
day the practice of exchanging sets is almost everywhere followed. The
great growers of potatoes in Lancashire formerly used to get tubers
from Scotland, but they found that “a change from the moss-lands, and
_vice versa,_ was generally sufficient.” In former times in France the
crop of potatoes in the Vosges had become reduced in the course of
fifty or sixty years in the proportion from 120-150 to 30-40 bushels;
and the famous Oberlin attributed the surprising good which he effected
in large part to changing the sets.[4]

A well-known practical gardener, Mr. Robson[5] positively states that
he has himself witnessed decided advantage from obtaining bulbs of the
onion, tubers of the potato, and various seeds, all of the same kind,
from different soils and distant parts of England. He further states
that with plants propagated by cuttings, as with the Pelargonium, and
especially the Dahlia, manifest advantage is derived from getting
plants of the same variety, which have been cultivated in another
place; or, “where the extent of the place allows, to take cuttings from
one description of soil to plant on another, so as to afford the change
that seems so necessary to the well-being of the plants.” He maintains
that after a time an exchange of this nature is “forced on the grower,
whether he be prepared for it or not.” Similar remarks have been made
by another excellent gardener, Mr. Fish, namely, that cuttings of the
same variety of Calceolaria, which he obtained from a neighbour,
“showed much greater vigour than some of his own that were treated in
exactly the same manner,” and he attributed this solely to his own
plants having become “to a certain extent worn out or tired of their
quarters.” Something of this kind apparently occurs in grafting and
budding fruit-trees; for, according to Mr. Abbey, grafts or buds
generally take with greater facility on a distinct variety or even
species, or on a stock previously grafted, than on stocks raised from
seeds of the variety which is to be grafted; and he believes this
cannot be altogether explained by the stocks in question being better
adapted to the soil and climate of the place. It should, however, be
added, that varieties grafted or budded on very distinct kinds, though
they may take more readily and grow at first more vigorously than when
grafted on closely allied stocks, afterwards often become unhealthy.

I have studied M. Tessier’s careful and elaborate experiments[6] made
to disprove the common belief that good is derived from a change of
seed; and he certainly shows that the same seed may with care be
cultivated on the same farm (it is not stated whether on exactly the
same soil) for ten consecutive years without loss. Another excellent
observer, Colonel Le Couteur[7] has come to the same conclusion; but
then he expressly adds, if the same seed be used, “that which is grown
on land manured from the mixen one year becomes seed for land prepared
with lime, and that again becomes seed for land dressed with ashes,
then for land dressed with mixed manure, and so on.” But this in effect
is a systematic exchange of seed, within the limits of the same farm.

On the whole the belief, which has long been held by many cultivators,
that good follows from exchanging seed, tubers, etc., seems to be
fairly well founded. It seems hardly credible that the advantage thus
derived can be due to the seeds, especially if very small ones,
obtaining in one soil some chemical element deficient in the other and
in sufficient quantity to influence the whole after-growth of the
plant. As plants after once germinating are fixed to the same spot, it
might have been anticipated that they would show the good effects of a
change more plainly than do animals which continually wander about; and
this apparently is the case. Life depending on, or consisting in, an
incessant play of the most complex forces, it would appear that their
action is in some way stimulated by slight changes in the circumstances
to which each organism is exposed. All forces throughout nature, as Mr.
Herbert Spencer[8] remarks, tend towards an equilibrium, and for the
life of each organism it is necessary that this tendency should be
checked. These views and the foregoing facts probably throw light, on
the one hand, on the good effects of crossing the breed, for the germ
will be thus slightly modified or acted on by new forces; and on the
other hand, on the evil effects of close interbreeding prolonged during
many generations, during which the germ will be acted on by a male
having almost identically the same constitution.

      _Sterility from Changed Conditions of Life._

I will now attempt to show that animals and plants, when removed from
their natural conditions, are often rendered in some degree infertile
or completely barren; and this occurs even when the conditions have not
been greatly changed. This conclusion is not necessarily opposed to
that at which we have just arrived, namely, that lesser changes of
other kinds are advantageous to organic beings. Our present subject is
of some importance, from having an intimate connection with the causes
of variability. Indirectly it perhaps bears on the sterility of species
when crossed: for as, on the one hand, slight changes in the conditions
of life are favourable to plants and animals, and the crossing of
varieties adds to the size, vigour, and fertility of their offspring;
so, on the other hand, certain other changes in the conditions of life
cause sterility; and as this likewise ensues from crossing
much-modified forms or species, we have a parallel and double series of
facts, which apparently stand in close relation to each other.

It is notorious that many animals, though perfectly tamed, refuse to
breed in captivity. Isidore Geoffroy St.-Hilaire[9] consequently has
drawn a broad distinction between tamed animals which will not breed
under captivity, and truly domesticated animals which breed
freely—generally more freely, as shown in the sixteenth chapter, than
in a state of nature. It is possible and generally easy to tame most
animals; but experience has shown that it is difficult to get them to
breed regularly, or even at all. I shall discuss this subject in
detail; but will give only those cases which seem most illustrative. My
materials are derived from notices scattered through various works, and
especially from a Report, kindly drawn up for me by the officers of the
Zoological Society of London, which has especial value, as it records
all the cases, during nine years from 1838-46, in which the animals
were seen to couple but produced no offspring, as well as the cases in
which they never, as far as known, coupled. This MS. Report I have
corrected by the annual Reports subsequently published up to the year
1865.[10] Many facts are given on the breeding of the animals in that
magnificent work, ‘Gleanings from the Menageries of Knowsley Hall’ by
Dr. Gray. I made, also, particular inquiries from the experienced
keeper of the birds in the old Surrey Zoological Gardens. I should
premise that a slight change in the treatment of animals sometimes
makes a great difference in their fertility; and it is probable that
the results observed in different menageries would differ. Indeed, some
animals in our Zoological Gardens have become more productive since the
year 1846. It is, also, manifest from F. Cuvier’s account of the Jardin
des Plantes[11] that the animals formerly bred much less freely there
than with us; for instance, in the Duck tribe, which is highly
prolific, only one species had at that period produced young.

The most remarkable cases, however, are afforded by animals kept in
their native country, which, though perfectly tamed, quite healthy, and
allowed some freedom, are absolutely incapable of breeding.
Rengger,[12] who in Paraguay particularly attended to this subject,
specifies six quadrupeds in this condition; and he mentions two or
three others which most rarely breed. Mr. Bates, in his admirable work
on the Amazons, strongly insists on similar cases;[13] and he remarks,
that the fact of thoroughly tamed native mammals and birds not breeding
when kept by the Indians, cannot be wholly accounted for by their
negligence or indifference, for the turkey and fowl are kept and bred
by various remote tribes. In almost every part of the world—for
instance, in the interior of Africa, and in several of the Polynesian
islands—the natives are extremely fond of taming the indigenous
quadrupeds and birds; but they rarely or never succeed in getting them
to breed.

The most notorious case of an animal not breeding in captivity is that
of the elephant. Elephants are kept in large numbers in their native
Indian home, live to old age, and are vigorous enough for the severest
labour; yet, with a very few exceptions, they have never been known
even to couple, though both males and females have their proper
periodical seasons. If, however, we proceed a little eastward to Ava,
we hear from Mr. Crawfurd[14] that their “breeding in the domestic
state, or at least in the half-domestic state in which the female
elephants are generally kept, is of everyday occurrence;” and Mr.
Crawfurd informs me that he believes that the difference must be
attributed solely to the females being allowed to roam the forest with
some degree of freedom. The captive rhinoceros, on the other hand,
seems from Bishop Heber’s account[15] to breed in India far more
readily than the elephant. Four wild species of the horse genus have
bred in Europe, though here exposed to a great change in their natural
habits of life; but the species have generally been crossed one with
another. Most of the members of the pig family breed readily in our
menageries; even the Red River hog (_Potamochœrus penicillatus_), from
the sweltering plains of West Africa, has bred twice in the Zoological
Gardens. Here also the Peccary (_Dicotyles torquatus_) has bred several
times; but another species, the _D. labiatus,_ though rendered so tame
as to be half-domesticated, is said to breed so rarely in its native
country of Paraguay, that according to Rengger[16] the fact requires
confirmation. Mr. Bates remarks that the tapir, though often kept tame
in Amazonia by the Indians, never breeds.

Ruminants generally breed quite freely in England, though brought from
widely different climates, as may be seen in the Annual Reports of the
Zoological Gardens, and in the Gleanings from Lord Derby’s menagerie.

The Carnivora, with the exception of the Plantigrade division, breed
(though with capricious exceptions) about half as freely as ruminants.
Many species of Felidae have bred in various menageries, although
imported from diverse climates and closely confined. Mr. Bartlett, the
present superintendent of the Zoological Gardens[17] remarks that the
lion appears to breed more frequently and to bring forth more young at
a birth than any other species of the family. He adds that the tiger
has rarely bred; “but there are several well-authenticated instances of
the female tiger breeding with the lion.” Strange as the fact may
appear, many animals under confinement unite with distinct species and
produce hybrids quite as freely as, or even more freely than, with
their own species. On inquiring from Dr. Falconer and others, it
appears that the tiger when confined in India does not breed, though it
has been known to couple. The chetah (_Felis jubata_) has never been
known by Mr. Bartlett to breed in England, but it has bred at
Frankfort; nor does it breed in India, where it is kept in large
numbers for hunting; but no pains would be taken to make them breed, as
only those animals which have hunted for themselves in a state of
nature are serviceable and worth training.[18] According to Rengger,
two species of wild cats in Paraguay, though thoroughly tamed, have
never bred. Although so many of the Felidae breed readily in the
Zoological Gardens, yet conception by no means always follows union: in
the nine-year Report, various species are specified which were observed
to couple seventy-three times, and no doubt this must have passed many
times unnoticed; yet from the seventy- three unions only fifteen births
ensued. The Carnivora in the Zoological Gardens were formerly less
freely exposed to the air and cold than at present, and this change of
treatment, as I was assured by the former superintendent, Mr. Miller,
greatly increased their fertility. Mr. Bartlett, and there cannot be a
more capable judge, says, “it is remarkable that lions breed more
freely in travelling collections than in the Zoological Gardens;
probably the constant excitement and irritation produced by moving from
place to place, or change of air, may have considerable influence in
the matter.”

Many members of the Dog family breed readily when confined. The Dhole
is one of the most untamable animals in India, yet a pair kept there by
Dr. Falconer produced young. Foxes, on the other hand, rarely breed,
and I have never heard of such an occurrence with the European fox: the
silver fox of North America (_Canis argentatus_), however, has bred
several times in the Zoological Gardens. Even the otter has bred there.
Every one knows how readily the semi-domesticated ferret breeds, though
shut up in miserably small cages; but other species of Viverra and
Paradoxurus absolutely refuse to breed in the Zoological Gardens. The
Genetta has bred both here and in the Jardin des Plantes, and produced
hybrids. The _Herpestes fasciatus_ has likewise bred; but I was
formerly assured that the _H. griseus,_ though many were kept in the
Gardens, never bred.

The Plantigrade Carnivora breed under confinement much less freely than
other Carnivora, although no reason can be assigned for this fact. In
the nine-year Report it is stated that the bears had been seen in the
Zoological Gardens to couple freely, but previously to 1848 had most
rarely conceived. In the Reports published since this date three
species have produced young (hybrids in one case), and, wonderful to
relate, the white Polar bear has produced young. The badger (_Meles
taxus_) has bred several times in the Gardens; but I have not heard of
this occurring elsewhere in England, and the event must be very rare,
for an instance in Germany has been thought worth recording.[19] In
Paraguay the native Nasua, though kept in pairs during many years and
perfectly tamed, has never been known, according to Rengger, to breed
or show any sexual passion; nor, as I hear from Mr. Bates, does this
animal, or the Cercoleptes, breed in Amazonia. Two other plantigrade
genera, Procyon and Gulo, though often kept tame in Paraguay, never
breed there. In the Zoological Gardens species of Nasua and Procyon
have been seen to couple; but they did not produce young.

As domesticated rabbits, guinea-pigs, and white mice breed so
abundantly when closely confined under various climates, it might have
been thought that most other members of the Rodent order would have
bred in captivity, but this is not the case. It deserves notice, as
showing how the capacity to breed sometimes goes by affinity, that the
one native rodent of Paraguay, which there breeds _freely_ and has
yielded successive generations, is the _Cavia aperea_; and this animal
is so closely allied to the guinea-pig, that it has been erroneously
thought to be the parent form.[20] In the Zoological Gardens, some
rodents have coupled, but have never produced young; some have neither
coupled nor bred; but a few have bred, as the porcupine more than once,
the Barbary mouse, lemming, chinchilla, and agouti (_Dasyprocta aguti_)
several times. This latter animal has also produced young in Paraguay,
though they were born dead and ill-formed; but in Amazonia, according
to Mr. Bates, it never breeds, though often kept tame about the houses.
Nor does the paca (_Cœlogenys paca_) breed there. The common hare when
confined has, I believe, never bred in Europe; though, according to a
recent statement, it has crossed with the rabbit.[21] I have never
heard of the dormouse breeding in confinement. But squirrels offer a
more curious case: with one exception, no species has bred in the
Zoological Gardens, yet as many as fourteen individuals of _S.
palmarum_ were kept together during several years. The _S. cinera_ has
been seen to couple, but it did not produce young; nor has this
species, when rendered extremely tame in its native country, North
America, been ever known to breed.[22] At Lord Derby’s menagerie
squirrels of many kinds were kept in numbers, but Mr. Thompson, the
superintendent, told me that none had ever bred there, or elsewhere as
far as he knew. I have never heard of the English squirrel breeding in
confinement. But the species which has bred more than once in the
Zoological Gardens is the one which perhaps might have been least
expected, namely, the flying squirrel (_Sciuropterus volucella_): it
has, also, bred several times near Birmingham; but the female never
produced more than two young at a birth, whereas in its native American
home she bears from three to six young.[23]

Monkeys, in the nine-year Report from the Zoological Gardens, are
stated to unite most freely, but during this period, though many
individuals were kept, there were only seven births. I have heard of
only one American monkey, the Ouistiti, breeding in Europe.[24] A
Macacus, according to Flourens, bred in Paris; and more than one
species of this genus has produced young in London, especially the
_Macacus rhesus,_ which everywhere shows a special capacity to breed
under confinement. Hybrids have been produced both in Paris and London
from this same genus. The Arabian baboon, or _ Cynocephalus
hamadryas,_[25] and a Cercopithecus have bred in the Zoological
Gardens, and the latter species at the Duke of Northumberland’s.
Several members of the family of Lemurs have produced hybrids in the
Zoological Gardens. It is much more remarkable that monkeys very rarely
breed when confined in their native country; thus the Cay (_Cebus
azaræ_) is frequently and completely tamed in Paraguay, but Rengger[26]
says that it breeds so rarely, that he never saw more than two females
which had produced young. A similar observation has been made with
respect to the monkeys which are frequently tamed by the aborigines in
Brazil.[27] In Amazonia, these animals are so often kept in a tame
state, that Mr. Bates in walking through the streets of Para counted
thirteen species; but, as he asserts, they have never been known to
breed in captivity.[28]

      _Birds._

Birds offer in some respects better evidence than quadrupeds, from
their breeding more rapidly and being kept in greater numbers.[29] We
have seen that carnivorous animals are more fertile under confinement
than most other mammals. The reverse holds good with carnivorous birds.
It is said[30] that as many as eighteen species have been used in
Europe for hawking, and several others in Persia and India;[31] they
have been kept in their native country in the finest condition, and
have been flown during six, eight, or nine years;[32] yet there is no
record of their having ever produced young. As these birds were
formerly caught whilst young, at great expense, being imported from
Iceland, Norway, and Sweden, there can be little doubt that, if
possible, they would have been propagated. In the Jardin des Plantes,
no bird of prey has been known to couple.[33] No hawk, vulture, or owl
has ever produced fertile eggs in the Zoological Gardens, or in the old
Surrey Gardens, with the exception, in the former place on one
occasion, of a condor and a kite (_Milvus niger_). Yet several species,
namely, the _Aquila fusca, Haliaetus leucocephalus, Falco tinnunculus,
F. subbuteo,_ and _Buteo vulgaris,_ have been seen to couple in the
Zoological Gardens. Mr. Morris[34] mentions as a unique fact that a
kestrel (_Falco tinnunculus_) bred in an aviary. The one kind of owl
which has been known to couple in the Zoological Gardens was the Eagle
Owl (_Bubo maximus_); and this species shows a special inclination to
breed in captivity; for a pair at Arundel Castle, kept more nearly in a
state of nature “than ever fell to the lot of an animal deprived of its
liberty,”[35] actually reared their young. Mr. Gurney has given another
instance of this same owl breeding in confinement; and he records the
case of a second species of owl, the _Strix passerina,_ breeding in
captivity.[36]

Of the smaller graminivorous birds, many kinds have been kept tame in
their native countries, and have lived long; yet, as the highest
authority on cage-birds[37] remarks, their propagation is “uncommonly
difficult.” The canary-bird shows that there is no inherent difficulty
in these birds breeding freely in confinement; and Audubon says[38]
that the _ Fringilla (Spiza) ciris_ of North America breeds as
perfectly as the canary. The difficulty with the many finches which
have been kept in confinement is all the more remarkable as more than a
dozen species could be named which have yielded hybrids with the
canary; but hardly any of these, with the exception of the siskin
(_Fringilla spinus_), have reproduced their own kind. Even the
bullfinch (_Loxia pyrrhula_) has bred as frequently with the canary,
though belonging to a distinct genus, as with its own species.[39] With
respect to the skylark (_Alauda arvensis_), I have heard of birds
living for seven years in an aviary, which never produced young; and a
great London bird-fancier assured me that he had never known an
instance of their breeding; nevertheless one case has been
recorded.[40] In the nine-year Report from the Zoological Society,
twenty-four insessorial species are enumerated which had not bred, and
of these only four were known to have coupled.

Parrots are singularly long-lived birds; and Humboldt mentions the
curious fact of a parrot in South America, which spoke the language of
an extinct Indian tribe, so that this bird preserved the sole relic of
a lost language. Even in this country there is reason to believe[41]
that parrots have lived to the age of nearly one hundred years; yet
they breed so rarely, though many have been kept in Europe, that the
event has been thought worth recording in the gravest publications.[42]
Nevertheless, when Mr. Buxton turned out a large number of parrots in
Norfolk, three pairs bred and reared ten young birds in the course of
two seasons; and this success may be attributed to their free life.[43]
According to Bechstein[44] the African _Psittacus erithacus_ breeds
oftener than any other species in Germany: the _P. macoa_ occasionally
lays fertile eggs, but rarely succeeds in hatching them; this bird,
however, has the instinct of incubation sometimes so strongly
developed, that it will hatch the eggs of fowls or pigeons. In the
Zoological Gardens and in the old Surrey Gardens some few species have
coupled, but, with the exception of three species of parakeets, none
have bred. It is a much more remarkable fact that in Guiana parrots of
two kinds, as I am informed by Sir R. Schomburgk, are often taken from
the nests by the Indians and reared in large numbers; they are so tame
that they fly freely about the houses, and come when called to be fed,
like pigeons; yet he has never heard of a single instance of their
breeding.[45] In Jamaica, a resident naturalist, Mr. R. Hill,[46] says,
“no birds more readily submit to human dependence than the
parrot-tribe, but no instance of a parrot breeding in this tame life
has been known yet.” Mr. Hill specifies a number of other native birds
kept tame in the West Indies, which never breed in this state.

The great pigeon family offers a striking contrast with the parrots: in
the nine-year Report thirteen species are recorded as having bred, and,
what is more noticeable, only two were seen to couple without any
result. Since the above date every annual Report gives many cases of
various pigeons breeding. The two magnificent crowned pigeons (_Goura
coronata_ and _ victoriæ_) produced hybrids; nevertheless, of the
former species more than a dozen birds were kept, as I am informed by
Mr. Crawfurd, in a park at Penang, under a perfectly well-adapted
climate, but never once bred. The _Columba migratoria_ in its native
country, North America, invariably lays two eggs, but in Lord Derby’s
menagerie never more than one. The same fact has been observed with the
_C. leucocephala._[47]

Gallinaceous birds of many genera likewise show an eminent capacity for
breeding under captivity. This is particularly the case with pheasants,
yet our English species seldom lays more than ten eggs in confinement;
whilst from eighteen to twenty is the usual number in the wild
state.[48] With the Gallinaceæ, as with all other orders, there are
marked and inexplicable exceptions in regard to the fertility of
certain species and genera under confinement. Although many trials have
been made with the common partridge, it has rarely bred, even when
reared in large aviaries; and the hen will never hatch her own
eggs.[49] The American tribe of Guans or Cracidæ are tamed with
remarkable ease, but are very shy breeders in this country;[50] but
with care various species were formerly made to breed rather freely in
Holland.[51] Birds of this tribe are often kept in a perfectly tamed
condition in their native country by the Indians, but they never
breed.[52] It might have been expected that grouse from their habits of
life would not have bred in captivity, more especially as they are said
soon to languish and die.[53] But many cases are recorded of their
breeding: the capercailzie (_Tetrao urogallus_) has bred in the
Zoological Gardens; it breeds without much difficulty when confined in
Norway, and in Russia five successive generations have been reared:
_Tetrao tetrix_ has likewise bred in Norway; _ T. scoticus_ in Ireland;
_T. umbellus_ at Lord Derby’s; and _T. cupido_ in North America.

It is scarcely possible to imagine a greater change in habits than that
which the members of the ostrich family must suffer, when cooped up in
small enclosures under a temperate climate, after freely roaming over
desert and tropical plains or entangled forests; yet almost all the
kinds have frequently produced young in the various European
menageries, even the mooruk (_Casuarius bennetii_) from New Ireland.
The African ostrich, though perfectly healthy and living long in the
South of France, never lays more than from twelve to fifteen eggs,
though in its native country it lays from twenty-five to thirty.[54]
Here we have another instance of fertility impaired, but not lost,
under confinement, as with the flying squirrel, the hen-pheasant, and
two species of American pigeons.

Most Waders can be tamed, as the Rev. E. S. Dixon informs me, with
remarkable facility; but several of them are short-lived under
confinement, so that their sterility in this state is not surprising.
The cranes breed more readily than other genera: _Grus montigresia_ has
bred several times in Paris and in the Zoological Gardens, as has _G.
cinerea_ at the latter place, and _G. antigone_ at Calcutta. Of other
members of this great order, _Tetrapteryx paradisea_ has bred at
Knowsley, a Porphyrio in Sicily, and the _Gallinula chloropus_ in the
Zoological Gardens. On the other hand, several birds belonging to this
order will not breed in their native country, Jamaica; and the Psophia,
though often kept by the Indians of Guiana about their houses, “is
seldom or never known to breed.”[55]

The members of the great Duck family breed as readily in confinement as
do the Columbæ and Gallinæ and this, considering their aquatic and
wandering habits, and the nature of their food, could not have been
anticipated. Even some time ago above two dozen species had bred in the
Zoological Gardens; and M. Selys-Longchamps has recorded the production
of hybrids from forty-four different members of the family; and to
these Professor Newton has added a few more cases.[56] “There is not,”
says Mr. Dixon,[57] “in the wide world, a goose which is not in the
strict sense of the word domesticable;” that is, capable of breeding
under confinement; but this statement is probably too bold. The
capacity to breed sometimes varies in individuals of the same species;
thus Audubon[58] kept for more than eight years some wild geese (_Anser
canadensis_), but they would not mate; whilst other individuals of the
same species produced young during the second year. I know of but one
instance in the whole family of a species which absolutely refuses to
breed in captivity, namely, the _Dendrocygna viduata,_ although,
according to Sir R. Schomburgk,[59] it is easily tamed, and is
frequently kept by the Indians of Guiana. Lastly, with respect to
Gulls, though many have been kept in the Zoological Gardens and in the
old Surrey Gardens, no instance was known before the year 1848 of their
coupling or breeding; but since that period the herring gull (_Larus
argentatus_) has bred many times in the Zoological Gardens and at
Knowsley.

There is reason to believe that insects are affected by confinement
like the higher animals. It is well known that the Sphingidae rarely
breed when thus treated. An entomologist[60] in Paris kept twenty-five
specimens of _Saturnia pyri,_ but did not succeed in getting a single
fertile egg. A number of females of _Orthosia munda_ and of _Mamestra
suasa_ reared in confinement were unattractive to the males.[61] Mr.
Newport kept nearly a hundred individuals of two species of Vanessa,
but not one paired; this, however, might have been due to their habit
of coupling on the wing.[62] Mr. Atkinson could never succeed in India
in making the Tarroo silk-moth breed in confinement.[63] It appears
that a number of moths, especially the Sphingidae, when hatched in the
autumn out of their proper season, are completely barren; but this
latter case is still involved in some obscurity.[64]

Independently of the fact of many animals under confinement not
coupling, or, if they couple, not producing young, there is evidence of
another kind that their sexual functions are disturbed. For many cases
have been recorded of the loss by male birds when confined of their
characteristic plumage. Thus the common linnet (_Linota cannabina_)
when caged does not acquire the fine crimson colour on its breast, and
one of the buntings (_Emberiza passerina_) loses the black on its head.
A Pyrrhula and an Oriolus have been observed to assume the quiet
plumage of the hen-bird; and the _Falco albidus_ returned to the dress
of an earlier age.[65] Mr. Thompson, the superintendent of the Knowsley
menagerie, informed me that he had often observed analogous facts. The
horns of a male deer (_Cervus canadensis_) during the voyage from
America were badly developed; but subsequently in Paris perfect horns
were produced.

When conception takes place under confinement, the young are often born
dead, or die soon, or are ill-formed. This frequently occurs in the
Zoological Gardens, and, according to Rengger, with native animals
confined in Paraguay. The mother’s milk often fails. We may also
attribute to the disturbance of the sexual functions the frequent
occurrence of that monstrous instinct which leads the mother to devour
her own offspring,—a mysterious case of perversion, as it at first
appears.

Sufficient evidence has now been advanced to prove that animals when
first confined are eminently liable to suffer in their reproductive
systems. We feel at first naturally inclined to attribute the result to
loss of health, or at least to loss of vigour; but this view can hardly
be admitted when we reflect how healthy, long-lived, and vigorous many
animals are under captivity, such as parrots, and hawks when used for
hawking, cheetahs when used for hunting, and elephants. The
reproductive organs themselves are not diseased; and the diseases, from
which animals in menageries usually perish, are not those which in any
way affect their fertility. No domestic animal is more subject to
disease than the sheep, yet it is remarkably prolific. The failure of
animals to breed under confinement has been sometimes attributed
exclusively to a failure in their sexual instincts: this may
occasionally come into play, but there is no obvious reason why this
instinct should be especially liable to be affected with perfectly
tamed animals, except, indeed, indirectly through the reproductive
system itself being disturbed. Moreover, numerous cases have been given
of various animals which couple freely under confinement, but never
conceive; or, if they conceive and produce young, these are fewer in
number than is natural to the species. In the vegetable kingdom
instinct of course can play no part; and we shall presently see that
plants when removed from their natural conditions are affected in
nearly the same manner as animals. Change of climate cannot be the
cause of the loss of fertility, for, whilst many animals imported into
Europe from extremely different climates breed freely, many others when
confined in their native land are completely sterile. Change of food
cannot be the chief cause; for ostriches, ducks, and many other
animals, which must have undergone a great change in this respect,
breed freely. Carnivorous birds when confined are extremely sterile,
whilst most carnivorous mammals, except plantigrades, are moderately
fertile. Nor can the amount of food be the cause; for a sufficient
supply will certainly be given to valuable animals; and there is no
reason to suppose that much more food would be given to them than to
our choice domestic productions which retain their full fertility.
Lastly, we may infer from the case of the elephant, cheetah, various
hawks, and of many animals which are allowed to lead an almost free
life in their native land, that want of exercise is not the sole cause.

It would appear that any change in the habits of life, whatever these
habits may be, if great enough, tends to affect in an inexplicable
manner the powers of reproduction. The result depends more on the
constitution of the species than on the nature of the change; for
certain whole groups are affected more than others; but exceptions
always occur, for some species in the most fertile groups refuse to
breed, and some in the most sterile groups breed freely. Those animals
which usually breed freely under confinement, rarely breed, as I was
assured, in the Zoological Gardens, within a year or two after their
first importation. When an animal which is generally sterile under
confinement happens to breed, the young apparently do not inherit this
power: for had this been the case, various quadrupeds and birds, which
are valuable for exhibition, would have become common. Dr. Broca even
affirms[66] that many animals in the Jardin des Plantes, after having
produced young for three or four successive generations, become
sterile; but this may be the result of too close interbreeding. It is a
remarkable circumstance that many mammals and birds have produced
hybrids under confinement quite as readily as, or even more readily
than, they have procreated their own kind. Of this fact many instances
have been given;[67] and we are thus reminded of those plants which
when cultivated refuse to be fertilised by their own pollen, but can
easily be fertilised by that of a distinct species. Finally, we must
conclude, limited as the conclusion is, that changed conditions of life
have an especial power of acting injuriously on the reproductive
system. The whole case is quite peculiar, for these organs, though not
diseased, are thus rendered incapable of performing their proper
functions, or perform them imperfectly.

_Sterility of Domesticated Animals from changed conditions._—With
respect to domesticated animals, as their domestication mainly depends
on the accident of their breeding freely under captivity, we ought not
to expect that their reproductive system would be affected by any
moderate degree of change. Those orders of quadrupeds and birds, of
which the wild species breed most readily in our menageries, have
afforded us the greatest number of domesticated productions. Savages in
most parts of the world are fond of taming animals;[68] and if any of
these regularly produced young, and were at the same time useful, they
would be at once domesticated. If, when their masters migrated into
other countries, they were in addition found capable of withstanding
various climates, they would be still more valuable; and it appears
that the animals which breed readily in captivity can generally
withstand different climates. Some few domesticated animals, such as
the reindeer and camel, offer an exception to this rule. Many of our
domesticated animals can bear with undiminished fertility the most
unnatural conditions; for instance, rabbits, guinea-pigs, and ferrets
breed in miserably confined hutches. Few European dogs of any kind
withstand the climate of India without degenerating, but as long as
they survive, they retain, as I hear from Dr. Falconer, their
fertility; so it is, according to Dr. Daniell, with English dogs taken
to Sierra Leone. The fowl, a native of the hot jungles of India,
becomes more fertile than its parent-stock in every quarter of the
world, until we advance as far north as Greenland and Northern Siberia,
where this bird will not breed. Both fowls and pigeons, which I
received during the autumn direct from Sierra Leone, were at once ready
to couple.[69] I have, also, seen pigeons breeding as freely as the
common kinds within a year after their importation from the upper Nile.
The guinea- fowl, an aboriginal of the hot and dry deserts of Africa,
whilst living under our damp and cool climate, produces a large supply
of eggs.

Nevertheless, our domesticated animals under new conditions
occasionally show signs of lessened fertility. Roulin asserts that in
the hot valleys of the equatorial Cordillera sheep are not fully
fecund;[70] and according to Lord Somerville[71] the merino-sheep which
he imported from Spain were not at first perfectly fertile, it is
said[72] that mares brought up on dry food in the stable, and turned
out to grass, do not at first breed. The peahen, as we have seen, is
said not to lay so many eggs in England as in India. It was long before
the canary-bird was fully fertile, and even now first-rate breeding
birds are not common.[73] In the hot and dry province of Delhi, as I
hear from Dr. Falconer, the eggs of the turkey, though placed under a
hen, are extremely liable to fail. According to Roulin, geese taken to
the lofty plateau of Bogota, at first laid seldom, and then only a few
eggs; of these scarcely a fourth were hatched, and half the young birds
died; in the second generation they were more fertile; and when Roulin
wrote they were becoming as fertile as our geese in Europe. With
respect to the valley of Quito, Mr. Orton says[74] “the only geese in
the valley are a few imported from Europe, and these refuse to
propagate.” In the Philippine Archipelago the goose, it is asserted,
will not breed or even lay eggs.[75] A more curious case is that of the
fowl, which, according to Roulin, when first introduced would not breed
at Cusco in Bolivia, but subsequently became quite fertile; and the
English Game fowl, lately introduced, had not as yet arrived at its
full fertility, for to raise two or three chickens from a nest of eggs
was thought fortunate. In Europe close confinement has a marked effect
on the fertility of the fowl: it has been found in France that with
fowls allowed considerable freedom only twenty per cent of the eggs
failed; when allowed less freedom forty per cent failed; and in close
confinement sixty out of the hundred were not hatched.[76] So we see
that unnatural and changed conditions of life produce some effect on
the fertility of our most thoroughly domesticated animals, in the same
manner, though in a far less degree, as with captive wild animals.

It is by no means rare to find certain males and females which will not
breed together, though both are known to be perfectly fertile with
other males and females. We have no reason to suppose that this is
caused by these animals having been subjected to any change in their
habits of life; therefore such cases are hardly related to our present
subject. The cause apparently lies in an innate sexual incompatibility
of the pair which are matched. Several instances have been communicated
to me by Mr. W. C. Spooner (well known for his essay on
Cross-breeding), by Mr. Eyton of Eyton, by Mr. Wicksted and other
breeders, and especially by Mr. Waring of Chelsfield, in relation to
horses, cattle, pigs, foxhounds, other dogs, and pigeons.[77] In these
cases, females, which either previously or subsequently were proved to
be fertile, failed to breed with certain males, with whom it was
particularly desired to match them. A change in the constitution of the
female may sometimes have occurred before she was put to the second
male; but in other cases this explanation is hardly tenable, for a
female, known not to be barren, has been unsuccessfully paired seven or
eight times with the same male likewise known to be perfectly fertile.
With cart-mares, which sometimes will not breed with stallions of pure
blood, but subsequently have bred with cart-stallions, Mr. Spooner is
inclined to attribute the failure to the lesser sexual power of the
racehorse. But I have heard from the greatest breeder of racehorses at
the present day, through Mr. Waring, that “it frequently occurs with a
mare to be put several times during one or two seasons to a particular
stallion of acknowledged power, and yet prove barren; the mare
afterwards breeding at once with some other horse.” These facts are
worth recording, as they show, like so many previous facts, on what
slight constitutional differences the fertility of an animal often
depends.

      _Sterility of Plants from changed Conditions of Life, and from
      other causes._

In the vegetable kingdom cases of sterility frequently occur, analogous
with those previously given in the animal kingdom. But the subject is
obscured by several circumstances, presently to be discussed, namely,
the contabescence of the anthers, as Gärtner has named a certain
affection—monstrosities—doubleness of the flower—much-enlarged
fruit—and long-continued or excessive propagation by buds.

It is notorious that many plants in our gardens and hot-houses, though
preserved in the most perfect health, rarely or never produce seed. I
do not allude to plants which run to leaves, from being kept too damp,
or too warm, or too much manured; for these do not flower, and the case
may be wholly different. Nor do I allude to fruit not ripening from
want of heat or rotting from too much moisture. But many exotic plants,
with their ovules and pollen appearing perfectly sound, will not set
any seed. The sterility in many cases, as I know from my own
observation, is simply due to the absence of the proper insects for
carrying the pollen to the stigma. But after excluding the several
cases just specified, there are many plants in which the reproductive
system has been seriously affected by the altered conditions of life to
which they have been subjected.

It would be tedious to enter on many details. Linnæus long ago
observed[78] that Alpine plants, although naturally loaded with seed,
produce either few or none when cultivated in gardens. But exceptions
often occur: the _Draba sylvestris,_ one of our most thoroughly Alpine
plants, multiplies itself by seed in Mr. H. C. Watson’s garden, near
London; and Kerner, who has particularly attended to the cultivation of
Alpine plants, found that various kinds, when cultivated, spontaneously
sowed themselves.[79] Many plants which naturally grow in peat-earth
are entirely sterile in our gardens. I have noticed the same fact with
several liliaceous plants, which nevertheless grew vigorously.

Too much manure renders some kinds utterly sterile, as I have myself
observed. The tendency to sterility from this cause runs in families;
thus, according to Gärtner,[80] it is hardly possible to give too much
manure to most Gramineæ, Cruciferæ, and Leguminosæ, whilst succulent
and bulbous-rooted plants are easily affected. Extreme poverty of soil
is less apt to induce sterility; but dwarfed plants of _Trifolium
minus_ and _repens,_ growing on a lawn often mown and never manured,
were found by me not to produce any seed. The temperature of the soil,
and the season at which plants are watered, often have a marked effect
on their fertility, as was observed by Kölreuter in the case of
Mirabilis.[81] Mr. Scott, in the Botanic Gardens of Edinburgh, observed
that _Oncidium divaricatum_ would not set seed when grown in a basket
in which it throve, but was capable of fertilisation in a pot where it
was a little damper. _Pelargonium fulgidum,_ for many years after its
introduction, seeded freely; it then became sterile; now it is
fertile[82] if kept in a dry stove during the winter. Other varieties
of pelargonium are sterile and others fertile without our being able to
assign any cause. Very slight changes in the position of a plant,
whether planted on a bank or at its base, sometimes make all the
difference in its producing seed. Temperature apparently has a much
more powerful influence on the fertility of plants than on that of
animals. Nevertheless it is wonderful what changes some few plants will
withstand with undiminished fertility: thus the _Zephyranthes candida,_
a native of the moderately warm banks of the Plata, sows itself in the
hot dry country near Lima, and in Yorkshire resists the severest
frosts, and I have seen seeds gathered from pods which had been covered
with snow during three weeks.[83] _Berberis wallichii,_ from the hot
Khasia range in India, is uninjured by our sharpest frosts, and ripens
its fruit under our cool summers. Nevertheless, I presume we must
attribute to change of climate the sterility of many foreign plants;
thus, the Persian and Chinese lilacs (_Syringa persica_ and
_chinensis_), though perfectly hardy here, never produce a seed; the
common lilac (_S. vulgaris_) seeds with us moderately well, but in
parts of Germany the capsules never contain seed.[84] Some few of the
cases, given in the last chapter, of self-impotent plants, might have
been here introduced, as their state seems due to the conditions to
which they have been subjected.

The liability of plants to be affected in their fertility by slightly
changed conditions is the more remarkable, as the pollen when once in
process of formation is not easily injured; a plant may be
transplanted, or a branch with flower-buds be cut off and placed in
water, and the pollen will be matured. Pollen, also, when once mature,
may be kept for weeks or even months.[85] The female organs are more
sensitive, for Gärtner[86] found that dicotyledonous plants, when
carefully removed so that they did not in the least flag, could seldom
be fertilised; this occurred even with potted plants if the roots had
grown out of the hole at the bottom. In some few cases, however, as
with Digitalis, transplantation did not prevent fertilisation; and
according to the testimony of Mawz, _Brassica rapa,_ when pulled up by
its roots and placed in water, ripened its seed. Flower-stems of
several monocotyledonous plants when cut off and placed in water
likewise produce seed. But in these cases I presume that the flowers
had been already fertilised, for Herbert[87] found with the Crocus that
the plants might be removed or mutilated after the act of
fertilisation, and would still perfect their seeds; but that, if
transplanted before being fertilised, the application of pollen was
powerless.

Plants which have been long cultivated can generally endure with
undiminished fertility various and great changes; but not in most cases
so great a change of climate as domesticated animals. It is remarkable
that many plants under these circumstances are so much affected that
the proportion and the nature of their chemical ingredients are
modified, yet their fertility is unimpaired. Thus, as Dr. Falconer
informs me, there is a great difference in the character of the fibre
in hemp, in the quantity of oil in the seed of the Linum, in the
proportion of narcotin to morphine in the poppy, in gluten to starch in
wheat, when these plants are cultivated on the plains and on the
mountains of India; nevertheless, they all remain fully fertile.

_Contabescence._—Gärtner has designated by this term a peculiar
condition of the anthers in certain plants, in which they are
shrivelled, or become brown and tough, and contain no good pollen. When
in this state they exactly resemble the anthers of the most sterile
hybrids. Gärtner,[88] in his discussion on this subject, has shown that
plants of many orders are occasionally thus affected; but the
Caryophyllaceæ and Liliaceæ suffer most, and to these orders, I think,
the Ericaceæ may be added. Contabescence varies in degree, but on the
same plant all the flowers are generally affected to nearly the same
extent. The anthers are affected at a very early period in the
flower-bud, and remain in the same state (with one recorded exception)
during the life of the plant. The affection cannot be cured by any
change of treatment, and is propagated by layers, cuttings, etc., and
perhaps even by seed. In contabescent plants the female organs are
seldom affected, or merely become precocious in their development. The
cause of this affection is doubtful, and is different in different
cases. Until I read Gärtner’s discussion I attributed it, as apparently
did Herbert, to the unnatural treatment of the plants; but its
permanence under changed conditions, and the female organs not being
affected, seem incompatible with this view. The fact of several endemic
plants becoming contabescent in our gardens seems, at first sight,
equally incompatible with this view; but Kölreuter believes that this
is the result of their transplantation. The contabescent plants of
Dianthus and Verbascum, found wild by Wiegmann, grew on a dry and
sterile bank. The fact that exotic plants are eminently liable to this
affection also seems to show that it is in some manner caused by their
unnatural treatment. In some instances, as with Silene, Gärtner’s view
seems the most probable, namely, that it is caused by an inherent
tendency in the species to become dioecious. I can add another cause,
namely, the illegitimate unions of heterostyled plants, for I have
observed seedlings of three species of Primula and of _ Lythrum
salicaria,_ which had been raised from plants illegitimately fertilised
by their own-form pollen, with some or all their anthers in a
contabescent state. There is perhaps an additional cause, namely,
self-fertilisation; for many plants of Dianthus and Lobelia, which had
been raised from self-fertilised seeds, had their anthers in this
state; but these instances are not conclusive, as both genera are
liable from other causes to this affection.

Cases of an opposite nature likewise occur, namely, plants with the
female organs struck with sterility, whilst the male organs remain
perfect. _Dianthus japonicus,_ a Passiflora, and Nicotiana, have been
described by Gärtner[89] as being in this unusual condition.

_Monstrosities as a cause of sterility._—Great deviations of structure,
even when the reproductive organs themselves are not seriously
affected, sometimes cause plants to become sterile. But in other cases
plants may become monstrous to an extreme degree and yet retain their
full fertility. Gallesio, who certainly had great experience,[90] often
attributes sterility to this cause; but it may be suspected that in
some of his cases sterility was the cause, and not the result, of the
monstrous growths. The curious St. Valery apple, although it bears
fruit, rarely produces seed. The wonderfully anomalous flowers of
_Begonia frigida,_ formerly described, though they appear fit for
fructification, are sterile.[91] Species of Primula in which the calyx
is brightly coloured are said[92] to be often sterile, though I have
known them to be fertile. On the other hand, Verlot gives several cases
of proliferous flowers which can be propagated by seed. This was the
case with a poppy, which had become monopetalous by the union of its
petals.[93] Another extraordinary poppy, with the stamens replaced by
numerous small supplementary capsules, likewise reproduces itself by
seed. This has also occurred with a plant of _Saxifraga geum,_ in which
a series of adventitious carpels, bearing ovules on their margins, had
been developed between the stamens and the normal carpels[94] Lastly,
with respect to peloric flowers, which depart wonderfully from the
natural structure,—those of _Linaria vulgaris_ seem generally to be
more or less sterile, whilst those before described of _ Antirrhinum
majus,_ when artificially fertilised with their own pollen, are
perfectly fertile, though sterile when left to themselves, for bees are
unable to crawl into the narrow tubular flower. The peloric flowers of
_Corydalis solida,_ according to Godron,[95] are sometimes barren and
sometimes fertile; whilst those of Gloxinia are well known to yield
plenty of seed. In our greenhouse Pelargoniums, the central flower of
the truss is often peloric, and Mr. Masters informs me that he tried in
vain during several years to get seed from these flowers. I likewise
made many vain attempts, but sometimes succeeded in fertilising them
with pollen from a normal flower of another variety; and conversely I
several times fertilised ordinary flowers with peloric pollen. Only
once I succeeded in raising a plant from a peloric flower fertilised by
pollen from a peloric flower borne by another variety; but the plant,
it may be added, presented nothing particular in its structure. Hence
we may conclude that no general rule can be laid down; but any great
deviation from the normal structure, even when the reproductive organs
themselves are not seriously affected, certainly often leads to sexual
impotence.

_Double Flowers._—When the stamens are converted into petals, the plant
becomes on the male side sterile; when both stamens and pistils are
thus changed, the plant becomes completely barren. Symmetrical flowers
having numerous stamens and petals are the most liable to become
double, as perhaps follows from all multiple organs being the most
subject to variability. But flowers furnished with only a few stamens,
and others which are asymmetrical in structure, sometimes become
double, as we see with the double gorse or Ulex, and Antirrhinum. The
Compositæ bear what are called double flowers by the abnormal
development of the corolla of their central florets. Doubleness is
sometimes connected with prolification,[96] or the continued growth of
the axis of the flower. Doubleness is strongly inherited. No one has
produced, as Lindley remarks,[97] double flowers by promoting the
perfect health of the plant. On the contrary, unnatural conditions of
life favour their production. There is some reason to believe that
seeds kept during many years, and seeds believed to be imperfectly
fertilised, yield double flowers more freely than fresh and perfectly
fertilised seed.[98] Long-continued cultivation in rich soil seems to
be the commonest exciting cause. A double narcissus and a double
_Anthemis nobilis,_ transplanted into very poor soil, has been observed
to become single;[99] and I have seen a completely double white
primrose rendered permanently single by being divided and transplanted
whilst in full flower. It has been observed by Professor E. Morren that
doubleness of the flowers and variegation of the leaves are
antagonistic states; but so many exceptions to the rule have lately
been recorded,[100] that, though general, it cannot be looked at as
invariable. Variegation seems generally to result from a feeble or
atrophied condition of the plant, and a large proportion of the
seedlings raised from parents, if both are variegated, usually perish
at an early age; hence we may perhaps infer that doubleness, which is
the antagonistic state, commonly arises from a plethoric condition. On
the other hand, extremely poor soil sometimes, though rarely, appears
to cause doubleness: I formerly described[101] some completely double,
bud-like, flowers produced in large numbers by stunted wild plants of
_Gentiana amarella_ growing on a poor chalky bank. I have also noticed
a distinct tendency to doubleness in the flowers of a Ranunculus,
Horse-chestnut, and Bladder-nut (_Ranunculus repens, Aesculus pavia,_
and _Staphylea_), growing under very unfavourable conditions. Professor
Lehmann[102] found several wild plants growing near a hot spring with
double flowers. With respect to the cause of doubleness, which arises,
as we see, under widely different circumstances, I shall presently
attempt to show that the most probable view is that unnatural
conditions first give a tendency to sterility, and that then, on the
principle of compensation, as the reproductive organs do not perform
their proper functions, they either become developed into petals, or
additional petals are formed. This view has lately been supported by
Mr. Laxton[103] who advances the case of some common peas, which, after
long-continued heavy rain, flowered a second time, and produced double
flowers.

_Seedless Fruit._—Many of our most valuable fruits, although consisting
in a homological sense of widely different organs, are either quite
sterile, or produce extremely few seeds. This is notoriously the case
with our best pears, grapes, and figs, with the pine-apple, banana,
bread-fruit, pomegranate, azarole, date-palms, and some members of the
orange-tribe. Poorer varieties of these same fruits either habitually
or occasionally yield seed.[104] Most horticulturists look at the great
size and anomalous development of the fruit as the cause, and sterility
as the result; but the opposite view, as we shall presently see, is
more probable.

_Sterility from the excessive development of the organs of Growth or
Vegetation._—Plants which from any cause grow too luxuriantly, and
produce leaves, stems, runners, suckers, tubers, bulbs, etc., in
excess, sometimes do not flower, or if they flower do not yield seed.
To make European vegetables under the hot climate of India yield seed,
it is necessary to check their growth; and, when one-third grown, they
are taken up, and their stems and tap-roots are cut or mutilated.[105]
So it is with hybrids; for instance, Prof. Lecoq[106] had three plants
of Mirabilis, which, though they grew luxuriantly and flowered, were
quite sterile; but after beating one with a stick until a few branches
alone were left, these at once yielded good seed. The sugar-cane, which
grows vigorously and produces a large supply of succulent stems, never,
according to various observers, bears seed in the West Indies, Malaga,
India, Cochin China, Mauritius, or the Malay Archipelago.[107] Plants
which produce a large number of tubers are apt to be sterile, as
occurs, to a certain extent, with the common potato; and Mr. Fortune
informs me that the sweet potato (_Convolvulus batatas_) in China
never, as far as he has seen, yields seed. Dr. Royle remarks[108] that
in India the _Agave vivipara,_ when grown in rich soil, invariably
produces bulbs, but no seeds; whilst a poor soil and dry climate lead
to an opposite result. In China, according to Mr. Fortune, an
extraordinary number of little bulbs are developed in the axils of the
leaves of the yam, and this plant does not bear seed. Whether in these
cases, as in those of double flowers and seedless fruit, sexual
sterility from changed conditions of life is the primary cause which
leads to the excessive development of the organs of vegetation, is
doubtful; though some evidence might be advanced in favour of this
view. It is perhaps a more probable view that plants which propagate
themselves largely by one method, namely by buds, have not sufficient
vital power or organised matter for the other method of sexual
generation.

Several distinguished botanists and good practical judges believe that
long- continued propagation by cuttings, runners, tubers, bulbs, etc.,
independently of any excessive development of these parts, is the cause
of many plants failing to produce flowers, or producing only barren
flowers,—it is as if they had lost the habit of sexual generation.[109]
That many plants when thus propagated are sterile there can be no
doubt, but as to whether the long continuance of this form of
propagation is the actual cause of their sterility, I will not venture,
from the want of sufficient evidence, to express an opinion.

That plants may be propagated for long periods by buds, without the aid
of sexual generation, we may safely infer from this being the case with
many plants which must have long survived in a state of nature. As I
have had occasion before to allude to this subject, I will here give
such cases as I have collected. Many alpine plants ascend mountains
beyond the height at which they can produce seed.[110] Certain species
of Poa and Festuca, when growing on mountain-pastures, propagate
themselves, as I hear from Mr. Bentham, almost exclusively by bulblets.
Kalm gives a more curious instance[111] of several American trees,
which grow so plentifully in marshes or in thick woods, that they are
certainly well adapted for these stations, yet scarcely ever produce
seeds; but when accidentally growing on the outside of the marsh or
wood, are loaded with seed. The common ivy is found in Northern Sweden
and Russia, but flowers and fruits only in the southern provinces. The
_Acorus calamus_ extends over a large portion of the globe, but so
rarely perfects fruit that this has been seen only by a few botanists;
according to Caspary, all its pollen-grains are in a worthless
condition.[112] The _Hypericum calycinum,_ which propagates itself so
freely in our shrubberies by rhizomes, and is naturalised in Ireland,
blossoms profusely, but rarely sets any seed, and this only during
certain years; nor did it set any when fertilised in my garden by
pollen from plants growing at a distance. The _Lysimachia nummularia,_
which is furnished with long runners, so seldom produces seed-capsules,
that Prof. Decaisne,[113] who has especially attended to this plant,
has never seen it in fruit. The _Carex rigida_ often fails to perfect
its seed in Scotland, Lapland, Greenland, Germany, and New Hampshire in
the United States.[114] The periwinkle (_Vinca minor_), which spreads
largely by runners, is said scarcely ever to produce fruit in
England;[115] but this plant requires insect-aid for its fertilisation,
and the proper insects may be absent or rare. The Jussiaea grandiflora
has become naturalised in Southern France, and has spread by its
rhizomes so extensively as to impede the navigation of the waters, but
never produces fertile seed.[116] The horse-radish (_Cochleria
armoracia_) spreads pertinaciously and is naturalised in various parts
of Europe; though it bears flowers, these rarely produce capsules:
Professor Caspary informs me that he has watched this plant since 1851,
but has never seen its fruit; 65 per cent of its pollen-grains are bad.
The common _ Ranunculus ficaria_ rarely bears seed in England, France,
or Switzerland; but in 1863 I observed seeds on several plants growing
near my house.[117] Other cases analogous with the foregoing could be
given; for instance, some kinds of mosses and lichens have never been
seen to fructify in France.

Some of these endemic and naturalised plants are probably rendered
sterile from excessive multiplication by buds, and their consequent
incapacity to produce and nourish seed. But the sterility of others
more probably depends on the peculiar conditions under which they live,
as in the case of the ivy in the northern part of Europe, and of the
trees in the swamps of the United States; yet these plants must be in
some respects eminently well adapted for the stations which they
occupy, for they hold their places against a host of competitors.

Finally, the high degree of sterility which often accompanies the
doubling of flowers, or an excessive development of fruit, seldom
supervenes at once. An incipient tendency is observed, and continued
selection completes the result. The view which seems the most probable,
and which connects together all the foregoing facts and brings them
within our present subject, is, that changed and unnatural conditions
of life first give a tendency to sterility; and in consequence of this,
the organs of reproduction being no longer able fully to perform their
proper functions, a supply of organised matter, not required for the
development of the seed, flows either into these organs and renders
them foliaceous, or into the fruit, stems, tubers, etc., increasing
their size and succulency. But it is probable that there exists,
independently of any incipient sterility, an antagonism between the two
forms of reproduction, namely, by seed and buds, when either is carried
to an extreme degree. That incipient sterility plays an important part
in the doubling of flowers, and in the other cases just specified, I
infer chiefly from the following facts. When fertility is lost from a
wholly different cause, namely, from hybridism, there is a strong
tendency, as Gärtner[118] affirms, for flowers to become double, and
this tendency is inherited. Moreover, it is notorious that with hybrids
the male organs become sterile before the female organs, and with
double flowers the stamens first become foliaceous. This latter fact is
well shown by the male flowers of dioecious plants, which, according to
Gallesio[119] first become double. Again, Gärtner[120] often insists
that the flowers of even utterly sterile hybrids, which do not produce
any seed, generally yield perfect capsules or fruit,—a fact which has
likewise been repeatedly observed by Naudin with the Cucurbitaceæ; so
that the production of fruit by plants rendered sterile through any
cause is intelligible. Kölreuter has also expressed his unbounded
astonishment at the size and development of the tubers in certain
hybrids; and all experimentalists[121] have remarked on the strong
tendency in hybrids to increase by roots, runners, and suckers. Seeing
that hybrid plants, which from their nature are more or less sterile,
thus tend to produce double flowers; that they have the parts including
the seed, that is the fruit, perfectly developed, even when containing
no seed; that they sometimes yield gigantic roots; that they almost
invariably tend to increase largely by suckers and other such
means;—seeing this, and knowing, from the many facts given in the
earlier parts of this chapter, that almost all organic beings when
exposed to unnatural conditions tend to become more or less sterile, it
seems much the most probable view that with cultivated plants sterility
is the exciting cause, and double flowers, rich seedless fruit, and in
some cases largely-developed organs of vegetation, etc., are the
indirect results—these results having been in most cases largely
increased through continued selection by man.

REFERENCES

 [1] For England, _see_ below. For Germany, _see_ Metzger,
 ‘Getreidearten,’ 1841, s. 63. For France, Loiseleur-Deslongchamps
 (‘Consid. sur les Céréales,’ 1843, p. 200) gives numerous references
 on this subject. For Southern France, _see_ Godron, ‘Florula
 Juvenalis,’ 1854, p. 28.

 [2] ‘A General Treatise of Husbandry,’ vol. 3 p. 58.

 [3] ‘Gardener’s Chronicle and Agricult. Gazette,’ 1858, p. 247; and
 for the second statement, Ibid., 1850, p. 702. On this same subject
 _see also_ Rev. D. Walker’s ‘Prize Essay of Highland Agricult. Soc.’
 vol. ii. p. 200. Also Marshall ‘Minutes of Agriculture,’ November,
 1775.

 [4] Oberlin’s ‘Memoirs,’ Eng. translat., p. 73. For Lancashire _see_
 Marshall’s ‘Review of Reports,’ 1808, p. 295.

 [5] ‘Cottage Gardener,’ 1856, p. 186. For Mr. Robson’s subsequent
 statements, _see_ ‘Journal of Horticulture,’ Feb. 18, 1866, p. 121.
 For Mr. Abbey’s remarks on grafting, etc., Ibid., July 18, 1865, p.
 44.

 [6] ‘Mém. de l’Acad. des Sciences,’ 1790, p. 209.

 [7] ‘On the Varieties of Wheat,’ p. 52.

 [8] Mr. Spencer has fully and ably discussed this whole subject in his
 ‘Principles of Biology,’ 1864, vol. ii. ch. x. In the first edition of
 my ‘Origin of Species,’ 1859, p. 267, I spoke of the good effects from
 slight changes in the conditions of life and from cross-breeding, and
 of the evil effects from great changes in the conditions and from
 crossing widely distinct forms, as a series of facts “connected
 together by some common but unknown bond, which is essentially related
 to the principle of life.”

 [9] ‘Essais de Zoologie Générale,’ 1841, p. 256.

 [10] Since the appearance of the first edition of this work, Mr.
 Sclater has published (‘Proc. Zoolog. Soc.,’ 1868, p. 623) a list of
 the species of mammals which have bred in the gardens from 1848 to
 1867 inclusive. Of the Artiodactyla 85 species have been kept, and of
 these 1 species in 1·9 have bred at least once during the 20 years; of
 28 Marsupialia, 1 in 2·5 have bred; of 74 Carnivora, 1 in 3·0 have
 bred; of 52 Rodentia, 1 in 4·7 have bred; and of Quadrumana 75 species
 have been kept, and 1 in 6·2 have bred.

 [11] Du Rut, ‘Annales du Muséum,’ 1807, tom. ix. p. 120.

 [12] ‘Saugethiere von Paraguay,’ 1830, s. 49, 106, 118, 124, 201, 208,
 249, 265, 327.

 [13] ‘The Naturalist on the Amazons,’ 1863, vol. i. pp. 99, 193; vol.
 ii. p. 113.

 [14] ‘Embassy to the Court of Ava,’ vol. i. p. 534.

 [15] ‘Journal,’ vol. i. p. 213.

 [16] ‘Säugethiere,’ s. 327.

 [17] On the Breeding of the Larger Felidæ, ‘Proc. Zoolog. Soc.,’ 1861,
 p. 140.

 [18] Sleeman’s ‘Rambles in India,’ vol. ii. p. 10.

 [19] Wiegmann’s ‘Archiv. fur Naturgesch.,’ 1837, s. 162.

 [20] Rengger ‘Säugethiere,’ etc., s. 276. On the parentage of the
 guinea-pig, _see also_ Isid. Geoffroy St.-Hilaire, ‘Hist. Nat. Gen.’ I
 sent to Mr. H. Denny of Leeds the lice which I collected from the wild
 aperea in La Plata, and he informs me that they belong to a genus
 distinct from those found on the guinea-pig. This is important
 evidence that the aperea is not the parent of the guinea-pig; and is
 worth giving, as some authors erroneously suppose that the guinea-pig
 since being domesticated has become sterile when crossed with the
 aperea.

 [21] Although the existence of the _Leporides,_ as described by Dr.
 Broca (‘Journal de Phys.,’ tom. ii. p. 370), has been positively
 denied, yet Dr. Pigeaux (‘Annals and Mag. of Nat. Hist.,’ vol. xx.,
 1867, p. 75) affirms that the hare and rabbit have produced hybrids.

 [22] ‘Quadrupeds of North America,’ by Audubon and Bachman, 1846, p.
 268.

 [23] Loudon’s ‘Mag. of Nat. Hist.,’ vol. ix., 1836, p. 571; Audubon
 and Bachman’s ‘Quadrupeds of North America,’ p. 221.

 [24] Flourens, ‘De l’Instinct,’ etc., 1845, p. 88.

 [25] _See_ ‘Annual Reports Zoolog. Soc.,’ 1855, 1858, 1863, 1864;
 ‘Times’ newspaper, Aug. 10th, 1847; Flourens, ‘De l’Instinct,’ p. 85.

 [26] ‘Säugethiere,’ etc., s. 34, 49.

 [27] Art. Brazil, ‘Penny Cyclop.,’ p. 363.

 [28] ‘The Naturalist on the Amazons,’ vol. i. p. 99.

 [29] A list of the species of birds which have bred in the Zoological
 Gardens from 1848 to 1867 inclusive has been published by Mr. Sclater
 in ‘Proc. Zoolog. Soc.,’ 1869, p. 626, since the first edition of this
 work appeared. Of Columbæ 51 species have been kept, and of Anseres 80
 species, and in both these families 1 species in 2·6 have bred at
 least once in the 20 years. Of Gallinæ 83 species have been kept and 1
 in 27 have bred; of 57 Grallæ 1 in 9 have bred; of 110 Prehensores 1
 in 22 have bred; of 178 Passeres 1 in 25·4 have bred; of 94 Accipitres
 1 in 47 have bred; of 25 Picariæ and of 35 Herodiones not one species
 in either group has bred.

 [30] ‘Encyclop. of Rural Sports,’ p. 691.

 [31] According to Sir A. Burnes (‘Cabool,’ etc., p. 51), eight species
 are used for hawking in Sinde.

 [32] Loudon’s ‘Mag. of Nat. Hist.,’ vol. vi., 1833, p. 110.

 [33] F. Cuvier, ‘Annal. du Muséum,’ tom. ix. p. 128.

 [34] ‘The Zoologist,’ vol. vii.-viii., 1849-50, p. 2648.

 [35] Knox, ‘Ornithological Rambles in Sussex,’ p. 91.

 [36] ‘The Zoologist,’ vol. vii.-viii., 1849-50, p. 2566; vol. ix.-x.,
 1851-2, p. 3207.

 [37] Bechstein, ‘Naturgesch. der Stubenvögel,’ 1840, s. 20.

 [38] ‘Ornithological Biography,’ vol. v. p. 517.

 [39] A case is recorded in ‘The Zoologist,’ vol. i.-ii., 1843-45, p.
 453. For the siskin breeding, vol. iii.-iv., 1845-46, p. 1075.
 Bechstein ‘Stubenvögel,’ s. 139, speaks of bullfinches making nests,
 but rarely producing young.

 [40] Yarrell’s ‘Hist. British Birds,’ 1839, vol. i. p. 412.

 [41] Loudon’s ‘Mag. of Nat. History,’ vol. xix., 1836, p. 347.

 [42] ‘Mémoires du Muséum d’Hist. Nat.,’ tom. x. p. 314: five cases of
 parrots breeding in France are here recorded. _ See also_ ‘Report
 Brit. Assoc. Zoolog.,’ 1843.

 [43] ‘Annals and Mag. of Nat. Hist.,’ Nov. 1868, p. 311.

 [44] ‘Stubenvögel,’ s. 105, 83.

 [45] Dr. Hancock remarks (‘Charlesworth’s Mag. of Nat. Hist.’ vol.
 ii., 1838, p. 492), “it is singular that, amongst the numerous useful
 birds that are indigenous to Guiana, none are found to propagate among
 the Indians; yet the common fowl is reared in abundance throughout the
 country.”

 [46] ‘A Week at Pert Royal,’ 1855, p. 7.

 [47] Audubon, ‘American Ornithology,’ vol. v. pp. 552, 557.

 [48] Mowbray on Poultry, 7th edit., p. 133.

 [49] Temminck, ‘Hist. Nat. Gén. des Pigeons,’ etc., 1813, tom. iii.
 pp. 288, 382; ‘Annals and Mag. of Nat. Hist.,’ vol. xii., 1843, p.
 453. Other species of partridge have occasionally bred; as the
 red-legged (_P. rubra_), when kept in a large court in France (_see_
 ‘Journal de Physique,’ tom. xxv. p. 294), and in the Zoological
 Gardens in 1856.

 [50] Rev. E. S. Dixon, ‘The Dovecote,’ 1851, pp. 243-252.

 [51] Temminck, ‘Hist. Nat. Gén. des Pigeons,’ etc., tom. ii. pp. 456,
 458; tom. iii. pp. 2, 13, 47.

 [52] Bates, ‘The Naturalist on the Amazons,’ vol. i. p. 193; vol. ii.
 p. 112.

 [53] Temminck, ‘Hist. Nat. Gén.,’ etc., tom. ii. p. 125. For _Tetrao
 urogallus, see_ L. Lloyd, ‘Field Sports of North of Europe,’ vol. i.
 pp. 287, 314; and ‘Bull. de la Soc. d’Acclimat.,’ tom. vii., 1860, p.
 600. For _T. scoticus,_ Thompson, ‘Nat. Hist. of Ireland,’ vol. ii.
 1850, p. 49. For _ T. cupido,_ ‘Boston Journal of Nat. Hist.,’ vol.
 iii. p. 199.

 [54] Marcel de Serres, ‘Annales des Sc. Nat.,’ 2nd series, Zoolog.,
 tom. xiii. p. 175.

 [55] Dr. Hancock, in ‘Charlesworth’s Mag. of Nat. Hist.,’ vol. ii.,
 1838, p. 491; R. Hill, ‘A Week at Port Royal,’ p. 8; ‘Guide to the
 Zoological Gardens,’ by P. L. Sclater, 1859, pp. 11, 12; ‘The Knowsley
 Menagerie,’ by D. Gray, 1846, pl. xiv.; E. Blyth, ‘Report Asiatic Soc.
 of Bengal,’ May 1855.

 [56] Prof. Newton, in ‘Proc. Zoolog. Soc.,’ 1860, p. 336.

 [57] ‘The Dovecote and Aviary,’ p. 428.

 [58] ‘Ornithological Biography,’ vol. iii. p. 9.

 [59] ‘Geograph. Journal,’ vol. xiii., 1844, p. 32.

 [60] Loudon’s ‘Mag. of Nat. Hist.,’ vol. v., 1832, p. 153.

 [61] ‘Zoologist,’ vols. v.-vi., 1847-48, p. 1660.

 [62] ‘Transact. Entomolog. Soc.,’ vol. iv., 1845, p. 60.

 [63] ‘Transact. Linn. Soc.,’ vol. vii. p. 40.

 [64] _See_ an interesting paper by Mr. Newman in the ‘Zoologist,’
 1857, p. 5764; and Dr. Wallace, in ‘Proc. Entomolog. Soc.,’ June 4th,
 1860, p. 119.

 [65] Yarrell’s ‘British Birds,’ vol. i. p. 506; Bechstein
 ‘Stubenvögel,’ s. 185; ‘Philosoph. Transact.,’ 1772, p. 271. Bronn
 (‘Geschichte der Natur,’ Band ii. s. 96) has collected a number of
 cases. For the case of the deer, _see_ ‘Penny Cyclop.,’ vol. viii. p.
 350.

 [66] ‘Journal de Physiologie,’ tom. ii. p. 347.

 [67] For additional evidence on this subject, _see_ F. Cuvier in
 ‘Annales du Muséum,’ tom. xii. p. 119.

 [68] Numerous instances could be given. Thus Livingstone (‘Travels,’
 p. 217) states that the King of the Barotse, an inland tribe which
 never had any communication with white men, was extremely fond of
 taming animals, and every young antelope was brought to him. Mr.
 Galton informs me that the Damaras are likewise fond of keeping pets.
 The Indians of South America follow the same habit. Capt. Wilkes
 states that the Polynesians of the Samoan Islands tamed pigeons; and
 the New Zealanders, as Mr. Mantell informs me, kept various kinds of
 birds.

 [69] For analogous cases with the fowl, _see_ Réaumur, ‘L’Art de faire
 Eclore,’ etc., 1749, p. 243; and Col. Sykes, in ‘Proc. Zoolog. Soc.,’
 1832, etc. With respect to the fowl not breeding in northern regions,
 _see_ Latham’s ‘Hist. of Birds,’ vol. viii., 1823, p. 169.

 [70] “Mém. par divers Savans,” ‘Acad. des Sciences,’ tom. vi., 1835,
 p. 347.

 [71] Youatt on Sheep, p. 181.

 [72] J. Mills, ‘Treatise on Cattle,’ 1776, p. 72.

 [73] Bechstein, ‘Stubenvögel,’ s. 242.

 [74] ‘The Andes and the Amazon,’ 1870, p. 107.

 [75] Crawfurd’s ‘Descriptive Dict. of the Indian Islands,’ 1856, p.
 145.

 [76] ‘Bull. de la Soc. d’Acclimat.,’ tom. ix., 1862, pp. 380, 384.

 [77] For pigeons, _see_ Dr. Chapuis, ‘Le Pigeon Voyageur Belge,’ 1865,
 p. 66.

 [78] ‘Swedish Acts,’ vol. i., 1739, p. 3. Pallas makes the same remark
 in his ‘Travels’ (Eng. translat.), vol. i. p. 292.

 [79] A. Kerner, ‘Die Cultur der Alpenpflanzen,’ 1864, s. 139; Watson’s
 ‘Cybele Britannica,’ vol. i. p. 131; Mr. D. Cameron, also, has written
 on the culture of Alpine plants in ‘Gard. Chronicle,’ 1848, pp. 253,
 268, and mentions a few which seed.

 [80] ‘Beiträge zur Kenntniss der Befruchtung,’ 1844 s. 333.

 [81] ‘Nova Acta Petrop.,’ 1793, p. 391.

 [82] ‘Cottage Gardener,’ 1856, pp. 44, 109.

 [83] Dr. Herbert, ‘Amaryllidaceæ,’ p. 176.

 [84] Gärtner, ‘Beiträge zur Kenntniss,’ etc., s. 560, 564.

 [85] ‘Gardener’s Chronicle,’ 1844, p. 215; 1850, p. 470. Faivre gives
 a good résumé on this subject in his ‘La Variabilité des Espèces,’
 1868, p. 155.

 [86] ‘Beiträge zur Kenntniss,’ etc., s. 252, 338.

 [87] ‘Journal of Hort. Soc.,’ vol. ii., 1847, p. 83.

 [88] ‘Beiträge zur Kenntniss,’ etc., s. 117 _et seq._; Kölreuter,
 ‘Zweite Fortsetzung,’ s. 10, 121; ‘Dritte Fortsetzung,’ s. 57.
 Herbert, ‘Amaryllidaceæ,’ p. 355. Wiegmann ‘Ueber die
 Bastarderzeugung,’ s. 27.

 [89] ‘Bastarderzengung,’ s. 356.

 [90] ‘Teoria della Riproduzione,’ 1816, p. 84; ‘Traité du Citrus,’
 1811, p. 67.

 [91] Mr. C. W. Crocker, in ‘Gardener’s Chronicle,’ 1861, p. 1092.

 [92] Verlot, ‘Des Variétés,’ 1865, p. 80.

 [93] Verlot, ibid., p. 88.

 [94] Prof. Allman, Brit. Assoc., quoted in the ‘Phytologist,’ vol. ii.
 p. 483. Prof. Harvey, on the authority of Mr. Andrews, who discovered
 the plant, informed me that this monstrosity could be propagated by
 seed. With respect to the poppy, _see_ Prof. Goeppert, as quoted in
 ‘Journal of Horticulture,’ July 1st, 1863, p. 171.

 [95] ‘Comptes Rendus,’ Dec. 19th, 1864, p. 1039.

 [96] ‘Gardener’s Chronicle,’ 1866, p. 681.

 [97] ‘Theory of Horticulture,’ p. 333.

 [98] Mr. Fairweather, in ‘Transact. Hort. Soc.,’ vol. iii. p. 406:
 Bosse, quoted by Bronn, ‘Geschichte der Natur,’ B. ii. s. 77. On the
 effects of the removal of the anthers, _see_ Mr. Leitner, in
 Silliman’s ‘North American Journ. of Science,’ vol. xxiii. p. 47; and
 Verlot, ‘Des Variétés,’ 1865, p. 84.

 [99] Lindley’s ‘Theory of Horticulture,’ p. 3?3.

 [100] ‘Gardener’s Chronicle,’ 1865, p. 626; 1866, pp. 290, 730; and
 Verlot, ‘Des Variétés,’ p. 75.

 [101] ‘Gardener’s Chronicle,’ 1843, p. 628. In this article I
 suggested the theory above given on the doubleness of flowers. This
 view is adopted by Carrière, ‘Production et Fix. des Variétés,’ 1865,
 p. 67.

 [102] Quoted by Gärtner, ‘Bastarderzeugung,’ s. 567.

 [103] ‘Gardener’s Chronicle,’ 1866, p. 901.

 [104] Lindley, ‘Theory of Horticulture,’ pp. 175-179; Godron, ‘De
 l’Espèce,’ tom. ii. p. 106; Pickering, ‘Races of Man;’ Gallesio,
 ‘Teoria della Riproduzione,’ l816, pp. 101-110. Meyen, (‘Reise um
 Erde,’ Th. ii. s. 214) states that at Manilla one variety of the
 banana is full of seeds: and Chamisso (Hooker’s ‘Bot. Misc.,’ vol. i.
 p. 310) describes a variety of the bread-fruit in the Mariana Islands
 with small fruit, containing seeds which are frequently perfect.
 Burnes, in his ‘Travels in Bokhara,’ remarks on the pomegranate
 seeding in Mazenderan, as a remarkable peculiarity.

 [105] Ingledew, in ‘Transact. of Agricult. and Hort. Soc. of India,’
 vol. ii.

 [106] ‘De la Fécondation,’ 1862, p. 308.

 [107] Hooker’s ‘Bot. Misc.,’ vol. i. p. 99; Gallesio, ‘Teoria della
 Riproduzione,’ p. 110. Dr. J. de Cordemoy, in ‘Transact. of the R.
 Soc. of Mauritius’ (new series), vol. vi. 1873, pp. 60-67, gives a
 large number of cases of plants which never seed, including several
 species indigenous in Mauritius.

 [108] ‘Transact. Linn. Soc.,’ vol. xvii. p. 563.

 [109] Godron, ‘De l’Espèce,’ tom. ii. p. 106; Herbert on Crocus, in
 ‘Journal of Hort. Soc.,’ vol. i., 1846, p. 254: Dr. Wight, from what
 he has seen in India, believes in this view; ‘Madras Journal of Lit.
 and Science,’ vol. iv., 1836, p. 61.

 [110] Wahlenberg specifies eight species in this state on the Lapland
 Alps: _see_ Appendix to Linnæus’ ‘Tour in Lapland,’ translated by Sir
 J. E. Smith, vol. ii. pp. 274-280.

 [111] ‘Travels in North America,’ Eng. translat., vol. iii. p. 175.

 [112] With respect to the ivy and Acorus, _see_ Dr. Broomfield in the
 ‘Phytologist,’ vol. iii. p. 376. Also Lindley and Vaucher on the
 Acorus, and _see_ Caspary as below.

 [113] ‘Annal. des Sc. Nat.,’ 3rd series, Zool., tom. iv. p. 280. Prof.
 Decaisne refers also to analogous cases with mosses and lichens near
 Paris.

 [114] Mr. Tuckermann, in Silliman’s ‘American Journal of Science,’
 vol. xlv. p. 1.

 [115] Sir J. E. Smith, ‘English Flora,’ vol. i. p. 339.

 [116] G. Planchon, ‘Flora de Montpellier,’ 1864, p. 20.

 [117] On the non-production of seeds in England, _see_ Mr. Crocker, in
 ‘Gardener’s Weekly Magazine,’ 1852, p. 70; Vaucher, ‘Hist. Phys.
 Plantes d’Europe,’ tom. i. p. 33; Lecoq, ‘Géograph. Bot. d’Europe,’
 tom. iv. p. 466; Dr. D. Clos, in ‘Annal. des Sc. Nat.,’ 3rd series,
 Bot., tom. xvii. 1852, p. 129: this latter author refers to other
 analogous cases. _See_ more especially on this plant and on other
 allied cases Prof. Caspary, “Die Nuphar,” ‘Abhand. Naturw. Gesellsch.
 zu Halle,’ B. xi. 1870, p. 40, 78.

 [118] ‘Bastarderzeugung,’ s. 565. Kölreuter (Dritte Fortsetzung, s.
 73, 87, 119) also shows that when two species, one single and the
 other double, are crossed, the hybrids are apt to be extremely double.

 [119] ‘Teoria della Riproduzione Veg.,’ 1816, p. 73.

 [120] ‘Bastarderzeugung,’ s. 573.

 [121] Ibid., s. 527.




CHAPTER XIX. SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS ON
HYBRIDISM.

ON THE GOOD DERIVED ON THE EFFECTS OF CROSSING—THE INFLUENCE OF
DOMESTICATION ON FERTILITY—CLOSE INTERBREEDING—GOOD AND EVIL RESULTS
FROM CHANGED CONDITIONS OF LIFE—VARIETIES WHEN CROSSED NOT INVARIABLY
FERTILE—ON THE DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND
VARIETIES—CONCLUSIONS WITH RESPECT TO HYBRIDISM—LIGHT THROWN ON
HYBRIDISM BY THE ILLEGITIMATE PROGENY OF HETEROSTYLED PLANTS—STERILITY
OF CROSSED SPECIES DUE TO DIFFERENCES CONFINED TO THE REPRODUCTIVE
SYSTEM—NOT ACCUMULATED THROUGH NATURAL SELECTION—REASONS WHY DOMESTIC
VARIETIES ARE NOT MUTUALLY STERILE—TOO MUCH STRESS HAS BEEN LAID ON THE
DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND CROSSED
VARIETIES—CONCLUSION.


It was shown in the fifteenth chapter that when individuals of the same
variety, or even of a distinct variety, are allowed freely to
intercross, uniformity of character is ultimately acquired. Some few
characters, however, are incapable of fusion, but these are
unimportant, as they are often of a semi-monstrous nature, and have
suddenly appeared. Hence, to preserve our domesticated breeds true, or
to improve them by methodical selection, it is obviously necessary that
they should be kept separate. Nevertheless, a whole body of individuals
may be slowly modified, through unconscious selection, as we shall see
in a future chapter, without separating them into distinct lots.
Domestic races have often been intentionally modified by one or two
crosses, made with some allied race, and occasionally even by repeated
crosses with very distinct races; but in almost all such cases,
long-continued and careful selection has been absolutely necessary,
owing to the excessive variability of the crossed offspring, due to the
principle of reversion. In a few instances, however, mongrels have
retained a uniform character from their first production.

When two varieties are allowed to cross freely, and one is much more
numerous than the other, the former will ultimately absorb the latter.
Should both varieties exist in nearly equal numbers, it is probable
that a considerable period would elapse before the acquirement of a
uniform character; and the character ultimately acquired would largely
depend on prepotency of transmission and on the conditions of life; for
the nature of these conditions would generally favour one variety more
than another, so that a kind of natural selection would come into play.
Unless the crossed offspring were slaughtered by man without the least
discrimination, some degree of unmethodical selection would likewise
come into action. From these several considerations we may infer, that
when two or more closely allied species first came into the possession
of the same tribe, their crossing will not have influenced, in so great
a degree as has often been supposed, the character of the offspring in
future times; although in some cases it probably has had a considerable
effect.

Domestication, as a general rule, increases the prolificness of animals
and plants. It eliminates the tendency to sterility which is common to
species when first taken from a state of nature and crossed. On this
latter head we have no direct evidence; but as our races of dogs,
cattle, pigs etc., are almost certainly descended from aboriginally
distinct stocks, and as these races are now fully fertile together, or
at least incomparably more fertile than most species when crossed, we
may with entire confidence accept this conclusion.

Abundant evidence has been given that crossing adds to the size,
vigour, and fertility of the offspring. This holds good when there has
been no previous close interbreeding. It applies to the individuals of
the same variety but belonging to different families, to distinct
varieties, sub-species, and even to species. In the latter case, though
size is gained, fertility is lost; but the increased size, vigour, and
hardiness of many hybrids cannot be accounted for solely on the
principle of compensation from the inaction of the reproductive system.
Certain plants whilst growing under their natural conditions, others
when cultivated, and others of hybrid origin, are completely
self-impotent, though perfectly healthy; and such plants can be
stimulated to fertility only by being crossed with other individuals of
the same or of a distinct species.

On the other hand, long-continued close interbreeding between the
nearest relations diminishes the constitutional vigour, size, and
fertility of the offspring; and occasionally leads to malformations,
but not necessarily to general deterioration of form or structure. This
failure of fertility shows that the evil results of interbreeding are
independent of the augmentation of morbid tendencies common to both
parents, though this augmentation no doubt is often highly injurious.
Our belief that evil follows from close interbreeding rests to a
certain extent on the experience of practical breeders, especially of
those who have reared many animals of quickly propagating kinds; but it
likewise rests on several carefully recorded experiments. With some
animals close interbreeding may be carried on for a long period with
impunity by the selection of the most vigorous and healthy individuals;
but sooner or later evil follows. The evil, however, comes on so slowly
and gradually that it easily escapes observation, but can be recognised
by the almost instantaneous manner in which size, constitutional
vigour, and fertility are regained when animals that have long been
interbred are crossed with a distinct family.

These two great classes of facts, namely, the good derived from
crossing, and the evil from close interbreeding, with the consideration
of the innumerable adaptations throughout nature for compelling, or
favouring, or at least permitting, the occasional union of distinct
individuals, taken together, lead to the conclusion that it is a law of
nature that organic beings shall not fertilise themselves for
perpetuity. This law was first plainly hinted at in 1799, with respect
to plants, by Andrew Knight[1] and, not long afterwards, that sagacious
observer Kölreuter, after showing how well the Malvaceæ are adapted for
crossing, asks, “an id aliquid in recessu habeat, quod hujuscemodi
flores nunquam proprio suo pulvere, sed semper eo aliarum su speciei
impregnentur, merito quæritur? Certe natura nil facit frustra.”
Although we may demur to Kölreuter’s saying that nature does nothing in
vain, seeing how many rudimentary and useless organs there are, yet
undoubtedly the argument from the innumerable contrivances, which
favour crossing, is of the greatest weight. The most important result
of this law is that it leads to uniformity of character in the
individuals of the same species. In the case of certain hermaphrodites,
which probably intercross only at long intervals of time, and with
unisexual animals inhabiting somewhat separated localities, which can
only occasionally come into contact and pair, the greater vigour and
fertility of the crossed offspring will ultimately tend to give
uniformity of character. But when we go beyond the limits of the same
species, free intercrossing is barred by the law of sterility.

In searching for facts which might throw light on the cause of the good
effects from crossing, and of the evil effects from close
interbreeding, we have seen that, on the one hand, it is a widely
prevalent and ancient belief, that animals and plants profit from
slight changes in their condition of life; and it would appear that the
germ, in a somewhat analogous manner, is more effectually stimulated by
the male element, when taken from a distinct individual, and therefore
slightly modified in nature, than when taken from a male having the
same identical constitution. On the other hand, numerous facts have
been given, showing that when animals are first subjected to captivity,
even in their native land, and although allowed much liberty, their
reproductive functions are often greatly impaired or quite annulled.
Some groups of animals are more affected than others, but with
apparently capricious exceptions in every group. Some animals never or
rarely couple under confinement; some couple freely, but never or
rarely conceive. The secondary male characters, the maternal functions
and instincts, are occasionally affected. With plants, when first
subjected to cultivation, analogous facts have been observed. We
probably owe our double flowers, rich seedless fruits, and in some
cases greatly developed tubers, etc., to incipient sterility of the
above nature combined with a copious supply of nutriment. Animals which
have long been domesticated, and plants which have long been
cultivated, can generally withstand, with unimpaired fertility, great
changes in their conditions of life; though both are sometimes slightly
affected. With animals the somewhat rare capacity of breeding freely
under confinement, together with their utility, mainly determine the
kinds which have been domesticated.

We can in no case precisely say what is the cause of the diminished
fertility of an animal when first captured, or of a plant when first
cultivated; we can only infer that it is caused by a change of some
kind in the natural conditions of life. The remarkable susceptibility
of the reproductive system to such changes,—a susceptibility not common
to any other organ,—apparently has an important bearing on Variability,
as we shall see in a future chapter.

It is impossible not to be struck with the double parallelism between
the two classes of facts just alluded to. On the one hand, slight
changes in the conditions of life, and crosses between slightly
modified forms or varieties, are beneficial as far as prolificness and
constitutional vigour are concerned. On the other hand, changes in the
conditions greater in degree, or of a different nature, and crosses
between forms which have been slowly and greatly modified by natural
means,—in other words, between species,—are highly injurious, as far as
the reproductive system is concerned, and in some few instances as far
as constitutional vigour is concerned. Can this parallelism be
accidental? Does it not rather indicate some real bond of connection?
As a fire goes out unless it be stirred up, so the vital forces are
always tending, according to Mr. Herbert Spencer, to a state of
equilibrium, unless disturbed and renovated through the action of other
forces.

In some few cases varieties tend to keep distinct, by breeding at
different seasons, by great difference in size, or by sexual
preference. But the crossing of varieties, far from diminishing,
generally adds to the fertility of the first union and of the mongrel
offspring. Whether all the more widely distinct domestic varieties are
invariably quite fertile when crossed, we do not positively know; much
time and trouble would be requisite for the necessary experiments, and
many difficulties occur, such as the descent of the various races from
aboriginally distinct species, and the doubts whether certain forms
ought to be ranked as species or varieties. Nevertheless, the wide
experience of practical breeders proves that the great majority of
varieties, even if some should hereafter prove not to be indefinitely
fertile _inter se,_ are far more fertile when crossed, than the vast
majority of closely allied natural species. A few remarkable cases
have, however, been given on the authority of excellent observers,
showing that with plants certain forms, which undoubtedly must be
ranked as varieties, yield fewer seeds when crossed than is natural to
the parent-species. Other varieties have had their reproductive powers
so far modified that they are either more or less fertile than their
parents, when crossed with a distinct species.

Nevertheless, the fact remains indisputable that domesticated
varieties, of animals and of plants, which differ greatly from one
another in structure, but which are certainly descended from the same
aboriginal species, such as the races of the fowl, pigeon, many
vegetables, and a host of other productions, are extremely fertile when
crossed; and this seems to make a broad and impassable barrier between
domestic varieties and natural species. But, as I will now attempt to
show, the distinction is not so great and overwhelmingly important as
it at first appears.

      _On the Difference in Fertility between Varieties and Species
      when crossed._

This work is not the proper place for fully treating the subject of
hybridism, and I have already given in my ‘Origin of Species’ a
moderately full abstract. I will here merely enumerate the general
conclusions which may be relied on, and which bear on our present
point.

_Firstly,_ the laws governing the production of hybrids are identical,
or nearly identical, in the animal and vegetable kingdoms.

_Secondly,_ the sterility of distinct species when first united, and
that of their hybrid offspring, graduate, by an almost infinite number
of steps, from zero, when the ovule is never impregnated and a
seed-capsule is never formed, up to complete fertility. We can only
escape the conclusion that some species are fully fertile when crossed,
by determining to designate as varieties all the forms which are quite
fertile. This high degree of fertility is, however, rare. Nevertheless,
plants, which have been exposed to unnatural conditions, sometimes
become modified in so peculiar a manner, that they are much more
fertile when crossed with a distinct species than when fertilised by
their own pollen. Success in effecting a first union between two
species, and the fertility of their hybrids, depend in an eminent
degree on the conditions of life being favourable. The innate sterility
of hybrids of the same parentage and raised from the same seed-capsule
often differs much in degree.

_Thirdly,_ the degree of sterility of a first cross between two species
does not always run strictly parallel with that of their hybrid
offspring. Many cases are known of species which can be crossed with
ease, but yield hybrids excessively sterile; and conversely some which
can be crossed with great difficulty, but produce fairly fertile
hybrids. This is an inexplicable fact, on the view that species have
been specially endowed with mutual sterility in order to keep them
distinct.

_Fourthly,_ the degree of sterility often differs greatly in two
species when reciprocally crossed; for the first will readily fertilise
the second; but the latter is incapable, after hundreds of trials, of
fertilising the former. Hybrids produced from reciprocal crosses
between the same two species likewise sometimes differ in their degree
of sterility. These cases also are utterly inexplicable on the view of
sterility being a special endowment.

_Fifthly,_ the degree of sterility of first crosses and of hybrids
runs, to a certain extent, parallel with the general or systematic
affinity of the forms which are united. For species belonging to
distinct genera can rarely, and those belonging to distinct families
can never, be crossed. The parallelism, however, is far from complete;
for a multitude of closely allied species will not unite, or unite with
extreme difficulty, whilst other species, widely different from one
another, can be crossed with perfect facility. Nor does the difficulty
depend on ordinary constitutional differences, for annual and perennial
plants, deciduous and evergreen trees, plants flowering at different
seasons, inhabiting different stations, and naturally living under the
most opposite climates, can often be crossed with ease. The difficulty
or facility apparently depends exclusively on the sexual constitution
of the species which are crossed; or on their sexual elective affinity,
_i.e. Wahlverwandtschaft_ of Gärtner. As species rarely or never become
modified in one character, without being at the same time modified in
many characters, and as systematic affinity includes all visible
similarities and dissimilarities, any difference in sexual constitution
between two species would naturally stand in more or less close
relation with their systematic position.

_Sixthly,_ the sterility of species when first crossed, and that of
hybrids, may possibly depend to a certain extent on distinct causes.
With pure species the reproductive organs are in a perfect condition,
whilst with hybrids they are often plainly deteriorated. A hybrid
embryo which partakes of the constitution of its father and mother is
exposed to unnatural conditions, as long as it is nourished within the
womb, or egg, or seed of the mother-form; and as we know that unnatural
conditions often induce sterility, the reproductive organs of the
hybrid might at this early age be permanently affected. But this cause
has no bearing on the infertility of first unions. The diminished
number of the offspring from first unions may often result, as is
certainly sometimes the case, from the premature death of most of the
hybrid embryos. But we shall immediately see that a law of an unknown
nature apparently exists, which leads to the offspring from unions,
which are infertile, being themselves more or less infertile; and this
at present is all that can be said.

_Seventhly,_ hybrids and mongrels present, with the one great exception
of fertility, the most striking accordance in all other respects;
namely, in the laws of their resemblance to their two parents, in their
tendency to reversion, in their variability, and in being absorbed
through repeated crosses by either parent-form.

After arriving at these conclusions, I was led to investigate a subject
which throws considerable light on hybridism, namely, the fertility of
heterostyled or dimorphic and trimorphic plants, when illegitimately
united. I have had occasion several times to allude to these plants,
and I may here give a brief abstract of my observations. Several plants
belonging to distinct orders present two forms, which exist in about
equal numbers, and which differ in no respect except in their
reproductive organs; one form having a long pistil with short stamens,
the other a short pistil with long stamens; both with differently sized
pollen-grains. With trimorphic plants there are three forms likewise
differing in the lengths of their pistils and stamens, in the size and
colour of the pollen-grains, and in some other respects; and as in each
of the three forms there are two sets of stamens, there are altogether
six sets of stamens and three kinds of pistils. These organs are so
proportioned in length to one another that, in any two of the forms,
half the stamens in each stand on a level with the stigma of the third
form. Now I have shown, and the result has been confirmed by other
observers, that, in order to obtain full fertility with these plants,
it is necessary that the stigma of the one form should be fertilised by
pollen taken from the stamens of corresponding height in the other
form. So that with dimorphic species two unions, which may be called
legitimate, are fully fertile, and two, which may be called
illegitimate, are more or less infertile. With trimorphic species six
unions are legitimate, or fully fertile, and twelve are illegitimate,
or more or less infertile.[2]

The infertility which may be observed in various dimorphic and
trimorphic plants, when illegitimately fertilised, that is, by pollen
taken from stamens not corresponding in height with the pistil, differs
much in degree, up to absolute and utter sterility; just in the same
manner as occurs in crossing distinct species. As the degree of
sterility in the latter case depends in an eminent degree on the
conditions of life being more or less favourable, so I have found it
with illegitimate unions. It is well known that if pollen of a distinct
species be placed on the stigma of a flower, and its own pollen be
afterwards, even after a considerable interval of time, placed on the
same stigma, its action is so strongly prepotent that it generally
annihilates the effect of the foreign pollen; so it is with the pollen
of the several forms of the same species, for legitimate pollen is
strongly prepotent over illegitimate pollen, when both are placed on
the same stigma. I ascertained this by fertilising several flowers,
first illegitimately, and twenty-four hours afterwards legitimately,
with pollen taken from a peculiarly coloured variety, and all the
seedlings were similarly coloured; this shows that the legitimate
pollen, though applied twenty-four hours subsequently, had wholly
destroyed or prevented the action of the previously applied
illegitimate pollen. Again, as, in making reciprocal crosses between
the same two species, there is occasionally a great difference in the
result, so the same thing occurs with trimorphic plants; for instance,
the mid-styled form of _Lythrum salicaria_ could be illegitimately
fertilised with the greatest ease by pollen from the longer stamens of
the short-styled form, and yielded many seeds; but the short-styled
form did not yield a single seed when fertilised by the longer stamens
of the mid-styled form.

In all these respects the forms of the same undoubted species, when
illegitimately united, behave in exactly the same manner as do two
distinct species when crossed. This led me carefully to observe during
four years many seedlings, raised from several illegitimate unions. The
chief result is that these illegitimate plants, as they may be called,
are not fully fertile. It is possible to raise from dimorphic species,
both long-styled and short-styled illegitimate plants, and from
trimorphic plants all three illegitimate forms. These can then be
properly united in a legitimate manner. When this is done, there is no
apparent reason why they should not yield as many seeds as did their
parents when legitimately fertilised. But such is not the case; they
are all infertile, but in various degrees; some being so utterly and
incurably sterile that they did not yield during four seasons a single
seed or even seed-capsule. These illegitimate plants, which are so
sterile, although united with each other in a legitimate manner, may be
strictly compared with hybrids when crossed _inter se,_ and it is well
known how sterile these latter generally are. When, on the other hand,
a hybrid is crossed with either pure parent-species, the sterility is
usually much lessened: and so it is when an illegitimate plant is
fertilised by a legitimate plant. In the same manner as the sterility
of hybrids does not always run parallel with the difficulty of making
the first cross between the two parent-species, so the sterility of
certain illegitimate plants was unusually great, whilst the sterility
of the union from which they were derived was by no means great. With
hybrids raised from the same seed-capsule the degree of sterility is
innately variable, so it is in a marked manner with illegitimate
plants. Lastly, many hybrids are profuse and persistent flowerers,
whilst other and more sterile hybrids produce few flowers, and are
weak, miserable dwarfs; exactly similar cases occur with the
illegitimate offspring of various dimorphic and trimorphic plants.

Although there is the closest identity in character and behaviour
between illegitimate plants and hybrids, it is hardly an exaggeration
to maintain that the former are hybrids, but produced within the limits
of the same species by the improper union of certain forms, whilst
ordinary hybrids are produced from an improper union between so-called
distinct species. We have already seen that there is the closest
similarity in all respects between first illegitimate unions, and first
crosses between distinct species. This will perhaps be made more fully
apparent by an illustration:—we may suppose that a botanist found two
well-marked varieties (and such occur) of the long-styled form of the
trimorphic _Lithrum salicaria,_ and that he determined to try by
crossing whether they were specifically distinct. He would find that
they yielded only about one-fifth of the proper number of seed, and
that they behaved in all the other above-specified respects as if they
had been two distinct species. But to make the case sure, he would
raise plants from his supposed hybridised seed, and he would find that
the seedlings were miserably dwarfed and utterly sterile, and that they
behaved in all other respects like ordinary hybrids, he might then
maintain that he had actually proved, in accordance with the common
view, that his two varieties were as good and as distinct species as
any in the world; but he would be completely mistaken.

The facts now given on dimorphic and trimorphic plants are important,
because they show us, first, that the physiological test of lessened
fertility, both in first crosses and in hybrids, is no criterion of
specific distinction; secondly, because we may conclude that there is
some unknown bond which connects the infertility of illegitimate unions
with that of their illegitimate offspring, and we are led to extend the
same view to first crosses and hybrids; thirdly, because we find, and
this seems to me of especial importance, that two or three forms of the
same species may exist and may differ in no respect whatever, either in
structure or in constitution, relatively to external conditions, and
yet be sterile when united in certain ways. For we must remember that
it is the union of the sexual elements of individuals of the same form,
for instance, of two long-styled forms, which results in sterility;
whilst it is the union of the sexual element proper to two distinct
forms which is fertile. Hence the case appears at first sight exactly
the reverse of what occurs in the ordinary unions of the individuals of
the same species, and with crosses between distinct species. It is,
however, doubtful whether this is really so; but I will not enlarge on
this obscure subject.

We may, however, infer as probable from the consideration of dimorphic
and trimorphic plants, that the sterility of distinct species when
crossed, and of their hybrid progeny, depends exclusively on the nature
of their sexual elements, and not on any difference in their structure
or general constitution. We are also led to this same conclusion by
considering reciprocal crosses, in which the male of one species cannot
be united, or only with great difficulty, with the female of a second
species, whilst the converse cross can be effected with perfect
facility. That excellent observer, Gärtner, likewise concluded that
species when crossed are sterile owing to differences confined to their
reproductive systems.

On the principle which makes it necessary for man, whilst he is
selecting and improving his domestic varieties, to keep them separate,
it would clearly be advantageous to varieties in a state of nature,
that is to incipient species, if they could be kept from blending,
either through sexual aversion, or by becoming mutually sterile. Hence
it at one time appeared to me probable, as it has to others, that this
sterility might have been acquired through natural selection. On this
view we must suppose that a shade of lessened fertility first
spontaneously appeared, like any other modification, in certain
individuals of a species when crossed with other individuals of the
same species; and that successive slight degrees of infertility, from
being advantageous, were slowly accumulated. This appears all the more
probable, if we admit that the structural differences between the forms
of dimorphic and trimorphic plants, as the length and curvature of the
pistil, etc., have been co-adapted through natural selection; for if
this be admitted, we can hardly avoid extending the same conclusion to
their mutual infertility. Sterility, moreover, has been acquired
through natural selection for other and widely different purposes, as
with neuter insects in reference to their social economy. In the case
of plants, the flowers on the circumference of the truss in the guelder
rose (_Viburnum opulus_) and those on the summit of the spike in the
feather-hyacinth (_Muscari comosum_) have been rendered conspicuous,
and apparently in consequence sterile, in order that insects might
easily discover and visit the perfect flowers. But when we endeavour to
apply the principle of natural selection to the acquirement by distinct
species of mutual sterility, we meet with great difficulties. In the
first place, it may be remarked that separate regions are often
inhabited by groups of species or by single species, which when brought
together and crossed are found to be more or less sterile; now it could
clearly have been no advantage to such separated species to have been
rendered mutually sterile, and consequently this could not have been
effected through natural selection; but it may perhaps be argued, that,
if a species were rendered sterile with some one compatriot, sterility
with other species would follow as a necessary consequence. In the
second place, it is as much opposed to the theory of natural selection,
as to the theory of special creation, that in reciprocal crosses the
male element of one form should have been rendered utterly impotent on
a second form, whilst at the same time the male element of this second
form is enabled freely to fertilise the first form; for this peculiar
state of the reproductive system could not possibly have been
advantageous to either species.

In considering the probability of natural selection having come into
action in rendering species mutually sterile, one of the greatest
difficulties will be found to lie in the existence of many graduated
steps from slightly lessened fertility to absolute sterility. It may be
admitted, on the principle above explained, that it would profit an
incipient species if it were rendered in some slight degree sterile
when crossed with its parent-form or with some other variety; for thus
fewer bastardised and deteriorated offspring would be produced to
commingle their blood with the new species in process of formation. But
he who will take the trouble to reflect on the steps by which this
first degree of sterility could be increased through natural selection
to that higher degree which is common to so many species, and which is
universal with species which have been differentiated to a generic or
family rank, will find the subject extraordinarily complex. After
mature reflection it seems to me that this could not have been effected
through natural selection. Take the case of any two species which, when
crossed, produce few and sterile offspring; now, what is there which
could favour the survival of those individuals which happened to be
endowed in a slightly higher degree with mutual infertility, and which
thus approached by one small step towards absolute sterility? Yet an
advance of this kind, if the theory of natural selection be brought to
bear, must have incessantly occurred with many species, for a multitude
are mutually quite barren. With sterile neuter insects we have reason
to believe that modifications in their structure and fertility have
been slowly accumulated by natural selection, from an advantage having
been thus indirectly given to the community to which they belonged over
other communities of the same species; but an individual animal not
belonging to a social community, if rendered slightly sterile when
crossed with some other variety, would not thus itself gain any
advantage or indirectly give any advantage to the other individuals of
the same variety, thus leading to their preservation.

But it would be superfluous to discuss this question in detail; for
with plants we have conclusive evidence that the sterility of crossed
species must be due to some principle, quite independent of natural
selection. Both Gärtner and Kolreuter have proved that in general
including numerous species, a series can be formed from species which
when crossed yield fewer and fewer seeds, to species which never
produce a single seed, but yet are affected by the pollen of certain
other species, for the germen swells. It is here manifestly impossible
to select the more sterile individuals, which have already ceased to
yield seeds; so that this acme of sterility, when the germen alone is
affected, cannot have been gained through selection; and from the laws
governing the various grades of sterility being so uniform throughout
the animal and vegetable kingdoms, we may infer that the cause,
whatever it may be, is the same or nearly the same in all cases.

As species have not been rendered mutually infertile through the
accumulative action of natural selection, and as we may safely
conclude, from the previous as well as from other and more general
considerations, that they have not been endowed through an act of
creation with this quality, we must infer that it has arisen
incidentally during their slow formation in connection with other and
unknown changes in their organisation. By a quality arising
incidentally, I refer to such cases as different species of animals and
plants being differently affected by poisons to which they are not
naturally exposed; and this difference in susceptibility is clearly
incidental on other and unknown differences in their organisation. So
again the capacity in different kinds of trees to be grafted on each
other, or on a third species, differs much, and is of no advantage to
these trees, but is incidental on structural or functional differences
in their woody tissues. We need not feel surprise at sterility
incidentally resulting from crosses between distinct species,—the
modified descendants of a common progenitor,—when we bear in mind how
easily the reproductive system is affected by various causes—often by
extremely slight changes in the conditions of life, by too close
interbreeding, and by other agencies. It is well to bear in mind such
cases as that of the _Passiflora alata,_ which recovered its
self-fertility from being grafted on a distinct species—the cases of
plants which normally or abnormally are self-impotent, but can readily
be fertilised by the pollen of a distinct species—and lastly the cases
of individual domesticated animals which evince towards each other
sexual incompatibility.

We now at last come to the immediate point under discussion: how is it
that, with some few exceptions in the case of plants, domesticated
varieties, such as those of the dog, fowl, pigeon, several fruit-trees,
and culinary vegetables, which differ from each other in external
characters more than many species, are perfectly fertile when crossed,
or even fertile in excess, whilst closely allied species are almost
invariably in some degree sterile? We can, to a certain extent, give a
satisfactory answer to this question. Passing over the fact that the
amount of external difference between two species is no sure guide to
their degree of mutual sterility, so that similar differences in the
case of varieties would be no sure guide, we know that with species the
cause lies exclusively in differences in their sexual constitution. Now
the conditions to which domesticated animals and cultivated plants have
been subjected have had so little tendency towards modifying the
reproductive system in a manner leading to mutual sterility, that we
have very good grounds for admitting the directly opposite doctrine of
Pallas, namely, that such conditions generally eliminate this tendency;
so that the domesticated descendants of species, which in their natural
state would have been in some degree sterile when crossed, become
perfectly fertile together. With plants, so far is cultivation from
giving a tendency towards mutual sterility, that in several
well-authenticated cases, already often alluded to, certain species
have been affected in a very different manner, for they have become
self-impotent, whilst still retaining the capacity of fertilising, and
being fertilised by, distinct species. If the Pallasian doctrine of the
elimination of sterility through long-continued domestication be
admitted, and it can hardly be rejected, it becomes in the highest
degree improbable that similar circumstances should commonly both
induce and eliminate the same tendency; though in certain cases, with
species having a peculiar constitution, sterility might occasionally be
thus induced. Thus, as I believe, we can understand why with
domesticated animals varieties have not been produced which are
mutually sterile; and why with plants only a few such cases have been
observed, namely, by Gärtner, with certain varieties of maize and
verbascum, by other experimentalists with varieties of the gourd and
melon, and by Kölreuter with one kind of tobacco.

With respect to varieties which have originated in a state of nature,
it is almost hopeless to expect to prove by direct evidence that they
have been rendered mutually sterile; for if even a trace of sterility
could be detected, such varieties would at once be raised by almost
every naturalist to the rank of distinct species. If, for instance,
Gärtner’s statement were fully confirmed, that the blue and red
flowered forms of the pimpernel (_Anagallis arvensis_) are sterile when
crossed, I presume that all the botanists who now maintain on various
grounds that these two forms are merely fleeting varieties, would at
once admit that they were specifically distinct.

The real difficulty in our present subject is not, as it appears to me,
why domestic varieties have not become mutually infertile when crossed,
but why this has so generally occurred with natural varieties as soon
as they have been modified in a sufficient and permanent degree to take
rank as species. We are far from precisely knowing the cause; but we
can see that the species, owing to their struggle for existence with
numerous competitors, must have been exposed to more uniform conditions
of life during long periods of time than domestic varieties have been,
and this may well make a wide difference in the result. For we know how
commonly wild animals and plants, when taken from their natural
conditions and subjected to captivity, are rendered sterile; and the
reproductive functions of organic beings which have always lived and
been slowly modified under natural conditions would probably in like
manner be eminently sensitive to the influence of an unnatural cross.
Domesticated productions, on the other hand, which, as shown by the
mere fact of their domestication, were not originally highly sensitive
to changes in their conditions of life, and which can now generally
resist with undiminished fertility repeated changes of conditions,
might be expected to produce varieties, which would be little liable to
have their reproductive powers injuriously affected by the act of
crossing with other varieties which had originated in a like manner.

Certain naturalists have recently laid too great stress, as it appears
to me, on the difference in fertility between varieties and species
when crossed. Some allied species of trees cannot be grafted on one
another, whilst all varieties can be so grafted. Some allied animals
are affected in a very different manner by the same poison, but with
varieties no such case until recently was known; whilst now it has been
proved that immunity from certain poisons sometimes stands in
correlation with the colour of the individuals of the same species. The
period of gestation generally differs much in distinct species, but
with varieties until lately no such difference had been observed. Here
we have various physiological differences, and no doubt others could be
added, between one species and another of the same genus, which do not
occur, or occur with extreme rarity, in the case of varieties; and
these differences are apparently wholly or in chief part incidental on
other constitutional differences, just in the same manner as the
sterility of crossed species is incidental on differences confined to
the sexual system. Why, then, should these latter differences, however
serviceable they may indirectly be in keeping the inhabitants of the
same country distinct, be thought of such paramount importance, in
comparison with other incidental and functional differences? No
sufficient answer to this question can be given. Hence the fact that
widely distinct domestic varieties are, with rare exceptions, perfectly
fertile when crossed, and produce fertile offspring, whilst closely
allied species are, with rare exceptions, more or less sterile, is not
nearly so formidable an objection as it appears at first to the theory
of the common descent of allied species.

REFERENCES

 [1] ‘Transactions Phil. Soc.,’ 1799, p. 202. For Kölreuter _see_ ‘Mém.
 de l’Acad. de St.-Pétersbourg,’ tom. iii. 1809 (published 1811) p.
 197. In reading C. K. Sprengel’s remarkable work, ‘Das entdeckte
 Geheimniss,’ etc., 1793, it is curious to observe how often this
 wonderfully acute observer failed to understand the full meaning of
 the structure of the flowers which he has so well described, from not
 always having before his mind the key to the problem, namely, the good
 derived from the crossing of distinct individual plants.

 [2] My observations ‘On the Character and hybrid-like nature of the
 offspring from the illegitimate union of Dimorphic and Trimorphic
 Plants’ were published in the ‘Journal of the Linnean Soc.,’ vol. x.
 p. 393. The abstract here given is nearly the same with that which
 appeared in the 6th edition of my ‘Origin of Species.’




CHAPTER XX. SELECTION BY MAN.

SELECTION A DIFFICULT ART—METHODICAL, UNCONSCIOUS, AND NATURAL
SELECTION—RESULTS OF METHODICAL SELECTION—CARE TAKEN IN
SELECTION—SELECTION WITH PLANTS—SELECTION CARRIED ON BY THE ANCIENTS
AND BY SEMI-CIVILISED PEOPLE—UNIMPORTANT CHARACTERS OFTEN ATTENDED
TO—UNCONSCIOUS SELECTION—AS CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR
DOMESTICATED ANIMALS CHANGED THROUGH THE ACTION OF UNCONSCIOUS
SELECTION—INFLUENCE OF DIFFERENT BREEDERS ON THE SAME
SUB-VARIETY—PLANTS AS AFFECTED BY UNCONSCIOUS SELECTION—EFFECTS OF
SELECTION AS SHOWN BY THE GREAT AMOUNT OF DIFFERENCE IN THE PARTS MOST
VALUED BY MAN.


The power of Selection, whether exercised by man, or brought into play
under nature through the struggle for existence and the consequent
survival of the fittest, absolutely depends on the variability of
organic beings. Without variability nothing can be effected; slight
individual differences, however, suffice for the work, and are probably
the chief or sole means in the production of new species. Hence our
discussion on the causes and laws of variability ought in strict order
to have preceded the present subject, as well as inheritance, crossing,
etc.; but practically the present arrangement has been found the most
convenient. Man does not attempt to cause variability; though he
unintentionally effects this by exposing organisms to new conditions of
life, and by crossing breeds already formed. But variability being
granted, he works wonders. Unless some degree of selection be
exercised, the free commingling of the individuals of the same variety
soon obliterates, as we have previously seen, the slight differences
which arise, and gives uniformity of character to the whole body of
individuals. In separated districts, long-continued exposure to
different conditions of life may produce new races without the aid of
selection; but to this subject of the direct action of the conditions
of life I shall recur in a future chapter.

When animals or plants are born with some conspicuous and firmly
inherited new character, selection is reduced to the preservation of
such individuals, and to the subsequent prevention of crosses; so that
nothing more need be said on the subject. But in the great majority of
cases a new character, or some superiority in an old character, is at
first faintly pronounced, and is not strongly inherited; and then the
full difficulty of selection is experienced. Indomitable patience, the
finest powers of discrimination, and sound judgment must be exercised
during many years. A clearly predetermined object must be kept steadily
in view. Few men are endowed with all these qualities, especially with
that of discriminating very slight differences; judgment can be
acquired only by long experience; but if any of these qualities be
wanting, the labour of a life may be thrown away. I have been
astonished when celebrated breeders, whose skill and judgment have been
proved by their success at exhibitions, have shown me their animals,
which appeared all alike, and have assigned their reasons for matching
this and that individual. The importance of the great principle of
Selection mainly lies in this power of selecting scarcely appreciable
differences, which nevertheless are found to be transmissible, and
which can be accumulated until the result is made manifest to the eyes
of every beholder.

The principle of selection may be conveniently divided into three
kinds. _Methodical selection_ is that which guides a man who
systematically endeavours to modify a breed according to some
predetermined standard. _Unconscious selection_ is that which follows
from men naturally preserving the most valued and destroying the less
valued individuals, without any thought of altering the breed; and
undoubtedly this process slowly works great changes. Unconscious
selection graduates into methodical, and only extreme cases can be
distinctly separated; for he who preserves a useful or perfect animal
will generally breed from it with the hope of getting offspring of the
same character; but as long as he has not a predetermined purpose to
improve the breed, he may be said to be selecting unconsciously.[1]
Lastly, we have _Natural selection,_ which implies that the individuals
which are best fitted for the complex, and in the course of ages
changing conditions to which they are exposed, generally survive and
procreate their kind. With domestic productions, natural selection
comes to a certain extent into action, independently of, and even in
opposition to, the will of man.

_Methodical Selection._—What man has effected within recent times in
England by methodical selection is clearly shown by our exhibitions of
improved quadrupeds and fancy birds. With respect to cattle, sheep, and
pigs, we owe their great improvement to a long series of well-known
names—Bakewell, Coiling, Ellman, Bates, Jonas Webb, Lords Leicester and
Western, Fisher Hobbs, and others. Agricultural writers are unanimous
on the power of selection: any number of statements to this effect
could be quoted; a few will suffice. Youatt, a sagacious and
experienced observer, writes[2] the principle of selection is “that
which enables the agriculturist, not only to modify the character of
his flock, but to change it altogether.” A great breeder of
Shorthorns[3] says, “In the anatomy of the shoulder modern breeders
have made great improvement on the Ketton shorthorns by correcting the
defect in the knuckle or shoulder-joint, and by laying the top of the
shoulder more snugly in the crop, and thereby filling up the hollow
behind it . . . The eye has its fashion at different periods: at one
time the eye high and outstanding from the head, and at another time
the sleepy eye sunk into the head; but these extremes have merged into
the medium of a full, clear and prominent eye with a placid look.”

Again, hear what an excellent judge of pigs[4] says: “The legs should
be no longer than just to prevent the animal’s belly from trailing on
the ground. The leg is the least profitable portion of the hog, and we
therefore require no more of it than is absolutely necessary for the
support of the rest.” Let any one compare the wild-boar with any
improved breed, and he will see how effectually the legs have been
shortened.

Few persons, except breeders, are aware of the systematic care taken in
selecting animals, and of the necessity of having a clear and almost
prophetic vision into futurity. Lord Spencer’s skill and judgment were
well known; and he writes,[5] “It is therefore very desirable, before
any man commences to breed either cattle or sheep, that he should make
up his mind to the shape and qualities he wishes to obtain, and
steadily pursue this object.” Lord Somerville, in speaking of the
marvellous improvement of the New Leicester sheep, effected by Bakewell
and his successors, says, “It would seem as if they had first drawn a
perfect form, and then given it life.” Youatt[6] urges the necessity of
annually drafting each flock, as many animals will certainly degenerate
“from the standard of excellence which the breeder has established in
his own mind.” Even with a bird of such little importance as the
canary, long ago (1780-1790) rules were established, and a standard of
perfection was fixed according to which the London fanciers tried to
breed the several sub-varieties.[7] A great winner of prizes at the
Pigeon-shows,[8] in describing the short-faced Almond Tumbler, says,
“There are many first-rate fanciers who are particularly partial to
what is called the goldfinch-beak, which is very beautiful; others say,
take a full-size round cherry then take a barleycorn, and judiciously
placing and thrusting it into the cherry, form as it were your beak;
and that is not all, for it will form a good head and beak, provided,
as I said before, it is judiciously done; others take an oat; but as I
think the goldfinch-beak the handsomest, I would advise the
inexperienced fancier to get the head of a goldfinch, and keep it by
him for his observation.” Wonderfully different as are the beaks of the
rock pigeon and goldfinch, the end has undoubtedly been nearly gained,
as far as external shape and proportions are concerned.

Not only should our animals be examined with the greatest care whilst
alive, but, as Anderson remarks[9] their carcases should be
scrutinised, “so as to breed from the descendants of such only as, in
the language of the butcher, cut up well.” The “grain of the meat” in
cattle, and its being well marbled with fat,[10] and the greater or
less accumulation of fat in the abdomen of our sheep, have been
attended to with success. So with poultry, a writer,[11] speaking of
Cochin-China fowls, which are said to differ much in the quality of
their flesh, says, “the best mode is to purchase two young
brother-cocks, kill, dress, and serve up one; if he be indifferent,
similarly dispose of the other, and try again; if, however, he be fine
and well-flavoured, his brother will not be amiss for breeding purposes
for the table.”

The great principle of the division of labour has been brought to bear
on selection. In certain districts[12] “the breeding of bulls is
confined to a very limited number of persons, who by devoting their
whole attention to this department, are able from year to year to
furnish a class of bulls which are steadily improving the general breed
of the district.” The rearing and letting of choice rams has long been,
as is well known, a chief source of profit to several eminent breeders.
In parts of Germany this principle is carried with merino sheep to an
extreme point.[13] So “important is the proper selection of breeding
animals considered, that the best flock-masters do not trust to their
own judgment or to that of their shepherds, but employ persons called
‘sheep-classifiers’ who make it their special business to attend to
this part of the management of several flocks, and thus to preserve, or
if possible to improve, the best qualities of both parents in the
lambs.” In Saxony, “when the lambs are weaned, each in his turn is
placed upon a table that his wool and form may be minutely observed.
The finest are selected for breeding and receive a first mark. When
they are one year old, and prior to shearing them, another close
examination of those previously marked takes place: those in which no
defect can be found receive a second mark, and the rest are condemned.
A few months afterwards a third and last scrutiny is made; the prime
rams and ewes receive a third and final mark, but the slightest blemish
is sufficient to cause the rejection of the animal.” These sheep are
bred and valued almost exclusively for the fineness of their wool; and
the result corresponds with the labour bestowed on their selection.
Instruments have been invented to measure accurately the thickness of
the fibres; and “an Austrian fleece has been produced of which twelve
hairs equalled in thickness one from a Leicester sheep.”

Throughout the world, wherever silk is produced, the greatest care is
bestowed on selecting the cocoons from which the moths for breeding are
to be reared. A careful cultivator[14] likewise examines the moths
themselves, and destroys those that are not perfect. But what more
immediately concerns us is that certain families in France devote
themselves to raising eggs for sale.[15] In China, near Shanghai, the
inhabitants of two small districts have the privilege of raising eggs
for the whole surrounding country, and that they may give up their
whole time to this business, they are interdicted by law from producing
silk.[16]

The care which successful breeders take in matching their birds is
surprising. Sir John Sebright, whose fame is perpetuated by the
“Sebright Bantam,” used to spend “two and three days in examining,
consulting, and disputing with a friend which were the best of five or
six birds.”[17] Mr. Bult, whose pouter-pigeons won so many prizes, and
were exported to North America under the charge of a man sent on
purpose, told me that he always deliberated for several days before he
matched each pair. Hence we can understand the advice of an eminent
fancier, who writes[18] “I would here particularly guard you against
having too great a variety of pigeons, otherwise you will know a little
of all, but nothing about one as it ought to be known.” Apparently it
transcends the power of the human intellect to breed all kinds: “it is
possible that there may be a few fanciers that have a good general
knowledge of fancy pigeons; but there are many more who labour under
the delusion of supposing they know what they do not.” The excellence
of one sub-variety, the Almond Tumbler, lies in the plumage, carriage,
head, beak, and eye; but it is too presumptuous in the beginner to try
for all these points. The great judge above quoted says, “There are
some young fanciers who are over-covetous, who go for all the above
five properties at once; they have their reward by getting nothing.” We
thus see that breeding even fancy pigeons is no simple art: we may
smile at the solemnity of these precepts, but he who laughs will win no
prizes.

What methodical selection has effected for our animals is sufficiently
proved, as already remarked, by our Exhibitions. So greatly were the
sheep belonging to some of the earlier breeders, such as Bakewell and
Lord Western, changed, that many persons could not be persuaded that
they had not been crossed. Our pigs, as Mr. Corringham remarks[19]
during the last twenty years have undergone, through rigorous selection
together with crossing, a complete metamorphosis. The first exhibition
for poultry was held in the Zoological Gardens in 1845; and the
improvement effected since that time has been great. As Mr. Bailey, the
great judge, remarked to me, it was formerly ordered that the comb of
the Spanish cock should be upright, and in four or five years all good
birds had upright combs; it was ordered that the Polish cock should
have no comb or wattles, and now a bird thus furnished would be at once
disqualified; beards were ordered, and out of fifty-seven pens lately
(1860) exhibited at the Crystal Palace, all had beards. So it has been
in many other cases. But in all cases the judges order only what is
occasionally produced and what can be improved and rendered constant by
selection. The steady increase in weight during the last few years in
our fowls, turkeys, ducks, and geese is notorious; “six-pound ducks are
now common, whereas four pounds was formerly the average.” As the time
required to make a change has not often been recorded, it may be worth
mentioning that it took Mr. Wicking thirteen years to put a clean white
head on an almond tumbler’s body, “a triumph,” says another fancier,
“of which he may be justly proud.”[20]

Mr. Tollet, of Betley Hall, selected cows, and especially bulls,
descended from good milkers, for the sole purpose of improving his
cattle for the production of cheese; he steadily tested the milk with
the lactometer, and in eight years he increased, as I was informed by
him, the product in proportion of four to three. Here is a curious
case[21] of steady but slow progress, with the end not as yet fully
attained: in 1784 a race of silkworms was introduced into France, in
which one hundred in the thousand failed to produce white cocoons; but
now after careful selection during sixty-five generations, the
proportion of yellow cocoons has been reduced to thirty-five in the
thousand.

With plants selection has been followed with the same good result as
with animals. But the process is simpler, for plants in the great
majority of cases bear both sexes. Nevertheless, with most kinds it is
necessary to take as much care to prevent crosses as with animals or
unisexual plants; but with some plants, such as peas, this care is not
necessary. With all improved plants, excepting of course those which
are propagated by buds, cuttings, etc., it is almost indispensable to
examine the seedlings and destroy those which depart from the proper
type. This is called “roguing,” and is, in fact, a form of selection,
like the rejection of inferior animals. Experienced horticulturists and
agriculturists incessantly urge every one to preserve the finest plants
for the production of seed.

Although plants often present much more conspicuous variations than
animals, yet the closest attention is generally requisite to detect
each slight and favourable change. Mr. Masters relates[22] how “many a
patient hour was devoted,” whilst he was young, to the detection of
differences in peas intended for seed. Mr. Barnet[23] remarks that the
old scarlet American strawberry was cultivated for more than a century
without producing a single variety; and another writer observes how
singular it was that when gardeners first began to attend to this fruit
it began to vary; the truth no doubt being that it had always varied,
but that, until slight variations were selected and propagated by seed,
no conspicuous result was obtained. The finest shades of difference in
wheat have been discriminated and selected with almost as much care as,
in the case of the higher animals, for instance by Col. Le Couteur and
more especially by Major Hallett.

It may be worth while to give a few examples of methodical selection
with plants; but in fact the great improvement of all our anciently
cultivated plants may be attributed to selection long carried on, in
part methodically, and in part unconsciously. I have shown in a former
chapter how the weight of the gooseberry has been increased by
systematic selection and culture. The flowers of the Heartsease have
been similarly increased in size and regularity of outline. With the
Cineraria, Mr. Glenny[24] “was bold enough when the flowers were ragged
and starry and ill defined in colour, to fix a standard which was then
considered outrageously high and impossible, and which, even if
reached, it was said, we should be no gainers by, as it would spoil the
beauty of the flowers. He maintained that he was right; and the event
has proved it to be so.” The doubling of flowers has several times been
effected by careful selection: the Rev. W. Williamson,[25] after sowing
during several years seed of _Anemone coronaria,_ found a plant with
one additional petal; he sowed the seed of this, and by perseverance in
the same course obtained several varieties with six or seven rows of
petals. The single Scotch rose was doubled, and yielded eight good
varieties in nine or ten years.[26] The Canterbury bell (_Campanula
medium_) was doubled by careful selection in four generations.[27] In
four years Mr. Buckman,[28] by culture and careful selection, converted
parsnips, raised from wild seed, into a new and good variety. By
selection during a long course of years, the early maturity of peas has
been hastened by between ten and twenty-one days.[29] A more curious
case is offered by the beet plant, which since its cultivation in
France, has almost exactly doubled its yield of sugar. This has been
effected by the most careful selection; the specific gravity of the
roots being regularly tested, and the best roots saved for the
production of seed.[30]

      _Selection by Ancient and Semi-civilised People._

In attributing so much importance to the selection of animals and
plants, it may be objected, that methodical selection would not have
been carried on during ancient times. A distinguished naturalist
considers it as absurd to suppose that semi-civilised people should
have practised selection of any kind. Undoubtedly the principle has
been systematically acknowledged and followed to a far greater extent
within the last hundred years than at any former period, and a
corresponding result has been gained; but it would be a greater error
to suppose, as we shall immediately see, that its importance was not
recognised and acted on during the most ancient times, and by
semi-civilised people. I should premise that many facts now to be given
only show that care was taken in breeding; but when this is the case,
selection is almost sure to be practised to a certain extent. We shall
hereafter be enabled better to judge how far selection, when only
occasionally carried on, by a few of the inhabitants of a country, will
slowly produce a great effect.

In a well-known passage in the thirtieth chapter of Genesis, rules are
given for influencing, as was then thought possible, the colour of
sheep; and speckled and dark breeds are spoken of as being kept
separate. By the time of David the fleece was likened to snow.
Youatt,[31] who has discussed all the passages in relation to breeding
in the Old Testament, concludes that at this early period “some of the
best principles of breeding must have been steadily and long pursued.”
It was ordered, according to Moses, that “Thou shalt not let thy cattle
gender with a diverse kind;” but mules were purchased[32] so that at
this early period other nations must have crossed the horse and ass. It
is said[33] that Erichthonius, some generations before the Trojan war,
had many brood-mares, “which by his care and judgment in the choice of
stallions produced a breed of horses superior to any in the surrounding
countries.” Homer (Book 5) speaks of Aeneas’ horses as bred from mares
which were put to the steeds of Laomedon. Plato, in his ‘Republic’ says
to Glaucus, “I see that you raise at your house a great many dogs for
the chase. Do you take care about breeding and pairing them? Among
animals of good blood, are there not always some which are superior to
the rest?” To which Glaucus answers in the affirmative.[34] Alexander
the Great selected the finest Indian cattle to send to Macedonia to
improve the breed.[35] According to Pliny,[36] King Pyrrhus had an
especially valuable breed of oxen: and he did not suffer the bulls and
cows to come together till four years old, that the breed might not
degenerate. Virgil, in his Georgics (lib. 3), gives as strong advice as
any modern agriculturist could do, carefully to select the breeding
stock; “to note the tribe, the lineage, and the sire; whom to reserve
for husband of the herd;”—to brand the progeny;—to select sheep of the
purest white, and to examine if their tongues are swarthy. We have seen
that the Romans kept pedigrees of their pigeons, and this would have
been a senseless proceeding had not great care been taken in breeding
them. Columella gives detailed instructions about breeding fowls: “Let
the breeding hens therefore be of a choice colour, a robust body,
square-built, full-breasted, with large heads, with upright and
bright-red combs. Those are believed to be the best bred which have
five toes.”[37] According to Tacitus, the Celts attended to the races
of their domestic animals; and Caesar states that they paid high prices
to merchants for fine imported horses.[38] In regard to plants, Virgil
speaks of yearly culling the largest seeds; and Celsus says, “where the
corn and crop is but small, we must pick out the best ears of corn, and
of them lay up our seed separately by itself.”[39]

Coming down the stream of time, we may be brief. At about the beginning
of the ninth century Charlemagne expressly ordered his officers to take
great care of his stallions; and if any proved bad or old, to forewarn
him in good time before they were put to the mares.[40] Even in a
country so little civilised as Ireland during the ninth century, it
would appear from some ancient verses,[41] describing a ransom demanded
by Cormac, that animals from particular places, or having a particular
character, were valued. Thus it is said,—

      Two pigs of the pigs of Mac Lir,
      A ram and ewe both round and red,
      I brought with me from Aengus.
      I brought with me a stallion and a mare
      From the beautiful stud of Manannan,
      A bull and a white cow from Druim Cain.

Athelstan, in 930, received running-horses as a present from Germany;
and he prohibited the exportation of English horses. King John imported
“one hundred chosen stallions from Flanders.”[42] On June 16th, 1305,
the Prince of Wales wrote to the Archbishop of Canterbury, begging for
the loan of any choice stallion, and promising its return at the end of
the season.[43] There are numerous records at ancient periods in
English history of the importation of choice animals of various kinds,
and of foolish laws against their exportation. In the reigns of Henry
VII. and VIII. it was ordered that the magistrates, at Michaelmas,
should scour the heaths and commons, and destroy all mares beneath a
certain size.[44] Some of our earlier kings passed laws against the
slaughtering rams of any good breed before they were seven years old,
so that they might have time to breed. In Spain Cardinal Ximenes
issued, in 1509, regulations on the _ selection_ of good rams for
breeding.[45]

The Emperor Akbar Khan before the year l600 is said to have
“wonderfully improved” his pigeons by crossing the breeds; and this
necessarily implies careful selection. About the same period the Dutch
attended with the greatest care to the breeding of these birds. Belon
in 1555 says that good managers in France examined the colour of their
goslings in order to get geese of a white colour and better kinds.
Markham in 1631 tells the breeder “to elect the largest and goodliest
conies,” and enters into minute details. Even with respect to seeds of
plants for the flower-garden, Sir J. Hanmer writing about the year
1660[46] says, in “choosing seed, the best seed is the most weighty,
and is had from the lustiest and most vigorous stems;” and he then
gives rules about leaving only a few flowers on plants for seed; so
that even such details were attended to in our flower-gardens two
hundred years ago. In order to show that selection has been silently
carried on in places where it would not have been expected, I may add
that in the middle of the last century, in a remote part of North
America, Mr. Cooper improved by careful selection all his vegetables,
“so that they were greatly superior to those of any other person. When
his radishes, for instance, are fit for use, he takes ten or twelve
that he most approves, and plants them at least 100 yards from others
that blossom at the same time. In the same manner he treats all his
other plants, varying the circumstances according to their nature.”[47]

In the great work on China published in the last century by the
Jesuits, and which is chiefly compiled from ancient Chinese
encyclopaedias, it is said that with sheep “improving the breed
consists in choosing with particular care the lambs which are destined
for propagation, in nourishing them well, and in keeping the flocks
separate.” The same principles were applied by the Chinese to various
plants and fruit-trees.[48] An imperial edict recommends the choice of
seed of remarkable size; and selection was practised even by imperial
hands, for it is said that the Ya-mi, or imperial rice, was noticed at
an ancient period in a field by the Emperor Khang-hi, was saved and
cultivated in his garden, and has since become valuable from being the
only kind which will grow north of the Great Wall.[49] Even with
flowers, the tree paeony (_P. moutan_) has been cultivated, according
to Chinese traditions, for 1400 years; between 200 and 300 varieties
have been raised, which are cherished like tulips formerly were by the
Dutch.[50]

Turning now to semi-civilised people and to savages: it occurred to me,
from what I had seen of several parts of South America, where fences do
not exist, and where the animals are of little value, that there would
be absolutely no care in breeding or selecting them; and this to a
large extent is true. Roulin,[51] however, describes in Columbia a
naked race of cattle, which are not allowed to increase, on account of
their delicate constitution. According to Azara[52] horses are often
born in Paraguay with curly hair; but, as the natives do not like them,
they are destroyed. On the other hand, Azara states that a hornless
bull, born in 1770, was preserved and propagated its race. I was
informed of the existence in Banda Oriental of a breed with reversed
hair; and the extraordinary niata cattle first appeared and have since
been kept distinct in La Plata. Hence certain conspicuous variations
have been preserved, and others have been habitually destroyed, in
these countries, which are so little favourable for careful selection.
We have also seen that the inhabitants sometimes introduce fresh cattle
on their estates to prevent the evil effects of close interbreeding. On
the other hand, I have heard on reliable authority that the Gauchos of
the Pampas never take any pains in selecting the best bulls or
stallions for breeding; and this probably accounts for the cattle and
horses being remarkably uniform in character throughout the immense
range of the Argentine republic.

Looking to the Old World, in the Sahara Desert “The Touareg is as
careful in the selection of his breeding Mahari (a fine race of the
dromedary) as the Arab is in that of his horse. The pedigrees are
handed down, and many a dromedary can boast a genealogy far longer than
the descendants of the Darley Arabian.”[53] According to Pallas the
Mongolians endeavour to breed the Yaks or horse-tailed buffaloes with
white tails, for these are sold to the Chinese mandarins as
fly-flappers; and Moorcroft, about seventy years after Pallas, found
that white-tailed animals were still selected for breeding.[54]

We have seen in the chapter on the Dog that savages in different parts
of North America and in Guiana cross their dogs with wild Canidæ, as
did the ancient Gauls, according to Pliny. This was done to give their
dogs strength and vigour, in the same way as the keepers in large
warrens now sometimes cross their ferrets (as I have been informed by
Mr. Yarrell) with the wild polecat, “to give them more devil.”
According to Varro, the wild ass was formerly caught and crossed with
the tame animal to improve the breed, in the same manner as at the
present day the natives of Java sometimes drive their cattle into the
forests to cross with the wild Banteng (_Bos sondaicus_).[55] In
Northern Siberia, among the Ostyaks, the dogs vary in markings in
different districts, but in each place they are spotted black and white
in a remarkably uniform manner;[56] and from this fact alone we may
infer careful breeding, more especially as the dogs of one locality are
famed throughout the country for their superiority. I have heard of
certain tribes of Esquimaux who take pride in their teams of dogs being
uniformly coloured. In Guiana, as Sir H. Schomburgk informs me,[57] the
dogs of the Turuma Indians are highly valued and extensively bartered:
the price of a good one is the same as that given for a wife: they are
kept in a sort of cage, and the Indians “take great care when the
female is in season to prevent her uniting with a dog of an inferior
description.” The Indians told Sir Robert that, if a dog proved bad or
useless, he was not killed, but was left to die from sheer neglect.
Hardly any nation is more barbarous than the Fuegians, but I hear from
Mr. Bridges, the Catechist to the Mission, that, “when these savages
have a large, strong, and active bitch, they take care to put her to a
fine dog, and even take care to feed her well, that her young may be
strong and well favoured.”

In the interior of Africa, negroes, who have not associated with white
men, show great anxiety to improve their animals; they “always choose
the larger and stronger males for stock;” the Malakolo were much
pleased at Livingstone’s promise to send them a bull, and some Bakalolo
carried a live cock all the way from Loanda into the interior.[58] At
Falaba Mr. Winwood Reade noticed an unusually fine horse, and the negro
King informed him that “the owner was noted for his skill in breeding
horses.” Further south on the same continent, Andersson states that he
has known a Damara give two fine oxen for a dog which struck his fancy.
The Damaras take great delight in having whole droves of cattle of the
same colour, and they prize their oxen in proportion to the size of
their horns. “The Namaquas have a perfect mania for a uniform team; and
almost all the people of Southern Africa value their cattle next to
their women, and take a pride in possessing animals that look
high-bred. They rarely or never make use of a handsome animal as a
beast of burden.”[59] The power of discrimination which these savages
possess is wonderful, and they can recognise to which tribe any cattle
belong. Mr. Andersson further informs me that the natives frequently
match a particular bull with a particular cow.

The most curious case of selection by semi-civilised people, or indeed
by any people, which I have found recorded, is that given by Garcilazo
de la Vega, a descendant of the Incas, as having been practised in Peru
before the country was subjugated by the Spaniards.[60] The Incas
annually held great hunts, when all the wild animals were driven from
an immense circuit to a central point. The beasts of prey were first
destroyed as injurious. The wild Guanacos and Vicunas were sheared; the
old males and females killed, and the others set at liberty. The
various kinds of deer were examined; the old males and females were
likewise killed, “but the young females, with a certain number of
males, selected from the most beautiful and strong,” were given their
freedom. Here, then, we have selection by man aiding natural selection.
So that the Incas followed exactly the reverse system of that which our
Scottish sportsman are accused of following, namely, of steadily
killing the finest stags, thus causing the whole race to
degenerate.[61] In regard to the domesticated llamas and alpacas, they
were separated in the time of the Incas according to colour: and if by
chance one in a flock was born of the wrong colour, it was eventually
put into another flock.

In the genus Auchenia there are four forms,—the Guanaco and Vicuna,
found wild and undoubtedly distinct species; the Llama and Alpaca,
known only in a domesticated condition. These four animals appear so
different, that most naturalists, especially those who have studied
these animals in their native country, maintain that they are
specifically distinct, notwithstanding that no one pretends to have
seen a wild llama or alpaca. Mr. Ledger, however, who has closely
studied these animals both in Peru and during their exportation to
Australia, and who has made many experiments on their propagation,
adduces arguments[62] which seem to me conclusive, that the llama is
the domesticated descendant of the guanaco, and the alpaca of the
vicuna. And now that we know that these animals were systematically
bred and selected many centuries ago, there is nothing surprising in
the great amount of change which they have undergone.

It appeared to me at one time probable that, though ancient and
semi-civilised people might have attended to the improvement of their
more useful animals in essential points, yet that they would have
disregarded unimportant characters. But human nature is the same
throughout the world: fashion everywhere reigns supreme, and man is apt
to value whatever he may chance to possess. We have seen that in South
America the niata cattle, which certainly are not made useful by their
shortened faces and upturned nostrils, have been preserved. The Damaras
of South Africa value their cattle for uniformity of colour and
enormously long horns. And I will now show that there is hardly any
peculiarity in our most useful animals which, from fashion,
superstition, or some other motive, has not been valued, and
consequently preserved. With respect to cattle, “an early record,”
according to Youatt[63] “speaks of a hundred white cows with red ears
being demanded as a compensation by the princes of North and South
Wales. If the cattle were of a dark or black colour, 150 were to be
presented.” So that colour was attended to in Wales before its
subjugation by England. In Central Africa, an ox that beats the ground
with its tail is killed; and in South Africa some of the Damaras will
not eat the flesh of a spotted ox. The Kaffirs value an animal with a
musical voice; and “at a sale in British Kaffraria the low of a heifer
excited so much admiration that a sharp competition sprung up for her
possession, and she realised a considerable price.”[64] With respect to
sheep, the Chinese prefer rams without horns; the Tartars prefer them
with spirally wound horns, because the hornless are thought to lose
courage.[65] Some of the Damaras will not eat the flesh of hornless
sheep. In regard to horses, at the end of the fifteenth century animals
of the colour described as liart pomme were most valued in France. The
Arabs have a proverb, “Never buy a horse with four white feet, for he
carries his shroud with him”;[66] the Arabs also, as we have seen,
despise dun-coloured horses. So with dogs, Xenophon and others at an
ancient period were prejudiced in favour of certain colours; and “white
or slate-coloured hunting dogs were not esteemed.”[67]

Turning to poultry, the old Roman gourmands thought that the liver of a
white goose was the most savoury. In Paraguay black-skinned fowls are
kept because they are thought to be more productive, and their flesh
the most proper for invalids.[68] In Guiana, as I am informed by Sir R.
Schomburgk, the aborigines will not eat the flesh or eggs of the fowl,
but two races are kept distinct merely for ornament. In the
Philippines, no less than nine sub-varieties of the game-cock are kept
and named, so that they must be separately bred.

At the present time in Europe, the smallest peculiarities are carefully
attended to in our most useful animals, either from fashion, or as a
mark of purity of blood. Many examples could be given; two will
suffice. “In the Western counties of England the prejudice against a
white pig is nearly as strong as against a black one in Yorkshire.” In
one of the Berkshire sub-breeds, it is said, “the white should be
confined to four white feet, a white spot between the eyes, and a few
white hairs behind each shoulder.” Mr. Saddler possessed “three hundred
pigs, every one of which was marked in this manner.”[69] Marshall,
towards the close of the last century, in speaking of a change in one
of the Yorkshire breeds of cattle, says the horns have been
considerably modified, as “a clean, small, sharp horn has been
_fashionable_ for the last twenty years.”[70] In a part of Germany the
cattle of the Race de Gfoehl are valued for many good qualities, but
they must have horns of a particular curvature and tint, so much so
that mechanical means are applied if they take a wrong direction; but
the inhabitants “consider it of the highest importance that the
nostrils of the bull should be flesh-coloured, and the eyelashes light;
this is an indispensable condition. A calf with blue nostrils would not
be purchased, or purchased at a very low price.”[71] Therefore let no
man say that any point or character is too trifling to be methodically
attended to and selected by breeders.

_Unconscious Selection._—By this term I mean, as already more than once
explained, the preservation by man of the most valued, and the
destruction of the least valued individuals, without any conscious
intention on his part of altering the breed. It is difficult to offer
direct proofs of the results which follow from this kind of selection;
but the indirect evidence is abundant. In fact, except that in the one
case man acts intentionally, and in the other unintentionally, there is
little difference between methodical and unconscious selection. In both
cases man preserves the animals which are most useful or pleasing to
him, and destroys or neglects the others. But no doubt a far more rapid
result follows from methodical than from unconscious selection. The
“roguing” of plants by gardeners, and the destruction by law in Henry
VIII.’s reign of all under-sized mares, are instances of a process the
reverse of selection in the ordinary sense of the word, but leading to
the same general result. The influence of the destruction of
individuals having a particular character is well shown by the
necessity of killing every lamb with a trace of black about it, in
order to keep the flock white; or again, by the effects on the average
height of the men of France of the destructive wars of Napoleon, by
which many tall men were killed, the short ones being left to be the
fathers of families. This at least is the conclusion of some of those
who have closely studied the effects of the conscription; and it is
certain that since Napoleon’s time the standard for the army has been
lowered two or three times.

Unconscious selection blends with methodical, so that it is scarcely
possible to separate them. When a fancier long ago first happened to
notice a pigeon with an unusually short beak, or one with the
tail-feathers unusually developed, although he bred from these birds
with the distinct intention of propagating the variety, yet he could
not have intended to make a short-faced tumbler or a fantail, and was
far from knowing that he had made the first step towards this end. If
he could have seen the final result, he would have been struck with
astonishment, but, from what we know of the habits of fanciers,
probably not with admiration. Our English carriers, barbs, and
short-faced tumblers have been greatly modified in the same manner, as
we may infer both from the historical evidence given in the chapters on
the Pigeon, and from the comparison of birds brought from distant
countries.

So it has been with dogs; our present fox-hounds differ from the old
English hound; our greyhounds have become lighter: the Scotch
deer-hound has been modified, and is now rare. Our bulldogs differ from
those which were formerly used for baiting bulls. Our pointers and
Newfoundlands do not closely resemble any native dog now found in the
countries whence they were brought. These changes have been effected
partly by crosses; but in every case the result has been governed by
the strictest selection. Nevertheless, there is no reason to suppose
that man intentionally and methodically made the breeds exactly what
they now are. As our horses became fleeter, and the country more
cultivated and smoother, fleeter fox-hounds were desired and produced,
but probably without any one distinctly foreseeing what they would
become. Our pointers and setters, the latter almost certainly descended
from large spaniels, have been greatly modified in accordance with
fashion and the desire for increased speed. Wolves have become extinct,
and so has the wolf-dog; deer have become rarer, bulls are no longer
baited, and the corresponding breeds of the dog have answered to the
change. But we may feel almost sure that when, for instance, bulls were
no longer baited, no man said to himself, I will now breed my dogs of
smaller size, and thus create the present race. As circumstances
changed, men unconsciously and slowly modified their course of
selection.

With racehorses selection for swiftness has been followed methodically,
and our horses now easily surpass their progenitors. The increased size
and different appearance of the English racehorse led a good observer
in India to ask, “Could any one in this year of 1856, looking at our
racehorses, conceive that they were the result of the union of the Arab
horse and the African mare?”[72] This change has, it is probable, been
largely effected through unconscious selection, that is, by the general
wish to breed as fine horses as possible in each generation, combined
with training and high feeding, but without any intention to give to
them their present appearance. According to Youatt,[73] the
introduction in Oliver Cromwell’s time of three celebrated Eastern
stallions speedily affected the English breed; “so that Lord Harleigh,
one of the old school, complained that the great horse was fast
disappearing.” This is an excellent proof how carefully selection must
have been attended to; for without such care, all traces of so small an
infusion of Eastern blood would soon have been absorbed and lost.
Notwithstanding that the climate of England has never been esteemed
particularly favourable to the horse, yet long-continued selection,
both methodical and unconscious, together with that practised by the
Arabs during a still longer and earlier period, has ended in giving us
the best breed of horses in the world. Macaulay[74] remarks, “Two men
whose authority on such subjects was held in great esteem, the Duke of
Newcastle and Sir John Fenwick, pronounced that the meanest hack ever
imported from Tangier would produce a finer progeny than could be
expected from the best sire of our native breed. They would not readily
have believed that a time would come when the princes and nobles of
neighbouring lands would be as eager to obtain horses from England as
ever the English had been to obtain horses from Barbary.”

The London dray-horse, which differs so much in appearance from any
natural species, and which from its size has so astonished many Eastern
princes, was probably formed by the heaviest and most powerful animals
having been selected during many generations in Flanders and England,
but without the least intention or expectation of creating a horse such
as we now see. If we go back to an early period of history, we behold
in the antique Greek statues, as Schaaffhausen has remarked,[75] a
horse equally unlike a race or dray horse, and differing from any
existing breed.

The results of unconscious selection, in an early stage, are well shown
in the difference between the flocks descended from the same stock, but
separately reared by careful breeders. Youatt gives an excellent
instance of this fact in the sheep belonging to Messrs. Buckley and
Burgess, which “have been purely bred from the original stock of Mr.
Bakewell for upwards of fifty years. There is not a suspicion existing
in the mind of any one at all acquainted with the subject that the
owner of either flock has deviated in any one instance from the pure
blood of Mr. Bakewell’s flock; yet the difference between the sheep
possessed by these two gentlemen is so great, that they have the
appearance of being quite different varieties.”[76] I have seen several
analogous and well marked cases with pigeons: for instance, I had a
family of barbs descended from those long bred by Sir J. Sebright, and
another family long bred by another fancier, and the two families
plainly differed from each other. Nathusius—and a more competent
witness could not be cited—observes that, though the Shorthorns are
remarkably uniform in appearance (except in colour), yet the individual
character and wishes of each breeder become impressed on his cattle, so
that different herds differ slightly from one another.[77] The Hereford
cattle assumed their present well-marked character soon after the year
1769, through careful selection by Mr. Tomkins[78] and the breed has
lately split into two strains—one strain having a white face, and
differing slightly, it is said,[79] in some other points: but there is
no reason to believe that this split, the origin of which is unknown,
was intentionally made; it may with much more probability be attributed
to different breeders having attended to different points. So again,
the Berkshire breed of swine in the year 1810 had greatly changed from
what it was in 1780; and since 1810 at least two distinct sub-breeds
have arisen bearing the same name.[80] Keeping in mind how rapidly all
animals increase, and that some must be annually slaughtered and some
saved for breeding, then, if the same breeder during a long course of
years deliberately settles which shall be saved and which shall be
killed, it is almost inevitable that his individual turn of mind will
influence the character of his stock, without his having had any
intention to modify the breed.

Unconscious selection in the strictest sense of the word, that is, the
saving of the more useful animals and the neglect or slaughter of the
less useful, without any thought of the future, must have gone on
occasionally from the remotest period and amongst the most barbarous
nations. Savages often suffer from famines, and are sometimes expelled
by war from their own homes. In such cases it can hardly be doubted
that they would save their most useful animals. When the Fuegians are
hard pressed by want, they kill their old women for food rather than
their dogs; for, as we were assured, “old women no use—dogs catch
otters.” The same sound sense would surely lead them to preserve their
more useful dogs when still harder pressed by famine. Mr. Oldfield, who
has seen so much of the aborigines of Australia, informs me that “they
are all very glad to get a European kangaroo dog, and several instances
have been known of the father killing his own infant that the mother
might suckle the much-prized puppy.” Different kinds of dogs would be
useful to the Australian for hunting opossums and kangaroos, and to the
Fuegian for catching fish and otters; and the occasional preservation
in the two countries of the most useful animals would ultimately lead
to the formation of two widely distinct breeds.

With plants, from the earliest dawn of civilisation, the best variety
which was known would generally have been cultivated at each period and
its seeds occasionally sown; so that there will have been some
selection from an extremely remote period, but without any prefixed
standard of excellence or thought of the future. We at the present day
profit by a course of selection occasionally and unconsciously carried
on during thousands of years. This is proved in an interesting manner
by Oswald Heer’s researches on the lake-inhabitants of Switzerland, as
given in a former chapter; for he shows that the grain and seed of our
present varieties of wheat, barley, oats, peas, beans, lentils, and
poppy, exceed in size those which were cultivated in Switzerland during
the Neolithic and Bronze periods. These ancient people, during the
Neolithic period, possessed also a crab considerably larger than that
now growing wild on the Jura.[81] The pears described by Pliny were
evidently extremely inferior in quality to our present pears. We can
realise the effects of long-continued selection and cultivation in
another way, for would any one in his senses expect to raise a
first-rate apple from the seed of a truly wild crab, or a luscious
melting pear from the wild pear? Alphonse de Candolle informs me that
he has lately seen on an ancient mosaic at Rome a representation of the
melon; and as the Rotnans, who were such gourmands, are silent on this
fruit, he infers that the melon has been greatly ameliorated since the
classical period.

Coming to later times, Buffon[82] on comparing the flowers, fruit, and
vegetables which were then cultivated with some excellent drawings made
a hundred and fifty years previously, was struck with surprise at the
great improvement which had been effected; and remarks that these
ancient flowers and vegetables would now be rejected, not only by a
florist but by a village gardener. Since the time of Buffon the work of
improvement has steadily and rapidly gone on. Every florist who
compares our present flowers with those figured in books published not
long since, is astonished at the change. A well-known amateur,[83] in
speaking of the varieties of Pelargonium raised by Mr. Garth only
twenty-two years before, remarks, “What a rage they excited: surely we
had attained perfection, it was said; and now not one of the flowers of
those days will be looked at. But none the less is the debt of
gratitude which we owe to those who saw what was to be done, and did
it.” Mr. Paul, the well-known horticulturist, in writing of the same
flower,[84] says he remembers when young being delighted with the
portraits in Sweet’s work; “but what are they in point of beauty
compared with the Pelargoniums of this day? Here again nature did not
advance by leaps; the improvement was gradual, and if we had neglected
those very gradual advances, we must have foregone the present grand
results.” How well this practical horticulturist appreciates and
illustrates the gradual and accumulative force of selection! The Dahlia
has advanced in beauty in a like manner; the line of improvement being
guided by fashion, and by the successive modifications which the flower
slowly underwent.[85] A steady and gradual change has been noticed in
many other flowers: thus an old florist,[86] after describing the
leading varieties of the Pink which were grown in 1813 adds, “the pinks
of those days would now be scarcely grown as border-flowers.” The
improvement of so many flowers and the number of the varieties which
have been raised is all the more striking when we hear that the
earliest known flower-garden in Europe, namely at Padua, dates only
from the year 1545.[87]

_Effects of Selection, as shown by the parts most valued by man
presenting the greatest amount of difference._—The power of
long-continued selection, whether methodical or unconscious, or both
combined, is well shown in a general way, namely, by the comparison of
the differences between the varieties of distinct species, which are
valued for different parts, such as for the leaves, or stems, or
tubers, the seed, or fruit, or flowers. Whatever part man values most,
that part will be found to present the greatest amount of difference.
With trees cultivated for their fruit, Sageret remarks that the fruit
is larger than in the parent-species, whilst with those cultivated for
the seed, as with nuts, walnuts, almonds, chestnuts, etc., it is the
seed itself which is larger; and he accounts for this fact by the fruit
in the one case, and by the seed in the other, having been carefully
attended to and selected during many ages. Gallesio has made the same
observation. Godron insists on the diversity of the tuber in the
potato, of the bulb in the onion, and of the fruit in the melon; and on
the close similarity of the other parts in these same plants.[88]

In order to judge how far my own impression on this subject was
correct, I cultivated numerous varieties of the same species close to
one another. The comparison of the amount of difference between widely
different organs is necessarily vague; I will therefore give the
results in only a few cases. We have previously seen in the ninth
chapter how greatly the varieties of the cabbage differ in their
foliage and stems, which are the selected parts, and how closely they
resemble one another in their flowers, capsules, and seeds. In seven
varieties of the radish, the roots differed greatly in colour and
shape, but no difference whatever could be detected in their foliage,
flowers, or seeds. Now what a contrast is presented, if we compare the
flowers of the varieties of these two plants with those of any species
cultivated in our flower-gardens for ornament; or if we compare their
seeds with those of the varieties of maize, peas, beans, etc., which
are valued and cultivated for their seeds. In the ninth chapter it was
shown that the varieties of the pea differ but little except in the
tallness of the plant, moderately in the shape of the pod, and greatly
in the pea itself, and these are all selected points. The varieties,
however, of the _Pois sans parchemin_ differ much more in their pods,
and these are eaten and valued. I cultivated twelve varieties of the
common bean; one alone, the Dwarf Fan, differed considerably in general
appearance; two differed in the colour of their flowers, one being an
albino, and the other being wholly instead of partially purple; several
differed considerably in the shape and size of the pod, but far more in
the bean itself, and this is the valued and selected part. Toker’s
bean, for instance, is twice-and-a-half as long and broad as the
horse-bean, and is much thinner and of a different shape.

The varieties of the gooseberry, as formerly described, differ much in
their fruit, but hardly perceptibly in their flowers or organs of
vegetation. With the plum, the differences likewise appear to be
greater in the fruit than in the flowers or leaves. On the other hand,
the seed of the strawberry, which corresponds with the fruit of the
plum, differs hardly at all; whilst every one knows how greatly the
fruit—that is, the enlarged receptacle—differs in several varieties. In
apples, pears, and peaches the flowers and leaves differ considerably,
but not, as far as I can judge, in proportion with the fruit. The
Chinese double-flowering peaches, on the other hand, show that
varieties of this tree have been formed, which differ more in flower
than in fruit. If, as is highly probable, the peach is the modified
descent of the almond, a surprising amount of change has been effected
in the same species, in the fleshy covering of the former and in the
kernels of the latter.

When parts stand in close relationship to each other, such as the seed
and the fleshy covering of the fruit (whatever its homological nature
may be), changes in the one are usually accompanied by modifications in
the other, though not necessarily to the same degree. With the
plum-tree, for instance, some varieties produce plums which are nearly
alike, but include stones extremely dissimilar in shape; whilst
conversely other varieties produce dissimilar fruit with barely
distinguishable stones; and generally the stones, though they have
never been subjected to selection, differ greatly in the several
varieties of the plum. In other cases organs which are not manifestly
related, through some unknown bond vary together, and are consequently
liable, without any intention on man’s part, to be simultaneously acted
on by selection. Thus the varieties of the stock (Matthiola) have been
selected solely for the beauty of their flowers, but the seeds differ
greatly in colour and somewhat in size. Varieties of the lettuce have
been selected solely on account of their leaves, yet produce seeds
which likewise differ in colour. Generally, through the law of
correlation, when a variety differs greatly from its fellow-varieties
in any one character, it differs to a certain extent in several other
characters. I observed this fact when I cultivated together many
varieties of the same species, for I used first to make a list of the
varieties which differed most from each other in their foliage and
manner of growth, afterwards of those that differed most in their
flowers, then in their seed-capsules, and lastly in their mature seed;
and I found that the same names generally occurred in two, three, or
four of the successive lists. Nevertheless the greatest amount of
difference between the varieties was always exhibited, as far as I
could judge, by that part or organ for which the plant was cultivated.

When we bear in mind that each plant was at first cultivated because
useful to man, and that its variation was a subsequent, often a long
subsequent, event, we cannot explain the greater amount of diversity in
the valuable parts by supposing that species endowed with an especial
tendency to vary in any particular manner were originally chosen. We
must attribute the result to the variations in these parts having been
successively preserved, and thus continually augmented; whilst other
variations, excepting such as inevitably appeared through correlation,
were neglected and lost. We may therefore infer that most plants might
be made, through long-continued selection, to yield races as different
from one another in any character as they now are in those parts for
which they are valued and cultivated.

With animals we see nothing of the same kind; but a sufficient number
of species have not been domesticated for a fair comparison. Sheep are
valued for their wool, and the wool differs much more in the several
races than the hair in cattle. Neither sheep, goats, European cattle,
nor pigs are valued for their fleetness or strength; and we do not
possess breeds differing in these respects like the racehorse and
dray-horse. But fleetness and strength are valued in camels and dogs;
and we have with the former the swift dromedary and heavy camel; with
the latter the greyhound and mastiff. But dogs are valued even in a
higher degree for their mental qualities and senses; and every one
knows how greatly the races differ in these respects. On the other
hand, where the dog is kept solely to serve for food, as in the
Polynesian islands and China, it is described as an extremely stupid
animal.[89] Blumenbach remarks that “many dogs, such as the badger-dog,
have a build so marked and so appropriate for particular purposes, that
I should find it very difficult to persuade myself that this
astonishing figure was an accidental consequence of degeneration.”[90]
Had Blumenbach reflected on the great principle of selection, he would
not have used the term degeneration, and he would not have been
astonished that dogs and other animals should become excellently
adapted for the service of man.

On the whole we may conclude that whatever part or character is most
valued—whether the leaves, stems, tubers, bulbs, flowers, fruit, or
seed of plants, or the size, strength, fleetness, hairy covering, or
intellect of animals—that character will almost invariably be found to
present the greatest amount of difference both in kind and degree. And
this result may be safely attributed to man having preserved during a
long course of generations the variations which were useful to him, and
neglected the others.

I will conclude this chapter by some remarks on an important subject.
With animals such as the giraffe, of which the whole structure is
admirably co-ordinated for certain purposes, it has been supposed that
all the parts must have been simultaneously modified; and it has been
argued that, on the principle of natural selection, this is scarcely
possible. But in thus arguing, it has been tacitly assumed that the
variations must have been abrupt and great. No doubt, if the neck of a
ruminant were suddenly to become greatly elongated, the fore limbs and
back would have to be simultaneously strengthened and modified; but it
cannot be denied that an animal might have its neck, or head, or
tongue, or fore-limbs elongated a very little without any corresponding
modification in other parts of the body; and animals thus slightly
modified would, during a dearth, have a slight advantage, and be
enabled to browse on higher twigs, and thus survive. A few mouthfuls
more or less every day would make all the difference between life and
death. By the repetition of the same process, and by the occasional
intercrossing of the survivors, there would be some progress, slow and
fluctuating though it would be, towards the admirably coordinated
structure of the giraffe. If the short-faced tumbler-pigeon, with its
small conical beak, globular head, rounded body, short wings, and small
feet—characters which appear all in harmony—had been a natural species,
its whole structure would have been viewed as well fitted for its life;
but in this case we know that inexperienced breeders are urged to
attend to point after point, and not to attempt improving the whole
structure at the same time. Look at the greyhound, that perfect image
of grace, symmetry, and vigour; no natural species can boast of a more
admirably co-ordinated structure, with its tapering head, slim body,
deep chest, tucked-up abdomen, rat-like tail, and long muscular limbs,
all adapted for extreme fleetness, and for running down weak prey. Now,
from what we see of the variability of animals, and from what we know
of the method which different men follow in improving their stock—some
chiefly attending to one point, others to another point, others again
correcting defects by crosses, and so forth—we may feel assured that if
we could see the long line of ancestors of a first-rate greyhound up to
its wild wolf-like progenitor, we should behold an infinite number of
the finest gradations, sometimes in one character and sometimes in
another, but all leading towards our present perfect type. By small and
doubtful steps such as these, nature, as we may confidently believe,
has progressed, on her grand march of improvement and development.

A similar line of reasoning is as applicable to separate organs as to
the whole organisation. A writer[91] has recently maintained that “it
is probably no exaggeration to suppose that in order to improve such an
organ as the eye at all, it must be improved in ten different ways at
once. And the improbability of any complex organ being produced and
brought to perfection in any such way is an improbability of the same
kind and degree as that of producing a poem or a mathematical
demonstration by throwing letters at random on a table.” If the eye
were abruptly and greatly modified, no doubt many parts would have to
be simultaneously altered, in order that the organ should remain
serviceable.

But is this the case with smaller changes? There are persons who can
see distinctly only in a dull light, and this condition depends, I
believe, on the abnormal sensitiveness of the retina, and is known to
be inherited. Now if a bird, for instance, receive some great advantage
from seeing well in the twilight, all the individuals with the most
sensitive retina would succeed best and be the most likely to survive;
and why should not all those which happened to have the eye itself a
little larger, or the pupil capable of greater dilatation, be likewise
preserved, whether or not these modifications were strictly
simultaneous? These individuals would subsequently intercross and blend
their respective advantages. By such slight successive changes, the eye
of a diurnal bird would be brought into the condition of that of an
owl, which has often been advanced as an excellent instance of
adaptation. Short-sight, which is often inherited, permits a person to
see distinctly a minute object at so near a distance that it would be
indistinct to ordinary eyes; and here we have a capacity which might be
serviceable under certain conditions, abruptly gained. The Fuegians on
board the Beagle could certainly see distant objects more distinctly
than our sailors with all their long practice; I do not know whether
this depends upon sensitiveness or on the power of adjustment in the
focus; but this capacity for distant vision might, it is probable, be
slightly augmented by successive modifications of either kind.
Amphibious animals which are enabled to see both in the water and in
the air, require and possess, as M. Plateau has shown,[92] eyes
constructed on the following plan: “the cornea is always flat, or at
least much flattened in the front of the crystalline and over a space
equal to the diameter of that lens, whilst the lateral portions may be
much curved.” The crystalline is very nearly a sphere, and the humours
have nearly the same density as water. Now as a terrestrial animal
became more and more aquatic in its habits, very slight changes, first
in the curvature of the cornea or crystalline, and then in the density
of the humours, or conversely, might successively occur, and would be
advantageous to the animal whilst under water, without serious
detriment to its power of vision in the air. It is of course impossible
to conjecture by what steps the fundamental structure of the eye in the
Vertebrata was originally acquired, for we know nothing about this
organ in the first progenitors of the class. With respect to the lowest
animals in the scale, the transitional states through which the eye at
first probably passed, can by the aid of analogy be indicated, as I
have attempted to show in my ‘Origin of Species.’[93]

REFERENCES

 [1] The term _unconscious selection_ has been objected to as a
 contradiction; but _see_ some excellent observations on this head by
 Prof. Huxley (‘Nat. Hist. Review,’ Oct. 1864, p. 578), who remarks
 that when the wind heaps up sand-dunes it sifts and _unconsciously
 selects_ from the gravel on the beach grains of sand of equal size.

 [2] ‘On Sheep,’ 1838, p. 60.

 [3] Mr. J. Wright on Shorthorn Cattle, in ‘Journal of Royal Agricult.
 Soc.,’ vol. vii. pp. 208, 209.

 [4] H. D. Richardson ‘On Pigs,’ 1847, p. 44.

 [5] ‘Journal of Royal Agricult. Soc.,’ vol. i. p. 24.

 [6] ‘On Sheep,’ pp. 520, 319.

 [7] Loudon’s ‘Mag. of Nat. Hist.,’ vol. viii., 1835, p. 618.

 [8] ‘A treatise on the Art of Breeding the Almond Tumbler.’ 1851. p.
 9.

 [9] ‘Recreations in Agriculture,’ vol. ii. p. 409.

 [10] Youatt on Cattle, pp. 191, 227.

 [11] Ferguson, ‘Prize Poultry,’ 1854, p. 208.

 [12] Wilson, in ‘Transact. Highland Agricult. Soc.,’ quoted in
 ‘Gardener’s Chronicle,’ 1844, p. 29.

 [13] Simmonds, quoted in ‘Gardener’s Chronicle,’ 1855, p. 637. And for
 the second quotation, _see_ Youatt on Sheep, p. 171.

 [14] Robinet, ‘Vers à Soie,’ 1848, p. 271.

 [15] Quatrefages, ‘Les Maladies du Ver à Soie,’ 1859, p. 101.

 [16] M. Simon, in ‘Bull. de la Soc. d’Acclimat.,’ tom. ix., 1862, p.
 221.

 [17] ‘The Poultry Chronicle,’ vol. i., 1854, p. 607.

 [18] J. M. Eaton, ‘A Treatise on Fancy Pigeons,’ 1852, p. xiv., and ‘A
 Treatise on the Almond Tumbler,’ 1851, p. 11.

 [19] ‘Journal Royal Agricultural Soc.,’ vol. vi., p. 22.

 [20] ‘Poultry Chronicle,’ vol. ii., 1855, p. 596.

 [21] Isid. Geoffroy St.-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. p. 254.

 [22] ‘Gardener’s Chronicle,’ 1850, p. 198.

 [23] ‘Transact. Hort. Soc.,’ vol. vi. p. 152.

 [24] ‘Journal of Horticulture,’ 1862, p. 369.

 [25] ‘Transact. Hort. Soc.,’ vol. iv. p. 381.

 [26] ‘Transact. Hort. Soc.,’ vol. iv. p. 285.

 [27] Rev. W. Bromehead, in ‘Gardener’s Chronicle,’ 1857, p. 550.

 [28] ‘Gardener’s Chronicle,’ 1862, p. 721.

 29[] Dr. Anderson, in ‘The Bee,’ vol. vi. p. 96; Mr. Barnes in
 ‘Gardener’s Chronicle,’ 1844, p. 476.

 [30] Godron, ‘De l’Espèce,’ 1859, tom. ii. p. 69; ‘Gardener’s
 Chronicle,’ 1854, p. 258.

 [31] On Sheep, p. 18.

 [32] Volz, ‘Beiträge zur Kulturgeschichte,’ 1852, s. 47.

 [33] Mitford’s ‘History of Greece,’ vol. i. p. 73.

 [34] Dr. Dally, translated in ‘Anthropological Review,’ May 1864, p.
 101.

 [35] Volz, ‘Beiträge,’ etc., 1852, s. 80.

 [36] ‘History of the World,’ ch. 45.

 [37] ‘Gardener’s Chronicle,’ 1848, p. 323.

 [38] Reynier, ‘De l’Économie des Celtes,’ 1818, pp. 487, 503.

 [39] Le Couteur on Wheat, p. 15.

 [40] Michel, ‘Des Haras,’ 1861, p. 84.

 [41] Sir W. Wilde, an ‘Essay on Unmanufactured Animal Remains,’ etc.,
 1860, p. 11.

 [42] Col. Hamilton Smith, ‘Nat. Library,’ vol. xii., Horses, pp. 135,
 140.

 [43] Michel, ‘Des Haras,’ p. 90.

 [44] Mr. Baker, ‘History of the Horse,’ ‘Veterinary,’ vol. xiii. p.
 423.

 [45] M. l’Abbé Carlier, in ‘Journal de Physique,’ vol. xxiv., 1784, p.
 181; this memoir contains much information on the ancient selection of
 sheep; and is my authority for rams not being killed young in England.

 [46] ‘Gardener’s Chronicle,’ 1843, p. 389.

 [47] ‘Communications to Board of Agriculture’ quoted in Dr. Darwin’s
 ‘Phytologia,’ 1800, p. 451.

 [48] ‘Mémoire sur les Chinois,’ 1786, tom. xi. p. 55; tom. v. p. 507.

 [49] ‘Recherches sur l’Agriculture des Chinois,’ par L. D’Hervey
 Saint-Denys, 1850, p. 229. With respect to Khang-hi _see_ Huc’s
 ‘Chinese Empire,’ p. 311.

 [50] Anderson, in ‘Linn. Transact.,’ vol. xii. p. 253.

 [51] ‘Mém. de l’Acad.’ (divers savants), tom. vi., 1835, p. 333.

 [52] ‘Des Quadrupèdes du Paraguay,’ 1801, tom. ii. pp. 333, 371.

 [53] ‘The Great Sahara,’ by the Rev. H. B. Tristram, 1860, p. 238.

 [54] Pallas, ‘Act. Acad. St. Petersburg,’ 1777, p. 249; Moorcroft and
 Trebeck, ‘Travels in the Himalayan Provinces,’ 1841.

 [55] Quoted from Raffles, in the ‘Indian Field,’ 1859, p. 196: for
 Varro, _see_ Pallas _ut supra._

 [56] Erman’s ‘Travels in Siberia,’ Eng. translat., vol. i. p. 453.

 [57] _See also_ ‘Journal of R. Geograph. Soc.,’ vol. xiii. part i. p.
 65.

 [58] Livingstone’s ‘First Travels,’ pp. 191, 439, 565; _see also_
 ‘Expedition to the Zambesi,’ 1865, p. 495, for an analogous case
 respecting a good breed of goats.

 [59] Andersson’s ‘Travels in South Africa,’ pp. 232, 318, 319.

 [60] Dr. Vavasseur, in ‘Bull. de La Soc. d’Acclimat.,’ tom. viii.
 1861, p. 136.

 [61] ‘The Natural History of Dee Side,’ 1855, p. 476.

 [62] ‘Bull. de la Soc. d’Acclimat.,’ tom. vii. 1860, p. 457.

 [63] ‘Cattle,’ p. 48.

 [64] Livingstone’s Travels, p. 576; Andersson, ‘Lake Ngami,’ 1856, p.
 222. With respect to the sale in Kaffraria, _see_ ‘Quarterly Review,’
 1860, p. 139.

 [65] ‘Mémoire sur les Chinois’ (by the Jesuits), 1786, tom. xi. p. 57.

 [66] F. Michel, ‘Des Haras,’ pp. 47, 50.

 [67] Col. Hamilton Smith, Dogs, in ‘Nat. Lib.,’ vol. x. p. 103.

 [68] Azara, ‘Quadrupèdes du Paraguay,’ tom. ii. p. 324.

 [69] Sidney’s edit. of Youatt, 1860, pp. 24, 25.

 [70] ‘Rural Economy of Yorkshire,’ vol. ii. p. 182.

 [71] Moll et Gayot, ‘Du Boeuf,’ 1860, p. 547.

 [72] ‘The India Sporting Review,’ vol. ii. p. 181; ‘The Stud Farm,’ by
 Cecil, p. 58.

 [73] ‘The Horse,’ p. 22.

 [74] ‘History of England,’ vol. i. p. 316.

 [75] ‘Ueber Beständigkeit der Arten.’

 [76] Youatt on Sheep, p. 315.

 [77] ‘Ueber Shorthorn Rindvieh,’ 1857, s. 51.

 [78] Low, ‘Domesticated Animals,’ 1845, p. 363.

 [79] ‘Quarterly Review,’ 1849, p. 392.

 [80] H. von Nathusius, ‘Vorstudien . . . Schweineschädel,’ 1864, s
 140.

 [81] _See also_ Dr. Christ, in Rütimeyer’s ‘Pfahlbauten,’ 1861, s.
 226.

 [82] The passage is given, ‘Bull. Soc. d’Acclimat.,’ 1858, p. 11.

 [83] ‘Journal of Horticulture,’ 1862, p. 394.

 [84] ‘Gardener’s Chronicle,’ 1857, p. 85.

 [85] _See_ Mr. Wildman’s address to the Floricult. Soc. in ‘Gardener’s
 Chronicle,’ 1843, p. 86.

 [86] ‘Journal of Horticulture,’ Oct. 24th, 1865, p. 239.

 [87] Prescott’s ‘Hist. of Mexico,’ vol. ii. p. 61.

 [88] Sagaret, ‘Pomologie Physiologique,’ 1830, p. 47; Gallesio,
 ‘Teoria della Riproduzione,’ 1816, p. 88; Godron, ‘De l’Espèce,’ 1859,
 tom. 2 pp. 63, 67, 70. In my tenth and eleventh chapters I have given
 details on the potato; and I can confirm similar remarks with respect
 to the onion. I have also shown how far Naudin concurs in regard to
 the varieties of the melon.

 [89] Godron, ‘De l’Espèce,’ tom. ii. p. 27.

 [90] ‘The Anthropological Treatises of Blumenbach,’ 1856, p. 292.

 [91] Mr. J. J. Murphy, in his opening address to the Belfast Nat.
 Hist. Soc., as given in the ‘Belfast Northern Whig,’ Nov. 19th, 1866.
 Mr. Murphy here follows the line of argument against my views
 previously and more cautiously given by the Rev. C. Pritchard, Pres.
 Royal Astronomical Soc., in his sermon (Appendix, p. 33) preached
 before the British Association at Nottingham, 1866.

 [92] On the Vision of Fishes and Amphibia, translated in ‘Annals and
 Mag. of Nat. Hist.,’ vol. xviii., 1866, p. 469.

 [93] Sixth edition, 1872, p. 144.





CHAPTER XXI. SELECTION, _continued._

NATURAL SELECTION AS AFFECTING DOMESTIC PRODUCTIONS—CHARACTERS WHICH
APPEAR OF TRIFLING VALUE OFTEN OF REAL IMPORTANCE—CIRCUMSTANCES
FAVOURABLE TO SELECTION BY MAN—FACILITY IN PREVENTING CROSSES, AND THE
NATURE OF THE CONDITIONS—CLOSE ATTENTION AND PERSEVERANCE
INDISPENSABLE—THE PRODUCTION OF A LARGE NUMBER OF INDIVIDUALS
ESPECIALLY FAVOURABLE—WHEN NO SELECTION IS APPLIED, DISTINCT RACES ARE
NOT FORMED—HIGHLY-BRED ANIMALS LIABLE TO DEGENERATION—TENDENCY IN MAN
TO CARRY THE SELECTION OF EACH CHARACTER TO AN EXTREME POINT, LEADING
TO DIVERGENCE OF CHARACTER, RARELY TO CONVERGENCE—CHARACTERS CONTINUING
TO VARY IN THE SAME DIRECTION IN WHICH THEY HAVE ALREADY
VARIED—DIVERGENCE OF CHARACTER, WITH THE EXTINCTION OF INTERMEDIATE
VARIETIES, LEADS TO DISTINCTNESS IN OUR DOMESTIC RACES—LIMIT TO THE
POWER OF SELECTION—LAPSE OF TIME IMPORTANT—MANNER IN WHICH DOMESTIC
RACES HAVE ORIGINATED—SUMMARY.


_Natural Selection, or the Survival of the Fittest, as affecting
domestic productions._—We know little on this head. But as animals kept
by savages have to provide throughout the year their own food either
entirely or to a large extent, it can hardly be doubted that in
different countries, varieties differing in constitution and in various
characters would succeed best, and so be naturally selected. Hence
perhaps it is that the few domesticated animals kept by savages
partake, as has been remarked by more than one writer, of the wild
appearance of their masters, and likewise resemble natural species.
Even in long-civilised countries, at least in the wilder parts, natural
selection must act on our domestic races. It is obvious that varieties
having very different habits, constitution, and structure, would
succeed best on mountains and on rich lowland pastures. For example,
the improved Leicester sheep were formerly taken to the Lammermuir
Hills; but an intelligent sheep-master reported that “our coarse lean
pastures were unequal to the task of supporting such heavy-bodied
sheep; and they gradually dwindled away into less and less bulk: each
generation was inferior to the preceding one; and when the spring was
severe, seldom more than two-thirds of the lambs survived the ravages
of the storms.”[1] So with the mountain cattle of North Wales and the
Hebrides, it has been found that they could not withstand being crossed
with the larger and more delicate lowland breeds. Two French
naturalists, in describing the horses of Circassia, remark that,
subjected as they are to extreme vicissitudes of climate, having to
search for scanty pasture, and exposed to constant danger from wolves,
the strongest and most vigorous alone survive.[2]

Every one must have been struck with the surpassing grace, strength,
and vigour of the Game-cock, with its bold and confident air, its long,
yet firm neck, compact body, powerful and closely pressed wings,
muscular thighs, strong beak massive at the base, dense and sharp spurs
set low on the legs for delivering the fatal blow, and its compact,
glossy, and mail-like plumage serving as a defence. Now the English
game-cock has not only been improved during many years by man’s careful
selection, but in addition, as Mr. Tegetmeier has remarked,[3] by a
kind of natural selection, for the strongest, most active and
courageous birds have stricken down their antagonists in the cockpit,
generation after generation, and have subsequently served as the
progenitors of their race. The same kind of double selection has come
into play with the carrier pigeon, for during their training the
inferior birds fail to return home and are lost, so that even without
selection by man only the superior birds propagate their race.

In Great Britain, in former times, almost every district had its own
breed of cattle and sheep; “they were indigenous to the soil, climate,
and pasturage of the locality on which they grazed: they seemed to have
been formed for it and by it.”[4] But in this case we are quite unable
to disentangle the effects of the direct action of the conditions of
life,—of use or habit—of natural selection—and of that kind of
selection which we have seen is occasionally and unconsciously followed
by man even during the rudest periods of history.

Let us now look to the action of natural selection on special
characters. Although nature is difficult to resist, yet man often
strives against her power, and sometimes with success. From the facts
to be given, it will also be seen that natural selection would
powerfully affect many of our domestic productions if left unprotected.
This is a point of much interest, for we thus learn that differences
apparently of very slight importance would certainly determine the
survival of a form when forced to struggle for its own existence. It
may have occurred to some naturalists, as it formerly did to me, that,
though selection acting under natural conditions would determine the
structure of all important organs, yet that it could not affect
characters which are esteemed by us of little importance; but this is
an error to which we are eminently liable, from our ignorance of what
characters are of real value to each living creature.

When man attempts to make a breed with some serious defect in
structure, or in the mutual relation of the several parts, he will
partly or completely fail, or encounter much difficulty; he is in fact
resisted by a form of natural selection. We have seen that an attempt
was once made in Yorkshire to breed cattle with enormous buttocks, but
the cows perished so often in bringing forth their calves, that the
attempt had to be given up. In rearing short-faced tumblers, Mr. Eaton
says,[5] “I am convinced that better head and beak birds have perished
in the shell than ever were hatched; the reason being that the
amazingly short-faced bird cannot reach and break the shell with its
beak, and so perishes.” Here is a more curious case, in which natural
selection comes into play only at long intervals of time: during
ordinary seasons the Niata cattle can graze as well as others, but
occasionally, as from 1827 to 1830 the plains of La Plata suffer from
long-continued droughts and the pasture is burnt up; at such times
common cattle and horses perish by the thousand, but many survive by
browsing on twigs, reeds, etc.; this the Niata cattle cannot so well
effect from their upturned jaws and the shape of their lips;
consequently, if not attended to, they perish before the other cattle.
In Columbia, according to Roulin, there is a breed of nearly hairless
cattle, called Pelones; these succeed in their native hot district, but
are found too tender for the Cordillera; in this case, however, natural
selection determines only the range of the variety. It is obvious that
a host of artificial races could never survive in a state of
nature;—such as Italian greyhounds,—hairless and almost toothless
Turkish dogs,—fantail pigeons, which cannot fly well against a strong
wind,—barbs and Polish fowls, with their vision impeded by their eye
wattles and great topknots,—hornless bulls and rams, which consequently
cannot cope with other males, and thus have a poor chance of leaving
offspring,—seedless plants, and many other such cases.

Colour is generally esteemed by the systematic naturalist as
unimportant: let us, therefore, see how far it indirectly affects our
domestic productions, and how far it would affect them if they were
left exposed to the full force of natural selection. In a future
chapter I shall have to show that constitutional peculiarities of the
strangest kind, entailing liability to the action of certain poisons,
are correlated with the colour of the skin. I will here give a single
case, on the high authority of Professor Wyman; he informs me that,
being surprised at all the pigs in a part of Virginia being black, he
made inquiries, and ascertained that these animals feed on the roots of
the _Lachnanthes tinctoria,_ which colours their bones pink, and,
excepting in the case of the black varieties, causes the hoofs to drop
off. Hence, as one of the squatters remarked, “we select the black
members of the litter for raising, as they alone have a good chance of
living.” So that here we have artificial and natural selection working
hand in hand. I may add that in the Tarentino the inhabitants keep
black sheep alone, because the _Hypericum crispum_ abounds there; and
this plant does not injure black sheep, but kills the white ones in
about a fortnight’s time.[6]

Complexion, and liability to certain diseases, are believed to run
together in man and the lower animals. Thus white terriers suffer more
than those of any other colour from the fatal distemper.[7] In North
America plum-trees are liable to a disease which Downing[8] believes is
not caused by insects; the kinds bearing purple fruit are most
affected, “and we have never known the green or yellow fruited
varieties infected until the other sorts had first become filled with
the knots.” On the other hand, peaches in North America suffer much
from a disease called the _yellows,_ which seems to be peculiar to that
continent, and more than nine-tenths of the victims, “when the disease
first appeared, were the yellow-fleshed peaches. The white-fleshed
kinds are much more rarely attacked; in some parts of the country
never.” In Mauritius, the white sugar-canes have of late years been so
severely attacked by a disease, that many planters have been compelled
to give up growing this variety (although fresh plants were imported
from China for trial), and cultivate only red canes.[9] Now, if these
plants had been forced to struggle with other competing plants and
enemies, there cannot be a doubt that the colour of the flesh or skin
of the fruit, unimportant as these characters are considered, would
have rigorously determined their existence.

Liability to the attacks of parasites is also connected with colour.
White chickens are certainly more subject than dark-coloured chickens
to the “gapes,” which is caused by a parasitic worm in the trachea.[10]
On the other hand, experience has shown that in France the caterpillars
which produce white cocoons resist the deadly fungus better than those
producing yellow cocoons.[11] Analogous facts have been observed with
plants: a new and beautiful white onion, imported from France, though
planted close to other kinds, was alone attacked by a parasitic
fungus.[12] White verbenas are especially liable to mildew.[13] Near
Malaga, during an early period of the vine-disease, the green sorts
suffered most; “and red and black grapes, even when interwoven with the
sick plants, suffered not at all.” In France whole groups of varieties
were comparatively free, and others, such as the Chasselas, did not
afford a single fortunate exception; but I do not know whether any
correlation between colour and liability to disease was here
observed.[14] In a former chapter it was shown how curiously liable one
variety of the strawberry is to mildew.

It is certain that insects regulate in many cases the range and even
the existence of the higher animals, whilst living under their natural
conditions. Under domestication light-coloured animals suffer most: in
Thuringia[15] the inhabitants do not like grey, white, or pale cattle,
because they are much more troubled by various kinds of flies than the
brown, red, or black cattle. An Albino negro, it has been remarked,[16]
was peculiarly sensitive to the bites of insects. In the West
Indies[17] it is said that “the only horned cattle fit for work are
those which have a good deal of black in them. The white are terribly
tormented by the insects; and they are weak and sluggish in proportion
to the white.”

In Devonshire there is a prejudice against white pigs, because it is
believed that the sun blisters them when turned out;[18] and I knew a
man who would not keep white pigs in Kent, for the same reason. The
scorching of flowers by the sun seems likewise to depend much on
colour; thus, dark pelargoniums suffer most; and from various accounts
it is clear that the cloth-of-gold variety will not withstand a degree
of exposure to sunshine which other varieties enjoy. Another amateur
asserts that not only all dark-coloured verbenas, but likewise
scarlets, suffer from the sun: “the paler kinds stand better, and pale
blue is perhaps the best of all.” So again with the heartsease (_Viola
tricolor_); hot weather suits the blotched sorts, whilst it destroys
the beautiful markings of some other kinds.[19] During one extremely
cold season in Holland all red-flowered hyacinths were observed to be
very inferior in quality. It is believed by many agriculturists that
red wheat is hardier in northern climates than white wheat.[20]

With animals, white varieties from being conspicuous are the most
liable to be attacked by beasts and birds of prey. In parts of France
and Germany where hawks abound, persons are advised not to keep white
pigeons; for, as Parmentier says, “it is certain that in a flock the
white always first fall victims to the kite.” In Belgium, where so many
societies have been established for the flight of carrier-pigeons,
white is the one colour which for the same reason is disliked.[21]
Prof. G. Jaeger[22] whilst fishing found four pigeons which had been
killed by hawks, and all were white; on another occasion he examined
the eyrie of a hawk, and the feathers of the pigeons which had been
caught were all of a white or yellow colour. On the other hand, it is
said that the sea-eagle (_Falco ossifragus,_ Linn.) on the west coast
of Ireland picks out the black fowls, so that “the villagers avoid as
much as possible rearing birds of that colour.” M. Daudin,[23] speaking
of white rabbits kept in warrens in Russia, remarks that their colour
is a great disadvantage, as they are thus more exposed to attack, and
can be seen during bright nights from a distance. A gentleman in Kent,
who failed to stock his woods with a nearly white and hardy kind of
rabbit, accounted in the same manner for their early disappearance. Any
one who will watch a white cat prowling after her prey will soon
perceive under what a disadvantage she lies.

The white Tartarian cherry, “owing either to its colour being so much
like that of the leaves, or to the fruit always appearing from a
distance unripe,” is not so readily attacked by birds as other sorts.
The yellow-fruited raspberry, which generally comes nearly true by
seed, “is very little molested by birds, who evidently are not fond of
it; so that nets may be dispensed with in places where nothing else
will protect the red fruit.”[24] This immunity, though a benefit to the
gardener, would be a disadvantage in a state of nature both to the
cherry and raspberry, as dissemination depends on birds. I noticed
during several winters that some trees of the yellow-berried holly,
which were raised from seed from a tree found wild by my father
remained covered with fruit, whilst not a scarlet berry could be seen
on the adjoining trees of the common kind. A friend informs me that a
mountain-ash (_Pyrus aucuparia_) growing in his garden bears berries
which, though not differently coloured, are always devoured by birds
before those on the other trees. This variety of the mountain-ash would
thus be more freely disseminated, and the yellow-berried variety of the
holly less freely, than the common varieties of these two trees.

Independently of colour, trifling differences are sometimes found to be
of importance to plants under cultivation, and would be of paramount
importance if they had to fight their own battle and to struggle with
many competitors. The thin-shelled peas, called _pois sans parchemin,_
are attacked by birds[25] much more commonly than ordinary peas. On the
other hand, the purple-podded pea, which has a hard shell, escaped the
attacks of tomtits (_Parus major_) in my garden far better than any
other kind. The thin-shelled walnut likewise suffers greatly from the
tomtit.[26] These same birds have been observed to pass over and thus
favour the filbert, destroying only the other kinds of nuts which grew
in the same orchard.[27]

Certain varieties of the pear have soft bark, and these suffer severely
from wood-boring beetles; whilst other varieties are known to resist
their attacks much better.[28] In North America the smoothness, or
absence of down on the fruit, makes a great difference in the attacks
of the weevil, “which is the uncompromising foe of all smooth
stone-fruits;” and the cultivator “has the frequent mortification of
seeing nearly all, or indeed often the whole crop, fall from the trees
when half or two-thirds grown.” Hence the nectarine suffers more than
the peach. A particular variety of the Morello cherry, raised in North
America, is, without any assignable cause, more liable to be injured by
this same insect than other cherry-trees.[29] From some unknown cause,
certain varieties of the apple enjoy, as we have seen, the great
advantage in various parts of the world of not being infested by the
coccus. On the other hand, a particular case has been recorded in which
aphides confined themselves to the Winter Nelis pear and touched no
other kind in an extensive orchard.[30] The existence of minute glands
on the leaves of peaches, nectarines, and apricots, would not be
esteemed by botanists as a character of the least importance for they
are present or absent in closely-related sub-varieties, descended from
the same parent-tree; yet there is good evidence[31] that the absence
of glands leads to mildew, which is highly injurious to these trees.

A difference either in flavour or in the amount of nutriment in certain
varieties causes them to be more eagerly attacked by various enemies
than other varieties of the same species. Bullfinches (_Pyrrhula
vulgaris_) injure our fruit-trees by devouring the flower-buds, and a
pair of these birds have been seen “to denude a large plum-tree in a
couple of days of almost every bud;” but certain varieties[32] of the
apple and thorn (_Cratægus oxyacantha_) are more especially liable to
be attacked. A striking instance of this was observed in Mr. Rivers’s
garden, in which two rows of a particular variety of plum[33] had to be
carefully protected, as they were usually stripped of all their buds
during the winter, whilst other sorts growing near them escaped. The
root (or enlarged stem) of Laing’s Swedish turnip is preferred by
hares, and therefore suffers more than other varieties. Hares and
rabbits eat down common rye before St. John’s-day-rye, when both grow
together.[34] In the south of France, when an orchard of almond-trees
is formed, the nuts of the bitter variety are sown, “in order that they
may not be devoured by field-mice”;[35] so we see the use of the bitter
principle in almonds.

Other slight differences, which would be thought quite unimportant, are
no doubt sometimes of great service both to plants and animals. The
Whitesmith’s gooseberry, as formerly stated, produces its leaves later
than other varieties, and, as the flowers are thus left unprotected,
the fruit often fails. In one variety of the cherry, according to Mr.
Rivers,[36] the petals are much curled backwards, and in consequence of
this the stigmas were observed to be killed by a severe frost; whilst
at the same time, in another variety with incurved petals, the stigmas
were not in the least injured. The straw of the Fenton wheat is
remarkably unequal in height; and a competent observer believes that
this variety is highly productive, partly because the ears from being
distributed at various heights above the ground are less crowded
together. The same observer maintains that in the upright varieties the
divergent awns are serviceable by breaking the shocks when the ears are
dashed together by the wind.[37] If several varieties of a plant are
grown together, and the seed is indiscriminately harvested, it is clear
that the hardier and more productive kinds will, by a sort of natural
selection, gradually prevail over the others; this takes place, as
Colonel Le Couteur believes,[38] in our wheat-fields, for, as formerly
shown, no variety is quite uniform in character. The same thing, as I
am assured by nurserymen, would take place in our flower-gardens, if
the seed of the different varieties were not separately saved. When the
eggs of the wild and tame duck are hatched together, the young wild
ducks almost invariably perish, from being of smaller size and not
getting their fair share of food.[39]

Facts in sufficient number have now been given showing that natural
selection often checks, but occasionally favours, man’s power of
selection. These facts teach us, in addition, a valuable lesson,
namely, that we ought to be extremely cautious in judging what
characters are of importance in a state of nature to animals and
plants, which have to struggle for existence from the hour of their
birth to that of their death,—their existence depending on conditions,
about which we are profoundly ignorant.

      _Circumstances favourable to Selection by Man._

The possibility of selection rests on variability, and this, as we
shall see in the following chapters, mainly depends on changed
conditions of life, but is governed by infinitely complex and unknown
laws. Domestication, even when long continued, occasionally causes but
a small amount of variability, as in the case of the goose and turkey.
The slight differences, however, which characterise each individual
animal and plant would in most, probably in all, cases suffice for the
production of distinct races through careful and prolonged selection.
We see what selection, though acting on mere individual differences,
can effect when families of cattle, sheep, pigeons, etc., of the same
race, have been separately bred during a number of years by different
men without any wish on their part to modify the breed. We see the same
fact in the difference between hounds bred for hunting in different
districts,[40] and in many other such cases.

In order that selection should produce any result, it is manifest that
the crossing of distinct races must be prevented; hence facility in
pairing, as with the pigeon, is highly favourable for the work; and
difficulty in pairing, as with cats, prevents the formation of distinct
breeds. On nearly the same principle the cattle of the small island of
Jersey have been improved in their milking qualities “with a rapidity
that could not have been obtained in a widely extended country like
France.”[41] Although free crossing is a danger on the one side which
every one can see, too close interbreeding is a hidden danger on the
other side. Unfavourable conditions of life overrule the power of
selection. Our improved heavy breeds of cattle and sheep could not have
been formed on mountainous pastures; nor could dray-horses have been
raised on a barren and inhospitable land, such as the Falkland Islands,
where even the light horses of La Plata rapidly decrease in size. It
seems impossible to preserve several English breeds of sheep in France;
for as soon as the lambs are weaned their vigour decays as the heat of
the summer increases:[42] it would be impossible to give great length
of wool to sheep within the tropics; yet selection has kept the Merino
breed nearly true under diversified and unfavourable conditions. The
power of selection is so great, that breeds of the dog, sheep, and
poultry, of the largest and smallest size, long and short beaked
pigeons, and other breeds with opposite characters, have had their
characteristic qualities augmented, though treated in every way alike,
being exposed to the same climate and fed on the same food. Selection,
however, is either checked or favoured by the effects of use or habit.
Our wonderfully-improved pigs could never have been formed if they had
been forced to search for their own food; the English racehorse and
greyhound could not have been improved up to their present high
standard of excellence without constant training.

As conspicuous deviations of structure occur rarely, the improvement of
each breed is generally the result of the selection of slight
individual differences. Hence the closest attention, the sharpest
powers of observation, and indomitable perseverance, are indispensable.
It is, also, highly important that many individuals of the breed which
is to be improved should be raised; for thus there will be a better
chance of the appearance of variations in the right direction, and
individuals varying in an unfavourable manner may be freely rejected or
destroyed. But that a large number of individuals should be raised, it
is necessary that the conditions of life should favour the propagation
of the species. Had the peacock been reared as easily as the fowl, we
should probably ere this have had many distinct races. We see the
importance of a large number of plants, from the fact of nursery
gardeners almost always beating amateurs in the exhibition of new
varieties. In 1845 it was estimated[43] that between 4000 and 5000
pelargoniums were annually raised from seed in England, yet a decidedly
improved variety is rarely obtained. At Messrs. Carter’s grounds, in
Essex, where such flowers as the Lobelia, Nemophila, Mignonette, etc.,
are grown by the acre for seed, “scarcely a season passes without some
new kinds being raised, or some improvement effected on old kinds.”[44]
At Kew, as Mr. Beaton remarks, where many seedlings of common plants
are raised, “you see new forms of Laburnums, Spiraeas, and other
shrubs.”[45] So with animals: Marshall,[46] in speaking of the sheep in
one part of Yorkshire, remarks, “as they belong to poor people, and are
mostly in small lots, they never can be improved.” Lord Rivers, when
asked how he succeeded in always having first-rate greyhounds,
answered, “I breed many, and hang many.” This, as another man remarks,
“was the secret of his success; and the same will be found in
exhibiting fowls,— successful competitors breed largely, and keep the
best.”[47]

It follows from this that the capacity of breeding at an early age and
at short intervals, as with pigeons, rabbits, etc., facilitates
selection; for the result is thus soon made visible, and perseverance
in the work encouraged. It can hardly be an accident that the great
majority of the culinary and agricultural plants which have yielded
numerous races are annuals or biennials, which therefore are capable of
rapid propagation, and thus of improvement. Sea-kale, asparagus, common
and Jerusalem artichokes, potatoes, and onions, must be excepted, as
they are perennials: but onions are propagated like annuals, and of the
other plants just specified, none, with the exception of the potato,
have yielded in this country more than one or two varieties. In the
Mediterranean region, where artichokes are often raised from seed,
there are several kinds, as I hear from Mr. Bentham. No doubt
fruit-trees, which cannot be propagated quickly by seed, have yielded a
host of varieties, though not permanent races; but these, judging from
prehistoric remains, have been produced at a comparatively late period.

A species may be highly variable, but distinct races will not be
formed, if from any cause selection be not applied. It would be
difficult to select slight variations in fishes from their place of
habitation; and though the carp is extremely variable and is much
attended to in Germany, only one well-marked race has been formed, as I
hear from Lord A. Russell, namely the _spiegel-carpe_; and this is
carefully secluded from the common scaly kind. On the other hand, a
closely allied species, the gold-fish, from being reared in small
vessels, and from having been carefully attended to by the Chinese, has
yielded many races. Neither the bee, which has been semi-domesticated
from an extremely remote period, nor the cochineal insect, which was
cultivated by the aboriginal Mexicans,[48] has yielded races; and it
would be impossible to match the queen-bee with any particular drone,
and most difficult to match cochineal insects. Silk-moths, on the other
hand, have been subjected to rigorous selection, and have produced a
host of races. Cats, which from their nocturnal habits cannot be
selected for breeding, do not, as formerly remarked, yield distinct
races within the same country. Dogs are held in abomination in the
East, and their breeding is neglected; consequently, as Prof. Moritz
Wagner[49] remarks, one kind alone exists there. The ass in England
varies much in colour and size; but as it is an animal of little value
and bred by poor people, there has been no selection, and distinct
races have not been formed. We must not attribute the inferiority of
our asses to climate, for in India they are of even smaller size than
in Europe. But when selection is brought to bear on the ass, all is
changed. Near Cordova, as I am informed (Feb. 1860) by Mr. W. E. Webb,
C.E., they are carefully bred, as much as 200_l._ having been paid for
a stallion ass, and they have been immensely improved. In Kentucky,
asses have been imported (for breeding mules) from Spain, Malta, and
France; these “seldom averaged more than fourteen hands high: but the
Kentuckians, by great care, have raised them up to fifteen hands, and
sometimes even to sixteen. The prices paid for these splendid animals,
for such they really are, will prove how much they are in request. One
male, of great celebrity, was sold for upwards of one thousand pounds
sterling.” These choice asses are sent to cattle-shows, a day being
given for their exhibition.[50]

Analogous facts have been observed with plants: the nutmeg-tree in the
Malay archipelago is highly variable, but there has been no selection,
and there are no distinct races.[51] The common mignonette (_Reseda
odorata_), from bearing inconspicuous flowers, valued solely for their
fragrance, “remains in the same unimproved condition as when first
introduced.”[52] Our common forest-trees are very variable, as may be
seen in every extensive nursery-ground; but as they are not valued like
fruit-trees, and as they seed late in life, no selection has been
applied to them; consequently, as Mr. Patrick Matthews remarks,[53]
they have not yielded distinct races, leafing at different periods,
growing to different sizes, and producing timber fit for different
purposes. We have gained only some fanciful and semi-monstrous
varieties, which no doubt appeared suddenly as we now see them.

Some botanists have argued that plants cannot have so strong a tendency
to vary as is generally supposed, because many species long grown in
botanic gardens, or unintentionally cultivated year after year mingled
with our corn crops, have not produced distinct races; but this is
accounted for by slight variations not having been selected and
propagated. Let a plant which is now grown in a botanic garden, or any
common weed, be cultivated on a large scale, and let a sharp-sighted
gardener look out for each slight variety and sow the seed, and then,
if distinct races are not produced, the argument will be valid.

The importance of selection is likewise shown by considering special
characters. For instance, with most breeds of fowls the form of the
comb and the colour of the plumage have been attended to, and are
eminently characteristic of each race; but in Dorkings fashion has
never demanded uniformity of comb or colour; and the utmost diversity
in these respects prevails. Rose-combs, double-combs, cup-combs, etc.,
and colours of all kinds, may be seen in purely bred and closely
related Dorking fowls, whilst other points, such as the general form of
body, and the presence of an additional toe, have been attended to, and
are invariably present. It has also been ascertained that colour can be
fixed in this breed, as well as in any other.[54]

During the formation or improvement of a breed, its members will always
be found to vary much in those characters to which especial attention
is directed, and of which each slight improvement is eagerly sought and
selected. Thus, with short-faced tumbler-pigeons, the shortness of the
beak, shape of head and plumage,—with carriers, the length of the beak
and wattle,—with fantails, the tail and carriage,—with Spanish fowls,
the white face and comb,—with long-eared rabbits, the length of ear,
are all points which are eminently variable. So it is in every case;
and the large price paid for first-rate animals proves the difficulty
of breeding them up to the highest standard of excellence. This subject
has been discussed by fanciers,[55] and the greater prizes given for
highly improved breeds, in comparison with those given for old breeds
which are not now undergoing rapid improvement, have been fully
justified. Nathusius makes[56] a similar remark when discussing the
less uniform character of improved Shorthorn cattle and of the English
horse, in comparison, for example, with the unennobled cattle of
Hungary, or with the horses of the Asiatic steppes. This want of
uniformity in the parts which at the time are undergoing selection
chiefly depends on the strength of the principle of reversion; but it
likewise depends to a certain extent on the continued variability of
the parts which have recently varied. That the same parts do continue
varying in the same manner we must admit, for if it were not so, there
could be no improvement beyond an early standard of excellence, and we
know that such improvement is not only possible, but is of general
occurrence.

As a consequence of continued variability, and more especially of
reversion, all highly improved races, if neglected or not subjected to
incessant selection, soon degenerate. Youatt gives a curious instance
of this in some cattle formerly kept in Glamorganshire; but in this
case the cattle were not fed with sufficient care. Mr. Baker, in his
memoir on the Horse, sums up: “It must have been observed in the
preceding pages that, whenever there has been neglect, the breed has
proportionally deteriorated.”[57] If a considerable number of improved
cattle, sheep, or other animals of the same race, were allowed to breed
freely together, with no selection, but with no change in their
condition of life, there can be no doubt that after a score or hundred
generations they would be very far from excellent of their kind; but,
from what we see of the many common races of dogs, cattle, fowls,
pigeons, etc., which without any particular care have long retained
nearly the same character, we have no grounds for believing that they
would altogether depart from their type.

It is a general belief amongst breeders that characters of all kinds
become fixed by long-continued inheritance. But I have attempted to
show in the fourteenth chapter that this belief apparently resolves
itself into the following proposition, namely, that all characters
whatever, whether recently acquired or ancient, tend to be transmitted,
but that those which have already long withstood all counteracting
influences, will, as a general rule, continue to withstand them, and
consequently be faithfully transmitted.

      _Tendency in Man to carry the practice of Selection to an extreme
      point._

It is an important principle that in the process of selection man
almost invariably wishes to go to an extreme point. Thus, there is no
limit to his desire to breed certain kinds of horses and dogs as fleet
as possible, and others as strong as possible; certain kinds of sheep
for extreme fineness, and others for extreme length of wool; and he
wishes to produce fruit, grain, tubers, and other useful parts of
plants, as large and excellent as possible. With animals bred for
amusement, the same principle is even more powerful; for fashion, as we
see in our dress, always runs to extremes. This view has been expressly
admitted by fanciers. Instances were given in the chapters on the
pigeon, but here is another: Mr. Eaton, after describing a
comparatively new variety, namely, the Archangel, remarks, “What
fanciers intend doing with this bird I am at a loss to know, whether
they intend to breed it down to the tumbler’s head and beak, or carry
it out to the carrier’s head and beak; leaving it as they found it, is
not progressing.” Ferguson, speaking of fowls, says, “their
peculiarities, whatever they may be, must necessarily be fully
developed: a little peculiarity forms nought but ugliness, seeing it
violates the existing laws of symmetry.” So Mr. Brent, in discussing
the merits of the sub-varieties of the Belgian canary-bird, remarks,
“Fanciers always go to extremes; they do not admire indefinite
properties.”[58]

This principle, which necessarily leads to divergence of character,
explains the present state of various domestic races. We can thus see
how it is that racehorses and dray-horses, greyhounds and mastiffs,
which are opposed to each other in every character,—how varieties so
distinct as Cochin-china fowls and bantams, or carrier-pigeons with
very long beaks, and tumblers with excessively short beaks, have been
derived from the same stock. As each breed is slowly improved, the
inferior varieties are first neglected and finally lost. In a few
cases, by the aid of old records, or from intermediate varieties still
existing in countries where other fashions have prevailed, we are
enabled partially to trace the graduated changes through which certain
breeds have passed. Selection, whether methodical or unconscious,
always tending towards an extreme point, together with the neglect and
slow extinction of the intermediate and less-valued forms, is the key
which unlocks the mystery of how man has produced such wonderful
results.

In a few instances selection, guided by utility for a single purpose,
has led to convergence of character. All the improved and different
races of the pig, as Nathusius has well shown,[59] closely approach
each other in character, in their shortened legs and muzzles, their
almost hairless, large, rounded bodies, and small tusks. We see some
degree of convergence in the similar outline of the body in well-bred
cattle belonging to distinct races.[60] I know of no other such cases.

Continued divergence of character depends on, and is indeed a clear
proof, as previously remarked, of the same parts continuing to vary in
the same direction. The tendency to mere general variability or
plasticity of organisation can certainly be inherited, even from one
parent, as has been shown by Gärtner and Kölreuter, in the production
of varying hybrids from two species, of which one alone was variable.
It is in itself probable that, when an organ has varied in any manner,
it will again vary in the same manner, if the conditions which first
caused the being to vary remain, as far as can be judged, the same.
This is either tacitly or expressly admitted by all horticulturists: if
a gardener observes one or two additional petals in a flower, he feels
confident that in a few generations he will be able to raise a double
flower, crowded with petals. Some of the seedlings from the weeping
Moccas oak were so prostrate that they only crawled along the ground. A
seedling from the fastigiate or upright Irish yew is described as
differing greatly from the parent-form “by the exaggeration of the
fastigiate habit of its branches.”[61] Mr. Shirreff, who has been
highly successful in raising new kinds of wheat, remarks, “A good
variety may safely be regarded as the forerunner of a better one.”[62]
A great rose-grower, Mr. Rivers, has made the same remark with respect
to roses. Sageret,[63] who had large experience, in speaking of the
future progress of fruit-trees, observes that the most important
principle is “that the more plants have departed from their original
type, the more they tend to depart from it.” There is apparently much
truth in this remark; for we can in no other way understand the
surprising amount of difference between varieties in the parts or
qualities which are valued, whilst other parts retain nearly their
original character.

The foregoing discussion naturally leads to the question, what is the
limit to the possible amount of variation in any part or quality, and,
consequently, is there any limit to what selection can effect? Will a
racehorse ever be reared fleeter than Eclipse? Can our prize-cattle and
sheep be still further improved? Will a gooseberry ever weigh more than
that produced by “London” in 1852? Will the beet-root in France yield a
greater percentage of sugar? Will future varieties of wheat and other
grain produce heavier crops than our present varieties? These questions
cannot be positively answered; but it is certain that we ought to be
cautious in answering them by a negative. In some lines of variation
the limit has probably been reached. Youatt believes that the reduction
of bone in some of our sheep has already been carried so far that it
entails great delicacy of constitution.[64] But seeing the great
improvement within recent times in our cattle and sheep, and especially
in our pigs; seeing the wonderful increase in weight in our poultry of
all kinds during the last few years; he would be a bold man who would
assert that perfection has been reached. It has often been said that
Eclipse never was, and never will be, beaten in speed by any other
horse; but on making inquiries I find that the best judges believe that
our present racehorses are fleeter.[65] The attempt to raise a new
variety of wheat more productive than the many old kinds, might have
been thought until lately quite hopeless; but this has been effected by
Major Hallett, by careful selection. With respect to almost all our
animals and plants, those who are best qualified to judge do not
believe that the extreme point of perfection has yet been reached even
in the characters which have already been carried to a high standard.
For instance, the short-faced tumbler-pigeon has been greatly modified;
nevertheless, according to Mr. Eaton[66] “the field is still as open
for fresh competitors as it was one hundred years ago.” Over and over
again it has been said that perfection had been attained with our
flowers, but a higher standard has soon been reached. Hardly any fruit
has been more improved than the strawberry, yet a great authority
remarks,[67] “it must not be concealed that we are far from the extreme
limits at which we may arrive.”

No doubt there is a limit beyond which the organisation cannot be
modified compatibly with health or life. The extreme degree of
fleetness, for instance, of which a terrestrial animal is capable, may
have been acquired by our present racehorses; but as Mr. Wallace has
well remarked,[68] the question that interests us, “is not whether
indefinite and unlimited change in any or all directions is possible,
but whether such differences as do occur in nature could have been
produced by the accumulation of varieties by selection.” And in the
case of our domestic productions, there can be no doubt that many parts
of the organisation, to which man has attended, have been thus modified
to a greater degree than the corresponding parts in the natural species
of the same genera or even families. We see this in the form and size
of our light and heavy dogs or horses,—in the beak and many other
characters of our pigeons,—in the size and quality of many fruits,—in
comparison with the species belonging to the same natural groups.

Time is an important element in the formation of our domestic races, as
it permits innumerable individuals to be born, and these when exposed
to diversified conditions are rendered variable. Methodical selection
has been occasionally practised from an ancient period to the present
day, even by semi-civilised people, and during former times will have
produced some effect. Unconscious selection will have been still more
effective; for during a lengthened period the more valuable individual
animals will occasionally have been saved, and the less valuable
neglected. In the course of time, different varieties, especially in
the less civilised countries, will also have been more or less modified
through natural selection. It is generally believed, though on this
head we have little or no evidence, that new characters in time become
fixed; and after having long remained fixed it seems possible that
under new conditions they might again be rendered variable.

How great the lapse of time has been since man first domesticated
animals and cultivated plants, we begin dimly to see. When the
lake-dwellings of Switzerland were inhabited during the Neolithic
period, several animals were already domesticated and various plants
cultivated. The science of language tells us that the art of ploughing
and sowing the land was followed, and the chief animals had been
already domesticated, at an epoch so immensely remote, that the
Sanskrit, Greek, Latin, Gothic, Celtic, and Sclavonic languages had not
as yet diverged from their common parent-tongue.[69]

It is scarcely possible to overrate the effects of selection
occasionally carried on in various ways and places during thousands of
generations. All that we know, and, in a still stronger degree, all
that we do not know,[70] of the history of the great majority of our
breeds, even of our more modern breeds, agrees with the view that their
production, through the action of unconscious and methodical selection,
has been almost insensibly slow. When a man attends rather more closely
than is usual to the breeding of his animals, he is almost sure to
improve them to a slight extent. They are in consequence valued in his
immediate neighbourhood, and are bred by others; and their
characteristic features, whatever these may be, will then slowly but
steadily be increased, sometimes by methodical and almost always by
unconscious selection. At last a strain, deserving to be called a
sub-variety, becomes a little more widely known, receives a local name,
and spreads. The spreading will have been extremely slow during ancient
and less civilised times, but now is rapid. By the time that the new
breed had assumed a somewhat distinct character, its history, hardly
noticed at the time, will have been completely forgotten; for, as Low
remarks,[71] “we know how quickly the memory of such events is
effaced.”

As soon as a new breed is thus formed, it is liable through the same
process to break up into new strains and sub-varieties. For different
varieties are suited for, and are valued under, different
circumstances. Fashion changes, but, should a fashion last for even a
moderate length of time, so strong is the principle of inheritance,
that some effect will probably be impressed on the breed. Thus
varieties go on increasing in number, and history shows us how
wonderfully they have increased since the earliest records.[72] As each
new variety is produced, the earlier, intermediate, and less valuable
forms will be neglected, and perish. When a breed, from not being
valued, is kept in small numbers, its extinction almost inevitably
follows sooner or later, either from accidental causes of destruction
or from close interbreeding; and this is an event which, in the case of
well-marked breeds, excites attention. The birth or production of a new
domestic race is so slow a process that it escapes notice; its death or
destruction is comparatively sudden, is often recorded, and when too
late sometimes regretted.

Several authors have drawn a wide distinction between artificial and
natural races. The latter are more uniform in character, possessing in
a high degree the appearance of natural species, and are of ancient
origin. They are generally found in less civilised countries, and have
probably been largely modified by natural selection, and only to a
small extent by man’s unconscious and methodical selection. They have,
also, during a long period, been directly acted on by the physical
conditions of the countries which they inhabit. The so-called
artificial races, on the other hand, are not so uniform in character;
some have a semi-monstrous character, such as “the wry-legged terriers
so useful in rabbit-shooting,”[73] turnspit dogs, ancon sheep, niata
oxen, Polish fowls, fantail-pigeons, etc.; their characteristic
features have generally been acquired suddenly, though subsequently
increased by careful selections in many cases. Other races, which
certainly must be called artificial, for they have been largely
modified by methodical selection and by crossing, as the English
racehorse, terrier-dogs, the English game-cock, Antwerp
carrier-pigeons, etc., nevertheless cannot be said to have an unnatural
appearance; and no distinct line, as it seems to me, can be drawn
between natural and artificial races.

It is not surprising that domestic races should generally present a
different aspect from natural species. Man selects and propagates
modifications solely for his own use or fancy, and not for the
creature’s own good. His attention is struck by strongly marked
modifications, which have appeared suddenly, due to some great
disturbing cause in the organisation. He attends almost exclusively to
external characters; and when he succeeds in modifying internal
organs,—when for instance he reduces the bones and offal, or loads the
viscera with fat, or gives early maturity, etc.-the chances are strong
that he will at the same time weaken the constitution. On the other
hand, when an animal has to struggle throughout its life with many
competitors and enemies, under circumstances inconceivably complex and
liable to change, modifications of the most varied nature in the
internal organs as well as in external characters, in the functions and
mutual relations of parts, will be rigorously tested, preserved, or
rejected. Natural selection often checks man’s comparatively feeble and
capricious attempts at improvement; and if it were not so, the result
of his work, and of nature’s work, would be even still more different.
Nevertheless, we must not overrate the amount of difference between
natural species and domestic races; the most experienced naturalists
have often disputed whether the latter are descended from one or from
several aboriginal stocks, and this clearly shows that there is no
palpable difference between species and races.

Domestic races propagate their kind far more truly, and endure for
munch longer periods, than most naturalists are willing to admit.
Breeders feel no doubt on this head: ask a man who has long reared
Shorthorn or Hereford cattle, Leicester or Southdown sheep, Spanish or
Game poultry, tumbler or carrier-pigeons, whether these races may not
have been derived from common progenitors, and he will probably laugh
you to scorn. The breeder admits that he may hope to produce sheep with
finer or longer wool and with better carcases, or handsomer fowls, or
carrier-pigeons with beaks just perceptibly longer to the practised
eye, and thus be successful at an exhibition. Thus far he will go, but
no farther. He does not reflect on what follows from adding up during a
long course of time many slight, successive modifications; nor does he
reflect on the former existence of numerous varieties, connecting the
links in each divergent line of descent. He concludes, as was shown in
the earlier chapters, that all the chief breeds to which he has long
attended are aboriginal productions. The systematic naturalist, on the
other hand, who generally knows nothing of the art of breeding, who
does not pretend to know how and when the several domestic races were
formed, who cannot have seen the intermediate gradations, for they do
not now exist, nevertheless feels no doubt that these races are sprung
from a single source. But ask him whether the closely allied natural
species which he has studied may not have descended from a common
progenitor, and he in his turn will perhaps reject the notion with
scorn. Thus the naturalist and breeder may mutually learn a useful
lesson from each other.

_Summary on Selection by Man._—There can be no doubt that methodical
selection has effected and will effect wonderful results. It was
occasionally practised in ancient times, and is still practised by
semi-civilised people. Characters of the highest importance, and others
of trifling value, have been attended to, and modified. I need not here
repeat what has been so often said on the part which unconscious
selection has played: we see its power in the difference between flocks
which have been separately bred, and in the slow changes, as
circumstances have slowly changed, which many animals have undergone in
the same country, or when transported into a foreign land. We see the
combined effects of methodical and unconscious selection, in the great
amount of difference in those parts or qualities which are valued by
man in comparison with the parts which are not valued, and consequently
have not been attended to. Natural selection often determines man’s
power of selection. We sometimes err in imagining that characters,
which are considered as unimportant by the systematic naturalist, could
not be affected by the struggle for existence, and could not be acted
on by natural selection; but striking cases have been given, showing
how great an error this is.

The possibility of selection coming into action rests on variability;
and this is mainly caused, as we shall hereafter see, by changes in the
conditions of life. Selection is sometimes rendered difficult, or even
impossible, by the conditions being opposed to the desired character or
quality. It is sometimes checked by the lessened fertility and weakened
constitution which follow from long-continued close interbreeding. That
methodical selection may be successful, the closest attention and
discernment, combined with unwearied patience, are absolutely
necessary; and these same qualities, though not indispensable, are
highly serviceable in the case of unconscious selection. It is almost
necessary that a large number of individuals should be reared; for thus
there will be a fair chance of variations of the desired nature
arising, and of every individual with the slightest blemish or in any
degree inferior being freely rejected. Hence length of time is an
important element of success. Thus, also, reproduction at an early age
and at short intervals favours the work. Facility in pairing animals,
or their inhabiting a confined area, is advantageous as a check to free
crossing. Whenever and wherever selection is not practised, distinct
races are not formed within the same country. When any one part of the
body or one quality is not attended to, it remains either unchanged or
varies in a fluctuating manner, whilst at the same time other parts and
other qualities may become permanently and greatly modified. But from
the tendency to reversion and to continued variability, those parts or
organs which are now undergoing rapid improvement through selection,
are likewise found to vary much. Consequently highly-bred animals when
neglected soon degenerate; but we have no reason to believe that the
effects of long-continued selection would, if the conditions of life
remained the same, be soon and completely lost.

Man always tends to go to an extreme point in the selection, whether
methodical or unconscious, of all useful and pleasing qualities. This
is an important principle, as it leads to continued divergence, and in
some rare cases to convergence of character. The possibility of
continued divergence rests on the tendency in each part or organ to go
on varying in the same manner in which it has already varied; and that
this occurs, is proved by the steady and gradual improvement of many
animals and plants during lengthened periods. The principle of
divergence of character, combined with the neglect and final extinction
of all previous, less-valued, and intermediate varieties, explains the
amount of difference and the distinctness of our several races.
Although we may have reached the utmost limit to which certain
characters can be modified, yet we are far from having reached, as we
have good reason to believe, the limit in the majority of cases.
Finally, from the difference between selection as carried on by man and
by nature, we can understand how it is that domestic races often,
though by no means always, differ in general aspect from closely allied
natural species.

Throughout this chapter and elsewhere I have spoken of selection as the
paramount power, yet its action absolutely depends on what we in our
ignorance call spontaneous or accidental variability. Let an architect
be compelled to build an edifice with uncut stones, fallen from a
precipice. The shape of each fragment may be called accidental; yet the
shape of each has been determined by the force of gravity, the nature
of the rock, and the slope of the precipice,—events and circumstances,
all of which depend on natural laws; but there is no relation between
these laws and the purpose for which each fragment is used by the
builder. In the same manner the variations of each creature are
determined by fixed and immutable laws; but these bear no relation to
the living structure which is slowly built up through the power of
selection, whether this be natural or artificial selection.

If our architect succeeded in rearing a noble edifice, using the rough
wedge-shaped fragments for the arches, the longer stones for the
lintels, and so forth, we should admire his skill even in a higher
degree than if he had used stones shaped for the purpose. So it is with
selection, whether applied by man or by nature; for although
variability is indispensably necessary, yet, when we look at some
highly complex and excellently adapted organism, variability sinks to a
quite subordinate position in importance in comparison with selection,
in the same manner as the shape of each fragment used by our supposed
architect is unimportant in comparison with his skill.

REFERENCES

 [1] Quoted by Youatt on Sheep, p. 325. _See also_ Youatt on Cattle,
 pp. 62, 69.

 [2] MM. Lherbette and De Quatrefages, in ‘Bull. Soc. d’Acclimat.,’
 tom. viii. 1861, p. 311.

 [3] ‘The Poultry Book,’ 1866, p. 123. Mr. Tegetmeier, ‘The Homing or
 Carrier Pigeon,’ 1871, pp. 45-58.

 [4] Youatt on Sheep, p. 312.

 [5] ‘Treatise on the Almond Tumbler,’ 1851, p. 33.

 [6] Dr. Heusinger, ‘Wochenschrift für die Heilkunde,’ Berlin, 1846, s.
 279.

 [7] Youatt on the Dog, p. 232.

 [8] ‘The Fruit-trees of America,’ 1845, p. 270: for peaches, p. 466.

 [9] ‘Proc. Royal Soc. of Arts and Sciences of Mauritius,’ 1852, p.
 135.

 [10] ‘Gardener’s Chronicle,’ 1856, p. 379.

 [11] Quatrefages, ‘Maladies Actuelles du Ver à Soie,’ 1859, pp. 12,
 214.

 [12] ‘Gardener’s Chronicle,’ 1851, p. 595.

 [13] ‘Journal of Horticulture,’ 1862, p. 476.

 [14] ‘Gardener’s Chronicle,’ 1852, pp. 435, 691.

 [15] Bechstein, ‘Naturgesch. Deutschlands,’ 1801, B. 1 s. 310.

 [16] Prichard, ‘Phys. Hist. of Mankind,’ 1851, vol. i. p. 224.

 [17] G. Lewis’s ‘Journal of Residence in West Indies,’ ‘Home and Col.
 Library,’ p. 100.

 [18] Sidney’s edition of Youatt on the Pig, p. 24. I have given
 analogous facts in the case of mankind in my ‘Descent of Man,’ 2nd
 edit., p. 195.

 [19] ‘Journal of Horticulture,’ 1862, pp. 476, 498; 1865, p. 460. With
 respect to the heartsease, ‘Gardener’s Chronicle,’ 1863, p. 628.

 [20] ‘Des Jacinthes, de leur Culture,’ 1768, p. 53: on wheat
 ‘Gardener’s Chronicle,’ 1846, p. 653.

 [21] W. B. Tegetmeier, ‘The Field,’ Feb. 25, 1865. With respect to
 black fowls, _see_ a quotation in Thompson’s ‘Nat. Hist. of Ireland,’
 1849, vol. i. p. 22.

 [22] ‘In Sachen Darwin’s contra Wigand,’ 1874, p. 70.

 [23] ‘Bull. de la Soc. d’Acclimat.,’ tom. vii. 1860, p. 359.

 [24] ‘Transact. Hort. Soc.,’ vol. i. 2nd series, 1835, p. 275. For
 raspberries, _see_ ‘Gardener’s Chronicle,’ 1855, p. 154, and 1863 p.
 245.

 [25] ‘Gardener’s Chronicle,’ 1843, p. 806.

 [26] Ibid., 1850, p. 732.

 [27] Ibid., 1860, p. 956.

 [28] J. De Jonghe, in ‘Gardener’s Chronicle,’ 1860, p. 120.

 [29] Downing, ‘Fruit-trees of North America,’ pp. 266, 501: in regard
 to the cherry, p. 198.

 [30] ‘Gardener’s Chronicle,’ 1849, p. 755.

 [31] ‘Journal of Horticulture,’ Sept. 26th, 1865, p. 254; _ see_ other
 references given in chap. x.

 [32] Mr. Selby, in ‘Mag. of Zoology and Botany,’ Edinburgh, vol. ii.
 1838, p. 393.

 [33] The Reine Claude de Bavay, ‘Journal of Horticulture,’ Dec. 27,
 1864, p. 511.

 [34] Mr. Pusey, in ‘Journal of R. Agricult. Soc.,’ vol. vi. p. 179.
 For Swedish turnips, _see_ ‘Gardener’s Chronicle,’ 1847, p. 91.

 [35] Godron, ‘De l’Espèce,’ tom. ii. p. 98.

 [36] ‘Gardener’s Chronicle,’ 1866, p. 732.

 [37] ‘Gardener’s Chronicle,’ 1862, pp. 820, 821.

 [38] ‘On the Varieties of Wheat,’ p. 59.

 [39] Mr. Hewitt and others, in ‘Journal of Hort.,’ 1862, p. 773.

 [40] ‘Encyclop. of Rural Sports,’ p. 405.

 [41] Col. Le Couteur, ‘Journal Roy. Agricult. Soc.,’ vol. iv. p. 43.

 [42] Malingié-Nouel, ‘Journal R. Agricult. Soc.,’ vol. xiv. 1853, pp.
 215, 217.

 [43] ‘Gardener’s Chronicle,’ 1845, p. 273.

 [44] ‘Journal of Horticulture,’ 1862, p. 157.

 [45] ‘Cottage Gardener,’ 1860, p. 368.

 [46] ‘A Review of Reports,’ 1808, p. 406.

 [47] ‘Gardener’s Chronicle,’ 1853, p. 45.

 [48] Isidore Geoffroy Saint-Hilaire, ‘Hist. Nat. Gen.,’ tom. iii. p.
 49. ‘On the Cochineal Insect,’ p. 46.

 [49] ‘Die Darwin’sche Theorie und das Migrationsgesetz der
 Organismen,’ 1868, p. 19.

 [50] Capt. Marryat, quoted by Blyth in ‘Journ. Asiatic Soc. of
 Bengal,’ vol. xxviii. p. 229.

 [51] Mr. Oxley, ‘Journal of the Indian Archipelago,’ vol. ii. 1848, p.
 645.

 [52] Mr. Abbey, ‘Journal of Horticulture,’ Dec. 1, 1863, p. 430.

 [53] ‘On Naval Timber,’ 1831, p. 107.

 [54] Mr. Baily, in ‘The Poultry Chronicle,’ vol. ii. 1854, p. 150.
 Also vol. i. p. 342; vol. iii. p. 245.

 [55] ‘Cottage Gardener,’ 1855, December, p. 171; 1856, January, pp.
 248, 323.

 [56] ‘Ueber Shorthorn Rindvieh,’ 1857, s. 51.

 [57] ‘The Veterinary,’ vol. xiii. p. 720. For the Glamorganshire
 cattle, _see_ Youatt on Cattle, p. 51.

 [58] J. M. Eaton, ‘A Treatise on Fancy Pigeons,’ p. 82; Ferguson, on
 ‘Rare and Prize Poultry,’ p. 162; Mr. Brent, in ‘Cottage Gardener,’
 Oct. 1860, p. 13.

 [59] ‘Die Racen des Schweines,’ 1860, s. 48.

 [60] _See_ some good remarks on this head by M. de Quatrefages, ‘Unité
 de l’Espèce Humaine,’ 1861, p. 119.

 [61] Verlot, ‘Des Variétés,’ 1865, p. 94.

 [62] Mr. Patrick Shirreff, in ‘Gardener’s Chronicle,’ 1858, p. 771.

 [63] ‘Pomologie Physiolog.,’ 1830, p. 106.

 [64] Youatt on Sheep, p. 521.

 [65] _See also_ Stonehenge, ‘British Rural Sports,’ edition of 1871,
 p. 384.

 [66] ‘A Treatise on the Almond Tumbler,’ p. 1.

 [67] M. J. de Jonghe, in ‘Gardener’s Chronicle,’ 1858, p. 173.

 [68] ‘Contributions to the Theory of Natural Selection,’ 2nd edit.,
 1871, p. 292.

 [69] Max Müller, ‘Science of Language,’ 1861, p. 223.

 [70] Youatt on Cattle, pp. 116, 128.

 [71] ‘Domesticated Animals,’ p. 188.

 [72] Volz, ‘Beiträge zur Kulturgeschichte,’ 1852, s. 99 _et passim._

 [73] Blaine, ‘Encyclop. of Rural Sports,’ p. 213.




CHAPTER XXII. CAUSES OF VARIABILITY.

VARIABILITY DOES NOT NECESSARILY ACCOMPANY REPRODUCTION—CAUSES ASSIGNED
BY VARIOUS AUTHORS—INDIVIDUAL DIFFERENCES—VARIABILITY OF EVERY KIND DUE
TO CHANGED CONDITIONS OF LIFE—ON THE NATURE OF SUCH CHANGES—CLIMATE,
FOOD, EXCESS OF NUTRIMENT—SLIGHT CHANGES SUFFICIENT—EFFECTS OF GRAFTING
ON THE VARIABILITY OF SEEDLING-TREES—DOMESTIC PRODUCTIONS BECOME
HABITUATED TO CHANGED CONDITIONS—ON THE ACCUMULATIVE ACTION OF CHANGED
CONDITIONS—CLOSE INTERBREEDING AND THE IMAGINATION OF THE MOTHER
SUPPOSED TO CAUSE VARIABILITY—CROSSING AS A CAUSE OF THE APPEARANCE OF
NEW CHARACTERS—VARIABILITY FROM THE COMMINGLING OF CHARACTERS AND FROM
REVERSION—ON THE MANNER AND PERIOD OF ACTION OF THE CAUSES WHICH EITHER
DIRECTLY, OR INDIRECTLY THROUGH THE REPRODUCTIVE SYSTEM, INDUCE
VARIABILITY.


We will now consider, as far as we can, the causes of the almost
universal variability of our domesticated productions. The subject is
an obscure one; but it may be useful to probe our ignorance. Some
authors, for instance Dr. Prosper Lucas, look at variability as a
necessary contingent on reproduction, and as much an aboriginal law as
growth or inheritance. Others have of late encouraged, perhaps
unintentionally, this view by speaking of inheritance and variability
as equal and antagonistic principles. Pallas maintained, and he has had
some followers, that variability depends exclusively on the crossing of
primordially distinct forms. Other authors attribute variability to an
excess of food, and with animals to an excess relatively to the amount
of exercise taken, or again to the effects of a more genial climate.
That these causes are all effective is highly probable. But we must, I
think, take a broader view, and conclude that organic beings, when
subjected during several generations to any change whatever in their
conditions, tend to vary; the kind of variation which ensues depending
in most cases in a far higher degree on the nature or constitution of
the being, than on the nature of the changed conditions.

Those authors who believe that it is a law of nature that each
individual should differ in some slight degree from every other, may
maintain, apparently with truth, that this is the fact, not only with
all domesticated animals and cultivated plants, but likewise with all
organic beings in a state of nature. The Laplander by long practice
knows and gives a name to each reindeer, though, as Linnæus remarks,
“to distinguish one from another among such multitudes was beyond my
comprehension, for they were like ants on an anthill.” In Germany
shepherds have won wagers by recognising each sheep in a flock of a
hundred, which they had never seen until the previous fortnight. This
power of discrimination, however, is as nothing compared to that which
some florists have acquired. Verlot mentions a gardener who could
distinguish 150 kinds of camellia, when not in flower; and it has been
positively asserted that the famous old Dutch florist Voorhelm, who
kept above 1200 varieties of the hyacinth, was hardly ever deceived in
knowing each variety by the bulb alone. Hence we must conclude that the
bulbs of the hyacinth and the branches and leaves of the camellia,
though appearing to an unpractised eye absolutely undistinguishable,
yet really differ.[1]

As Linnæus has compared the reindeer in number to ants, I may add that
each ant knows its fellow of the same community. Several times I
carried ants of the same species (_Formica rufa_) from one ant-hill to
another, inhabited apparently by tens of thousands of ants; but the
strangers were instantly detected and killed. I then put some ants
taken from a very large nest into a bottle strongly perfumed with
assafœtida, and after an interval of twenty-four hours returned them to
their home; they were at first threatened by their fellows, but were
soon recognised and allowed to pass. Hence each ant certainly
recognised, independently of odour, its fellow; and if all the ants of
the same community have not some countersign or watchword, they must
present to each other’s senses some distinguishable character.

The dissimilarity of brothers or sisters of the same family, and of
seedlings from the same capsule, may be in part accounted for by the
unequal blending of the characters of the two parents, and by the more
or less complete recovery through reversion of ancestral characters on
either side; but we thus only push the difficulty further back in time,
for what made the parents or their progenitors different? Hence the
belief[2] that an innate tendency to vary exists, independently of
external differences, seems at first sight probable. But even the seeds
nurtured in the same capsule are not subjected to absolutely uniform
conditions, as they draw their nourishment from different points; and
we shall see in a future chapter that this difference sometimes
suffices to affect the character of the future plant. The greater
dissimilarity of the successive children of the same family in
comparison with twins, which often resemble each other in external
appearance, mental disposition, and constitution, in so extraordinary a
manner, apparently proves that the state of the parents at the exact
period of conception, or the nature of the subsequent embryonic
development, has a direct and powerful influence on the character of
the offspring. Nevertheless, when we reflect on the individual
differences between organic beings in a state of nature, as shown by
every wild animal knowing its mate; and when we reflect on the infinite
diversity of the many varieties of our domesticated productions, we may
well be inclined to exclaim, though falsely as I believe, that
Variability must be looked at as an ultimate fact, necessarily
contingent on reproduction.

Those authors who adopt this latter view would probably deny that each
separate variation has its own proper exciting cause. Although we can
seldom trace the precise relation between cause and effect, yet the
considerations presently to be given lead to the conclusion that each
modification must have its own distinct cause, and is not the result of
what we blindly call accident. The following striking case has been
communicated to me by Dr. William Ogle. Two girls, born as twins, and
in all respects extremely alike, had their little fingers on both hands
crooked; and in both children the second bicuspid tooth of the second
dentition on the right side in the upper jaw was misplaced; for,
instead of standing in a line with the others, it grew from the roof of
the mouth behind the first bicuspid. Neither the parents nor any other
members of the family were known to have exhibited any similar
peculiarity; but a son of one of these girls had the same tooth
similarly misplaced. Now, as both the girls were affected in exactly
the same manner, the idea of accident is at once excluded: and we are
compelled to admit that there must have existed some precise and
sufficient cause which, if it had occurred a hundred times, would have
given crooked fingers and misplaced bicuspid teeth to a hundred
children. It is of course possible that this case may have been due to
reversion to some long-forgotten progenitor, and this would much weaken
the value of the argument. I have been led to think of the probability
of reversion, from having been told by Mr. Galton of another case of
twin girls born with their little fingers slightly crooked, which they
inherited from their maternal grandmother.

We will now consider the general arguments, which appear to me to have
great weight, in favour of the view that variations of all kinds and
degrees are directly or indirectly caused by the conditions of life to
which each being, and more especially its ancestors, have been exposed.

No one doubts that domesticated productions are more variable than
organic beings which have never been removed from their natural
conditions. Monstrosities graduate so insensibly into mere variations
that it is impossible to separate them; and all those who have studied
monstrosities believe that they are far commoner with domesticated than
with wild animals and plants;[3] and in the case of plants,
monstrosities would be equally noticeable in the natural as in the
cultivated state. Under nature, the individuals of the same species are
exposed to nearly uniform conditions, for they are rigorously kept to
their proper places by a host of competing animals and plants; they
have, also, long been habituated to their conditions of life; but it
cannot be said that they are subject to quite uniform conditions, and
they are liable to a certain amount of variation. The circumstances
under which our domestic productions are reared are widely different:
they are protected from competition; they have not only been removed
from their natural conditions and often from their native land, but
they are frequently carried from district to district, where they are
treated differently, so that they rarely remain during any considerable
length of time exposed to closely similar conditions. In conformity
with this, all our domesticated productions, with the rarest
exceptions, vary far more than natural species. The hive-bee, which
feeds itself and follows in most respects its natural habits of life,
is the least variable of all domesticated animals, and probably the
goose is the next least variable; but even the goose varies more than
almost any wild bird, so that it cannot be affiliated with perfect
certainty to any natural species. Hardly a single plant can be named,
which has long been cultivated and propagated by seed, that is not
highly variable; common rye (_Secale cereale_) has afforded fewer and
less marked varieties than almost any other cultivated plant;[4] but it
may be doubted whether the variations of this, the least valuable of
all our cereals, have been closely observed.

Bud-variation, which was fully discussed in a former chapter, shows us
that variability may be quite independent of seminal reproduction, and
likewise of reversion to long-lost ancestral characters. No one will
maintain that the sudden appearance of a moss-rose on a Provence-rose
is a return to a former state, for mossiness of the calyx has been
observed in no natural species; the same argument is applicable to
variegated and laciniated leaves; nor can the appearance of nectarines
on peach-trees be accounted for on the principle of reversion. But
bud-variations more immediately concern us, as they occur far more
frequently on plants which have been highly cultivated during a length
of time, than on other and less highly cultivated plants; and very few
well-marked instances have been observed with plants growing under
strictly natural conditions. I have given one instance of an ash-tree
growing in a gentleman’s pleasure-grounds; and occasionally there may
be seen, on beech and other trees, twigs leafing at a different period
from the other branches. But our forest trees in England can hardly be
considered as living under strictly natural conditions; the seedlings
are raised and protected in nursery-grounds, and must often be
transplanted into places where wild trees of the kind would not
naturally grow. It would be esteemed a prodigy if a dog-rose growing in
a hedge produced by bud-variation a moss-rose, or a wild bullace or
wild cherry-tree yielded a branch bearing fruit of a different shape
and colour from the ordinary fruit. The prodigy would be enhanced if
these varying branches were found capable of propagation, not only by
grafts, but sometimes by seed; yet analogous cases have occurred with
many of our highly cultivated trees and herbs.

These several considerations alone render it probable that variability
of every kind is directly or indirectly caused by changed conditions of
life. Or, to put the case under another point of view, if it were
possible to expose all the individuals of a species during many
generations to absolutely uniform conditions of life, there would be no
variability.

      _On the Nature of the Changes in the Conditions of Life which
      induce Variability._

From a remote period to the present day, under climates and
circumstances as different as it is possible to conceive, organic
beings of all kinds, when domesticated or cultivated, have varied. We
see this with the many domestic races of quadrupeds and birds belonging
to different orders, with goldfish and silkworms, with plants of many
kinds, raised in various quarters of the world. In the deserts of
northern Africa the date-palm has yielded thirty-eight varieties; in
the fertile plains of India it is notorious how many varieties of rice
and of a host of other plants exist; in a single Polynesian island,
twenty-four varieties of the bread-fruit, the same number of the
banana, and twenty-two varieties of the arum, are cultivated by the
natives; the mulberry-tree in India and Europe has yielded many
varieties serving as food for the silkworm; and in China sixty-three
varieties of the bamboo are used for various domestic purposes.[5]
These facts, and innumerable others which could be added, indicate that
a change of almost any kind in the conditions of life suffices to cause
variability—different changes acting on different organisms.

Andrew Knight[6] attributed the variation of both animals and plants to
a more abundant supply of nourishment, or to a more favourable climate,
than that natural to the species. A more genial climate, however, is
far from necessary; the kidney-bean, which is often injured by our
spring frosts, and peaches, which require the protection of a wall,
have varied much in England, as has the orange-tree in northern Italy,
where it is barely able to exist.[7] Nor can we overlook the fact,
though not immediately connected with our present subject, that the
plants and shells of the Arctic regions are eminently variable.[8]
Moreover, it does not appear that a change of climate, whether more or
less genial, is one of the most potent causes of variability; for in
regard to plants Alph. De Candolle, in his ‘Géographie Botanique’
repeatedly shows that the native country of a plant, where in most
cases it has been longest cultivated, is that where it has yielded the
greatest number of varieties.

It is doubtful whether a change in the nature of the food is a potent
cause of variability. Scarcely any domesticated animal has varied more
than the pigeon or the fowl, but their food, especially that of
highly-bred pigeons, is generally the same. Nor can our cattle and
sheep have been subjected to any great change in this respect. But in
all these cases the food probably is much less varied in kind than that
which was consumed by the species in its natural state.[9]

Of all the causes which induce variability, excess of food, whether or
not changed in nature, is probably the most powerful. This view was
held with regard to plants by Andrew Knight, and is now held by
Schleiden, more especially in reference to the inorganic elements of
the food.[10] In order to give a plant more food it suffices in most
cases to grow it separately, and thus prevent other plants robbing its
roots. It is surprising, as I have often seen, how vigorously our
common wild species flourish when planted by themselves, though not in
highly manured land; separate growth is, in fact, the first step in
cultivation. We see the converse of the belief that excess of food
induces variability in the following statement by a great raiser of
seeds of all kinds:[11] “It is a rule invariably with us, when we
desire to keep a true stock of any one kind of seed, to grow it on poor
land without dung; but when we grow for quantity, we act contrary, and
sometimes have dearly to repent of it.” According also to Carrière, who
has had great experience with flower-garden seeds, “On remarque en
général les plantes de vigeur moyenne sont celles qui conservent le
mieux leurs caractères.”

In the case of animals the want of a proper amount of exercise, as
Bechstein remarked, has perhaps played, independently of the direct
effects of the disuse of any particular organ, an important part in
causing variability. We can see in a vague manner that, when the
organised and nutrient fluids of the body are not used during growth,
or by the wear and tear of the tissues, they will be in excess; and as
growth, nutrition, and reproduction are intimately allied processes,
this superfluity might disturb the due and proper action of the
reproductive organs, and consequently affect the character of the
future offspring. But it may be argued that neither an excess of food
nor a superfluity in the organised fluids of the body necessarily
induces variability. The goose and the turkey have been well fed for
many generations, yet have varied very little. Our fruit-trees and
culinary plants, which are so variable, have been cultivated from an
ancient period, and, though they probably still receive more nutriment
than in their natural state, yet they must have received during many
generations nearly the same amount; and it might be thought that they
would have become habituated to the excess. Nevertheless, on the whole,
Knight’s view, that excess of food is one of the most potent causes of
variability, appears, as far as I can judge, probable.

Whether or not our various cultivated plants have received nutriment in
excess, all have been exposed to changes of various kinds. Fruit-trees
are grafted on different stocks, and grown in various soils. The seeds
of culinary and agricultural plants are carried from place to place;
and during the last century the rotation of our crops and the manures
used have been greatly changed.

Slight changes of treatment often suffice to induce variability. The
simple fact of almost all our cultivated plants and domesticated
animals having varied in all places and at all times, leads to this
conclusion. Seeds taken from common English forest-trees, grown under
their native climate, not highly manured or otherwise artificially
treated, yield seedlings which vary much, as may be seen in every
extensive seed-bed. I have shown in a former chapter what a number of
well-marked and singular varieties the thorn (_Cratægus oxycantha_) has
produced: yet this tree has been subjected to hardly any cultivation.
In Staffordshire I carefully examined a large number of two British
plants, namely _Geranium phæum_ and _pyrenaicum,_ which have never been
highly cultivated. These plants had spread spontaneously by seed from a
common garden into an open plantation; and the seedlings varied in
almost every single character, both in their flower and foliage, to a
degree which I have never seen exceeded; yet they could not have been
exposed to any great change in their conditions.

With respect to animals, Azara has remarked with much surprise[12]
that, whilst the feral horses on the Pampas are always of one of three
colours, and the cattle always of a uniform colour, yet these animals,
when bred on the unenclosed estancias, though kept in a state which can
hardly be called domesticated, and apparently exposed to almost
identically the same conditions as when they are feral, nevertheless
display a great diversity of colour. So again in India several species
of fresh-water fish are only so far treated artificially, that they are
reared in great tanks; but this small change is sufficient to induce
much variability.[13]

Some facts on the effects of grafting, in regard to the variability of
trees, deserve attention. Cabanis asserts that when certain pears are
grafted on the quince, their seeds yield a greater number of varieties
than do the seeds of the same variety of pear when grafted on the wild
pear.[14] But as the pear and quince are distinct species, though so
closely related that the one can be readily grafted and succeeds
admirably on the other, the fact of variability being thus caused is
not surprising; as we are here enabled to see the cause, namely, the
very different nature of the stock and graft. Several North American
varieties of the plum and peach are well known to reproduce themselves
truly by seed; but Downing asserts,[15] “that when a graft is taken
from one of these trees and placed upon another stock, this grafted
tree is found to lose its singular property of producing the same
variety by seed, and becomes like all other worked trees;”—that is, its
seedlings become highly variable. Another case is worth giving: the
Lalande variety of the walnut-tree leafs between April 20th and May
15th, and its seedlings invariably inherit the same habit; whilst
several other varieties of the walnut leaf in June. Now, if seedlings
are raised from the May-leafing Lalande variety, grafted on another
May-leafing variety, though both stock and graft have the same early
habit of leafing, yet the seedlings leaf at various times, even as late
as the 5th of June.[16] Such facts as these are well fitted to show on
what obscure and slight causes variability depends.

I may here just allude to the appearance of new and valuable varieties
of fruit-trees and of wheat in woods and waste places, which at first
sight seems a most anomalous circumstance. In France a considerable
number of the best pears have been discovered in woods; and this has
occurred so frequently, that Poiteau asserts that “improved varieties
of our cultivated fruits rarely originate with nurserymen.”[17] In
England, on the other hand, no instance of a good pear having been
found wild has been recorded; and Mr. Rivers informs me that he knows
of only one instance with apples, namely, the Bess Poole, which was
discovered in a wood in Nottinghamshire. This difference between the
two countries may be in part accounted for by the more favourable
climate of France, but chiefly from the great number of seedlings which
spring up there in the woods. I infer that this is the case from a
remark made by a French gardener,[18] who regards it as a national
calamity that such a number of pear-trees are periodically cut down for
firewood, before they have borne fruit. The new varieties which thus
spring up in the woods, though they cannot have received any excess of
nutriment, will have been exposed to abruptly changed conditions, but
whether this is the cause of their production is very doubtful. These
varieties, however, are probably all descended[19] from old cultivated
kinds growing in adjoining orchards— a circumstance which will account
for their variability; and out of a vast number of varying trees there
will always be a good chance of the appearance of a valuable kind. In
North America, where fruit-trees frequently spring up in waste places,
the Washington pear was found in a hedge, and the Emperor peach in a
wood.[20]

With respect to wheat, some writers have spoken[21] as if it were an
ordinary event for new varieties to be found in waste places; the
Fenton wheat was certainly discovered growing on a pile of basaltic
detritus in a quarry, but in such a situation the plant would probably
receive a sufficient amount of nutriment. The Chidham wheat was raised
from an ear found _on_ a hedge; and Hunter’s wheat was discovered _by_
the roadside in Scotland, but it is not said that this latter variety
grew where it was found.[22]

Whether our domestic productions would ever become so completely
habituated to the conditions under which they now live, as to cease
varying, we have no sufficient means for judging. But, in fact, our
domestic productions are never exposed for a great length of time to
uniform conditions, and it is certain that our most anciently
cultivated plants, as well as animals, still go on varying, for all
have recently undergone marked improvement. In some few cases, however,
plants have become habituated to new conditions. Thus, Metzger, who
cultivated in Germany during many years numerous varieties of wheat,
brought from different countries,[23] states that some kinds were at
first extremely variable, but gradually, in one instance after an
interval of twenty-five years, became constant; and it does not appear
that this resulted from the selection of the more constant forms.

_On the Accumulative Action of changed Conditions of Life._—We have
good grounds for believing that the influence of changed conditions
accumulates, so that no effect is produced on a species until it has
been exposed during several generations to continued cultivation or
domestication. Universal experience shows us that when new flowers are
first introduced into our gardens they do not vary; but ultimately all,
with the rarest exceptions, vary to a greater or less extent. In a few
cases the requisite number of generations, as well as the successive
steps in the progress of variation, have been recorded, as in the often
quoted instance of the Dahlia.[24] After several years’ culture the
Zinnia has only lately (1860) begun to vary in any great degree. “In
the first seven or eight years of high cultivation, the Swan River
daisy (_Brachycome iberidifolia_) kept to its original colour; it then
varied into lilac and purple and other minor shades.”[25] Analogous
facts have been recorded with the Scotch rose. In discussing the
variability of plants several experienced horticulturists have spoken
to the same general effect. Mr. Salter[26] remarks, “Every one knows
that the chief difficulty is in breaking through the original form and
colour of the species, and every one will be on the look-out for any
natural sport, either from seed or branch; that being once obtained,
however trifling the change may be, the result depends upon himself.”
M. de Jonghe, who has had so much success in raising new varieties of
pears and strawberries,[27] remarks with respect to the former, “There
is another principle, namely, that the more a type has entered into a
state of variation, the greater is its tendency to continue doing so;
and the more it has varied from the original type, the more it is
disposed to vary still farther.” We have, indeed, already discussed
this latter point when treating of the power which man possesses,
through selection, of continually augmenting in the same direction each
modification; for this power depends on continued variability of the
same general kind. The most celebrated horticulturist in France,
namely, Vilmorin,[28] even maintains that, when any particular
variation is desired, the first step is to get the plant to vary in any
manner whatever, and to go on selecting the most variable individuals,
even though they vary in the wrong direction; for the fixed character
of the species being once broken, the desired variation will sooner or
later appear.

As nearly all our animals were domesticated at an extremely remote
epoch, we cannot, of course, say whether they varied quickly or slowly
when first subjected to new conditions. But Dr. Bachman[29] states that
he has seen turkeys raised from the eggs of the wild species lose their
metallic tints and become spotted with white in the third generation.
Mr. Yarrell many years ago informed me that the wild ducks bred on the
ponds in St. James’s Park, which had never been crossed, as it is
believed, with domestic ducks, lost their true plumage after a few
generations. An excellent observer,[30] who has often reared ducks from
the eggs of the wild bird, and who took precautions that there should
be no crossing with domestic breeds, has given, as previously stated,
full details on the changes which they gradually undergo. He found that
he could not breed these wild ducks true for more than five or six
generations, “as they then proved so much less beautiful. The white
collar round the neck of the mallard became much broader and more
irregular, and white feathers appeared in the ducklings’ wings.” They
increased also in size of body; their legs became less fine, and they
lost their elegant carriage. Fresh eggs were then procured from wild
birds; but again the same result followed. In these cases of the duck
and turkey we see that animals, like plants, do not depart from their
primitive type until they have been subjected during several
generations to domestication. On the other hand, Mr. Yarrell informed
me that the Australian dingos, bred in the Zoological Gardens, almost
invariably produced in the first generation puppies marked with white
and other colours; but, these introduced dingos had probably been
procured from the natives, who keep them in a semi-domesticated state.
It is certainly a remarkable fact that changed conditions should at
first produce, as far as we can see, absolutely no effect; but that
they should subsequently cause the character of the species to change.
In the chapter on pangenesis I shall attempt to throw a little light on
this fact.

Returning now to the causes which are supposed to induce variability.
Some authors[31] believe that close interbreeding gives this tendency,
and leads to the production of monstrosities. In the seventeenth
chapter some few facts were advanced, showing that monstrosities are,
as it appears, occasionally thus induced; and there can be no doubt
that close interbreeding causes lessened fertility and a weakened
constitution; hence it may lead to variability: but I have not
sufficient evidence on this head. On the other hand, close
interbreeding, if not carried to an injurious extreme, far from causing
variability, tends to fix the character of each breed.

It was formerly a common belief, still held by some persons, that the
imagination of the mother affects the child in the womb.[32] This view
is evidently not applicable to the lower animals, which lay
unimpregnated eggs, or to plants. Dr. William Hunter, in the last
century, told my father that during many years every woman in a large
London Lying-in Hospital was asked before her confinement whether
anything had specially affected her mind, and the answer was written
down; and it so happened that in no one instance could a coincidence be
detected between the woman’s answer and any abnormal structure; but
when she knew the nature of the structure, she frequently suggested
some fresh cause. The belief in the power of the mother’s imagination
may perhaps have arisen from the children of a second marriage
resembling the previous father, as certainly sometimes occurs, in
accordance with the facts given in the eleventh chapter.

_Crossing as a Cause of Variability._—In an early part of this chapter
it was stated that Pallas[33] and a few other naturalists maintain that
variability is wholly due to crossing. If this means that new
characters never spontaneously appear in our domestic races, but that
they are all directly derived from certain aboriginal species, the
doctrine is little less than absurd; for it implies that animals like
Italian greyhounds, pug-dogs, bull-dogs, pouter and fantail pigeons,
etc., were able to exist in a state of nature. But the doctrine may
mean something widely different, namely, that the crossing of distinct
species is the sole cause of the first appearance of new characters,
and that without this aid man could not have formed his various breeds.
As, however, new characters have appeared in certain cases by
bud-variation, we may conclude with certainty that crossing is not
necessary for variability. It is, moreover, certain that the breeds of
various animals, such as of the rabbit, pigeon, duck, etc., and the
varieties of several plants, are the modified descendants of a single
wild species. Nevertheless, it is probable that the crossing of two
forms, when one or both have long been domesticated or cultivated, adds
to the variability of the offspring, independently of the commingling
of the characters derived from the two parent-forms; and this implies
that new characters actually arise. But we must not forget the facts
advanced in the thirteenth chapter, which clearly prove that the act of
crossing often leads to the reappearance or reversion of long-lost
characters; and in most cases it would be impossible to distinguish
between the reappearance of ancient characters and the first appearance
of absolutely new characters. Practically, whether new or old, they
would be new to the breed in which they reappeared.

Gärtner declares,[34] and his experience is of the highest value on
such a point, that, when he crossed native plants which had not been
cultivated, he never once saw in the offspring any new character; but
that from the odd manner in which the characters derived from the
parents were combined, they sometimes appeared as if new. When, on the
other hand, he crossed cultivated plants, he admits that new characters
occasionally appeared, but he is strongly inclined to attribute their
appearance to ordinary variability, not in any way to the cross. An
opposite conclusion, however, appears to me the more probable.
According to Kölreuter, hybrids in the genus Mirabilis vary almost
infinitely, and he describes new and singular characters in the form of
the seeds, in the colour of the anthers, in the cotyledons being of
immense size, in new and highly peculiar odours, in the flowers
expanding early in the season, and in their closing at night. With
respect to one lot of these hybrids, he remarks that they presented
characters exactly the reverse of what might have been expected from
their parentage.[35]

Prof. Lecoq[36] speaks strongly to the same effect in regard to this
same genus, and asserts that many of the hybrids from _Mirabilis
jalapa_ and _multiflora_ might easily be mistaken for distinct species,
and adds that they differed in a greater degree than the other species
of the genus, from _M. jalapa._ Herbert, also, has described[37]
certain hybrid Rhododendrons as being “as _unlike all others_ in
foliage, as if they had been a separate species.” The common experience
of floriculturists proves that the crossing and recrossing of distinct
but allied plants, such as the species of Petunia, Calceolaria,
Fuchsia, Verbena, etc., induces excessive variability; hence the
appearance of quite new characters is probable. M. Carrière[38] has
lately discussed this subject: he states that _Erythrina cristagalli_
had been multiplied by seed for many years, but had not yielded any
varieties: it was then crossed with the allied _E. herbacea,_ and “the
resistance was now overcome, and varieties were produced with flowers
of extremely different size, form, and colour.”

From the general and apparently well-founded belief that the crossing
of distinct species, besides commingling their characters, adds greatly
to their variability, it has probably arisen that some botanists have
gone so far as to maintain[39] that, when a genus includes only a
single species, this when cultivated never varies. The proposition made
so broadly cannot be admitted; but it is probably true that the
variability of monotypic genera when cultivated is generally less than
that of genera including numerous species, and this quite independently
of the effects of crossing. I have shown in my ‘Origin of Species’ that
the species belonging to small genera generally yield a less number of
varieties in a state of nature than those belonging to large genera.
Hence the species of small genera would, it is probable, produce fewer
varieties under cultivation than the already variable species of larger
genera.

Although we have not at present sufficient evidence that the crossing
of species, which have never been cultivated, leads to the appearance
of new characters, this apparently does occur with species which have
been already rendered in some degree variable through cultivation.
Hence crossing, like any other change in the conditions of life, seems
to be an element, probably a potent one, in causing variability. But we
seldom have the means of distinguishing, as previously remarked,
between the appearance of really new characters and the reappearance of
long-lost characters, evoked through the act of crossing. I will give
an instance of the difficulty in distinguishing such cases. The species
of Datura may be divided into two sections, those having white flowers
with green stems, and those having purple flowers with brown stems: now
Naudin[40] crossed _Datura lævis_ and _ ferox,_ both of which belong to
the white section, and raised from them 205 hybrids. Of these hybrids,
every one had brown stems and bore purple flowers; so that they
resembled the species of the other section of the genus, and not their
own two parents. Naudin was so much astonished at this fact, that he
was led carefully to observe both parent-species, and he discovered
that the pure seedlings of _D. ferox,_ immediately after germination,
had dark purple stems, extending from the young roots up to the
cotyledons, and that this tint remained ever afterwards as a ring round
the base of the stem of the plant when old. Now I have shown in the
thirteenth chapter that the retention or exaggeration of an early
character is so intimately related to reversion, that it evidently
comes under the same principle. Hence probably we ought to look at the
purple flowers and brown stems of these hybrids, not as new characters
due to variability, but as a return to the former state of some ancient
progenitor.

Independently of the appearance of new characters from crossing, a few
words may be added to what has been said in former chapters on the
unequal combination and transmission of the characters proper to the
two parent-forms. When two species or races are crossed, the offspring
of the first generation are generally uniform, but those subsequently
produced display an almost infinite diversity of character. He who
wishes, says Kölreuter,[41] to obtain an endless number of varieties
from hybrids should cross and recross them. There is also much
variability when hybrids or mongrels are reduced or absorbed by
repeated crosses with either pure parent-form: and a still higher
degree of variability when three distinct species, and most of all when
four species, are blended together by successive crosses. Beyond this
point Gärtner,[42] on whose authority the foregoing statements are
made, never succeeded in effecting a union; but Max Wichura[43] united
six distinct species of willows into a single hybrid. The sex of the
parent species affects in an inexplicable manner the degree of
variability of hybrids; for Gärtner[44] repeatedly found that when a
hybrid was used as a father and either one of the pure parent-species,
or a third species, was used as the mother, the offspring were more
variable than when the same hybrid was used as the mother, and either
pure parent or the same third species as the father: thus seedlings
from _Dianthus barbatus_ crossed by the hybrid _D. chinensi-barbatus_
were more variable than those raised from this latter hybrid fertilised
by the pure _D. barbatus._ Max Wichura[45] insists strongly on an
analogous result with his hybrid willows. Again Gärtner[46] asserts
that the degree of variability sometimes differs in hybrids raised from
reciprocal crosses between the same two species; and here the sole
difference is, that the one species is first used as the father and
then as the mother. On the whole we see that, independently of the
appearance of new characters, the variability of successive crossed
generations is extremely complex, partly from the offspring partaking
unequally of the characters of the two parent-forms, and more
especially from their unequal tendency to revert to such characters or
to those of more ancient progenitors.

_On the Manner and on the Period of Action of the Causes which induce
Variability._—This is an extremely obscure subject, and we need here
only consider, whether inherited variations are due to certain parts
being acted on after they have been formed, or through the reproductive
system being affected before their formation; and in the former case at
what period of growth or development the effect is produced. We shall
see in the two following chapters that various agencies, such as an
abundant supply of food, exposure to a different climate, increased use
or disuse of parts, etc., prolonged during several generations,
certainly modify either the whole organisation or certain organs; and
it is clear at least in the case of bud-variation that the action
cannot have been through the reproductive system.

With respect to the part which the reproductive system takes in causing
variability, we have seen in the eighteenth chapter that even slight
changes in the conditions of life have a remarkable power in causing a
greater or less degree of sterility. Hence it seems not improbable that
beings generated through a system so easily affected should themselves
be affected, or should fail to inherit, or inherit in excess,
characters proper to their parents. We know that certain groups of
organic beings, but with exceptions in each group, have their
reproductive systems much more easily affected by changed conditions
than other groups; for instance, carnivorous birds, more readily than
carnivorous mammals, and parrots more readily than pigeons; and this
fact harmonises with the apparently capricious manner and degree in
which various groups of animals and plants vary under domestication.

Kölreuter[47] was struck with the parallelism between the excessive
variability of hybrids when crossed and recrossed in various
ways,—these hybrids having their reproductive powers more or less
affected,—and the variability of anciently cultivated plants. Max
Wichura[48] has gone one step farther, and shows that with many of our
highly cultivated plants, such as the hyacinth, tulip, auricula,
snapdragon, potato, cabbage, etc., which there is no reason to believe
have been hybridised, the anthers contain many irregular pollen-grains
in the same state as in hybrids. He finds also in certain wild forms,
the same coincidence between the state of the pollen and a high degree
of variability, as in many species of Rubus; but in R. caesius and
idaeus, which are not highly variable species, the pollen is sound. It
is also notorious that many cultivated plants, such as the banana,
pineapple, bread-fruit, and others previously mentioned, have their
reproductive organs so seriously affected as to be generally quite
sterile; and when they do yield seed, the seedlings, judging from the
large number of cultivated races which exist, must be variable in an
extreme degree. These facts indicate that there is some relation
between the state of the reproductive organs and a tendency to
variability; but we must not conclude that the relation is strict.
Although many of our highly cultivated plants may have their pollen in
a deteriorated condition, yet, as we have previously seen, they yield
more seeds, and our anciently domesticated animals are more prolific,
than the corresponding species in a state of nature. The peacock is
almost the only bird which is believed to be less fertile under
domestication than in its native state, and it has varied in a
remarkably small degree. From these considerations it would seem that
changes in the conditions of life lead either to sterility or to
variability, or to both; and not that sterility induces variability. On
the whole it is probable that any cause affecting the organs of
reproduction would likewise affect their product,—that is, the
offspring thus generated.

The period of life at which the causes that induce variability act, is
likewise an obscure subject, which has been discussed by various
authors.[49] In some of the cases, to be given in the following
chapter, of modifications from the direct action of changed conditions,
which are inherited, there can be no doubt that the causes have acted
on the mature or nearly mature animal. On the other hand,
monstrosities, which cannot be distinctly separated from lesser
variations, are often caused by the embryo being injured whilst in the
mother’s womb or in the egg. Thus I. Geoffroy Saint-Hilaire[50] asserts
that poor women who work hard during their pregnancy, and the mothers
of illegitimate children troubled in their minds and forced to conceal
their state, are far more liable to give birth to monsters than women
in easy circumstances. The eggs of the fowl when placed upright or
otherwise treated unnaturally frequently produce monstrous chickens. It
would, however, appear that complex monstrosities are induced more
frequently during a rather late than during a very early period of
embryonic life; but this may partly result from some one part, which
has been injured during an early period, affecting by its abnormal
growth other parts subsequently developed; and this would be less
likely to occur with parts injured at a later period.[51] When any part
or organ becomes monstrous through abortion, a rudiment is generally
left, and this likewise indicates that its development had already
commenced.

Insects sometimes have their antennae or legs in a monstrous condition,
the larvae of which do not possess either antennae or legs; and in
these cases, as Quatrefages[52] believes, we are enabled to see the
precise period at which the normal progress of development was
troubled. But the nature of the food given to a caterpillar sometimes
affects the colours of the moth, without the caterpillar itself being
affected; therefore it seems possible that other characters in the
mature insect might be indirectly modified through the larvae. There is
no reason to suppose that organs which have been rendered monstrous
have always been acted on during their development; the cause may have
acted on the organisation at a much earlier stage. It is even probable
that either the male or female sexual elements, or both, before their
union, may be affected in such a manner as to lead to modifications in
organs developed at a late period of life; in nearly the same manner as
a child may inherit from his father a disease which does not appear
until old age.

In accordance with the facts above given, which prove that in many
cases a close relation exists between variability and the sterility
following from changed conditions, we may conclude that the exciting
cause often acts at the earliest possible period, namely, on the sexual
elements, before impregnation has taken place. That an affection of the
female sexual element may induce variability we may likewise infer as
probable from the occurrence of bud-variations; for a bud seems to be
the analogue of an ovule. But the male element is apparently much
oftener affected by changed conditions, at least in a visible manner,
than the female element or ovule and we know from Gärtner’s and
Wichura’s statements that a hybrid used as the father and crossed with
a pure species gives a greater degree of variability to the offspring,
than does the same hybrid when used as the mother. Lastly, it is
certain that variability may be transmitted through either sexual
element, whether or not originally excited in them, for Kölreuter and
Gärtner[53] found that when two species were crossed, if either one was
variable, the offspring were rendered variable.

_Summary._—From the facts given in this chapter, we may conclude that
the variability of organic beings under domestication, although so
general, is not an inevitable contingent on life, but results from the
conditions to which the parents have been exposed. Changes of any kind
in the conditions of life, even extremely slight changes, often suffice
to cause variability. Excess of nutriment is perhaps the most efficient
single exciting cause. Animals and plants continue to be variable for
an immense period after their first domestication; but the conditions
to which they are exposed never long remain quite constant. In the
course of time they can be habituated to certain changes, so as to
become less variable; and it is possible that when first domesticated
they may have been even more variable than at present. There is good
evidence that the power of changed conditions accumulates; so that two,
three, or more generations must be exposed to new conditions before any
effect is visible. The crossing of distinct forms, which have already
become variable, increases in the offspring the tendency to further
variability, by the unequal commingling of the characters of the two
parents, by the reappearance of long-lost characters, and by the
appearance of absolutely new characters. Some variations are induced by
the direct action of the surrounding conditions on the whole
organisation, or on certain parts alone; other variations appear to be
induced indirectly through the reproductive system being affected, as
we know is often the case with various beings, which when removed from
their natural conditions become sterile. The causes which induce
variability act on the mature organism, on the embryo, and, probably,
on the sexual elements before impregnation has been effected.

REFERENCES

 [1] ‘Des Jacinthes,’ etc., Amsterdam, 1768, p. 43; Verlot, ‘Des
 Variétés,’ etc., p. 86. On the reindeer _see_ Linnæus, ‘Tour in
 Lapland,’ translated by Sir J. E. Smith, vol. i. p. 314. The statement
 in regard to German shepherds is given on the authority of Dr.
 Weinland.

 [2] Müller’s ‘Physiology,’ Eng. translation, vol. ii. p. 1662. With
 respect to the similarity of twins in constitution, Dr. William Ogle
 has given me the following extract from Professor Trousseau’s Lectures
 (‘Clinique Médicale,’ tom. i.1 p. 523), in which a curious case is
 recorded:—“J’ai donné mes soins à deux frères jumeaux, tous deux si
 extraordinairement ressemblants qu’il m’était impossible de les
 reconnaitre, à moin de les voir l’un à côté de l’autre. Cette
 ressemblance physique s’étendait plus loin: ils avaient, permettez-moi
 l’expression, une similitude pathologique plus remarquable encore.
 Ainsi l’un d’eux que je voyais aux néothermes à Paris malade d’une
 ophthalmie rhumatismale me disait, ‘En ce moment mon frere doit avoir
 une ophthalmie comme la mienne;’ et comme je m’etais recrie, il me
 montrait quelques jours apres une lettre qu’il venait de recevoir de
 ce frère alors à Vienne, et qui lui écrivait en effet—‘J’ai mon
 ophthalmie, tu dois avoir la tienne.’ Quelque singulier que ceci
 puisse paraître, le fait n’en est pas moins exact: on ne me l’a pas
 raconté, je l’ai vu, et j’en ai vu d’autres analogues dans ma
 pratique. Ces deux jumeaux étaient aussi tous deux asthmatiques, et
 asthmatiques a un effroyable degré. Originaires de Marseille, ils
 n’ont jamais pu demeurer dans cette ville, ou leurs intérêts les
 appelaient souvent, sans etre pris de leurs acces; jamais ils n’en
 eprouvaient a Paris. Bien mieux, il leur suffisait de gagner Toulon
 pour être guéris de leurs attaques de Marseille. Voyageant sans cesse
 et dans tous pays pour leurs affaires, ils avaient remarque que
 certaines localités leur étaient funestes, que dans d’autres ils
 etaient exempts de tout phénomène d’oppression.”

 [3] Isid. Geoffroy St.-Hilaire, ‘Hist. des Anomalies,’ tom. iii. p.
 352; Moquin-Tandon, ‘Tératologie Végétale,’ 1841, p. 115.

 [4] Metzger, ‘Die Getreidarten,’ 1841, s. 39.

 [5] On the date-palm _see_ Vogel, ‘Annals and Mag. of Nat. Hist.,’
 1854, p. 460. On Indian varieties, Dr. F. Hamilton, ‘Transact. Linn.
 Soc.,’ vol. xiv. p. 296. On the varieties cultivated in Tahiti, _see_
 Dr. Bennett, in Loudon’s ‘Mag. of N. Hist.,’ vol. v. 1832, p. 484.
 Also Ellis, ‘Polynesian Researches,’ vol. i. pp. 370, 375. On twenty
 varieties of the Pandanus and other trees in the Marianne Island,
 _see_ ‘Hooker’s Miscellany,’ vol. i. p. 308. On the bamboo in China,
 _see_ Huc’s ‘Chinese Empire,’ vol. ii. p. 307.

 [6] ‘Treatise on the Culture of the Apple,’ etc., p. 3.

 [7] Gallesio, ‘Teoria della Riproduzione Veg.,’ p. 125.

 [8] _See_ Dr. Hooker’s Memoir on Arctic Plants in ‘Linn. Transact.,’
 vol. xxiii. part ii. Mr. Woodward, and a higher authority cannot be
 quoted, speaks of the Arctic mollusca (in his ‘Rudimentary Treatise,’
 1856, p. 355) as remarkably subject to variation.

 [9] Bechstein, in his ‘Naturgeschichte der Stubenvögel,’ 1840, s. 238,
 has some good remarks on this subject. He states that his canary-birds
 varied in colour, though kept on uniform food.

 [10] ‘The Plant,’ by Schleiden, translated by Henfrey, 1848, p. 169.
 _See also_ Alex. Braun, in ‘Bot. Memoirs,’ Ray Soc., 1853, p. 313.

 [11] Messrs. Hardy and Son, of Maldon, in ‘Gardener’s Chronicle,’
 1856, p. 458. Carrière, ‘Production et Fixation des Variétés,’ 1865,
 p. 31.

 [12] ‘Quadrupedes du Paraguay,’ 1801, tom. ii. p. 319.

 [13] M’Clelland on Indian Cyprinidæ, ‘Asiatic Researches,’ vol. xix.
 part ii., 1839, pp. 266, 268, 313.

 [14] Quoted by Sageret, ‘Pom. Phys.,’ 1830, p. 43. This statement,
 however, is not believed by Decaisne.

 [15] ‘The Fruits of America,’ 1845, p. 5.

 [16] M. Cardan, in ‘Comptes Rendus,’ Dec. 1848, quoted in ‘Gardener’s
 Chronicle,’ 1849, p. 101.

 [17] M. Alexis Jordan mentions four excellent pears found in woods in
 France, and alludes to others (‘Mém. Acad. de Lyon,’ tom. ii. 1852, p.
 159). Poiteau’s remark is quoted in ‘Gardener’s Mag.,’ vol. iv., 1828,
 p. 385. _See_ ‘Gardener’s Chronicle,’ 1862, p. 335, for another case
 of a new variety of the pear found in a hedge in France. Also for
 another case, _see_ Loudon’s ‘Encyclop. of Gardening,’ p. 901. Mr.
 Rivers has given me similar information.

 [18] Duval, ‘Hist. du Poirier,’ 1849, p. 2.

 [19] I infer that this is the fact from Van Mons’ statement (‘Arbres
 Fruitiers,’ 1835, tom. i. p. 446) that he finds in the woods seedlings
 resembling all the chief cultivated races of both the pear and apple.
 Van Mons, however, looked at these wild varieties as aboriginal
 species.

 [20] Downing, ‘Fruit-trees of North America,’ p. 422; Foley, in
 ‘Transact. Hort. Soc.,’ vol. vi. p. 412.

 [21] ‘Gardener’s Chronicle,’ 1847, p. 244.

 [22] ‘Gardener’s Chronicle,’ 1841, p. 383; 1850, p. 700; 1854, p. 650.

 [23] ‘Die Getreidearten,’ 1843, s. 66, 116, 117.

 [24] Sabine, in ‘Hort. Transact.,’ vol. iii. p. 225; Bronn,
 ‘Geschichte der Natur,’ b. ii. s. 119.

 [25] ‘Journal of Horticulture,’ 1861, p. 112; on Zinnia, ‘Gardener’s
 Chronicle,’ 1860, p. 852.

 [26] ‘The Chrysanthemum, its History, etc.,’ 1865, p. 3.

 [27] ‘Gardener’s Chronicle,’ 1855, p. 54; ‘Journal of Horticulture,’
 May 9, 1865, p. 363.

 [28] Quoted by Verlot, ‘Des Variétés,’ etc., 1865, p. 28.

 [29] ‘Examination of the Characteristics of Genera and Species,’
 Charleston, 1855, p. 14.

 [30] Mr. Hewitt, ‘Journal of Hort.,’ 1863, p. 39.

 [31] Devay, ‘Mariages Consanguins,’ pp. 97, 125. In conversation I
 have found two or three naturalists of the same opinion.

 [32] Müller has conclusively argued against this belief, ‘Elements of
 Phys.,’ Eng. translat., vol. ii. 1842, p. 1405.

 [33] ‘Act. Acad. St. Petersburg,’ 1780, part ii. p. 84, etc.

 [34] ‘Bastarderzeugung,’ s. 249, 255, 295.

 [35] ‘Nova Acta, St. Petersburg,’ 1794, p. 378; 1795, pp. 307, 313,
 316; 1787, p. 407.

 [36] ‘De la Fécondation,’ 1862, p. 311.

 [37] ‘Amaryllidaceæ,’ 1837, p. 362.

 [38] Abstracted in ‘Gardener’s Chronicle,’ 1860, p. 1081.

 [39] This was the opinion of the elder De Candolle, as quoted in ‘Dic.
 Class. d’Hist. Nat.,’ tom. viii. p. 405. Puvis, in his work, ‘De la
 Dégénération,’ 1837, p. 37, has discussed this same point.

 [40] ‘Comptes Rendus,’ Novembre 21, 1864, p. 838.

 [41] ‘Nova Acta, St. Petersburg,’ 1794, p. 391.

 [42] ‘Bastarderzeugung,’ s. 507, 516, 572.

 [43] ‘Die Bastardbefruchtung,’ etc., 1865, s. 24.

 [44] ‘Bastarderzeugung,’ s. 452, 507.

 [45] ‘Die Bastardbefruchtung,’ s. 56.

 [46] ‘Bastarderzeugung,’ s. 423.

 [47] ‘Dritte Fortsetzung,’ etc., 1766, s. 85.

 [48] ‘Die Bastardbefruchtung,’ etc., 1865, s. 92: _see also_ the Rev.
 M. J. Berkeley on the same subject, in ‘Journal of Royal Hort. Soc.,’
 1866, p. 80.

 [49] Dr. P. Lucas has given a history of opinion on this subject:
 ‘Héréd. Nat.,’ 1847, tom. i. p. 175.

 [50] ‘Hist. des Anomalies,’ tom. iii. p. 499.

 [51] Ibid., tom. iii. pp. 392, 502. The several memoirs by M. Dareste
 hereafter referred to are of special value on this whole subject.

 [52] _See_ his interesting work, ‘Métamorphoses de l’Homme,’ etc.,
 1862, p. 129.

 [53] ‘Dritte Fortsetzung,’ etc., s. 123; ‘Bastarderzeugung’ s. 249.




CHAPTER XXIII. DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF
LIFE.

SLIGHT MODIFICATIONS IN PLANTS FROM THE DEFINITE ACTION OF CHANGED
CONDITIONS, IN SIZE, COLOUR, CHEMICAL PROPERTIES, AND IN THE STATE OF
THE TISSUES—LOCAL DISEASES—CONSPICUOUS MODIFICATIONS FROM CHANGED
CLIMATE OR FOOD, ETC—PLUMAGE OF BIRDS AFFECTED BY PECULIAR NUTRIMENT,
AND BY THE INOCULATION OF POISON—LAND-SHELLS—MODIFICATIONS OF ORGANIC
BEINGS IN A STATE OF NATURE THROUGH THE DEFINITE ACTION OF EXTERNAL
CONDITIONS—COMPARISON OF AMERICAN AND EUROPEAN TREES—GALLS—EFFECTS OF
PARASITIC FUNGI—CONSIDERATIONS OPPOSED TO THE BELIEF IN THE POTENT
INFLUENCE OF CHANGED EXTERNAL CONDITIONS—PARALLEL SERIES OF
VARIETIES—AMOUNT OF VARIATION DOES NOT CORRESPOND WITH THE DEGREE OF
CHANGE IN THE CONDITIONS—BUD-VARIATION—MONSTROSITIES PRODUCED BY
UNNATURAL TREATMENT—SUMMARY.


If we ask ourselves why this or that character has been modified under
domestication, we are, in most cases, lost in utter darkness. Many
naturalists, especially of the French school, attribute every
modification to the “monde ambiant,” that is, to changed climate, with
all its diversities of heat and cold, dampness and dryness, light and
electricity, to the nature of the soil, and to varied kinds and amount
of food. By the term definite action, as used in this chapter, I mean
an action of such a nature that, when many individuals of the same
variety are exposed during several generations to any particular change
in their conditions of life, all, or nearly all the individuals, are
modified in the same manner. The effects of habit, or of the increased
use and disuse of various organs, might have been included under this
head; but it will be convenient to discuss this subject in a separate
chapter. By the term indefinite action I mean an action which causes
one individual to vary in one way and another individual in another
way, as we often see with plants and animals after they have been
subjected for some generations to changed conditions of life. But we
know far too little of the causes and laws of variation to make a sound
classification. The action of changed conditions, whether leading to
definite or indefinite results, is a totally distinct consideration
from the effects of selection; for selection depends on the
preservation by man of certain individuals, or on their survival under
various and complex natural circumstances, and has no relation whatever
to the primary cause of each particular variation.

I will first give in detail all the facts which I have been able to
collect, rendering it probable that climate, food, etc., have acted so
definitely and powerfully on the organisation of our domesticated
productions, that new sub-varieties or races have been thus formed
without the aid of selection by man or nature. I will then give the
facts and considerations opposed to this conclusion, and finally we
will weigh, as fairly as we can, the evidence on both sides.

When we reflect that distinct races of almost all our domesticated
animals exist in each kingdom of Europe, and formerly even in each
district of England, we are at first strongly inclined to attribute
their origin to the definite action of the physical conditions of each
country; and this has been the conclusion of many authors. But we
should bear in mind that man annually has to choose which animals shall
be preserved for breeding, and which shall be slaughtered. We have also
seen that both methodical and unconscious selection were formerly
practised, and are now occasionally practised by the most barbarous
races, to a much greater extent than might have been anticipated. Hence
it is difficult to judge how far differences in the conditions between,
for instance, the several districts in England, have sufficed to modify
the breeds which have been reared in each. It may be argued that, as
numerous wild animals and plants have ranged during many ages
throughout Great Britain, and still retain the same character, the
difference in conditions between the several districts could not have
modified in a marked manner the various native races of cattle, sheep,
pigs, and horses. The same difficulty of distinguishing between the
effects of natural selection and the definite action of external
conditions is encountered in a still higher degree when we compare
closely allied species inhabiting two countries, such as North America
and Europe, which do not differ greatly in climate, nature of soil,
etc., for in this case natural selection will inevitably and rigorously
have acted during a long succession of ages.

Prof. Weismann has suggested[1] that when a variable species enters a
new and isolated country, although the variations may be of the same
general nature as before, yet it is improbable that they should occur
in the same proportional numbers. After a longer or shorter period, the
species will tend to become nearly uniform in character from the
incessant crossing of the varying individuals; but owing to the
proportion of the individuals varying in different ways not being the
same in the two cases, the final result will be the production of two
forms somewhat different from one another. In cases of this kind it
would falsely appear as if the conditions had induced certain definite
modifications, whereas they had only excited indefinite variability,
but with the variations in slightly different proportional numbers.
This view may throw some light on the fact that the domestic animals
which formerly inhabited the several districts in Great Britain, and
the half wild cattle lately kept in several British parks, differed
slightly from one another; for these animals were prevented from
wandering over the whole country and intercrossing, but would have
crossed freely within each district or park.

From the difficulty of judging how far changed conditions have caused
definite modifications of structure, it will be advisable to give as
large a body of facts as possible, showing that extremely slight
differences within the same country, or during different seasons,
certainly produce an appreciable effect, at least on varieties which
are already in an unstable condition. Ornamental flowers are good for
this purpose, as they are highly variable, and are carefully observed.
All floriculturists are unanimous that certain varieties are affected
by very slight differences in the nature of the artificial compost in
which they are grown, and by the natural soil of the district, as well
as by the season. Thus, a skilful judge, in writing on Carnations and
Picotees[2] asks “where can Admiral Curzon be seen possessing the
colour, size, and strength which it has in Derbyshire? Where can
Flora’s Garland be found equal to those at Slough? Where do
high-coloured flowers revel better than at Woolwich and Birmingham? Yet
in no two of these districts do the same varieties attain an equal
degree of excellence, although each may be receiving the attention of
the most skilful cultivators.” The same writer then recommends every
cultivator to keep five different kinds of soil and manure, “and to
endeavour to suit the respective appetites of the plants you are
dealing with, for without such attention all hope of general success
will be vain.” So it is with the Dahlia:[3] the Lady Cooper rarely
succeeds near London, but does admirably in other districts; the
reverse holds good with other varieties; and again, there are others
which succeed equally well in various situations. A skilful gardener[4]
states that he procured cuttings of an old and well-known variety
(pulchella) of Verbena, which from having been propagated in a
different situation presented a slightly different shade of colour; the
two varieties were afterwards multiplied by cuttings, being carefully
kept distinct; but in the second year they could hardly be
distinguished, and in the third year no one could distinguish them.

The nature of the season has an especial influence on certain varieties
of the Dahlia: in 1841 two varieties were pre-eminently good, and the
next year these same two were pre-eminently bad. A famous amateur[5]
asserts that in 1861 many varieties of the Rose came so untrue in
character, “that it was hardly possible to recognise them, and the
thought was not seldom entertained that the grower had lost his tally.”
The same amateur[6] states that in 1862 two-thirds of his Auriculas
produced central trusses of flowers, and such trusses are liable not to
keep true; and he adds that in some seasons certain varieties of this
plant all prove good, and the next season all prove bad; whilst exactly
the reverse happens with other varieties. In 1845 the editor of the
‘Gardener’s Chronicle’[7] remarked how singular it was that this year
many Calceolarias tended to assume a tubular form. With Heartsease[8]
the blotched sorts do not acquire their proper character until hot
weather sets in; whilst other varieties lose their beautiful marks as
soon as this occurs.

Analogous facts have been observed with leaves: Mr. Beaton asserts[9]
that he raised at Shrubland, during six years, twenty thousand
seedlings from the Punch Pelargonium, and not one had variegated
leaves; but at Surbiton, in Surrey, one-third, or even a greater
proportion, of the seedlings from this same variety were more or less
variegated. The soil of another district in Surrey has a strong
tendency to cause variegation, as appears from information given me by
Sir F. Pollock. Verlot[10] states that the variegated strawberry
retains its character as long as grown in a dryish soil, but soon loses
it when planted in fresh and humid soil. Mr. Salter, who is well known
for his success in cultivating variegated plants, informs me that rows
of strawberries were planted in his garden in 1859, in the usual way;
and at various distances in one row, several plants simultaneously
became variegated; and what made the case more extraordinary, all were
variegated in precisely the same manner. These plants were removed, but
during the three succeeding years other plants in the same row became
variegated, and in no instance were the plants in any adjoining row
affected.

The chemical qualities, odours, and tissues of plants are often
modified by a change which seems to us slight. The Hemlock is said not
to yield conicine in Scotland. The root of the _Aconitum napellus_
becomes innocuous in frigid climates. The medicinal properties of the
Digitalis are easily affected by culture. As the _Pistacia lentiscus_
grows abundantly in the South of France, the climate must suit it, but
it yields no mastic. The Laurus sassafras in Europe loses the odour
proper to it in North America.[11] Many similar facts could be given,
and they are remarkable because it might have been thought that
definite chemical compounds would have been little liable to change
either in quality or quantity.

The wood of the American Locust-tree (_Robinia_) when grown in England
is nearly worthless, as is that of the Oak-tree when grown at the Cape
of Good Hope.[12] Hemp and flax, as I hear from Dr. Falconer, flourish
and yield plenty of seed on the plains of India, but their fibres are
brittle and useless. Hemp, on the other hand, fails to produce in
England that resinous matter which is so largely used in India as an
intoxicating drug.

The fruit of the Melon is greatly influenced by slight differences in
culture and climate. Hence it is generally a better plan, according to
Naudin, to improve an old kind than to introduce a new one into any
locality. The seed of the Persian Melon produces near Paris fruit
inferior to the poorest market kinds, but at Bordeaux yields delicious
fruit.[13] Seed is annually brought from Thibet to Kashmir[14] and
produces fruit weighing from four to ten pounds, but plants raised next
year from seed saved in Kashmir give fruit weighing only from two to
three pounds. It is well known that American varieties of the Apple
produce in their native land magnificent and brightly-coloured fruit,
but these in England are of poor quality and a dull colour. In Hungary
there are many varieties of the kidney-bean, remarkable for the beauty
of their seeds, but the Rev. M.J. Berkeley[15] found that their beauty
could hardly ever be preserved in England, and in some cases the colour
was greatly changed. We have seen in the ninth chapter, with respect to
wheat, what a remarkable effect transportal from the north to the south
of France, and conversely, produced on the weight of the grain.

When man can perceive no change in plants or animals which have been
exposed to a new climate or to different treatment, insects can
sometimes perceive a marked change. A cactus has been imported into
India from Canton, Manilla Mauritius, and from the hot-houses of Kew,
and there is likewise a so-called native kind which was formerly
introduced from South America; all these plants belong to the same
species and are alike in appearance, but the cochineal insect
flourishes only on the native kind, on which it thrives
prodigiously.[16] Humboldt remarks[17] that white men “born in the
torrid zone walk barefoot with impunity in the same apartment where a
European, recently landed, is exposed to the attacks of the _Pulex
penetrans._” This insect, the too well-known chigoe, must therefore be
able to perceive what the most delicate chemical analysis fails to
discover, namely, a difference between the blood or tissues of a
European and those of a white man born in the tropics. But the
discernment of the chigoe is not so surprising as it at first appears;
for according to Liebig[18] the blood of men with different
complexions, though inhabiting the same country, emits a different
odour.

Diseases peculiar to certain localities, heights, or climates, may be
here briefly noticed, as showing the influence of external
circumstances on the human body. Diseases confined to certain races of
man do not concern us, for the constitution of the race may play the
more important part, and this may have been determined by unknown
causes. The Plica Polonica stands, in this respect, in a nearly
intermediate position; for it rarely affects Germans, who inhabit the
neighbourhood of the Vistula, where so many Poles are grievously
affected; neither does it affect Russians, who are said to belong to
the same original stock as the Poles.[19] The elevation of a district
often governs the appearance of diseases; in Mexico the yellow fever
does not extend above 924 metres; and in Peru, people are affected with
the _verugas_ only between 600 and 1600 metres above the sea; many
other such cases could be given. A peculiar cutaneous complaint, called
the _Bouton d’Alep,_ affects in Aleppo and some neighbouring districts
almost every native infant, and some few strangers; and it seems fairly
well established that this singular complaint depends on drinking
certain waters. In the healthy little island of St. Helena the
scarlet-fever is dreaded like the Plague; analogous facts have been
observed in Chili and Mexico.[20] Even in the different departments of
France it is found that the various infirmities which render the
conscript unfit for serving in the army, prevail with remarkable
inequality, revealing, as Boudin observes, that many of them are
endemic, which otherwise would never have been suspected.[21] Any one
who will study the distribution of disease will be struck with surprise
at what slight differences in the surrounding circumstances govern the
nature and severity of the complaints by which man is at least
temporarily affected.

The modifications as yet referred to are extremely slight, and in most
cases have been caused, as far as we can judge, by equally slight
differences in the conditions. But such conditions acting during a
series of generations would perhaps produce a marked effect.

With plants, a considerable change of climate sometimes produces a
conspicuous result. I have given in the ninth chapter the most
remarkable case known to me, namely, that of varieties of maize, which
were greatly modified in the course of only two or three generations
when taken from a tropical country to a cooler one, or conversely. Dr.
Falconer informs me that he has seen the English Ribston-pippin apple,
a Himalayan oak, Prunus and Pyrus, all assume in the hotter parts of
India a fastigiate or pyramidal habit; and this fact is the more
interesting, as a Chinese tropical species of Pyrus naturally grows
thus. Although in these cases the changed manner of growth seems to
have been directly caused by the great heat, we know that many
fastigiate trees have originated in their temperate homes. In the
Botanic Gardens of Ceylon the apple-tree[22] “sends out numerous
runners under ground, which continually rise into small stems, and form
a growth around the parent-tree.” The varieties of the cabbage which
produce heads in Europe fail to do so in certain tropical
countries.[23] The _Rhododendron ciliatum_ produced at Kew flowers so
much larger and paler-coloured than those which it bears on its native
Himalayan mountain, that Dr. Hooker[24] would hardly have recognised
the species by the flowers alone. Many similar facts with respect to
the colour and size of flowers could be given.

The experiments of Vilmorin and Buckman on carrots and parsnips prove
that abundant nutriment produces a definite and inheritable effect on
the roots, with scarcely any change in other parts of the plant. Alum
directly influences the colour of the flowers of the Hydrangea.[25]
Dryness seems generally to favour the hairiness or villosity of plants.
Gärtner found that hybrid Verbascums became extremely woolly when grown
in pots. Mr. Masters, on the other hand, states that the _Opuntia
leucotricha_ “is well clothed with beautiful white hairs when grown in
a damp heat, but in a dry heat exhibits none of this peculiarity.”[26]
Slight variations of many kinds, not worth specifying in detail, are
retained only as long as plants are grown in certain soils, of which
Sageret[27] gives some instances from his own experience. Odart, who
insists strongly on the permanence of the varieties of the grape,
admits[28] that some varieties, when grown under a different climate or
treated differently, vary in a slight degree, as in the tint of the
fruit and in the period of ripening. Some authors have denied that
grafting causes even the slightest difference in the scion; but there
is sufficient evidence that the fruit is sometimes slightly affected in
size and flavour, the leaves in duration, and the flowers in
appearance.[29]

There can be no doubt, from the facts given in the first chapter, that
European dogs deteriorate in India, not only in their instincts but in
structure; but the changes which they undergo are of such a nature,
that they may be partly due to reversion to a primitive form, as in the
case of feral animals. In parts of India the turkey becomes reduced in
size, “with the pendulous appendage over the beak enormously
developed.”[30] We have seen how soon the wild duck, when domesticated,
loses its true character, from the effects of abundant or changed food,
or from taking little exercise. From the direct action of a humid
climate and poor pasture the horse rapidly decreases in size in the
Falkland Islands. From information which I have received, this seems
likewise to be the case to a certain extent with sheep in Australia.

Climate definitely influences the hairy covering of animals; in the
West Indies a great change is produced in the fleece of sheep, in about
three generations. Dr. Falconer states[31] that the Thibet mastiff and
goat, when brought down from the Himalaya to Kashmir, lose their fine
wool. At Angora not only goats, but shepherd-dogs and cats, have fine
fleecy hair, and Mr. Ainsworth[32] attributes the thickness of the
fleece to the severe winters, and its silky lustre to the hot summers.
Burnes states positively[33] that the Karakool sheep lose their
peculiar black curled fleeces when removed into any other country. Even
within the limits of England, I have been assured that the wool of two
breeds of sheep was slightly changed by the flocks being pastured in
different localities.[34] It has been asserted on good authority[35]
that horses kept during several years in the deep coal-mines of Belgium
become covered with velvety hair, almost like that on the mole. These
cases probably stand in close relation to the natural change of coat in
winter and summer. Naked varieties of several domestic animals have
occasionally appeared; but there is no reason to believe that this is
in any way related to the nature of the climate to which they have been
exposed.[36]

It appears at first sight probable that the increased size, the
tendency to fatten, the early maturity and altered forms of our
improved cattle, sheep, and pigs, have directly resulted from their
abundant supply of food. This is the opinion of many competent judges,
and probably is to a great extent true. But as far as form is
concerned, we must not overlook the more potent influence of lessened
use on the limbs and lungs. We see, moreover, as far as size is
concerned, that selection is apparently a more powerful agent than a
large supply of food, for we can thus only account for the existence,
as remarked to me by Mr. Blyth, of the largest and smallest breeds of
sheep in the same country, of Cochin-China fowls and Bantams, of small
Tumbler and large Runt pigeons, all kept together and supplied with
abundant nourishment. Nevertheless there can be little doubt that our
domesticated animals have been modified, independently of the increased
or lessened use of parts, by the conditions to which they have been
subjected, without the aid of selection. For instance, Prof.
Rütimeyer[37] shows that the bones of domesticated quadrupeds can be
distinguished from those of wild animals by the state of their surface
and general appearance. It is scarcely possible to read Nathusius’s
excellent ‘Vorstudien’[38] and doubt that, with the highly improved
races of the pig, abundant food has produced a conspicuous effect on
the general form of the body, on the breadth of the head and face, and
even on the teeth. Nathusius rests much on the case of a purely bred
Berkshire pig, which when two months old became diseased in its
digestive organs, and was preserved for observation until nineteen
months old; at this age it had lost several characteristic features of
the breed, and had acquired a long, narrow head, of large size
relatively to its small body, and elongated legs. But in this case and
in some others we ought not to assume that, because certain characters
are lost, perhaps through reversion, under one course of treatment,
therefore that they were at first directly produced by an opposite
treatment.

In the case of the rabbit, which has become feral on the island of
Porto Santo, we are at first strongly tempted to attribute the whole
change—the greatly reduced size, the altered tints of the fur, and the
loss of certain characteristic marks—to the definite action of the new
conditions to which it has been exposed. But in all such cases we have
to consider in addition the tendency to reversion to progenitors more
or less remote, and the natural selection of the finest shades of
difference.

The nature of the food sometimes either definitely induces certain
peculiarities, or stands in some close relation with them. Pallas long
ago asserted that the fat-tailed sheep of Siberia degenerate and lose
their enormous tails when removed from certain saline pastures; and
recently Erman[39] states that this occurs with the Kirgisian sheep
when brought to Orenburgh.

It is well known that hemp-seed causes bullfinches and certain other
birds to become black. Mr. Wallace has communicated to me some much
more remarkable facts of the same nature. The natives of the Amazonian
region feed the common green parrot (_Chrysotis festiva,_ Linn.) with
the fat of large Siluroid fishes, and the birds thus treated become
beautifully variegated with red and yellow feathers. In the Malayan
archipelago, the natives of Gilolo alter in an analogous manner the
colours of another parrot, namely, the _Lorius garrulus,_ Linn., and
thus produce the _Lori rajah_ or King-Lory. These parrots in the Malay
Islands and South America, when fed by the natives on natural vegetable
food, such as rice and plaintains, retain their proper colours. Mr.
Wallace has, also, recorded[40] a still more singular fact. “The
Indians (of S. America) have a curious art by which they change the
colours of the feathers of many birds. They pluck out those from the
part they wish to paint, and inoculate the fresh wound with the milky
secretion from the skin of a small toad. The feathers grow of a
brilliant yellow colour, and on being plucked out, it is said, grow
again of the same colour without any fresh operation.”

Bechstein[41] does not entertain any doubt that seclusion from light
affects, at least temporarily, the colours of cage-birds.

It is well known that the shells of land-mollusca are affected by the
abundance of lime in different districts. Isidore Geoffroy
Saint-Hilaire[42] gives the case of _Helix lactea,_ which has recently
been carried from Spain to the South of France and to the Rio Plata,
and in both countries now presents a distinct appearance, but whether
this has resulted from food or climate is not known. With respect to
the common oyster, Mr. F. Buckland informs me that he can generally
distinguish the shells from different districts; young oysters brought
from Wales and laid down in beds where “_natives_” are indigenous, in
the short space of two months begin to assume the “native” character.
M. Costa[43] has recorded a much more remarkable case of the same
nature, namely, that young shells taken from the shores of England and
placed in the Mediterranean, at once altered their manner of growth and
formed prominent diverging rays, like those on the shells of the proper
Mediterranean oyster. The same individual shell, showing both forms of
growth, was exhibited before a society in Paris. Lastly, it is well
known that caterpillars fed on different food sometimes either
themselves acquire a different colour or produce moths differing in
colour.[44]

It would be travelling beyond my proper limits here to discuss how far
organic beings in a state of nature are definitely modified by changed
conditions. In my ‘Origin of Species’ I have given a brief abstract of
the facts bearing on this point, and have shown the influence of light
on the colours of birds, and of residence near the sea on the lurid
tints of insects, and on the succulency of plants. Mr. Herbert
Spencer[45] has recently discussed with much ability this whole subject
on general grounds. He argues, for instance, that with all animals the
external and internal tissues are differently acted on by the
surrounding conditions, and they invariably differ in intimate
structure. So again the upper and lower surfaces of true leaves, as
well as of stems and petioles, when these assume the function and
occupy the position of leaves, are differently circumstanced with
respect to light, etc., and apparently in consequence differ in
structure. But, as Mr. Herbert Spencer admits, it is most difficult in
all such cases to distinguish between the effects of the definite
action of physical conditions and the accumulation through natural
selection of inherited variations which are serviceable to the
organism, and which have arisen independently of the definite action of
these conditions.

Although we are not here concerned with the definite action of the
conditions of life on organisms in a state of nature, I may state that
much evidence has been gained during the last few years on this
subject. In the United States, for instance, it has been clearly
proved, more especially by Mr. J. A. Allen, that, with birds, many
species differ in tint, size of body and of beak, and in length of
tail, in proceeding from the North to the South; and it appears that
these differences must be attributed to the direct action of
temperature.[46] With respect to plants I will give a somewhat
analogous case: Mr. Meehan,[47] has compared twenty-nine kinds of
American trees with their nearest European allies, all grown in close
proximity and under as nearly as possible the same conditions. In the
American species he finds, with the rarest exceptions, that the leaves
fall earlier in the season, and assume before their fall a brighter
tint; that they are less deeply toothed or serrated; that the buds are
smaller; that the trees are more diffuse in growth and have fewer
branchlets; and, lastly, that the seeds are smaller—all in comparison
with the corresponding European species. Now considering that these
corresponding trees belong to several distinct orders, and that they
are adapted to widely different stations, it can hardly be supposed
that their differences are of any special service to them in the New
and Old worlds; and if so such differences cannot have been gained
through natural selection, and must be attributed to the long continued
action of a different climate.

_Galls._—Another class of facts, not relating to cultivated plants,
deserves attention. I allude to the production of galls. Every one
knows the curious, bright-red, hairy productions on the wild rose-tree,
and the various different galls produced by the oak. Some of the latter
resemble fruit, with one face as rosy as the rosiest apple. These
bright colours can be of no service either to the gall-forming insect
or to the tree, and probably are the direct result of the action of the
light, in the same manner as the apples of Nova Scotia or Canada are
brighter coloured than English apples. According to Osten Sacken’s
latest revision, no less than fifty-eight kinds of galls are produced
on the several species of oak, by Cynips with its sub-genera; and Mr.
B. D. Walsh[48] states that he can add many others to the list. One
American species of willow, the _Salix humilis,_ bears ten distinct
kinds of galls. The leaves which spring from the galls of various
English willows differ completely in shape from the natural leaves. The
young shoots of junipers and firs, when punctured by certain insects,
yield monstrous growths resembling flowers and fir-cones; and the
flowers of some plants become from the same cause wholly changed in
appearance. Galls are produced in every quarter of the world; of
several sent to me by Mr. Thwaites from Ceylon, some were as
symmetrical as a composite flower when in bud, others smooth and
spherical like a berry; some protected by long spines, others clothed
with yellow wool formed of long cellular hairs, others with regularly
tufted hairs. In some galls the internal structure is simple, but in
others it is highly complex; thus M. Lacaze-Duthiers[49] has figured in
the common ink-gall no less than seven concentric layers, composed of
distinct tissue, namely, the epidermic, sub-epidermic, spongy,
intermediate, and the hard protective layer formed of curiously
thickened woody cells, and, lastly, the central mass, abounding with
starch-granules on which the larvæ feed.

Galls are produced by insects of various orders, but the greater number
by species of Cynips. It is impossible to read M. Lacaze-Duthiers’
discussion and doubt that the poisonous secretion of the insect causes
the growth of the gall; and every one knows how virulent is the poison
secreted by wasps and bees, which belong to the same group with Cynips.
Galls grow with extraordinary rapidity, and it is said that they attain
their full size in a few days;[50] it is certain that they are almost
completely developed before the larvae are hatched. Considering that
many gall-insects are extremely small, the drop of secreted poison must
be excessively minute; it probably acts on one or two cells alone,
which, being abnormally stimulated, rapidly increase by a process of
self-division. Galls, as Mr. Walsh[51] remarks, afford good, constant,
and definite characters, each kind keeping as true to form as does any
independent organic being. This fact becomes still more remarkable when
we hear that, for instance, seven out of the ten different kinds of
galls produced on _Salix humilis_ are formed by gall-gnats
(_Cecidomyidæ_) which “though essentially distinct species, yet
resemble one another so closely that in almost all cases it is
difficult, and in most cases impossible, to distinguish the full-grown
insects one from the other.”[52] For in accordance with a wide-spread
analogy we may safely infer that the poison secreted by insects so
closely allied would not differ much in nature; yet this slight
difference is sufficient to induce widely different results. In some
few cases the same species of gall-gnat produces on distinct species of
willows galls which cannot be distinguished; the _Cynips fecundatrix,_
also, has been known to produce on the Turkish oak, to which it is not
properly attached, exactly the same kind of gall as on the European
oak.[53] These latter facts apparently prove that the nature of the
poison is a more powerful agent in determining the form of the gall
than the specific character of the tree which is acted on.

As the poisonous secretion of insects belonging to various orders has
the special power of affecting the growth of various plants; as a
slight difference in the nature of the poison suffices to produce
widely different results; and lastly, as we know that the chemical
compounds secreted by plants are eminently liable to be modified by
changed conditions of life, we may believe it possible that various
parts of a plant might be modified through the agency of its own
altered secretions. Compare, for instance, the mossy and viscid calyx
of a moss-rose, which suddenly appears through bud-variation on a
Provence-rose, with the gall of red moss growing from the inoculated
leaf of a wild rose, with each filament symmetrically branched like a
microscopical spruce-fir, bearing a glandular tip and secreting
odoriferous gummy matter.[54] Or compare, on the one hand, the fruit of
the peach, with its hairy skin, fleshy covering, hard shell and kernel,
and on the other hand one of the more complex galls with its epidermic,
spongy, and woody layers, surrounding tissue loaded with starch
granules. These normal and abnormal structures manifestly present a
certain degree of resemblance. Or, again, reflect on the cases above
given of parrots which have had their plumage brightly decorated
through some change in their blood, caused by having been fed on
certain fishes, or locally inoculated with the poison of a toad. I am
far from wishing to maintain that the moss-rose or the hard shell of
the peach-stone or the bright colours of birds are actually due to any
chemical change in the sap or blood; but these cases of galls and of
parrots are excellently adapted to show us how powerfully and
singularly external agencies may affect structure. With such facts
before us, we need feel no surprise at the appearance of any
modification in any organic being.

I may, also, here allude to the remarkable effects which parasitic
fungi sometimes produce on plants. Reissek[55] has described a Thesium,
affected by an Œcidium, which was greatly modified, and assumed some of
the characteristic features of certain allied species, or even genera.
Suppose, says Reissek, “the condition originally caused by the fungus
to become constant in the course of time, the plant would, if found
growing wild, be considered as a distinct species or even as belonging
to a new genus.” I quote this remark to show how profoundly, yet in how
natural a manner, this plant must have been modified by the parasitic
fungus. Mr. Meehan[56] also states that three species of Euphorbia and
_Portulaca olereacea,_ which naturally grow prostrate, become erect
when they are attacked by the Œcidium. _Euphorbia maculata_ in this
case also becomes nodose, with the branchlets comparatively smooth and
the leaves modified in shape, approaching in these respects to a
distinct species, namely, the _E. hypericifolia._

      _Facts and Considerations opposed to the belief that the
      Conditions of Life act in a potent manner in causing definite
      Modifications of Structure_

I have alluded to the slight differences in species naturally living in
distinct countries under different conditions; and such differences we
feel at first inclined to attribute, probably often with justice, to
the definite action of the surrounding conditions. But it must be borne
in mind that there exist many animals and plants which range widely and
have been exposed to great diversities of climate, yet remain uniform
in character. Some authors, as previously remarked, account for the
varieties of our culinary and agricultural plants by the definite
action of the conditions to which they have been exposed in the
different parts of Great Britain; but there are about 200 plants[57]
which are found in every single English county; and these plants must
have been exposed for an immense period to considerable differences of
climate and soil, yet do not differ. So, again, some animals and plants
range over a large portion of the world, yet retain the same character.

Notwithstanding the facts previously given on the occurrence of highly
peculiar local diseases and on the strange modifications of structure
in plants caused by the inoculated poison of insects, and other
analogous cases; still there are a multitude of variations—such as the
modified skull of the niata ox and bulldog, the long horns of Caffre
cattle, the conjoined toes of the solid-hoofed swine, the immense crest
and protuberant skull of Polish fowls, the crop of the pouter-pigeon,
and a host of other such cases—which we can hardly attribute to the
definite action, in the sense before specified, of the external
conditions of life. No doubt in every case there must have been some
exciting cause; but as we see innumerable individuals exposed to nearly
the same conditions, and one alone is affected, we may conclude that
the constitution of the individual is of far higher importance than the
conditions to which it has been exposed. It seems, indeed, to be a
general rule that conspicuous variations occur rarely, and in one
individual alone out of millions, though all may have been exposed, as
far as we can judge, to nearly the same conditions. As the most
strongly marked variations graduate insensibly into the most trifling,
we are led by the same train of thought to attribute each slight
variation much more to innate differences of constitution, however
caused, than to the definite action of the surrounding conditions.

We are led to the same conclusion by considering the cases, formerly
alluded to, of fowls and pigeons, which have varied and will no doubt
go on varying in directly opposite ways, though kept during many
generations under nearly the same conditions. Some, for instance, are
born with their beaks, wings, tails, legs, etc., a little longer, and
others with these same parts a little shorter. By the long-continued
selection of such slight individual differences which occur in birds
kept in the same aviary, widely different races could certainly be
formed; and long-continued selection, important as is the result, does
nothing but preserve the variations which arise, as it appears to us,
spontaneously.

In these cases we see that domesticated animals vary in an indefinite
number of particulars, though treated as uniformly as is possible. On
the other hand, there are instances of animals and plants, which,
though they have been exposed to very different conditions, both under
nature and domestication, have varied in nearly the same manner. Mr.
Layard informs me that he has observed amongst the Caffres of South
Africa a dog singularly like an arctic Esquimaux dog. Pigeons in India
present nearly the same wide diversities of colour as in Europe; and I
have seen chequered and simply barred pigeons, and pigeons with blue
and white loins, from Sierra Leone, Madeira, England, and India. New
varieties of flowers are continually raised in different parts of Great
Britain, but many of these are found by the judges at our exhibitions
to be almost identical with old varieties. A vast number of new
fruit-trees and culinary vegetables have been produced in North
America: these differ from European varieties in the same general
manner as the several varieties raised in Europe differ from one
another; and no one has ever pretended that the climate of America has
given to the many American varieties any general character by which
they can be recognised. Nevertheless, from the facts previously
advanced on the authority of Mr. Meehan with respect to American and
European forest-trees it would be rash to affirm that varieties raised
in the two countries would not in the course of ages assume a
distinctive character. Dr. M. Masters has recorded a striking fact[58]
bearing on this subject: he raised numerous plants of _Hybiscus
syriacus_ from seed collected in South Carolina and the Holy Land,
where the parent-plants must have been exposed to considerably
different conditions; yet the seedlings from both localities broke into
two similar strains, one with obtuse leaves and purple or crimson
flowers, and the other with elongated leaves and more or less pink
flowers.

We may, also, infer the prepotent influence of the constitution of the
organism over the definite action of the conditions of life, from the
several cases given in the earlier chapters of parallel series of
varieties,—an important subject, hereafter to be more fully discussed.
Sub-varieties of the several kinds of wheat, gourds, peaches, and other
plants, and to a limited extent sub-varieties of the fowl, pigeon, and
dog, have been shown either to resemble or to differ from one another
in a closely corresponding or parallel manner. In other cases, a
variety of one species resembles a distinct species; or the varieties
of two distinct species resemble one another. Although these parallel
resemblances no doubt often result from reversion to the former
characters of a common progenitor; yet in other cases, when new
characters first appear, the resemblance must be attributed to the
inheritance of a similar constitution, and consequently to a tendency
to vary in the same manner. We see something of a similar kind in the
same monstrosity appearing and reappearing many times in the same
species of animal, and, as Dr. Maxwell Masters has remarked to me, in
the same species of plant.

We may at least conclude, that the amount of modification which animals
and plants have undergone under domestication does not correspond with
the degree to which they have been subjected to changed circumstances.
As we know the parentage of domesticated birds far better than of most
quadrupeds, we will glance through the list. The pigeon has varied in
Europe more than almost any other bird; yet it is a native species, and
has not been exposed to any extraordinary change of conditions. The
fowl has varied equally, or almost equally, with the pigeon, and is a
native of the hot jungles of India. Neither the peacock, a native of
the same country, nor the guinea-fowl, an inhabitant of the dry deserts
of Africa, has varied at all, or only in colour. The turkey, from
Mexico, has varied but little. The duck, on the other hand, a native of
Europe, has yielded some well-marked races; and as this is an aquatic
bird, it must have been subjected to a far more serious change in its
habits than the pigeon or even the fowl, which nevertheless have varied
in a much higher degree. The goose, a native of Europe and aquatic like
the duck, has varied less than any other domesticated bird, except the
peacock.

Bud-variation is, also, important under our present point of view, in
some few cases, as when all the eyes on the same tuber of the potato,
or all the fruit on the same plum-tree, or all the flowers on the same
plant, have suddenly varied in the same manner, it might be argued that
the variation had been definitely caused by some change in the
conditions to which the plants had been exposed; yet, in other cases,
such an admission is extremely difficult. As new characters sometimes
appear by bud-variation, which do not occur in the parent-species or in
any allied species, we may reject, at least in these cases, the idea
that they are due to reversion. Now it is well worth while to reflect
maturely on some striking case of bud-variation, for instance that of
the peach. This tree has been cultivated by the million in various
parts of the world, has been treated differently, grown on its own
roots and grafted on various stocks, planted as a standard, trained
against a wall, or under glass; yet each bud of each sub-variety keeps
true to its kind. But occasionally, at long intervals of time, a tree
in England, or under the widely different climate of Virginia, produces
a single bud, and this yields a branch which ever afterwards bears
nectarines. Nectarines differ, as every one knows, from peaches in
their smoothness, size, and flavour; and the difference is so great
that some botanists have maintained that they are specifically
distinct. So permanent are the characters thus suddenly acquired, that
a nectarine produced by bud-variation has propagated itself by seed. To
guard against the supposition that there is some fundamental
distinction between bud and seminal variation, it is well to bear in
mind that nectarines have likewise been produced from the stone of the
peach; and, reversely, peaches from the stone of the nectarine. Now is
it possible to conceive external conditions more closely alike than
those to which the buds on the same tree are exposed? Yet one bud
alone, out of the many thousands borne by the same tree, has suddenly,
without any apparent cause, produced a nectarine. But the case is even
stronger than this, for the same flower-bud has yielded a fruit,
one-half or one-quarter a nectarine, and the other half or
three-quarters a peach. Again, seven or eight varieties of the peach
have yielded by bud-variation nectarines: the nectarines thus produced,
no doubt, differ a little from one another; but still they are
nectarines. Of course there must be some cause, internal or external,
to excite the peach-bud to change its nature; but I cannot imagine a
class of facts better adapted to force on our minds the conviction that
what we call the external conditions of life are in many cases quite
insignificant in relation to any particular variation, in comparison
with the organisation or constitution of the being which varies.

It is known from the labours of Geoffroy Saint-Hilaire, and recently
from those of Dareste and others, that eggs of the fowl, if shaken,
placed upright, perforated, covered in part with varnish, etc., produce
monstrous chickens. Now these monstrosities may be said to be directly
caused by such unnatural conditions, but the modifications thus induced
are not of a definite nature. An excellent observer, M. Camille
Dareste,[59] remarks “that the various species of monstrosities are not
determined by specific causes; the external agencies which modify the
development of the embryo act solely in causing a perturbation—a
perversion in the normal course of development.” He compares the result
to what we see in illness: a sudden chill, for instance, affects one
individual alone out of many, causing either a cold, or sore-throat,
rheumatism, or inflammation of the lungs or pleura. Contagious matter
acts in an analogous manner.[60] We may take a still more specific
instance: seven pigeons were struck by rattle-snakes:[61] some suffered
from convulsions; some had their blood coagulated, in others it was
perfectly fluid; some showed ecchymosed spots on the heart, others on
the intestines, etc.; others again showed no visible lesion in any
organ. It is well known that excess in drinking causes different
diseases in different men; but in the tropics the effects of
intemperance differ from those caused in a cold climate;[62] and in
this case we see the definite influence of opposite conditions. The
foregoing facts apparently give us as good an idea as we are likely for
a long time to obtain, how in many cases external conditions act
directly, though not definitely, in causing modifications of structure.

_Summary._—There can be no doubt, from the facts given in this chapter,
that extremely slight changes in the conditions of life sometimes,
probably often, act in a definite manner on our domesticated
productions; and, as the action of changed conditions in causing
indefinite variability is accumulative, so it may be with their
definite action. Hence considerable and definite modifications of
structure probably follow from altered conditions acting during a long
series of generations. In some few instances a marked effect has been
produced quickly on all, or nearly all, the individuals which have been
exposed to a marked change of climate, food, or other circumstance.
This has occurred with European men in the United States, with European
dogs in India, with horses in the Falkland Islands, apparently with
various animals at Angora, with foreign oysters in the Mediterranean,
and with maize transported from one climate to another. We have seen
that the chemical compounds of some plants and the state of their
tissues are readily affected by changed conditions. A relation
apparently exists between certain characters and certain conditions, so
that if the latter be changed the character is lost—as with the colours
of flowers, the state of some culinary plants, the fruit of the melon,
the tail of fat-tailed sheep, and the peculiar fleeces of other sheep.

The production of galls, and the change of plumage in parrots when fed
on peculiar food or when inoculated by the poison of a toad, prove to
us what great and mysterious changes in structure and colour, may be
the definite result of chemical changes in the nutrient fluids or
tissues.

We now almost certainly know that organic beings in a state of nature
may be modified in various definite ways by the conditions to which
they have been long exposed, as in the case of the birds and other
animals in the northern and southern United States, and of American
trees in comparison with their representatives in Europe. But in many
cases it is most difficult to distinguish between the definite result
of changed conditions, and the accumulation through natural selection
of indefinite variations which have proved serviceable. If it profited
a plant to inhabit a humid instead of an arid station, a fitting change
in its constitution might possibly result from the direct action of the
environment, though we have no grounds for believing that variations of
the right kind would occur more frequently with plants inhabiting a
station a little more humid than usual, than with other plants. Whether
the station was unusually dry or humid, variations adapting the plant
in a slight degree for directly opposite habits of life would
occasionally arise, as we have good reason to believe from what we
actually see in other cases.

The organisation or constitution of the being which is acted on, is
generally a much more important element than the nature of the changed
conditions, in determining the nature of the variation. We have
evidence of this in the appearance of nearly similar modifications
under different conditions, and of different modifications under
apparently nearly the same conditions. We have still better evidence of
this in closely parallel varieties being frequently produced from
distinct races, or even distinct species; and in the frequent
recurrence of the same monstrosity in the same species. We have also
seen that the degree to which domesticated birds have varied, does not
stand in any close relation with the amount of change to which they
have been subjected.

To recur once again to bud-variations. When we reflect on the millions
of buds which many trees have produced, before some one bud has varied,
we are lost in wonder as to what the precise cause of each variation
can be. Let us recall the case given by Andrew Knight of the
forty-year-old tree of the yellow magnum bonum plum, an old variety
which has been propagated by grafts on various stocks for a very long
period throughout Europe and North America, and on which a single bud
suddenly produced the red magnum bonum. We should also bear in mind
that distinct varieties, and even distinct species,—as in the case of
peaches, nectarines, and apricots,—of certain roses and
camellias,—although separated by a vast number of generations from any
progenitor in common, and although cultivated under diversified
conditions, have yielded by bud-variation closely analogous varieties.
When we reflect on these facts we become deeply impressed with the
conviction that in such cases the nature of the variation depends but
little on the conditions to which the plant has been exposed, and not
in any especial manner on its individual character, but much more on
the inherited nature or constitution of the whole group of allied
beings to which the plant in question belongs. We are thus driven to
conclude that in most cases the conditions of life play a subordinate
part in causing any particular modification; like that which a spark
plays, when a mass of combustibles bursts into flame—the nature of the
flame depending on the combustible matter, and not on the spark.[63]

No doubt each slight variation must have its efficient cause; but it is
as hopeless an attempt to discover the cause of each, as to say why a
chill or a poison affects one man differently from another. Even with
modifications resulting from the definite action of the conditions of
life, when all or nearly all the individuals, which have been similarly
exposed, are similarly affected, we can rarely see the precise relation
between cause and effect. In the next chapter it will be shown that the
increased use or disuse of various organs produces an inherited effect.
It will further be seen that certain variations are bound together by
correlation as well as by other laws. Beyond this we cannot at present
explain either the causes or nature of the variability of organic
beings.

REFERENCES

 [1] ‘Ueber den Einfluss der Isolirung auf die Artbildung,’ 1872.

 [2] ‘Gardener’s Chronicle,’ 1853, p. 183.

 [3] Mr. Wildman, ‘Floricultural Soc.,’ Feb. 7th, 1843, reported in
 ‘Gardener’s Chronicle,’ 1843, p. 86.

 [4] Mr. Robson, in ‘Journal of Horticulture,’ Feb. 13th, 1866, p. 122.

 [5] ‘Journal of Horticulture,’ 1861, p. 24.

 [6] Ibid., 1862, p. 83.

 [7] ‘Gardener’s Chronicle,’ 1845, p. 660.

 [8] Ibid., 1863, p. 628.

 [9] ‘Journal of Hort.,’ 1861, pp. 64, 309.

 [10] ‘Des Variétés,’ etc., p. 76.

 [11] Engel, ‘Sur les Prop. Médicales des Plantes,’ 1860, pp. 10, 25.
 On changes in the odours of plants,_ see_ Dalibert’s Experiments
 quoted by Beckman, ‘Inventions,’ vol. ii. p. 344; and Nees, in
 Ferussac, ‘Bull. des Sc. Nat.,’ 1824, tom. i. p. 60. With respect to
 the rhubarb, etc., _see also_ ‘Gardener’s Chronicle,’ 1849, p. 355;
 1862, p. 1123.

 [12] Hooker, ‘Flora Indica,’ p. 32.

 [13] Naudin, ‘Annales des Sc. Nat.,’ 4th series, Bot., tom. xi., 1859,
 p. 81. ‘Gardener’s Chronicle,’ 1859, p. 464.

 [14] Moorcroft’s ‘Travels,’ etc., vol. ii. p. 143.

 [15] ‘Gardener’s Chronicle,’ 1861, p. 1113.

 [16] Royle, ‘Productive Resources of India,’ p. 59.

 [17] ‘Personal Narrative,’ Eng. translat., vol. v. p. 101. This
 statement has been confirmed by Karsten (‘Beitrag zur Kenntniss der
 Rhynchoprion,’ Moscow, 1864, s. 39), and by others.

 [18] ‘Organic Chemistry,’ Eng. translat., 1st edit., p. 369.

 [19] Prichard, ‘Phys. Hist. of Mankind,’ 1851, vol. i. p. 155.

 [20] Darwin, ‘Journal of Researches,’ 1845, p. 434.

 [21] These statements on disease are taken from Dr. Boudin’s
 ‘Géographie et Statistique Médicale,’ 1857, tom. i. pp. xliv. and
 lii.; tom. ii. p. 315.

 [22] ‘Ceylon,’ by Sir J. E. Tennent, vol. i., 1859, p. 89.

 [23] Godron, ‘De l’Espèce,’ tom. ii. p. 52.

 [24] ‘Journal of Horticultural Soc.,’ vol. vii., 1852, p. 117.

 [25] ‘Journal of Hort. Soc.,’ vol. i. p. 160.

 [26] _See_ Lecoq, on the Villosity of Plants, ‘Géograph. Bot.,’ tom.
 iii. pp. 287, 291; Gärtner, ‘Bastarderz.,’ s. 261; Mr. Masters on the
 Opuntia, in ‘Gardener’s Chronicle,’ 1846, p. 444.

 [27] ‘Pom. Phys.,’ p. 136.

 [28] ‘Ampélographie,’ 1849, p. 19.

 [29] Gärtner, ‘Bastarderz.,’ s. 606, has collected nearly all recorded
 facts. Andrew Knight (in ‘Transact. Hort. Soc.,’ vol. ii. p. 160) goes
 so far as to maintain that few varieties are absolutely permanent in
 character when propagated by buds or grafts.

 [30] Mr. Blyth, ‘Annals and Mag. of Nat. Hist.,’ vol. xx. 1847, p.
 391.

 [31] ‘Natural History Review,’ 1862, p. 113.

 [32] ‘Journal of Roy. Geographical Soc.,’ vol. ix., 1839, p. 275.

 [33] ‘Travels in Bokhara,’ vol. iii. p. 151.

 [34] _See also,_ on the influence of marshy pastures on the wool,
 Godron, ‘L’Espèce,’ tom. ii. p. 22.

 [35] Isidore Geoffroy Saint-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. p.
 438.

 [36] Azara has made some good remarks on this subject, ‘Quadrupedes du
 Paraguay,’ tom. ii. p. 337. _See_ an account of a family of naked mice
 produced in England, ‘Proc. Zoolog. Soc.,’ 1856, p. 38.

 [37] ‘Die Fauna der Pfahlbauten,’ 1861, s. 15.

 [38] ‘Schweineschädel,’ 1864, s. 99.

 [39] ‘Travels in Siberia,’ Eng. translat., vol. i. p. 228.

 [40] A. R. Wallace, ‘Travels on the Amazon and Rio Negro,’ p. 294.

 [41] ‘Naturgeschichte der Stubenvögel,’ 1840, s. 262, 308.

 [42] ‘Hist. Nat Gén.,’ tom. iii. p. 402.

 [43] ‘Bull. de La Soc. Imp. d’Acclimat.,’ tom. viii. p. 351.

 [44] _See_ an account of Mr. Gregson’s experiments on the _ Abraxus
 grossulariata,_ ‘Proc. Entomolog. Soc.,’ Jan. 6th, 1862: these
 experiments have been confirmed by Mr. Greening, in ‘Proc. of the
 Northern Entomolog. Soc.,’ July 28th, 1862. For the effects of food on
 caterpillars, _see_ a curious account by M. Michely in ‘Bull. De La
 Soc. Imp. d’Acclimat.,’ tom. viii. p. 563. For analogous facts from
 Dahlbom on Hymenoptera, _see_ Westwood’s ‘Modern Class. of Insects,’
 vol. ii. p. 98. _See also_ Dr. L. Moller ‘Die Abhängigkeit der
 Insecten,’ 1867, s. 70.

 [45] ‘The Principles of Biology,’ vol. ii., 1866. The present chapters
 were written before I had read Mr. Herbert Spencer’s work, so that I
 have not been able to make so much use of it as I should otherwise
 probably have done.)

 [46] Professor Weismann comes to the same conclusion with respect to
 certain European butterflies in his valuable essay, ‘Ueber den
 Saison-Dimorphismus,’ 1875. I might also refer to the recent works of
 several other authors on the present subject; for instance to Kerner’s
 ‘Gute und schlechte Arten,’ 1866.

 [47] ‘Proc. Acad. Nat. Soc. of Philadelphia,’ Jan. 28th, 1862.

 [48] _See_ Mr. B. D. Walsh’s excellent papers in ‘Proc. Entomolog.
 Soc. Philadelphia,’ Dec. 1866,, p. 284. With respect to the willow,
 _see_ ibid., 1864. p. 546.

 [49] See his admirable ‘Histoire des Galles’ in ‘Annal. des Sc. Nat.
 Bot.’ 3rd series tom. 19 1853 p. 273.)

 [50] Kirby and Spence’s ‘Entomology,’ 1818, vol. i. p. 450;
 Lacaze-Duthiers, ibid., p. 284.

 [51] ‘Proc. Entomolog. Soc. Philadelphia,’ 1864, p. 558.

 [52] Mr. B. D. Walsh, ibid., p. 633, and Dec. 1866, p. 275.

 [53] Mr. B. D. Walsh, ibid., 1864, pp. 545, 411, 495; and Dec. 1866,
 p. 278. _See also_ Lacaze-Duthiers.

 [54] Lacaze-Duthiers, ibid., pp. 325, 328.

 [55] ‘Linnæa,’ vol. xvii. 1843; quoted by Dr. M. T. Masters, Royal
 Institution, March 16th, 1860.

 [56] ‘Proc. Acad. Nat. Sc., Philadelphia,’ June 16th, 1874, and July
 23rd, 1875.

 [57] Hewett C. Watson ‘Cybele Britannica,’ vol. i., 1847, p. 11.

 [58] ‘Gardener’s Chronicle,’ 1857, p. 629.

 [59] ‘Mémoire sur la Production Artificielle des Monstruosités,’ 1862,
 pp. 8-12; ‘Recherches sur les Conditions, etc., chez les Monstres,’
 1863, p. 6. An abstract is given of Geoffroy’s Experiments by his son,
 in his ‘Vie, Travaux,’ etc., 1847, p. 290.

 [60] Paget, ‘Lectures on Surgical Pathology,’ 1853, vol. i. p. 483.

 [61] ‘Researches upon the Venom of the Rattle-snake,’ Jan. 1861, by
 Dr. Mitchell, p. 67.

 [62] Mr. Sedgwick, in ‘British and Foreign Medico-Chirurg. Review,’
 July 1863, p. 175.

 [63] Professor Weismann argues strongly in favour of this view in his
 ‘Saison-Dimorphismus der Schmetterlinge,’ 1875, pp. 40-43.




CHAPTER XXIV. LAWS OF VARIATION—USE AND DISUSE, ETC.

NISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF THE ORGANISATION—ON THE
EFFECTS OF THE INCREASED USE AND DISUSE OF ORGANS—CHANGED HABITS OF
LIFE—ACCLIMATISATION WITH ANIMALS AND PLANTS—VARIOUS METHODS BY WHICH
THIS CAN BE EFFECTED—ARRESTS OF DEVELOPMENT—RUDIMENTARY ORGANS.


In this and the two following chapters I shall discuss, as well as the
difficulty of the subject permits, the several laws which govern
Variability. These may be grouped under the effects of use and disuse,
including changed habits and acclimatisation—arrest of
development—correlated variation—the cohesion of homologous parts-the
variability of multiple parts—compensation of growth—the position of
buds with respect to the axis of the plant—and lastly, analogous
variation. These several subjects so graduate into one another that
their distinction is often arbitrary.

It may be convenient first briefly to discuss that coordinating and
reparative power which is common, in a higher or lower degree, to all
organic beings, and which was formerly designated by physiologists as
_nisus formativus._

Blumenbach and others[1] have insisted that the principle which permits
a Hydra, when cut into fragments, to develop itself into two or more
perfect animals, is the same with that which causes a wound in the
higher animals to heal by a cicatrice. Such cases as that of the Hydra
are evidently analogous to the spontaneous division or fissiparous
generation of the lowest animals, and likewise to the budding of
plants. Between these extreme cases and that of a mere cicatrice we
have every gradation. Spallanzani[2] by cutting off the legs and tail
of a Salamander, got in the course of three months six crops of these
members; so that 687 perfect bones were reproduced by one animal during
one season. At whatever point the limb was cut off, the deficient part,
and no more, was exactly reproduced. When a diseased bone has been
removed, a new one sometimes “gradually assumes the regular form, and
all the attachments of muscles, ligaments, etc., become as complete as
before.”[3]

This power of regrowth does not, however, always act perfectly; the
reproduced tail of a lizard differs in the form of the scales from the
normal tail: with certain Orthopterous insects the large hind legs are
reproduced of smaller size:[4] the white cicatrice which in the higher
animals unites the edges of a deep wound is not formed of perfect skin,
for elastic tissue is not produced till long afterwards.[5] “The
activity of the _nisus formativus,_” says Blumenbach, “is in an inverse
ratio to the age of the organised body.” Its power is also greater with
animals, the lower they stand in the scale of organisation; and animals
low in the scale correspond with the embryos of higher animals
belonging to the same class. Newport’s observations[6] afford a good
illustration of this fact, for he found that “myriapods, whose highest
development scarcely carries them beyond the larva of perfect insects,
can regenerate limbs and antennae up to the time of their last moult;”
and so can the larvae of true insects, but, except in one order, not in
the mature insect. Salamanders correspond in development with the
tadpoles or larvae of the tailless Batrachians, and both possess to a
large extent the power of regrowth; but not so the mature tailless
Batrachians.

Absorption often plays an important part in the repair of injuries.
When a bone is broken and does not unite, the ends are absorbed and
rounded, so that a false joint is formed; or if the ends unite, but
overlap, the projecting parts are removed.[7] A dislocated bone will
form for itself a new socket. Displaced tendons and varicose veins
excavate new channels in the bones against which they press. But
absorption comes into action, as Virchow remarks, during the normal
growth of bones; parts which are solid during youth become hollowed out
for the medullary tissue as the bone increases in size. In trying to
understand the many well-adapted cases of regrowth when aided by
absorption, we should remember that almost all parts of the
organisation, even whilst retaining the same form, undergo constant
renewal; so that a part which is not renewed would be liable to
absorption.

Some cases, usually classed under the so-called _nisus formativus,_ at
first appear to come under a distinct head; for not only are old
structures reproduced, but new structures are formed. Thus, after
inflammation “false membranes,” furnished with blood-vessels,
lymphatics, and nerves, are developed; or a fœtus escapes from the
Fallopian tubes, and falls into the abdomen, “nature pours out a
quantity of plastic lymph, which forms itself into organised membrane,
richly supplied with blood-vessels,” and the fœtus is nourished for a
time. In certain cases of hydrocephalus the open and dangerous spaces
in the skull are filled up with new bones, which interlock by perfect
serrated sutures.[8] But most physiologists, especially on the
Continent, have now given up the belief in plastic lymph or blastema,
and Virchow[9] maintains that every structure, new or old, is formed by
the proliferation of pre-existing cells. On this view false membranes,
like cancerous or other tumours, are merely abnormal developments of
normal growths; and we can thus understand how it is that they resemble
adjoining structures; for instance, that a “false membrane in the
serous cavities acquires a covering of epithelium exactly like that
which covers the original serous membrane; adhesions of the iris may
become black apparently from the production of pigment-cells like those
of the uvea.”[10]

No doubt the power of reparation, though not always perfect, is an
admirable provision, ready for various emergencies, even for such as
occur only at long intervals of time.[11] Yet this power is not more
wonderful than the growth and development of every single creature,
more especially of those which are propagated by fissiparous
generation. This subject has been here noticed, because we may infer
that, when any part or organ is either greatly increased in size or
wholly suppressed through variation and continued selection, the
co-ordinating power of the organisation will continually tend to bring
again all the parts into harmony with one another.

      _On the Effects of the Increased Use and Disuse of Organs._

It is notorious, and we shall immediately adduce proofs, that increased
use or action strengthens muscles, glands, sense-organs, etc.; and that
disuse, on the other hand, weakens them. It has been experimentally
proved by Ranke[12] that the flow of blood is greatly increased towards
any part which is performing work, and sinks again when the part is at
rest. Consequently, if the work is frequent, the vessels increase in
size and the part is better nourished. Paget[13] also accounts for the
long, thick, dark-coloured hairs which occasionally grow, even in young
children, near old-standing inflamed surfaces or fractured bones by an
increased flow of blood to the part. When Hunter inserted the spur of a
cock into the comb, which is well supplied with blood-vessels, it grew
in one case spirally to a length of six inches, and in another case
forward, like a horn, so that the bird could not touch the ground with
its beak. According to the interesting observations of M. Sedillot,[14]
when a portion of one of the bones of the leg of an animal is removed,
the associated bone enlarges till it attains a bulk equal to that of
the two bones, of which it has to perform the functions. This is best
exhibited in dogs in which the tibia has been removed; the companion
bone, which is naturally almost filiform and not one-fifth the size of
the other, soon acquires a size equal to or greater than that of the
tibia. Now, it is at first difficult to believe that increased weight
acting on a straight bone could, by alternately increasing and
diminishing the pressure, cause the blood to flow more freely in the
vessels which permeate the periosteum and thus supply more nutriment to
the bone. Nevertheless the observations adduced by Mr. Spencer,[15] on
the strengthening of the bowed bones of rickety children, along their
concave sides, leads to the belief that this is possible.

The rocking of the stem of a tree increases in a marked manner the
growth of the woody tissue in the parts which are strained. Prof. Sachs
believes, from reasons which he assigns, that this is due to the
pressure of the bark being relaxed in such parts, and not as Knight and
H. Spencer maintain, to an increased flow of sap caused by the movement
of the trunk.[16] But hard woody tissue may be developed without the
aid of any movement, as we see with ivy closely attached to an old
wall. In all such cases, it is very difficult to distinguish between
the effects of long-continued selection and those which follow from the
increased action of the part, or directly from some other cause. Mr. H.
Spencer[17] acknowledges this difficulty, and gives as an instance the
thorns on trees and the shells of nuts. Here we have extremely hard
woody tissue without the possibility of any movement, and without, as
far as we can see, any other directly exciting cause; and as the
hardness of these parts is of manifest service to the plant, we may
look at the result as probably due to the selection of so-called
spontaneous variations. Every one knows that hard work thickens the
epidermis on the hands; and when we hear that with infants, long before
birth, the epidermis is thicker on the palms and soles of the feet than
on any other part of the body, as was observed with admiration by
Albinus,[18] we are naturally inclined to attribute this to the
inherited effects of long-continued use or pressure. We are tempted to
extend the same view even to the hoofs of quadrupeds; but who will
pretend to determine how far natural selection may have aided in the
formation of structures of such obvious importance to the animal?

That use strengthens the muscles may be seen in the limbs of artisans
who follow different trades; and when a muscle is strengthened, the
tendons, and the crests of bone to which they are attached, become
enlarged; and this must likewise be the case with the blood-vessels and
nerves. On the other hand, when a limb is not used, as by Eastern
fanatics, or when the nerve supplying it with nervous power is
effectually destroyed, the muscles wither. So again, when the eye is
destroyed the optic nerve becomes atrophied, sometimes even in the
course of a few months.[19] The Proteus is furnished with branchiae as
well as with lungs: and Schreibers[20] found that when the animal was
compelled to live in deep water, the branchiae were developed to thrice
their ordinary size, and the lungs were partially atrophied. When, on
the other hand, the animal was compelled to live in shallow water, the
lungs became larger and more vascular, whilst the branchiae disappeared
in a more or less complete degree. Such modifications as these are,
however, of comparatively little value for us, as we do not actually
know that they tend to be inherited.

In many cases there is reason to believe that the lessened use of
various organs has affected the corresponding parts in the offspring.
But there is no good evidence that this ever follows in the course of a
single generation. It appears, as in the case of general or indefinite
variability, that several generations must be subjected to changed
habits for any appreciable result. Our domestic fowls, ducks, and geese
have almost lost, not only in the individual but in the race, their
power of flight; for we do not see a young fowl, when frightened, take
flight like a young pheasant. Hence I was led carefully to compare the
limb-bones of fowls, ducks, pigeons, and rabbits, with the same bones
in the wild parent-species. As the measurements and weights were fully
given in the earlier chapters I need here only recapitulate the
results. With domestic pigeons, the length of the sternum, the
prominence of its crest, the length of the scapulae and furculum, the
length of the wings as measured from tip to tip of the radii, are all
reduced relatively to the same parts in the wild pigeon. The wing and
tail feathers, however, are increased in length, but this may have as
little connection with the use of the wings or tail, as the lengthened
hair on a dog with the amount of exercise which it has habitually
taken. The feet of pigeons, except in the long-beaked races, are
reduced in size. With fowls the crest of the sternum is less prominent,
and is often distorted or monstrous; the wing-bones have become lighter
relatively to the leg-bones, and are apparently a little shorter in
comparison with those of the parent-form, the _Gallus bankiva._ With
ducks, the crest of the sternum is affected in the same manner as in
the foregoing cases: the furculum, coracoids, and scapulae are all
reduced in weight relatively to the whole skeleton: the bones of the
wings are shorter and lighter, and the bones of the legs longer and
heavier, relatively to each other, and relatively to the whole
skeleton, in comparison with the same bones in the wild-duck. The
decreased weight and size of the bones, in the foregoing cases, is
probably the indirect result of the reaction of the weakened muscles on
the bones. I failed to compare the feathers of the wings of the tame
and wild duck; but Gloger[21] asserts that in the wild duck the tips of
the wing-feathers reach almost to the end of the tail, whilst in the
domestic duck they often hardly reach to its base. He remarks also on
the greater thickness of the legs, and says that the swimming membrane
between the toes is reduced; but I was not able to detect this latter
difference.

With the domesticated rabbit the body, together with the whole
skeleton, is generally larger and heavier than in the wild animal, and
the leg-bones are heavier in due proportion; but whatever standard of
comparison be taken, neither the leg-bones nor the scapulae have
increased in length proportionally with the increased dimensions of the
rest of the skeleton. The skull has become in a marked manner narrower,
and, from the measurements of its capacity formerly given, we may
conclude, that this narrowness results from the decreased size of the
brain, consequent on the mentally inactive life led by these
closely-confined animals.

We have seen in the eighth chapter that silk-moths, which have been
kept during many centuries closely confined, emerge from their cocoons
with their wings distorted, incapable of flight, often greatly reduced
in size, or even, according to Quatrefages, quite rudimentary. This
condition of the wings may be largely owing to the same kind of
monstrosity which often affects wild Lepidoptera when artificially
reared from the cocoon; or it may be in part due to an inherent
tendency, which is common to the females of many Bombycidae, to have
their wings in a more or less rudimentary state; but part of the effect
may be attributed to long-continued disuse.

From the foregoing facts there can be no doubt that with our anciently
domesticated animals, certain bones have increased or decreased in size
and weight owing to increased or decreased use; but they have not been
modified, as shown in the earlier chapters, in shape or structure. With
animals living a free life and occasionally exposed to severe
competition the reduction would tend to be greater, as it would be an
advantage to them to have the development of every superfluous part
saved. With highly-fed domesticated animals, on the other hand, there
seems to be no economy of growth, nor any tendency to the elimination
of superfluous details. But to this subject I shall recur.

Turning now to more general observations, Nathusius has shown that with
the improved races of the pig, the shortened legs and snout, the form
of the articular condyles of the occiput, and the position of the jaws
with the upper canine teeth projecting in a most anomalous manner in
front of the lower canines, may be attributed to these parts not having
been fully exercised. For the highly-cultivated races do not travel in
search of food, nor root up the ground with their ringed muzzles.[22]
These modifications of structure, which are all strictly inherited,
characterise several improved breeds, so that they cannot have been
derived from any single domestic stock. With respect to cattle,
Professor Tanner has remarked that the lungs and liver in the improved
breeds “are found to be considerably reduced in size when compared with
those possessed by animals having perfect liberty”;[23] and the
reduction of these organs affects the general shape of the body. The
cause of the reduced lungs in highly-bred animals which take little
exercise is obvious; and perhaps the liver may be affected by the
nutritious and artificial food on which they largely subsist. Again,
Dr. Wilckens asserts[24] that various parts of the body certainly
differ in Alpine and lowland breeds of several domesticated animals,
owing to their different habits of life; for instance, the neck and
fore-legs in length, and the hoofs in shape.

It is well known that, when an artery is tied, the anastomosing
branches, from being forced to transmit more blood, increase in
diameter; and this increase cannot be accounted for by mere extension,
as their coats gain in strength. With respect to glands, Sir J. Paget
observes that “when one kidney is destroyed the other often becomes
much larger, and does double work.”[25] If we compare the size of the
udders and their power of secretion in cows which have been long
domesticated, and in certain breeds of the goat in which the udders
nearly touch the ground, with these organs in wild or half-domesticated
animals, the difference is great. A good cow with us daily yields more
than five gallons, or forty pints of milk, whilst a first-rate animal,
kept, for instance, by the Damaras of South Africa,[26] “rarely gives
more than two or three pints of milk daily, and, should her calf be
taken from her, she absolutely refuses to give any.” We may attribute
the excellence of our cows and of certain goats, partly to the
continued selection of the best milking animals, and partly to the
inherited effects of the increased action, through man’s art, of the
secreting glands.

It is notorious that short-sight is inherited; and we have seen in the
twelfth chapter from the statistical researches of M. Giraud-Teulon,
that the habit of viewing near objects gives a tendency to short-sight.
Veterinarians are unanimous that horses are affected with spavins,
splints, ringbones, etc., from being shod and from travelling on hard
roads, and they are almost equally unanimous that a tendency to these
malformations is transmitted. Formerly horses were not shod in North
Carolina, and it has been asserted that they did not then suffer from
these diseases of the legs and feet.[27]

Our domesticated quadrupeds are all descended, as far as is known, from
species having erect ears; yet few kinds can be named, of which at
least one race has not drooping ears. Cats in China, horses in parts of
Russia, sheep in Italy and elsewhere, the guinea-pig formerly in
Germany, goats and cattle in India, rabbits, pigs, and dogs in all
long-civilised countries have dependent ears. With wild animals, which
constantly use their ears like funnels to catch every passing sound,
and especially to ascertain the direction whence it comes, there is
not, as Mr. Blyth has remarked, any species with drooping ears except
the elephant. Hence the incapacity to erect the ears is certainly in
some manner the result of domestication; and this incapacity has been
attributed by various authors[28] to disuse, for animals protected by
man are not compelled habitually to use their ears. Col. Hamilton
Smith[29] states that in ancient effigies of the dog, “with the
exception of one Egyptian instance, no sculpture of the earlier Grecian
era produces representations of hounds with completely drooping ears;
those with them half pendulous are missing in the most ancient; and
this character increases, by degrees, in the works of the Roman
period.” Godron also has remarked “that the pigs of the ancient
Egyptians had not their ears enlarged and pendent.”[30] But it is
remarkable that the drooping of the ear is not accompanied by any
decrease in size; on the contrary, animals so different as fancy
rabbits, certain Indian breeds of the goat, our petted spaniels,
blood-hounds, and other dogs, have enormously elongated ears, so that
it would appear as if their weight had caused them to droop, aided
perhaps by disuse. With rabbits, the drooping of the much elongated
ears has affected even the structure of the skull.

The tail of no wild animal, as remarked to me by Mr. Blyth, is curled;
whereas pigs and some races of dogs have their tails much curled. This
deformity, therefore, appears to be the result of domestication, but
whether in any way connected with the lessened use of the tail is
doubtful.

The epidermis on our hands is easily thickened, as every one knows, by
hard work. In a district of Ceylon the sheep have “horny callosities
that defend their knees, and which arise from their habit of kneeling
down to crop the short herbage, and this distinguishes the Jaffna
flocks from those of other portions of the island;” but it is not
stated whether this peculiarity is inherited.[31]

The mucous membrane which lines the stomach is continuous with the
external skin of the body; therefore it is not surprising that its
texture should be affected by the nature of the food consumed, but
other and more interesting changes likewise follow. Hunter long ago
observed that the muscular coat of the stomach of a gull (_Larus
tridactylus_) which had been fed for a year chiefly on grain was
thickened; and, according to Dr. Edmondston, a similar change
periodically occurs in the Shetland Islands in the stomach of the
_Larus argentatus,_ which in the spring frequents the cornfields and
feeds on the seed. The same careful observer has noticed a great change
in the stomach of a raven which had been long fed on vegetable food. In
the case of an owl (_Strix grallaria_), similarly treated, Menetries
states that the form of the stomach was changed, the inner coat became
leathery, and the liver increased in size. Whether these modifications
in the digestive organs would in the course of generations become
inherited is not known.[32]

The increased or diminished length of the intestines, which apparently
results from changed diet, is a more remarkable case, because it is
characteristic of certain animals in their domesticated condition, and
therefore must be inherited. The complex absorbent system, the
blood-vessels, nerves, and muscles, are necessarily all modified
together with the intestines. According to Daubenton, the intestines of
the domestic cat are one-third longer than those of the wild cat of
Europe; and although this species is not the parent-stock of the
domestic animal, yet, as Isidore Geoffroy has remarked, the several
species of cats are so closely allied that the comparison is probably a
fair one. The increased length appears to be due to the domestic cat
being less strictly carnivorous in its diet than any wild feline
species; for instance, I have seen a French kitten eating vegetables as
readily as meat. According to Cuvier, the intestines of the
domesticated pig exceed greatly in proportionate length those of the
wild boar. In the tame and wild rabbit the change is of an opposite
nature, and probably results from the nutritious food given to the tame
rabbit.[33]

_Changed and inherited Habits of Life._—This subject, as far as the
mental powers of animals are concerned, so blends into instinct, that I
will here only remind the reader of such cases as the tameness of our
domesticated animals—the pointing or retrieving of dogs— their not
attacking the smaller animals kept by man—and so forth. How much of
these changes ought to be attributed to mere habit, and how much to the
selection of individuals which have varied in the desired manner,
irrespectively of the special circumstances under which they have been
kept, can seldom be told.

We have already seen that animals may be habituated to a changed diet;
but some additional instances may be given. In the Polynesian Islands
and in China the dog is fed exclusively on vegetable matter, and the
taste for this kind of food is to a certain extent inherited.[34] Our
sporting dogs will not touch the bones of game birds, whilst most other
dogs devour them with greediness. In some parts of the world sheep have
been largely fed on fish. The domestic hog is fond of barley, the wild
boar is said to disdain it; and the disdain is partially inherited, for
some young wild pigs bred in captivity showed an aversion for this
grain, whilst others of the same brood relished it.[35] One of my
relations bred some young pigs from a Chinese sow by a wild Alpine
boar; they lived free in the park, and were so tame that they came to
the house to be fed; but they would not touch swill, which was devoured
by the other pigs. An animal when once accustomed to an unnatural diet,
which can generally be effected only during youth, dislikes its proper
food, as Spallanzani found to be the case with a pigeon which had been
long fed on meat. Individuals of the same species take to new food with
different degrees of readiness; one horse, it is stated, soon learned
to eat meat, whilst another would have perished from hunger rather than
have partaken of it.[36] The caterpillars of the _Bombyx hesperus_ feed
in a state of nature on the leaves of the _Café diable,_ but, after
having been reared on the Ailanthus, they would not touch the _ Café
diable,_ and actually died of hunger.[37]

It has been found possible to accustom marine fish to live in fresh
water; but as such changes in fish and other marine animals have been
chiefly observed in a state of nature, they do not properly belong to
our present subject. The period of gestation and of maturity, as shown
in the earlier chapters,—the season and the frequency of the act of
breeding,—have all been greatly modified under domestication. With the
Egyptian goose the rate of change with respect to the season has been
recorded.[38] The wild drake pairs with one female, the domestic drake
is polygamous. Certain breeds of fowls have lost the habit of
incubation. The paces of the horse, and the manner of flight of certain
breeds of the pigeon, have been modified and are inherited. Cattle,
horses, and pigs have learnt to browse under water in the St. John’s
River, East Florida, where the Vallisneria has been largely
naturalised. The cows were observed by Prof. Wyman to keep their heads
immersed for “a period varying from fifteen to thirty-five
seconds.”[39] The voice differs much in certain kinds of fowls and
pigeons. Some varieties are clamorous and others silent, as the Call
and common duck, or the Spitz and pointer dog. Every one knows how the
breeds of the dog differ from one another in their manner of hunting,
and in their ardour after different kinds of game or vermin.

With plants the period of vegetation is easily changed and is
inherited, as in the case of summer and winter wheat, barley, and
vetches; but to this subject we shall immediately return under
acclimatisation. Annual plants sometimes become perennial under a new
climate, as I hear from Dr. Hooker is the case with the stock and
mignonette in Tasmania. On the other hand, perennials sometimes become
annuals, as with the Ricinus in England, and as, according to Captain
Mangles, with many varieties of the heartsease. Von Berg[40] raised
from seed of _Verbascum phœniceum,_ which is usually a biennial, both
annual and perennial varieties. Some deciduous bushes become evergreen
in hot countries.[41] Rice requires much water, but there is one
variety in India which can be grown without irrigation.[42] Certain
varieties of the oat and of our other cereals are best fitted for
certain soils.[43] Endless similar facts could be given in the animal
and vegetable kingdoms. They are noticed here because they illustrate
analogous differences in closely allied natural species, and because
such changed habits of life, whether due to habit, or to the direct
action of external conditions, or to so-called spontaneous variability,
would be apt to lead to modifications of structure.

_Acclimatisation._—From the previous remarks we are naturally led to
the much disputed subject of acclimatisation. There are two distinct
questions: Do varieties descended from the same species differ in their
power of living under different climates? And secondly, if they so
differ, how have they become thus adapted? We have seen that European
dogs do not succeed well in India, and it is asserted,[44] that no one
has there succeeded in keeping the Newfoundland long alive; but then it
may be argued, and probably with truth, that these northern breeds are
specifically distinct from the native dogs which flourish in India. The
same remark may be made with respect to different breeds of sheep, of
which, according to Youatt,[45] not one brought “from a torrid climate
lasts out the second year,” in the Zoological Gardens. But sheep are
capable of some degree of acclimatisation, for Merino sheep bred at the
Cape of Good Hope have been found far better adapted for India than
those imported from England.[46] It is almost certain that all the
breeds of the fowl are descended from one species; but the Spanish
breed, which there is good reason to believe originated near the
Mediterranean,[47] though so fine and vigorous in England, suffers more
from frost than any other breed. The Arrindy silk moth introduced from
Bengal, and the Ailanthus moth from the temperate province of Shan
Tung, in China, belong to the same species, as we may infer from their
identity in the caterpillar, cocoon, and mature states;[48] yet they
differ much in constitution: the Indian form “will flourish only in
warm latitudes,” the other is quite hardy and withstands cold and rain.

Plants are more strictly adapted to climate than are animals. The
latter when domesticated withstand such great diversities of climate,
that we find nearly the same species in tropical and temperate
countries; whilst the cultivated plants are widely dissimilar. Hence a
larger field is open for inquiry in regard to the acclimatisation of
plants than of animals. It is no exaggeration to say that with almost
every plant which has long been cultivated, varieties exist which are
endowed with constitutions fitted for very different climates; I will
select only a few of the more striking cases, as it would be tedious to
give all. In North America numerous fruit-trees have been raised, and
in horticultural publications,—for instance, in that by Downing,—lists
are given of the varieties which are best able to withstand the severe
climate of the northern States and Canada. Many American varieties of
the pear, plum, and peach are excellent in their own country, but until
recently, hardly one was known that succeeded in England; and with
apples,[49] not one succeeds. Though the American varieties can
withstand a severer winter than ours, the summer here is not hot
enough. Fruit-trees have also originated in Europe with different
constitutions, but they are not much noticed, because nurserymen here
do not supply wide areas. The Forelle pear flowers early, and when the
flowers have just set, and this is the critical period, they have been
observed, both in France and England, to withstand with complete
impunity a frost of 18 deg and even 14° Fahr., which killed the
flowers, whether fully expanded or in bud, of all other kinds of
pears.[50] This power in the flower of resisting cold and afterwards
producing fruit does not invariably depend, as we know on good
authority,[51] on general constitutional vigour. In proceeding
northward, the number of varieties which are found capable of resisting
the climate rapidly decreases, as may be seen in the list of the
varieties of the cherry, apple, and pear, which can be cultivated in
the neighbourhood of Stockholm.[52] Near Moscow, Prince Troubetzkoy
planted for experiment in the open ground several varieties of the
pear, but one alone, the _Poire sans Pepins,_ withstood the cold of
winter.[53] We thus see that our fruit-trees, like distinct species of
the same genus, certainly differ from each other in their
constitutional adaptation to different climates.

With the varieties of many plants, the adaptation to climate is often
very close. Thus it has been proved by repeated trials “that few if any
of the English varieties of wheat are adapted for cultivation in
Scotland”;[54] but the failure in this case is at first only in the
quantity, though ultimately in the quality, of the grain produced. The
Rev. M. J. Berkeley sowed wheat-seed from India, and got “the most
meagre ears,” on land which would certainly have yielded a good crop
from English wheat.[55] In these cases varieties have been carried from
a warmer to a cooler climate; in the reverse case, as “when wheat was
imported directly from France into the West Indian Islands, it produced
either wholly barren spikes or furnished with only two or three
miserable seeds, while West Indian seed by its side yielded an enormous
harvest.”[56] Here is another case of close adaptation to a slightly
cooler climate; a kind of wheat which in England may be used
indifferently either as a winter or summer variety, when sown under the
warmer climate of Grignan, in France, behaved exactly as if it had been
a true winter wheat.[57]

Botanists believe that all the varieties of maize belong to the same
species; and we have seen that in North America, in proceeding
northward, the varieties cultivated in each zone produce their flowers
and ripen their seed within shorter and shorter periods. So that the
tall, slowly maturing southern varieties do not succeed in New England,
and the New English varieties do not succeed in Canada. I have not met
with any statement that the southern varieties are actually injured or
killed by a degree of cold which the northern varieties can withstand
with impunity, though this is probable; but the production of early
flowering and early seeding varieties deserves to be considered as one
form of acclimatisation. Hence it has been found possible, according to
Kalm, to cultivate maize further and further northwards in America. In
Europe, also, as we learn from the evidence given by Alph. De Candolle,
the culture of maize has extended since the end of the last century
thirty leagues north of its former boundary.[58] On the authority of
Linnæus,[59] I may quote an analogous case, namely, that in Sweden
tobacco raised from home-grown seed ripens its seed a month sooner and
is less liable to miscarry than plants raised from foreign seed.

With the Vine, differently from the maize, the line of practical
culture has retreated a little southward since the middle ages;[60] but
this seems due to commerce being now easier, so that it is better to
import wine from the south than to make it in northern districts.
Nevertheless the fact of the vine not having spread northward shows
that acclimatisation has made no progress during several centuries.
There is, however, a marked difference in the constitution of the
several varieties,— some being hardy, whilst others, like the muscat of
Alexandria, require a very high temperature to come to perfection.
According to Labat,[61] vines taken from France to the West Indies
succeed with extreme difficulty, whilst those imported from Madeira or
the Canary Islands thrive admirably.

Gallesio gives a curious account of the naturalisation of the Orange in
Italy. During many centuries the sweet orange was propagated
exclusively by grafts, and so often suffered from frosts, that it
required protection. After the severe frost of 1709, and more
especially after that of 1763, so many trees were destroyed, that
seedlings from the sweet orange were raised, and, to the surprise of
the inhabitants, their fruit was found to be sweet. The trees thus
raised were larger, more productive, and hardier than the old kinds;
and seedlings are now continually raised. Hence Gallesio concludes that
much more was effected for the naturalisation of the orange in Italy by
the accidental production of new kinds during a period of about sixty
years, than had been effected by grafting old varieties during many
ages.[62] I may add that Risso[63] describes some Portuguese varieties
of the orange as extremely sensitive to cold, and as much tenderer than
certain other varieties.

The peach was known to Theophrastus, 322 B.C.[64] According to the
authorities quoted by Dr. F. Rolle,[65] it was tender when first
introduced into Greece, and even in the island of Rhodes only
occasionally bore fruit. If this be correct, the peach, in spreading
during the last two thousand years over the middle parts of Europe,
must have become much hardier. At the present day different varieties
differ much in hardiness: some French varieties will not succeed in
England; and near Paris, the _Pavie de Bonneuil_ does not ripen its
fruit till very late in the season, even when grown on a wall; “it is,
therefore, only fit for a very hot southern climate.”[66]

I will briefly give a few other cases. A variety of _Magnolia
grandiflora,_ raised by M. Roy, withstands a temperature several
degrees lower than that which any other variety can resist. With
camellias there is much difference in hardiness. One particular variety
of the Noisette rose withstood the severe frost of 1860 “untouched and
hale amidst a universal destruction of other Noisettes.” In New York
the “Irish yew is quite hardy, but the common yew is liable to be cut
down.” I may add that there are varieties of the sweet potato
(_Convolvulus batatas_) which are suited for warmer, as well as for
colder, climates.[67]

The plants as yet mentioned have been found capable of resisting an
unusual degree of cold or heat, when fully grown. The following cases
refer to plants whilst young. In a large bed of young Araucarias of the
same age, growing close together and equally exposed, it was
observed,[68] after the unusually severe winter of 1860-61, that, “in
the midst of the dying, numerous individuals remained on which the
frost had absolutely made no kind of impression.” Dr. Lindley, after
alluding to this and other similar cases, remarks, “Among the lessons
which the late formidable winter has taught us, is that, even in their
power of resisting cold, individuals of the same species of plants are
remarkably different.” Near Salisbury, there was a sharp frost on the
night of May 24, 1836, and all the French beans (_Phaseolus vulgaris_)
in a bed were killed except about one in thirty, which completely
escaped.[69] On the same day of the month, but in the year 1864, there
was a severe frost in Kent, and two rows of scarlet-runners (_P.
multiflorus_) in my garden, containing 390 plants of the same age and
equally exposed, were all blackened and killed except about a dozen
plants. In an adjoining row of “Fulmer’s dwarf bean” (_P. vulgaris_),
one single plant escaped. A still more severe frost occurred four days
afterwards, and of the dozen plants which had previously escaped only
three survived; these were not taller or more vigorous than the other
young plants, but they escaped completely, with not even the tips of
their leaves browned. It was impossible to behold these three plants,
with their blackened, withered, and dead brethren all around, and not
see at a glance that they differed widely in constitutional power of
resisting frost.

This work is not the proper place to show that wild plants of the same
species, naturally growing at different altitudes or under different
latitudes, become to a certain extent acclimatised, as is proved by the
different behaviour of their seedlings when raised in another country.
In my ‘Origin of Species’ I have alluded to some cases, and I could add
many others. One instance must suffice: Mr. Grigor, of Forres,[70]
states that seedlings of the Scotch fir (_Pinus sylvestris_), raised
from seed from the Continent and from the forests of Scotland, differ
much. “The difference is perceptible in one-year-old, and more so in
two-year-old seedlings; but the effects of the winter on the second
year’s growth almost uniformly make those from the Continent quite
brown, and so damaged, that by the month of March they are quite
unsaleable, while the plants from the native Scotch pine, under the
same treatment, and standing alongside, although considerably shorter,
are rather stouter and quite green, so that the beds of the one can be
known from the other when seen from the distance of a mile.” Closely
similar facts have been observed with seedling larches.

Hardy varieties would alone be valued or noticed in Europe; whilst
tender varieties, requiring more warmth, would generally be neglected;
but such occasionally arise. Thus Loudon[71] describes a Cornish
variety of the elm which is almost an evergreen, and of which the
shoots are often killed by the autumnal frosts, so that its timber is
of little value. Horticulturists know that some varieties are much more
tender than others: thus all the varieties of the broccoli are more
tender than cabbages; but there is much difference in this respect in
the sub-varieties of the broccoli; the pink and purple kinds are a
little hardier than the white Cape broccoli, “but they are not to be
depended on after the thermometer falls below 24° Fahr.;” the Walcheren
broccoli is less tender than the Cape, and there are several varieties
which will stand much severer cold than the Walcheren.[72] Cauliflowers
seed more freely in India than cabbages.[73] To give one instance with
flowers: eleven plants raised from a hollyhock, called the _Queen of
the Whites,_[74] were found to be much more tender than various other
seedlings. It may be presumed that all tender varieties would succeed
better under a climate warmer than ours. With fruit-trees, it is well
known that certain varieties, for instance of the peach, stand forcing
in a hot-house better than others; and this shows either pliability of
organisation or some constitutional difference. The same individual
cherry-tree, when forced, has been observed during successive years
gradually to change its period of vegetation.[75] Few pelargoniums can
resist the heat of a stove, but _Alba Multiflora_ will, as a most
skilful gardener asserts, “stand pine-apple top and bottom heat the
whole winter; without looking any more drawn than if it had stood in a
common greenhouse; and _ Blanche Fleur_ seems as if it had been made on
purpose for growing in winter, like many bulbs, and to rest all
summer.”[76] There can hardly be a doubt that the _Alba Multiflora_
pelargonium must have a widely different constitution from that of most
other varieties of this plant; it would probably withstand even an
equatorial climate.

We have seen that according to Labat the vine and wheat require
acclimatisation in order to succeed in the West Indies. Similar facts
have been observed at Madras: “two parcels of mignonette-seed, one
direct from Europe, the other saved at Bangalore (of which the mean
temperature is much below that of Madras), were sown at the same time:
they both vegetated equally favourably, but the former all died off a
few days after they appeared above ground; the latter still survive,
and are vigorous, healthy plants.” “So again, turnip and carrot seed
saved at Hyderabad are found to answer better at Madras than seed from
Europe or from the Cape of Good Hope.”[77] Mr. J. Scott of the Calcutta
Botanic Gardens, informs me that seeds of the sweet-pea (_Lathyrus
odoratus_) imported from England produce plants, with thick, rigid
stems and small leaves, which rarely blossom and never yield seed;
plants raised from French seed blossom sparingly, but all the flowers
are sterile; on the other hand, plants raised from sweet-peas grown
near Darjeeling in Upper India, but originally derived from England,
can be successfully cultivated on the plains of India; for they flower
and seed profusely, and their stems are lax and scandent. In some of
the foregoing cases, as Dr. Hooker has remarked to me, the greater
success may perhaps be attributed to the seeds having been more fully
ripened under a more favourable climate; but this view can hardly be
extended to so many cases, including plants, which, from being
cultivated under a climate hotter than their native one, become fitted
for a still hotter climate. We may therefore safely conclude that
plants can to a certain extent become accustomed to a climate either
hotter or colder than their own; although the latter cases have been
more frequently observed.

We will now consider the means by which acclimatisation may be
effected, namely, through the appearance of varieties having a
different constitution, and through the effects of habit. In regard to
new varieties, there is no evidence that a change in the constitution
of the offspring necessarily stands in any direct relation with the
nature of the climate inhabited by the parents. On the contrary, it is
certain that hardy and tender varieties of the same species appear in
the same country. New varieties thus spontaneously arising become
fitted to slightly different climates in two different ways; firstly,
they may have the power, either as seedlings or when full-grown, of
resisting intense cold, as with the Moscow pear, or of resisting
intense heat, as with some kinds of Pelargonium, or the flowers may
withstand severe frost, as with the Forelle pear. Secondly, plants may
become adapted to climates widely different from their own, from
flowering and fruiting either earlier or later in the season. In both
these cases the power of acclimatisation by man consists simply in the
selection and preservation of new varieties. But without any direct
intention on his part of securing a hardier variety, acclimatisation
may be unconsciously effected by merely raising tender plants from
seed, and by occasionally attempting their cultivation further and
further northwards, as in the case of maize, the orange and the peach.

How much influence ought to be attributed to inherited habit or custom
in the acclimatisation of animals and plants is a much more difficult
question. In many cases natural selection can hardly have failed to
have come into play and complicated the result. It is notorious that
mountain sheep resist severe weather and storms of snow which would
destroy lowland breeds; but then mountain sheep have been thus exposed
from time immemorial, and all delicate individuals will have been
destroyed, and the hardiest preserved. So with the Arrindy silk-moths
of China and India; who can tell how far natural selection may have
taken a share in the formation of the two races, which are now fitted
for such widely different climates? It seems at first probable that the
many fruit-trees which are so well fitted for the hot summers and cold
winters of North America, in contrast with their poor success under our
climate, have become adapted through habit; but when we reflect on the
multitude of seedlings annually raised in that country, and that none
would succeed unless born with a fitting constitution, it is possible
that mere habit may have done nothing towards their acclimatisation. On
the other hand, when we hear that Merino sheep, bred during no great
number of generations at the Cape of Good Hope—that some European
plants raised during only a few generations in the cooler parts of
India, withstand the hotter parts of that country much better than the
sheep or seeds imported directly from England, we must attribute some
influence to habit. We are led to the same conclusion when we hear from
Naudin[78] that the races of melons, squashes, and gourds, which have
long been cultivated in Northern Europe, are comparatively more
precocious, and need much less heat for maturing their fruit, than the
varieties of the same species recently brought from tropical regions.
In the reciprocal conversion of summer and winter wheat, barley, and
vetches into each other, habit produces a marked effect in the course
of a very few generations. The same thing apparently occurs with the
varieties of maize, which, when carried from the Southern States of
America, or into Germany, soon became accustomed to their new homes.
With vine-plants taken to the West Indies from Madeira, which are said
to succeed better than plants brought directly from France, we have
some degree of acclimatisation in the individual, independently of the
production of new varieties by seed.

The common experience of agriculturists is of some value, and they
often advise persons to be cautious in trying the productions of one
country in another. The ancient agricultural writers of China recommend
the preservation and cultivation of the varieties peculiar to each
country. During the classical period, Columella wrote, “Vernaculum
pecus peregrino longe præstantius est.”[79]

I am aware that the attempt to acclimatise either animals or plants has
been called a vain chimera. No doubt the attempt in most cases deserves
to be thus called, if made independently of the production of new
varieties endowed with a different constitution. With plants propagated
by buds, habit rarely produces any effect; it apparently acts only
through successive seminal generations. The laurel, bay, laurestinus,
etc., and the Jerusalem artichoke, which are propagated by cuttings or
tubers, are probably now as tender in England as when first introduced;
and this appears to be the case with the potato, which until recently
was seldom multiplied by seed. With plants propagated by seed, and with
animals, there will be little or no acclimatisation unless the hardier
individuals are either intentionally or unconsciously preserved. The
kidney-bean has often been advanced as an instance of a plant which has
not become hardier since its first introduction into Britain. We hear,
however, on excellent authority[80] that some very fine seed, imported
from abroad, produced plants “which blossomed most profusely, but were
nearly all but abortive, whilst plants grown alongside from English
seed podded abundantly;” and this apparently shows some degree of
acclimatisation in our English plants. We have also seen that seedlings
of the kidney-bean occasionally appear with a marked power of resisting
frost; but no one, as far as I can hear, has ever separated such hardy
seedlings, so as to prevent accidental crossing, and then gathered
their seed, and repeated the process year after year. It may, however,
be objected with truth that natural selection ought to have had a
decided effect on the hardiness of our kidney-beans; for the tenderest
individuals must have been killed during every severe spring, and the
hardier preserved. But it should be borne in mind that the result of
increased hardiness would simply be that gardeners, who are always
anxious for as early a crop as possible, would sow their seed a few
days earlier than formerly. Now, as the period of sowing depends much
on the soil and elevation of each district, and varies with the season;
and as new varieties have often been imported from abroad, can we feel
sure that our kidney-beans are not somewhat hardier? I have not been
able, by searching old horticultural works, to answer this question
satisfactorily.

On the whole the facts now given show that, though habit does something
towards acclimatisation, yet that the appearance of constitutionally
different individuals is a far more effective agent. As no single
instance has been recorded either with animals or plants of hardier
individuals having been long and steadily selected, though such
selection is admitted to be indispensable for the improvement of any
other character, it is not surprising that man has done little in the
acclimatisation of domesticated animals and cultivated plants. We need
not, however, doubt that under nature new races and new species would
become adapted to widely different climates, by variation, aided by
habit, and regulated by natural selection.

      _Arrests of Development: Rudimentary and Aborted Organs._

Modifications of structure from arrested development, so great or so
serious as to deserve to be called monstrosities, are not infrequent
with domesticated animals, but, as they differ much from any normal
structure, they require only a passing notice. Thus the whole head may
be represented by a soft nipple-like projection, and the limbs by mere
papillae. These rudiments of limbs are sometimes inherited, as has been
observed in a dog.[81]

Many lesser anomalies appear to be due to arrested development. What
the cause of the arrest may be, we seldom know, except in the case of
direct injury to the embryo. That the cause does not generally act at
an extremely early embryonic period we may infer from the affected
organ seldom being wholly aborted,—a rudiment being generally
preserved. The external ears are represented by mere vestiges in a
Chinese breed of sheep; and in another breed, the tail is reduced “to a
little button, suffocated in a manner, by fat.”[82] In tailless dogs
and cats a stump is left. In certain breeds of fowls the comb and
wattles are reduced to rudiments; in the Cochin-China breed scarcely
more than rudiments of spurs exist. With polled Suffolk cattle,
“rudiments of horns can often be felt at an early age”;[83] and with
species in a state of nature, the relatively great development of
rudimentary organs at an early period of life is highly characteristic
of such organs. With hornless breeds of cattle and sheep, another and
singular kind of rudiment has been observed, namely, minute dangling
horns attached to the skin alone, and which are often shed and grow
again. With hornless goats, according to Desmarest,[84] the bony
protuberance which properly supports the horn exists as a mere
rudiment.

With cultivated plants it is far from rare to find the petals, stamens,
and pistils represented by rudiments, like those observed in natural
species. So it is with the whole seed in many fruits; thus, near
Astrakhan there is a grape with mere traces of seeds, “so small and
lying so near the stalk that they are not perceived in eating the
grape.”[85] In certain varieties of the gourd, the tendrils, according
to Naudin, are represented by rudiments or by various monstrous
growths. In the broccoli and cauliflower the greater number of the
flowers are incapable of expansion, and include rudimentary organs. In
the Feather hyacinth (_Muscari comosum_) in its natural state the upper
and central flowers are brightly coloured but rudimentary; under
cultivation the tendency to abortion travels downwards and outwards,
and all the flowers become rudimentary; but the abortive stamens and
pistils are not so small in the lower as in the upper flowers. In the
_Viburnum opulus,_ on the other hand, the outer flowers naturally have
their organs of fructification in a rudimentary state, and the corolla
is of large size; under cultivation, the change spreads to the centre,
and all the flowers become affected. In the compositae, the so-called
doubling of the flowers consists in the greater development of the
corolla of the central florets, generally accompanied with some degree
of sterility; and it has been observed[86] that the progressive
doubling invariably spreads from the circumference to the centre,—that
is, from the ray florets, which so often include rudimentary organs, to
those of the disc. I may add, as bearing on this subject, that with
Asters, seeds taken from the florets of the circumference have been
found to yield the greatest number of double flowers.[87] In the above
cases we have a natural tendency in certain parts to be rudimentary,
and this under culture spreads either to, or from, the axis of the
plant. It deserves notice, as showing how the same laws govern the
changes which natural species and artificial varieties undergo, that in
the species of Carthamus, one of the Compositae, a tendency to the
abortion of the pappus may be traced extending from the circumference
to the centre of the disc as in the so-called doubling of the flowers
in the members of the same family. Thus, according to A. de
Jussieu,[88] the abortion is only partial in _Carthamus creticus,_ but
more extended in _C. lanatus_; for in this species only two or three of
the central seeds are furnished with a pappus, the surrounding seeds
being either quite naked or furnished with a few hairs; and lastly in
_C. tinctorius,_ even the central seeds are destitute of pappus, and
the abortion is complete.

With animals and plants under domestication, when an organ disappears,
leaving only a rudiment, the loss has generally been sudden, as with
hornless and tailless breeds; and such cases may be ranked as inherited
monstrosities. But in some few cases the loss has been gradual, and has
been effected partly by selection, as with the rudimentary combs and
wattles of certain fowls. We have also seen that the wings of some
domesticated birds have been slightly reduced by disuse, and the great
reduction of the wings in certain silk-moths, with mere rudiments left,
has probably been aided by disuse.

With species in a state of nature, rudimentary organs are extremely
common. Such organs are generally variable, as several naturalists have
observed; for, being useless, they are not regulated by natural
selection, and they are more or less liable to reversion. The same rule
certainly holds good with parts which have become rudimentary under
domestication. We do not know through what steps under nature
rudimentary organs have passed in being reduced to their present
condition; but we so incessantly see in species of the same group the
finest gradations between an organ in a rudimentary and perfect state,
that we are led to believe that the passage must have been extremely
gradual. It may be doubted whether a change of structure so abrupt as
the sudden loss of an organ would ever be of service to a species in a
state of nature; for the conditions to which all organisms are closely
adapted usually change very slowly. Even if an organ did suddenly
disappear in some one individual by an arrest of development,
intercrossing with the other individuals of the same species would tend
to cause its partial reappearance; so that its final reduction could
only be effected by some other means. The most probable view is, that a
part which is now rudimentary, was formerly, owing to changed habits of
life, used less and less, being at the same time reduced in size by
disuse, until at last it became quite useless and superfluous. But as
most parts or organs are not brought into action during an early period
of life, disuse or decreased action will not lead to their reduction
until the organism arrives at a somewhat advanced age; and from the
principle of inheritance at corresponding ages the reduction will be
transmitted to the offspring at the same advanced stage of growth. The
part or organ will thus retain its full size in the embryo, as we know
to be the case with most rudiments. As soon as a part becomes useless,
another principle, that of economy of growth, will come into play, as
it would be an advantage to an organism exposed to severe competition
to save the development of any useless part; and individuals having the
part less developed will have a slight advantage over others. But, as
Mr. Mivart has justly remarked, as soon as a part is much reduced, the
saving from its further reduction will be utterly insignificant; so
that this cannot be effected by natural selection. This manifestly
holds good if the part be formed of mere cellular tissue, entailing
little expenditure of nutriment. How then can the further reduction of
an already somewhat reduced part be effected? That this has occurred
repeatedly under Nature is shown by the many gradations which exist
between organs in a perfect state and the merest vestiges of them. Mr.
Romanes[89] has, I think, thrown much light on this difficult problem.
His view, as far as it can be given in a few words, is as follows: all
parts are somewhat variable and fluctuate in size round an average
point. Now, when a part has already begun from any cause to decrease,
it is very improbable that the variations should be as great in the
direction of increase as of diminution; for the previous reduction
shows that circumstances have not been favourable for its development;
whilst there is nothing to check variations in the opposite direction.
If this be so, the long continued crossing of many individuals
furnished with an organ which fluctuates in a greater degree towards
decrease than towards increase, will slowly but steadily lead to its
diminution. With respect to the complete and absolute abortion of a
part, a distinct principle, which will be discussed in the chapter on
pangenesis, probably comes into action.

With animals and plants reared by man there is no severe or recurrent
struggle for existence, and the principle of economy will not come into
action, so that the reduction of an organ will not thus be aided. So
far, indeed, is this from being the case, that in some few instances
organs, which are naturally rudimentary in the parent-species, become
partially redeveloped in the domesticated descendants. Thus cows, like
most other ruminants, properly have four active and two rudimentary
mamma; but in our domesticated animals, the latter occasionally become
considerably developed and yield milk. The atrophied mammae, which, in
male domesticated animals, including man, have in some rare cases grown
to full size and secreted milk, perhaps offer an analogous case. The
hind feet of dogs naturally include rudiments of a fifth toe, and in
certain large breeds these toes, though still rudimentary, become
considerably developed and are furnished with claws. In the common Hen,
the spurs and comb are rudimentary, but in certain breeds these become,
independently of age or disease of the ovaria, well developed. The
stallion has canine teeth, but the mare has only traces of the alveoli,
which, as I am informed by the eminent veterinarian Mr. G. T. Brown,
frequently contain minute irregular nodules of bone. These nodules,
however, sometimes become developed into imperfect teeth, protruding
through the gums and coated with enamel; and occasionally they grow to
a fourth or even a third of the length of the canines in the stallion.
With plants I do not know whether the redevelopment of rudimentary
organs occurs more frequently under culture than under nature. Perhaps
the pear-tree may be a case in point, for when wild it bears thorns,
which consist of branches in a rudimentary condition and serve as a
protection, but, when the tree is cultivated, they are reconverted into
branches.

REFERENCES

 [1] ‘An Essay on Generation,’ Eng. translat., p. 18; p.t, ‘Lectures on
 Surgical Pathology,’ 1853, vol. i. p. 209.

 [2] ‘An Essay on Animal Reproduction,’ Eng. translat., 1769, p. 79.

 [3] Carpenter’s ‘Principles of Comp. Physiology,’ 1854, p. 479.

 [4] Charlesworth’s ‘Mag. of Nat. Hist.,’ vol. i. 1837, p. 145.

 [5] Paget, ‘Lectures on Surgical Pathology,’ vol. i. p. 239.

 [6] Quoted by Carpenter, ‘Comp. Phys.,’ p. 479.

 [7] Prof. Marey’s discussion on the power of co-adaptation in all
 parts of the organisation is excellent. ‘La Machine Animale,’ 1873,
 chap. ix. _See also_ Paget, ‘Lectures,’ etc., p. 257.

 [8] These cases are given by Blumenbach in his ‘Essay on Generation,’
 pp. 52, 54.

 [9] ‘Cellular Pathology,’ trans. by Dr. Chance, 1860, pp. 27, 441.

 [10] Paget, ‘Lectures on Pathology,’ vol. i. 1853, p. 357.

 [11] Paget, ibid., p. 150.

 [12] ‘Die Blutvertheilung, etc. der Organe,’ 1871, as quoted by
 Jaeger, ‘In Sachen Darwin’s,’ 1874, p. 48. _See also_ H. Spencer ‘The
 Principles of Biology,’ vol. ii. 1866, chap. 3-5.

 [13] ‘Lectures on Pathology,’ 1853, vol. i. p. 71.

 [14] ‘Comptes Rendus,’ Sept. 26th, 1864, p. 539.

 [15] H. Spencer, ‘The Principles of Biology,’ vol. ii. p. 243.

 [16] Ibid., vol. ii. p. 269. Sachs, ‘Text-book of Botany,’ 1875, p.
 734.

 [17] Ibid., vol. ii. p. 273.

 [18] Paget, ‘Lectures on Pathology,’ vol. ii. p. 209.

 [19] Müller’s ‘Phys.,’ Eng. translat., pp. 54, 791. Prof. Reed has
 given (‘Physiological and Anat. Researches,’ p. 10) a curious account
 of the atrophy of the limbs of rabbits after the destruction of the
 nerve.

 [20] Quoted by Lecoq, in ‘Géograph. Bot.,’ tom. i. 1854, p. 182.

 [21] ‘Das Abändern der Vögel,’ 1833, s. 74.

 [22] Nathusius, ‘Die Racen des Schweines,’ 1860, s. 53, 57;
 ‘Vorstudien . . . Schweineschädel,’ 1864, s. 103, 130, 133. Prof.
 Lucae supports and extends the conclusions of Von Nathusius: ‘Der
 Schädel des Maskenschweines,’ 1870.

 [23] ‘Journal of Agriculture of Highland Soc.,’ July 1860, p. 321.

 [24] ‘Landwirth. Wochenblatt,’ No. 10.

 [25] ‘Lectures on Surgical Pathology,’ 1853, vol. i. p. 27.

 [26] Andersson, ‘Travels in South Africa,’ p. 318. For analogous cases
 in South America _see_ Aug. St.-Hilaire ‘Voyage dans la Province de
 Goyaz,’ tom. i. p. 71.

 [27] Brickell’s ‘Nat. Hist. of North Carolina,’ 1739, p. 53.

 [28] Livingstone, quoted by Youatt on Sheep, p. 142. Hodgson in
 ‘Journal of Asiatic Soc. of Bengal,’ vol. xvi. 1847, p. 1006, etc.
 etc. On the other hand, Dr. Wilckens argues strongly against the
 belief that the drooping of the ears is the result of disuse:
 ‘Jahrbuch der deutschen Viehzucht,’ 1866.

 [29] ‘Naturalist’s Library,’ Dogs, vol. ii. 1840, p. 104.

 [30] ‘De l’Espèce,’ tom. i. 1859, p. 367.

 [31] ‘Ceylon,’ by Sir J. E. Tennent, 1859, vol. ii. p. 531.

 [32] For the foregoing statements, _see_ Hunter’s ‘Essays and
 Observations,’ 1861, vol. ii. p. 329; Dr. Edmondston, as quoted in
 Macgillivray’s ‘British Birds,’ vol. v. p. 550: Menetries, as quoted
 in Bronn’s ‘Geschichte der Natur,’ B. ii. s. 110.

 [33] These statements on the intestines are taken from Isidore
 Geoffroy Saint-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. pp. 427, 441.

 [34] Gilbert White, ‘Nat. Hist. Selborne,’ 1825, vol. ii. p. 121.

 [35] Burdach, ‘Traité de Phys.,’ tom. ii. p. 267, as quoted by Dr. P.
 Lucas, ‘L’Héréd. Nat.,’ tom. i. p. 388.

 [36] This and several other cases are given by Colin, ‘Physiologie
 Comp. des Animaux Dom.,’ 1854, tom. i. p. 426.

 [37] M. Michely de Cayenne, in ‘Bull. Soc. d’Acclimat.,’ tom. viii.
 1861, p. 563.

 [38] Quatrefages, ‘Unité de l’Espèce Humaine,’ 1861, p. 79.

 [39] ‘The American Naturalist,’ April 1874, p. 237.

 [40] ‘Flora,’ 1835, B. ii. p. 504.

 [41] Alph. de Candolle, ‘Géograph. Bot.,’ tom. ii. p. 1078.

 [42] Royle, ‘Illustrations of the Botany of the Himalaya,’ p. 19.

 [43] ‘Gardener’s Chronicle,’ 1850, pp. 204, 219.

 [44] Rev. R. Everest, ‘Journal As. Soc. of Bengal,’ vol. iii. p. 19.

 [45] Youatt on Sheep, 1838, p. 491.

 [46] Royle, ‘Prod. Resources of India,’ p. 153.

 [47] Tegetmeier, ‘Poultry Book,’ 1866, p. 102.

 [48] Dr. R. Paterson, in a paper communicated to Bot. Soc. of Canada
 quoted in the ‘Reader,’ 1863, Nov. 13th.

 [49] _See_ remarks by Editor in ‘Gardener’s Chronicle,’ 1848, p. 5.

 [50] ‘Gardener’s Chronicle,’ 1860, p. 938. Remarks by Editor and
 quotation from Decaisne.

 [51] J. de Jonghe, of Brussels, in ‘Gardener’s Chronicle,’ 1857, p.
 612.

 [52] Ch. Martius, ‘Voyage Bot. Côtes Sept. de la Norvège,’ p. 26.

 [53] ‘Journal de l’Acad. Hort. de Gand,’ quoted in ‘Gardener’s
 Chronicle,’ 1859, p. 7.

 [54] ‘Gardener’s Chronicle,’ 1851, p. 396.

 [55] Ibid., 1862, p. 235.

 [56] On the authority of Labat, quoted in ‘Gardener’s Chronicle,’
 1862, p. 235.

 [57] MM. Edwards and Colin, ‘Annal. des Sc. Nat.,’ 2nd series, Bot.,
 tom. v. p. 22.

 [58] ‘Géograph. Bot.,’ p. 337.

 [59] ‘Swedish Acts,’ Eng. translat., 1739-40, vol. i. Kalm, in his
 ‘Travels,’ vol. ii. p. 166, gives an analogous case with cotton-plants
 raised in New Jersey from Carolina seed.

 [60] De Candolle, ‘Géograph. Bot.,’ p. 339.

 [61] ‘Gardener’s Chronicle,’ 1862, p. 235.

 [62] Gallesio, ‘Teoria della Riproduzione Veg.,’ 1816, p. 125; and
 ‘Traité du Citrus,’ 1811, p. 359.

 [63] ‘Essai sur l’Hist. des Orangers,’ 1813, p. 20, etc.

 [64] Alph. de Candolle, ‘Géograph. Bot.,’ p. 882.

 [65] ‘Ch. Darwin’s Lehre von der Entstehung,’ etc., 1862, s. 87.

 [66] Decaisne, quoted in ‘Gardener’s Chronicle,’ 1865, p. 271.

 [67] For the magnolia, _see_ Loudon’s ‘Gardener’s Mag.,’ vol. xiii.
 1837, p. 21. For camellias and roses, _see_ ‘Gardener’s Chronicle,’
 1860, p. 384. For the yew, ‘Journal of Hort.,’ March 3rd, 1863, p.
 174. For sweet potatoes, _see_ Col. von Siebold, in ‘Gardener’s
 Chronicle,’ 1855, p. 822.

 [68] The Editor, ‘Gardener’s Chronicle,’ 1861, p. 239.

 [69] Loudon’s ‘Gardener’s Mag.,’ vol. xii. 1836, p. 378.

 [70] ‘Gardener’s Chronicle,’ 1865, p. 699. Mr. G. Maw gives
 (‘Gardener’s Chronicle,’ 1870, p. 895) a number of striking cases; he
 brought home from southern Spain and northern Africa several plants,
 which he cultivated in England alongside specimens from northern
 districts; and he found a great difference not only in their hardiness
 during the winter, but in the behaviour of some of them during the
 summer.

 [71] ‘Arboretum et Fruticetum,’ vol. iii. p. 1376.

 [72] Mr. Robson, in ‘Journal of Horticulture,’ 1861, p. 23.

 [73] Dr. Bonavia, ‘Report of the Agri.-Hort. Soc. of Oudh,’ 1866.

 [74] ‘Cottage Gardener,’ 1860, April 24th, p. 57.

 [75] ‘Gardener’s Chronicle,’ 1841, p. 291.

 [76] Mr. Beaton, in ‘Cottage Gardener,’ March 20th, 1860, p. 377.
 Queen Mab will also stand stove heat. _See_ ‘Gardener’s Chronicle,’
 1845, p. 226.

 [77] ‘Gardener’s Chronicle,’ 1841, p. 439.

 [78] Quoted by Asa Gray, in ‘Am. Journ. of Sc.,’ 2nd series, Jan.
 1865, p. 106.

 [79] For China, _see_ ‘Mémoire sur les Chinois,’ tom. xi. 1786, p. 60.
 Columella is quoted by Carlier, in ‘Journal de Physique,’ tom. xxiv.
 1784.

 [80] Messrs. Hardy and Son, in ‘Gardener’s Chronicle,’ 1856, p. 589.

 [81] Isid. Geoffroy Saint-Hilaire, ‘Hist. Nat. des Anomalies,’ 1836,
 tom. ii. pp. 210, 223, 224, 395; ‘Philosoph. Transact.,’ 1775, p. 313.

 [82] Pallas, quoted by Youatt on Sheep, p. 25.

 [83] Youatt on Cattle, 1834, p. 174.

 [84] ‘Encyclop. Méthod.,’ 1820, p. 483: _see_ p. 500, on the Indian
 zebu casting its horns. Similar cases in European cattle were given in
 the third chapter.

 [85] Pallas, ‘Travels,’ Eng. Translat., vol. i. p. 243.

 [86] Mr. Beaton, in ‘Journal of Horticulture,’ May 21st, 1861, p. 133.

 [87] Lecoq, ‘De la Fécondation,’ 1862, p. 233.

 [88] ‘Annales du Muséum,’ tom. vi. p. 319.

 [89] I suggested in ‘Nature’ (vol. 8 pp. 432, 505) that with organisms
 subjected to unfavourable conditions all the parts would tend towards
 reduction, and that under such circumstances any part which was not
 kept up to its standard size by natural selection would, owing to
 intercrossing, slowly but steadily decrease. In three subsequent
 communications to ‘Nature’ (March 12, April 9, and July 2, 1874), Mr.
 Romanes gives his improved view.




CHAPTER XXV. LAWS OF VARIATION, _continued._—CORRELATED VARIABILITY.

EXPLANATION OF TERM CORRELATION—CONNECTED WITH
DEVELOPMENT—MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED
SIZE OF PARTS—CORRELATED VARIATION OF HOMOLOGOUS PARTS—FEATHERED FEET
IN BIRDS ASSUMING THE STRUCTURE OF THE WINGS—CORRELATION BETWEEN THE
HEAD AND THE EXTREMITIES—BETWEEN THE SKIN AND DERMAL APPENDAGES—BETWEEN
THE ORGANS OF SIGHT AND HEARING—CORRELATED MODIFICATIONS IN THE ORGANS
OF PLANTS—CORRELATED MONSTROSITIES—CORRELATION BETWEEN THE SKULL AND
EARS—SKULL AND CREST OF FEATHERS—SKULL AND HORNS—CORRELATION OF GROWTH
COMPLICATED BY THE ACCUMULATED EFFECTS OF NATURAL SELECTION—COLOUR AS
CORRELATED WITH CONSTITUTIONAL PECULIARITIES.


All parts of the organisation are to a certain extent connected
together; but the connection may be so slight that it hardly exists, as
with compound animals or the buds on the same tree. Even in the higher
animals various parts are not at all closely related; for one part may
be wholly suppressed or rendered monstrous without any other part of
the body being affected. But in some cases, when one part varies,
certain other parts always, or nearly always, simultaneously vary; they
are then subject to the law of correlated variation. The whole body is
admirably co-ordinated for the peculiar habits of life of each organic
being, and may be said, as the Duke of Argyll insists in his ‘Reign of
Law’ to be correlated for this purpose. Again, in large groups of
animals certain structures always co-exist: for instance, a peculiar
form of stomach with teeth of peculiar form, and such structures may in
one sense be said to be correlated. But these cases have no necessary
connection with the law to be discussed in the present chapter; for we
do not know that the initial or primary variations of the several parts
were in any way related: slight modifications or individual differences
may have been preserved, first in one and then in another part, until
the final and perfectly co-adapted structure was acquired; but to this
subject I shall presently recur. Again, in many groups of animals the
males alone are furnished with weapons, or are ornamented with gay
colours; and these characters manifestly stand in some sort of
correlation with the male reproductive organs, for when the latter are
destroyed these characters disappear. But it was shown in the twelfth
chapter that the very same peculiarity may become attached at any age
to either sex, and afterwards be exclusively transmitted to the same
sex at a corresponding age. In these cases we have inheritance limited
by both sex and age; but we have no reason for supposing that the
original cause of the variation was necessarily connected with the
reproductive organs, or with the age of the affected being.

In cases of true correlated variation, we are sometimes able to see the
nature of the connection; but in most cases it is hidden from us, and
certainly differs in different cases. We can seldom say which of two
correlated parts first varies, and induces a change in the other; or
whether the two are the effects of some common cause. Correlated
variation is an important subject for us; for when one part is modified
through continued selection, either by man or under nature, other parts
of the organisation will be unavoidably modified. From this correlation
it apparently follows that with our domesticated animals and plants,
varieties rarely or never differ from one another by a single character
alone.

One of the simplest cases of correlation is that a modification which
arises during an early stage of growth tends to influence the
subsequent development of the same part, as well as of other and
intimately connected parts. Isidore Geoffroy Saint-Hilaire states[1]
that this may constantly be observed with monstrosities in the animal
kingdom; and Moquin-Tandon[2] remarks, that, as with plants the axis
cannot become monstrous without in some way affecting the organs
subsequently produced from it, so axial anomalies are almost always
accompanied by deviations of structure in the appended parts. We shall
presently see that with short-muzzled races of the dog certain
histological changes in the basal elements of the bones arrest their
development and shorten them, and this affects the position of the
subsequently developed molar teeth. It is probable that certain
modifications in the larvæ of insects would affect the structure of the
mature insects. But we must be careful not to extend this view too far,
for during the normal course of development, certain species pass
through an extraordinary course of change, whilst other and closely
allied species arrive at maturity with little change of structure.

Another simple case of correlation is that with the increased or
decreased dimensions of the whole body, or of any particular part,
certain organs are increased or diminished in number, or are otherwise
modified. Thus pigeon fanciers have gone on selecting pouters for
length of body, and we have seen that their vertebrae are generally
increased not only in size but in number, and their ribs in breadth.
Tumblers have been selected for their small bodies, and their ribs and
primary wing-feathers are generally lessened in number. Fantails have
been selected for their large widely-expanded tails, with numerous
tail-feathers, and the caudal vertebrae are increased in size and
number. Carriers have been selected for length of beak, and their
tongues have become longer, but not in strict accordance with the
length of beak. In this latter breed and in others having large feet,
the number of the scutellae on the toes is greater than in the breeds
with small feet. Many similar cases could be given. In Germany it has
been observed that the period of gestation is longer in large than in
small breeds of cattle. With our highly-improved breeds of all kinds,
the periods of maturity and of reproduction have advanced with respect
to the age of the animal; and, in correspondence with this, the teeth
are now developed earlier than formerly, so that, to the surprise of
agriculturists, the ancient rules for judging of the age of an animal
by the state of its teeth are no longer trustworthy.[3]

_Correlated Variation of Homologous Parts._—Parts which are homologous
tend to vary in the same manner; and this is what might have been
expected, for such parts are identical in form and structure during an
early period of embryonic development, and are exposed in the egg or
womb to similar conditions. The symmetry, in most kinds of animals, of
the corresponding or homologous organs on the right and left sides of
the body, is the simplest case in point; but this symmetry sometimes
fails, as with rabbits having only one ear, or stags with one horn, or
with many-horned sheep which sometimes carry an additional horn on one
side of their heads. With flowers which have regular corollas, all the
petals generally vary in the same manner, as we see in the complicated
and symmetrical pattern, on the flowers, for instance, of the Chinese
pink; but with irregular flowers, though the petals are of course
homologous, this symmetry often fails, as with the varieties of the
_Antirrhinum_ or snapdragon, or that variety of the kidney-bean
(_Phaseolus_) which has a white standard-petal.

In the Vertebrata the front and hind limbs are homologous, and they
tend to vary in the same manner, as we see in long and short legged, or
in thick and thin legged races of the horse and dog. Isidore
Geoffroy[4] has remarked on the tendency of supernumerary digits in man
to appear, not only on the right and left sides, but on the upper and
lower extremities. Meckel has insisted[5] that, when the muscles of the
arm depart in number or arrangement from their proper type, they almost
always imitate those of the leg; and so conversely the varying muscles
of the leg imitate the normal muscles of the arm.

In several distinct breeds of the pigeon and fowl, the legs and the two
outer toes are heavily feathered, so that in the trumpeter pigeon they
appear like little wings. In the feather-legged bantam the “boots” or
feathers, which grow from the outside of the leg and generally from the
two outer toes, have, according to the excellent authority of Mr.
Hewitt,[6] been seen to exceed the wing-feathers in length, and in one
case were actually nine and a half inches long! As Mr. Blyth has
remarked to me, these leg-feathers resemble the primary wing-feathers,
and are totally unlike the fine down which naturally grows on the legs
of some birds, such as grouse and owls. Hence it may be suspected that
excess of food has first given redundancy to the plumage, and then that
the law of homologous variation has led to the development of feathers
on the legs, in a position corresponding with those on the wing,
namely, on the outside of the tarsi and toes. I am strengthened in this
belief by the following curious case of correlation, which for a long
time seemed to me utterly inexplicable, namely, that in pigeons of any
breed, if the legs are feathered, the two outer toes are partially
connected by skin. These two outer toes correspond with our third and
fourth toes.[7] Now, in the wing of the pigeon or of any other bird,
the first and fifth digits are aborted; the second is rudimentary and
carries the so-called “bastard-wing;” whilst the third and fourth
digits are completely united and enclosed by skin, together forming the
extremity of the wing. So that in feather-footed pigeons, not only does
the exterior surface support a row of long feathers, like
wing-feathers, but the very same digits which in the wing are
completely united by skin become partially united by skin in the feet;
and thus by the law of the correlated variation of homologous parts we
can understand the curious connection of feathered legs and membrane
between the two outer toes.

Andrew Knight[8] has remarked that the face or head and the limbs
usually vary together in general proportions. Compare, for instance,
the limbs of a dray and race horse, or of a greyhound and mastiff. What
a monster a greyhound would appear with the head of a mastiff! The
modern bulldog, however, has fine limbs, but this is a
recently-selected character. From the measurements given in the sixth
chapter, we see that in several breeds of the pigeon the length of the
beak and the size of the feet are correlated. The view which, as before
explained, seems the most probable is, that disuse in all cases tends
to diminish the feet, the beak becoming at the same time shorter
through correlation; but that in some few breeds in which length of
beak has been a selected point, the feet, notwithstanding disuse, have
increased in size through correlation. In the following case some kind
of correlation is seen to exist between the feet and beak: several
specimens have been sent to Mr. Bartlett at different times, as hybrids
between ducks and fowls, and I have seen one; these were, as might be
expected, ordinary ducks in a semi-monstrous condition, and in all of
them the swimming-web between the toes was quite deficient or much
reduced, and in all the beak was narrow and ill-shaped.

With the increased length of the beak in pigeons, not only the tongue
increases in length, but likewise the orifice of the nostrils. But the
increased length of the orifice of the nostrils perhaps stands in
closer correlation with the development of the corrugated skin or
wattle at the base of the beak, for when there is much wattle round the
eyes, the eyelids are greatly increased or even doubled in length.

There is apparently some correlation even in colour between the head
and the extremities. Thus with horses a large white star or blaze on
the forehead is generally accompanied by white feet.[9] With white
rabbits and cattle, dark marks often co-exist on the tips of the ears
and on the feet. In black and tan dogs of different breeds,
tan-coloured spots over the eyes and tan-coloured feet almost
invariably go together. These latter cases of connected colouring may
be due either to reversion or to analogous variation,—subjects to which
I shall hereafter return,—but this does not necessarily determine the
question of their original correlation. Mr. H. W. Jackson informs me
that he has observed many hundred white-footed cats, and he finds that
all are more or less conspicuously marked with white on the front of
the neck or chest.

The lopping forwards and downwards of the immense ears of fancy rabbits
seems partly due to the disuse of the muscles, and partly to the weight
and length of the ears, which have been increased by selection during
many generations. Now, with the increased size and changed direction of
the ears not only has the bony auditory meatus become changed in
outline, direction, and greatly in size, but the whole skull has been
slightly modified. This could be clearly seen in “half-lops”—that is,
in rabbits with only one ear lopping forward— for the opposite sides of
their skulls were not strictly symmetrical. This seems to me a curious
instance of correlation, between hard bones and organs so soft and
flexible, as well as so unimportant under a physiological point of
view, as the external ears. The result no doubt is largely due to mere
mechanical action, that is, to the weight of the ears, on the same
principle that the skull of a human infant is easily modified by
pressure.

The skin and the appendages of hair, feathers, hoofs, horns, and teeth,
are homologous over the whole body. Every one knows that the colour of
the skin and that of the hair usually vary together; so that Virgil
advises the shepherd to look whether the mouth and tongue of the ram
are black, lest the lambs should not be purely white. The colour of the
skin and hair, and the odour emitted by the glands of the skin, are
said[10] to be connected, even in the same race of men. Generally the
hair varies in the same way all over the body in length, fineness, and
curliness. The same rule holds good with feathers, as we see with the
laced and frizzled breeds both of fowls and pigeons. In the common cock
the feathers on the neck and loins are always of a particular shape,
called hackles: now in the Polish breed, both sexes are characterised
by a tuft of feathers on the head, and through correlation these
feathers in the male always assume the form of hackles. The wing and
tail-feathers, though arising from parts not homologous, vary in length
together; so that long or short winged pigeons generally have long or
short tails. The case of the Jacobin-pigeon is more curious, for the
wing and tail feathers are remarkably long; and this apparently has
arisen in correlation with the elongated and reversed feathers on the
back of the neck, which form the hood.

The hoofs and hair are homologous appendages; and a careful observer,
namely Azara,[11] states that in Paraguay horses of various colours are
often born with their hair curled and twisted like that on the head of
a negro. This peculiarity is strongly inherited. But what is remarkable
is that the hoofs of these horses “are absolutely like those of a
mule.” The hair also of their manes and tails is invariably much
shorter than usual, being only from four to twelve inches in length; so
that curliness and shortness of the hair are here, as with the negro,
apparently correlated.

With respect to the horns of sheep, Youatt[12] remarks that
“multiplicity of horns is not found in any breed of much value; it is
generally accompanied by great length and coarseness of the fleece.”
Several tropical breeds of sheep which are clothed with hair instead of
wool, have horns almost like those of a goat. Sturm[13] expressly
declares that in different races the more the wool is curled the more
the horns are spirally twisted. We have seen in the third chapter,
where other analogous facts have been given, that the parent of the
Mauchamp breed, so famous for its fleece, had peculiarly shaped horns.
The inhabitants of Angora assert[14] that “only the white goats which
have horns wear the fleece in the long curly locks that are so much
admired; those which are not horned having a comparatively close coat.”
From these cases we may infer that the hair or wool and the horns tend
to vary in a correlated manner.[15] Those who have tried hydropathy are
aware that the frequent application of cold water stimulates the skin;
and whatever stimulates the skin tends to increase the growth of the
hair, as is well shown in the abnormal growth of hair near old inflamed
surfaces. Now, Professor Low[16] is convinced that with the different
races of British cattle thick skin and long hair depend on the humidity
of the climate which they inhabit. We can thus see how a humid climate
might act on the horns—in the first place directly on the skin and
hair, and secondly by correlation on the horns. The presence or absence
of horns, moreover, both in the case of sheep and cattle, acts, as will
presently be shown, by some sort of correlation on the skull.

With respect to hair and teeth, Mr. Yarrell[17] found many of the teeth
deficient in three hairless “Egyptian dogs,” and in a hairless terrier.
The incisors, canines, and the premolars suffered most, but in one case
all the teeth, except the large tubercular molar on each side, were
deficient. With man several striking cases have been recorded[18] of
inherited baldness with inherited deficiency, either complete or
partial, of the teeth. I may give an analogous case, communicated to me
by Mr. W. Wedderburn, of a Hindoo family in Scinde, in which ten men,
in the course of four generations, were furnished, in both jaws taken
together, with only four small and weak incisor teeth and with eight
posterior molars. The men thus affected have very little hair on the
body, and become bald early in life. They also suffer much during hot
weather from excessive dryness of the skin. It is remarkable that no
instance has occurred of a daughter being thus affected; and this fact
reminds us how much more liable men are in England to become bald than
women. Though the daughters in the above family are never affected,
they transmit the tendency to their sons; and no case has occurred of a
son transmitting it to his sons. The affection thus appears only in
alternate generations, or after longer intervals. There is a similar
connection between hair and teeth, according to Mr. Sedgwick, in those
rare cases in which the hair has been renewed in old age, for this has
“usually been accompanied by a renewal of the teeth.” I have remarked
in a former part of this volume that the great reduction in the size of
the tusks in domestic boars probably stands in close relation with
their diminished bristles, due to a certain amount of protection; and
that the reappearance of the tusks in boars, which have become feral
and are fully exposed to the weather, probably depends on the
reappearance of the bristles. I may add, though not strictly connected
with our present point, that an agriculturist[19] asserts that “pigs
with little hair on their bodies are most liable to lose their tails,
showing a weakness of the tegumental structure. It may be prevented by
crossing with a more hairy breed.”

In the previous cases deficient hair, and teeth deficient in number or
size, are apparently connected. In the following cases abnormally
redundant hair, and teeth either deficient or redundant, are likewise
connected. Mr. Crawfurd[20] saw at the Burmese Court a man, thirty
years old, with his whole body, except the hands and feet, covered with
straight silky hair, which on the shoulders and spine was five inches
in length. At birth the ears alone were covered. He did not arrive at
puberty, or shed his milk teeth, until twenty years old; and at this
period he acquired five teeth in the upper jaw, namely, four incisors
and one canine, and four incisor teeth in the lower jaw; all the teeth
were small. This man had a daughter who was born with hair within her
ears; and the hair soon extended over her body. When Captain Yule[21]
visited the Court, he found this girl grown up; and she presented a
strange appearance with even her nose densely covered with soft hair.
Like her father, she was furnished with incisor teeth alone. The King
had with difficulty bribed a man to marry her, and of her two children,
one, a boy fourteen months old, had hair growing out of his ears, with
a beard and moustache. This strange peculiarity has, therefore, been
inherited for three generations, with the molar teeth deficient in the
grandfather and mother; whether these teeth would likewise fail in the
infant could not then be told.

A parallel case of a man fifty-five years old, and of his son, with
their faces covered with hair, has recently occurred in Russia. Dr.
Alex. Brandt has sent me an account of this case, together with
specimens of the extremely fine hair from the cheeks. The man is
deficient in teeth, possessing only four incisors in the lower and two
in the upper jaw. His son, about three years old, has no teeth except
four lower incisors. The case, as Dr. Brandt remarks in his letter, no
doubt is due to an arrest of development in the hair and teeth. We here
see how independent of the ordinary conditions of existence such
arrests must be, for the lives of a Russian peasant and of a native of
Burmah are as different as possible.[22]

Here is another and somewhat different case communicated to me by Mr.
Wallace on the authority of Dr. Purland, a dentist: Julia Pastrana, a
Spanish dancer, was a remarkably fine woman, but she had a thick
masculine beard and a hairy forehead; she was photographed, and her
stuffed skin was exhibited as a show; but what concerns us is, that she
had in both the upper and lower jaw an irregular double set of teeth,
one row being placed within the other, of which Dr. Purland took a
cast. From the redundancy of teeth her mouth projected, and her face
had a gorilla-like appearance. These cases and those of the hairless
dogs forcibly call to mind the fact, that the two orders of
mammals—namely, the Edentata and Cetacea—which are the most abnormal in
their dermal covering, are likewise the most abnormal either by
deficiency or redundancy of teeth.

The organs of sight and hearing are generally admitted to be homologous
with one another and with various dermal appendages; hence these parts
are liable to be abnormally affected in conjunction. Mr. White Cowper
says “that in all cases of double microphthalmia brought under his
notice he has at the same time met with defective development of the
dental system.” Certain forms of blindness seem to be associated with
the colour of the hair; a man with black hair and a woman with
light-coloured hair, both of sound constitution, married and had nine
children, all of whom were born blind; of these children, five “with
dark hair and brown iris were afflicted with amaurosis; the four
others, with light-coloured hair and blue iris, had amaurosis and
cataract conjoined.” Several cases could be given, showing that some
relation exists between various affections of the eyes and ears; thus
Liebreich states that out of 241 deaf-mutes in Berlin, no less than
fourteen suffered from the rare disease called pigmentary retinitis.
Mr. White Cowper and Dr. Earle have remarked that inability to
distinguish different colours, or colour-blindness, “is often
associated with a corresponding inability to distinguish musical
sounds.”[23]

Here is a more curious case: white cats, if they have blue eyes, are
almost always deaf. I formerly thought that the rule was invariable,
but I have heard of a few authentic exceptions. The first two notices
were published in 1829 and relate to English and Persian cats: of the
latter, the Rev. W. T. Bree possessed a female, and he states, “that of
the offspring produced at one and the same birth, such as, like the
mother, were entirely white (with blue eyes) were, like her, invariably
deaf; while those that had the least speck of colour on their fur, as
invariably possessed the usual faculty of hearing.”[24] The Rev. W.
Darwin Fox informs me that he has seen more than a dozen instances of
this correlation in English, Persian, and Danish cats; but he adds
“that, if one eye, as I have several times observed, be not blue, the
cat hears. On the other hand, I have never seen a white cat with eyes
of the common colour that was deaf.” In France Dr. Sichel[25] has
observed during twenty years similar facts; he adds the remarkable case
of the iris beginning, at the end of four months, to grow
dark-coloured, and then the cat first began to hear.

This case of correlation in cats has struck many persons as marvellous.
There is nothing unusual in the relation between blue eyes and white
fur; and we have already seen that the organs of sight and hearing are
often simultaneously affected. In the present instance the cause
probably lies in a slight arrest of development in the nervous system
in connection with the sense-organs. Kittens during the first nine
days, whilst their eyes are closed, appear to be completely deaf; I
have made a great clanging noise with a poker and shovel close to their
heads, both when they were asleep and awake, without producing any
effect. The trial must not be made by shouting close to their ears, for
they are, even when asleep, extremely sensitive to a breath of air.
Now, as long as the eyes continue closed, the iris is no doubt blue,
for in all the kittens which I have seen this colour remains for some
time after the eyelids open. Hence, if we suppose the development of
the organs of sight and hearing to be arrested at the stage of the
closed eyelids, the eyes would remain permanently blue and the ears
would be incapable of perceiving sound; and we should thus understand
this curious case. As, however, the colour of the fur is determined
long before birth, and as the blueness of the eyes and the whiteness of
the fur are obviously connected, we must believe that some primary
cause acts at a much earlier period.

The instances of correlated variability hitherto given have been
chiefly drawn from the animal kingdom, and we will now turn to plants.
Leaves, sepals, petals, stamens, and pistils are all homologous. In
double flowers we see that the stamens and pistils vary in the same
manner, and assume the form and colour of the petals. In the double
columbine (_Aquilegia vulgaris_), the successive whorls of stamens are
converted into cornucopias, which are enclosed within one another and
resemble the true petals. In hose-in-hose flowers the sepals mock the
petals. In some cases the flowers and leaves vary together in tint: in
all the varieties of the common pea, which have purple flowers, a
purple mark may be seen on the stipules.

M. Faivre states that with the varieties of _ Primula sinensis_ the
colour of the flower is evidently correlated with the colour of the
under side of the leaves; and he adds that the varieties with
fimbriated flowers almost always have voluminous, balloon-like
calyces.[26] With other plants the leaves and fruit or seeds vary
together in colour, as in a curious pale-leaved variety of the
sycamore, which has recently been described in France,[27] and as in
the purple-leaved hazel, in which the leaves, the husk of the nut, and
the pellicle round the kernel are all coloured purple.[28] Pomologists
can predict to a certain extent, from the size and appearance of the
leaves of their seedlings, the probable nature of the fruit; for, as
Van Mons remarks[29] variations in the leaves are generally accompanied
by some modification in the flower, and consequently in the fruit. In
the Serpent melon, which has a narrow tortuous fruit above a yard in
length, the stem of the plant, the peduncle of the female flower, and
the middle lobe of the leaf, are all elongated in a remarkable manner.
On the other hand, several varieties of Cucurbita, which have dwarfed
stems, all produce, as Naudin remarks, leaves of the same peculiar
shape. Mr. G. Maw informs me that all the varieties of the scarlet
Pelargoniums which have contracted or imperfect leaves have contracted
flowers: the difference between “Brilliant” and its parent “Tom Thumb”
is a good instance of this. It may be suspected that the curious case
described by Risso,[30] of a variety of the Orange which produces on
the young shoots rounded leaves with winged petioles, and afterwards
elongated leaves on long but wingless petioles, is connected with the
remarkable change in form and nature which the fruit undergoes during
its development.

In the following instance we have the colour and the form of the petals
apparently correlated, and both dependent on the nature of the season.
An observer, skilled in the subject, writes,[31] “I noticed, during the
year 1842, that every Dahlia of which the colour had any tendency to
scarlet, was deeply notched—indeed, to so great an extent as to give
the petals the appearance of a saw; the indentures were, in some
instances, more than a quarter of an inch deep.” Again, Dahlias which
have their petals tipped with a different colour from the rest of the
flower are very inconstant, and during certain years some, or even all
the flowers, become uniformly coloured; and it has been observed with
several varieties[32] that when this happens the petals grow much
elongated and lose their proper shape. This, however, may be due to
reversion, both in colour and form, to the aboriginal species.

In this discussion on correlation, we have hitherto treated of cases in
which we can partly understand the bond of connection; but I will now
give cases in which we cannot even conjecture, or can only very
obscurely see, the nature of the bond. Isidore Geoffroy Saint-Hilaire,
in his work on Monstrosities, insists,[33] “que certaines anomalies
coexistent rarement entr’elles, d’autres fréquemment, d’autres enfin
presque constamment, malgré la différence très-grande de leur nature,
et quoiqu’elles puissent paraître _complètement indépendantes_ les unes
des autres.” We see something analogous in certain diseases: thus in a
rare affection of the renal capsules (of which the functions are
unknown), the skin becomes bronzed; and in hereditary syphilis, as I
hear from Sir J. Paget, both the milk and the second teeth assume a
peculiar and characteristic form. Professor Rolleston, also, informs me
that the incisor teeth are sometimes furnished with a vascular rim in
correlation with intra-pulmonary deposition of tubercles. In other
cases of phthisis and of cyanosis the nails and finger-ends become
clubbed like acorns. I believe that no explanation has been offered of
these and of many other cases of correlated disease.

What can be more curious and less intelligible than the fact previously
given, on the authority of Mr. Tegetmeier, that young pigeons of all
breeds, which when mature have white, yellow, silver-blue, or
dun-coloured plumage, come out of the egg almost naked; whereas pigeons
of other colours when first born are clothed with plenty of down? White
Pea-fowls, as has been observed both in England and France,[34] and as
I have myself seen, are inferior in size to the common coloured kind;
and this cannot be accounted for by the belief that albinism is always
accompanied by constitutional weakness; for white or albino moles are
generally larger than the common kind.

To turn to more important characters: the niata cattle of the Pampas
are remarkable from their short foreheads, upturned muzzles, and curved
lower jaws. In the skull the nasal and premaxillary bones are much
shortened, the maxillaries are excluded from any junction with the
nasals, and all the bones are slightly modified, even to the plane of
the occiput. From the analogous case of the dog, hereafter to be given,
it is probable that the shortening of the nasal and adjoining bones is
the proximate cause of the other modifications in the skull, including
the upward curvature of the lower jaw, though we cannot follow out the
steps by which these changes have been effected.

Polish fowls have a large tuft of feathers on their heads; and their
skulls are perforated by numerous holes, so that a pin can be driven
into the brain without touching any bone. That this deficiency of bone
is in some way connected with the tuft of feathers is clear from tufted
ducks and geese likewise having perforated skulls. The case would
probably be considered by some authors as one of balancement or
compensation. In the chapter on Fowls, I have shown that with Polish
fowls the tuft of feathers was probably at first small; by continued
selection it became larger, and then rested on a fibrous mass; and
finally, as it became still larger, the skull itself became more and
more protuberant until it acquired its present extraordinary structure.
Through correlation with the protuberance of the skull, the shape and
even the relative connection of the premaxillary and nasal bones, the
shape of the orifice of the nostrils, the breadth of the frontal bone,
the shape of the post-lateral processes of the frontal and squamosal
bones, and the direction of the bony cavity of the ear, have all been
modified. The internal configuration of the skull and the whole shape
of the brain have likewise been altered in a truly marvellous manner.

After this case of the Polish fowl it would be superfluous to do more
than refer to the details previously given on the manner in which the
changed form of the comb has affected the skull, in various breeds of
the fowl, causing by correlation crests, protuberances, and depressions
on its surface.

With our cattle and sheep the horns stand in close connection with the
size of the skull, and with the shape of the frontal bones; thus
Cline[35] found that the skull of a horned ram weighed five times as
much as that of a hornless ram of the same age. When cattle become
hornless, the frontal bones are “materially diminished in breadth
towards the poll;” and the cavities between the bony plates “are not so
deep, nor do they extend beyond the frontals.”[36] It may be well here
to pause and observe how the effects of correlated variability, of the
increased use of parts, and of the accumulation of so-called
spontaneous variations through natural selection, are in many cases
inextricably commingled. We may borrow an illustration from Mr. Herbert
Spencer, who remarks that, when the Irish elk acquired its gigantic
horns, weighing above one hundred pounds, numerous co-ordinated changes
of structure would have been indispensable,—namely, a thickened skull
to carry the horns; strengthened cervical vertebrae, with strengthened
ligaments; enlarged dorsal vertebrae to support the neck, with powerful
fore-legs and feet; all these parts being supplied with proper muscles,
blood-vessels, and nerves. How then could these admirably co-ordinated
modifications of structure have been acquired? According to the
doctrine which I maintain, the horns of the male elk were slowly gained
through sexual selection,—that is, by the best-armed males conquering
the worse-armed, and leaving a greater number of descendants. But it is
not at all necessary that the several parts of the body should have
simultaneously varied. Each stag presents individual characteristics,
and in the same district those which had slightly heavier horns, or
stronger necks, or stronger bodies, or were the most courageous, would
secure the greater number of does, and consequently have a greater
number of offspring. The offspring would inherit, in a greater or less
degree, these same qualities, would occasionally intercross with one
another, or with other individuals varying in some favourable manner;
and of their offspring, those which were the best endowed in any
respect would continue multiplying; and so onwards, always progressing,
sometimes in one direction, and sometimes in another, towards the
excellently co-ordinated structure of the male elk. To make this clear,
let us reflect on the probable steps, as shown in the twentieth
chapter, by which our race and dray horses have arrived at their
present state of excellence; if we could view the whole series of
intermediate forms between one of these animals and an early unimproved
progenitor, we should behold a vast number of animals, not equally
improved in each generation throughout their entire structure, but
sometimes a little more in one point, and sometimes in another, yet on
the whole gradually approaching in character to our present race or
dray horses, which are so admirably fitted in the one case for
fleetness and in the other for draught.

Although natural selection would thus[37] tend to give to the male elk
its present structure, yet it is probable that the inherited effects of
use, and of the mutual action of part on part, have been equally or
more important. As the horns gradually increased in weight the muscles
of the neck, with the bones to which they are attached, would increase
in size and strength; and these parts would react on the body and legs.
Nor must we overlook the fact that certain parts of the skull and the
extremities would, judging by analogy, tend from the first to vary in a
correlated manner. The increased weight of the horns would also act
directly on the skull, in the same manner as when one bone is removed
in the leg of a dog, the other bone, which has to carry the whole
weight of the body, increases in thickness. But from the fact given
with respect to horned and hornless cattle, it is probable that the
horns and skull would immediately act on each other through the
principle of correlation. Lastly, the growth and subsequent wear and
tear of the augmented muscles and bones would require an increased
supply of blood, and consequently increased supply of food; and this
again would require increased powers of mastication, digestion,
respiration, and excretion.

      _Colour as Correlated with Constitutional Peculiarities._

It is an old belief that with man there is a connection between
complexions and constitution; and I find that some of the best
authorities believe in this to the present day.[38] Thus Dr. Beddoe by
his tables shows[39] that a relation exists between liability to
consumption and the colour of the hair, eyes, and skin. It has been
affirmed[40] that, in the French army which invaded Russia, soldiers
having a dark complexion from the southern parts of Europe, withstood
the intense cold better than those with lighter complexions from the
north; but no doubt such statements are liable to error.

In the second chapter on Selection I have given several cases proving
that with animals and plants differences in colour are correlated with
constitutional differences, as shown by greater or less immunity from
certain diseases, from the attacks of parasitic plants and animals,
from scorching by the sun, and from the action of certain poisons. When
all the individuals of any one variety possess an immunity of this
nature, we do not know that it stands in any sort of correlation with
their colour; but when several similarly coloured varieties of the same
species are thus characterised, whilst other coloured varieties are not
thus favoured, we must believe in the existence of a correlation of
this kind. Thus, in the United States purple-fruited plums of many
kinds are far more affected by a certain disease than green or
yellow-fruited varieties. On the other hand, yellow-fleshed peaches of
various kinds suffer from another disease much more than the
white-fleshed varieties. In the Mauritius red sugar-canes are much less
affected by a particular disease than the white canes. White onions and
verbenas are the most liable to mildew; and in Spain the green-fruited
grapes suffered from the vine-disease more than other coloured
varieties. Dark-coloured pelargoniums and verbenas are more scorched by
the sun than varieties of other colours. Red wheats are believed to be
hardier than white; and red-flowered hyacinths were more injured during
one particular winter in Holland than other coloured varieties. With
animals, white terriers suffer most from the distemper, white chickens
from a parasitic worm in their tracheae, white pigs from scorching by
the sun, and white cattle from flies; but the caterpillars of the
silk-moth which yield white cocoons suffered in France less from the
deadly parasitic fungus than those producing yellow silk.

The cases of immunity from the action of certain vegetable poisons, in
connexion with colour, are more interesting, and are at present wholly
inexplicable. I have already given a remarkable instance, on the
authority of Professor Wyman, of all the hogs, excepting those of a
black colour, suffering severely in Virginia from eating the root of
the _Lachnanthes tinctoria._ According to Spinola and others,[41]
buckwheat (_Po1ygonum fagopyrum_), when in flower, is highly injurious
to white or white-spotted pigs, if they are exposed to the heat of the
sun, but is quite innocuous to black pigs. According to two accounts,
the _Hypericum crispum_ in Sicily is poisonous to white sheep alone;
their heads swell, their wool falls off, and they often die; but this
plant, according to Lecce, is poisonous only when it grows in swamps;
nor is this improbable, as we know how readily the poisonous principle
in plants is influenced by the conditions under which they grow.

Three accounts have been published in Eastern Prussia, of white and
white-spotted horses being greatly injured by eating mildewed and
honeydewed vetches; every spot of skin bearing white hairs becoming
inflamed and gangrenous. The Rev. J. Rodwell informs me that his father
turned out about fifteen cart-horses into a field of tares which in
parts swarmed with black aphides, and which no doubt were honeydewed,
and probably mildewed; the horses, with two exceptions, were chestnuts
and bays with white marks on their faces and pasterns, and the white
parts alone swelled and became angry scabs. The two bay horses with no
white marks entirely escaped all injury. In Guernsey, when horses eat
fool’s parsley (_Æthusa cynapium_) they are sometimes violently purged;
and this plant “has a peculiar effect on the nose and lips, causing
deep cracks and ulcers, particularly on horses with white muzzles.”[42]
With cattle, independently of the action of any poison, cases have been
published by Youatt and Erdt of cutaneous diseases with much
constitutional disturbance (in one instance after exposure to a hot
sun) affecting every single point which bore a white hair, but
completely passing over other parts of the body. Similar cases have
been observed with horses.[43]

We thus see that not only do those parts of the skin which bear white
hair differ in a remarkable manner from those bearing hair of any other
colour, but that some great constitutional difference must be
correlated with the colour of the hair; for in the above-mentioned
cases, vegetable poisons caused fever, swelling of the head, as well as
other symptoms, and even death, to all the white, or white-spotted
animals.

REFERENCES

 [1] ‘Hist. des Anomalies,’ tom. iii. p. 392. Prof. Huxley applies the
 same principle in accounting for the remarkable, though normal,
 differences in the arrangement of the nervous system in the Mollusca,
 in his paper on the Morphology of the Cephalous Mollusca in ‘Phil.
 Transact.,’ 1853, p. 56.

 [2] ‘Eléments de Tératologie Veg.,’ 1841, p. 13.

 [3] Prof. J. B. Simonds on the Age of the Ox, Sheep, etc., quoted in
 ‘Gardener’s Chronicle,’ 1854, p. 588.

 [4] ‘Hist. des Anomalies,’ tom. i. p. 674.

 [5] Quoted by Isid. Geoffroy, ibid., tom. i. p. 635.

 [6] ‘The Poultry Book,’ by W. B. Tegetmeier, 1866, p. 250.

 [7] Naturalists differ with respect to the homologies of the digits of
 birds; but several uphold the view above advanced. _ See_ on this
 subject Dr. E. S. Morse in ‘Annals of the Lyceum of Nat. Hist. of New
 York,’ vol. x. 1872, p. 16.

 [8] A. Walker on Intermarriage, 1838, p. 160.

 [9] ‘The Farrier and Naturalist,’ vol. i. 1828, p. 456. A gentleman
 who has attended to this point, tells me that about three-fourths of
 white-faced horses have white legs.

 [10] Godron, ‘Sur l’Espèce,’ tom. ii. p. 217.

 [11] ‘Quadrupèdes du Paraguay,’ tom. ii. p. 333.

 [12] On Sheep, p. 142.

 [13] ‘Ueber Racen, Kreuzungen,’ etc., 1825, s. 24.

 [14] Quoted from Conolly, in ‘The Indian Field,’ Feb. 1859, vol. ii.
 p. 266.

 [15] In the third chapter I have said that “the hair and horns are so
 closely related to each other, that they are apt to vary together.”
 Dr. Wilckens (“Darwin’s Theorie,” ‘Jahrbuch der Deutschen Viehzucht,’
 1866, 1. Heft) translates my words into “lang-und grobhaarige Thiere
 sollen geneigter sein, lange und viele Hörner zu bekommen” and he then
 justly disputes this proposition; but what I have really said, in
 accordance with the authorities just quoted, may, I think, be trusted.

 [16] ‘Domesticated Animals of the British Islands,’ pp. 307, 368. Dr.
 Wilckens argues (‘Landwirth. Wochenblatt,’ Nr. 10, 1869) to the same
 effect with respect to domestic animals in Germany.

 [17] ‘Proceedings Zoolog. Soc.,’ 1833, p. 113.

 [18] Sedgwick, ‘Brit. and Foreign Medico-Chirurg. Review,’ April 1863,
 p. 453.

 [19] ‘Gardener’s Chronicle,’ 1849, p. 205.

 [20] ‘Embassy to the Court of Ava,’ vol. i. p. 320.

 [21] ‘Narrative of a Mission to the Court of Ava in 1855,’ p. 94.

 [22] I owe to the kindness of M. Chauman, of St. Petersburg, excellent
 photographs of this man and his son, both of whom have since been
 exhibited in Paris and London.

 [23] These statements are taken from Mr. Sedgwick in the
 ‘Medico-Chirurg. Review,’ July, 1861, p. 198; April, 1863, pp. 455 and
 458. Liebreich is quoted by Professor Devay, in his ‘Mariages
 Consanguins,’ 1862, p. 116.

 [24] Loudon’s ‘Mag. of Nat. Hist.,’ vol. i. 1829, pp. 66, 178. _ See
 also_ Dr. P. Lucas, ‘L’Héréd. Nat.,’ tom. i. p. 428, on the
 inheritance of deafness in cats. Mr. Lawson Tait states (‘Nature,’
 1873, p. 323) that only male cats are thus affected; but this must be
 a hasty generalisation. The first case recorded in England by Mr. Bree
 related to a female, and Mr. Fox informs me that he has bred kittens
 from a white female with blue eyes, which was completely deaf; he has
 also observed other females in the same condition.

 [25] ‘Annales des Sc. Nat.’ Zoolog., 3rd series, 1847, tom. viii. p.
 239.

 [26] ‘Revue des Cours Scientifiques,’ June 5th, 1869, p. 430.

 [27] ‘Gardener’s Chronicle,’ 1864, p. 1202.

 [28] Verlot gives several other instances, ‘Des Variétés,’ 1865, p.
 72.

 [29] ‘Arbres Fruitiers,’ 1836, tom. ii. pp. 204, 226.

 [30] ‘Annales du Muséum,’ tom. xx. p. 188.

 [31] ‘Gardener’s Chronicle,’ 1843, p. 877.

 [32] Ibid., 1845, p. 102.

 [33] ‘Hist. des Anomalies,’ tom. iii. p. 402. _See also_ M. Camille
 Dareste, ‘Recherches sur les Conditions,’ etc., 1863, pp. 16, 48.

 [34] Rev. E. S. Dixon, ‘Ornamental Poultry,’ 1848, p. 111; Isidore
 Geoffroy, ‘Hist. Anomalies,’ tom. i. p. 211.

 [35] ‘On the Breeding of Domestic Animals,’ 1829, p. 6.

 [36] Youatt on Cattle, 1834, p. 283.

 [37] Mr. Herbert Spencer (‘Principles of Biology,’ 1864, vol. i. pp.
 452, 468) takes a different view; and in one place remarks: “We have
 seen reason to think that, as fast as essential faculties multiply,
 and as fast as the number of organs that co-operate in any given
 function increases, indirect equilibration through natural selection
 becomes less and less capable of producing specific adaptations; and
 remains fully capable only of maintaining the general fitness of
 constitution to conditions.” This view that natural selection can do
 little in modifying the higher animals surprises me, seeing that man’s
 selection has undoubtedly effected much with our domesticated
 quadrupeds and birds.

 [38] Dr. Prosper Lucas apparently disbelieves in any such connection;
 ‘L’Héréd. Nat.,’ tom. ii. pp. 88-94.

 [39] ‘British Medical Journal,’ 1862, p. 433.

 [40] Boudin, ‘Géograph. Médicale,’ tom. i. p. 406.

 [41] This fact and the following cases, when not stated to the
 contrary, are taken from a very curious paper by Prof. Heusinger, in
 ‘Wochenschrift fur Heilkunde,’ May, 1846, s. 277. Settegast (‘Die
 Thierzucht,’ 1868, p. 39) says that white or white-spotted sheep
 suffer like pigs, or even die from eating buckwheat; whilst black or
 dark-woolled individuals are not in the least affected.

 [42] Mr. Mogford, in the ‘Veterinarian,’ quoted in ‘The Field,’ Jan.
 22nd, 1861, p. 545.

 [43] ‘Edinburgh Veterinary Journal,’ Oct. 1860, p. 347.




CHAPTER XXVI. LAWS OF VARIATION, _continued._—SUMMARY.

THE FUSION OF HOMOLOGOUS PARTS—THE VARIABILITY OF MULTIPLE AND
HOMOLOGOUS PARTS—COMPENSATION OF GROWTH—MECHANICAL PRESSURE—RELATIVE
POSITION OF FLOWERS WITH RESPECT TO THE AXIS, AND OF SEEDS IN THE
OVARY, AS INDUCING VARIATION—ANALOGOUS OR PARALLEL VARIETIES—SUMMARY OF
THE THREE LAST CHAPTERS.


_The Fusion of Homologous Parts._—Geoffroy Saint-Hilaire formerly
propounded what he called _la loi de l’affinité de soi pour soi,_ which
has been discussed and illustrated by his son, Isidore, with respect to
monsters in the animal kingdom,[1] and by Moquin-Tandon, with respect
to monstrous plants. This law seems to imply that homologous parts
actually attract one another and then unite. No doubt there are many
wonderful cases, in which such parts become intimately fused together.
This is perhaps best seen in monsters with two heads, which are united,
summit to summit, or face to face, or Janus-like, back to back, or
obliquely side to side. In one instance of two heads united almost face
to face, but a little obliquely, four ears were developed, and on one
side a perfect face, which was manifestly formed by the fusion of two
half-faces. Whenever two bodies or two heads are united, each bone,
muscle, vessel, and nerve on the line of junction appears as if it had
sought out its fellow, and had become completely fused with it.
Lereboullet,[2] who carefully studied the development of double
monsters in fishes, observed in fifteen instances the steps by which
two heads gradually became united into one. In all such cases it is now
thought by the greater number of capable judges that the homologous
parts do not attract each other, but that in the words of Mr. Lowne:[3]
“As union takes place before the differentiation of distinct organs
occurs, these are formed in continuity with each other.” He adds that
organs already differentiated probably in no case become united to
homologous ones. M. Dareste does not speak[4] quite decisively against
the law of _soi pour soi,_ but concludes by saying, “On se rend
parfaitement compte de la formation des monstres, si l’on admet que les
embryons qui se soudent appartiennent à un même œuf; qu’ils s’unissent
en même temps qu’ils se forment, et que la soudure ne se produit que
pendant la première période de la vie embryonnaire, celle ou les
organes ne sont encore constitués que par des blastèmes homogènes.”

By whatever means the abnormal fusion of homologous parts is effected,
such cases throw light on the frequent presence of organs which are
double during an embryonic period (and throughout life in other and
lower members of the same class) but which afterwards unite by a normal
process into a single medial organ. In the vegetable kingdom
Moquin-Tandon[5] gives a long list of cases, showing how frequently
homologous parts, such as leaves, petals, stamens, and pistils,
flowers, and aggregates of homologous parts, such as buds, as well as
fruit, become blended, both normally and abnormally, with perfect
symmetry into one another.

_The Variability of Multiple and Homologous parts._—Isidore Geoffroy[6]
insists that, when any part or organ is repeated many times in the same
animal, it is particularly liable to vary both in number and structure.
With respect to number, the proposition may, I think, be considered as
fully established; but the evidence is chiefly derived from organic
beings living under their natural conditions, with which we are not
here concerned. Whenever such parts as the vertebrae or teeth, the rays
in the fins of fishes, or the feathers in the tails of birds, or
petals, stamens, pistils, or seeds, are very numerous, the number is
generally variable. With respect to the structure of multiple parts,
the evidence of variability is not so decisive; but the fact, as far as
it may be trusted, probably depends on multiple parts being of less
physiological importance than single parts; consequently their
structure has been less rigorously guarded by natural selection.

_Compensation of Growth, or Balancement._—This law, as applied to
natural species, was propounded by Goethe and Geoffroy Saint-Hilaire at
nearly the same time. It implies that, when much organised matter is
used in building up some one part, other parts are starved and become
reduced. Several authors, especially botanists, believe in this law;
others reject it. As far as I can judge, it occasionally holds good;
but its importance has probably been exaggerated. It is scarcely
possible to distinguish between the supposed effects of such
compensation, and the effects of long-continued selection which may
lead to the augmentation of one part, and simultaneously to the
diminution of another. Anyhow, there can be no doubt that an organ may
be greatly increased without any corresponding diminution of an
adjoining part. To recur to our former illustration of the Irish elk,
it may be asked what part has suffered in consequence of the immense
development of the horns?

It has already been observed that the struggle for existence does not
bear hard on our domesticated productions, and consequently the
principle of economy of growth will seldom come into play, so that we
ought not to expect to find with them frequent evidence of
compensation. We have, however, some such cases. Moquin-Tandon
describes a monstrous bean,[7] in which the stipules were enormously
developed, and the leaflets apparently in consequence completely
aborted; this case is interesting, as it represents the natural
condition of _Lathyrus aphaca,_ with its stipules of great size, and
its leaves reduced to mere threads, which act as tendrils. De
Candolle[8] has remarked that the varieties of _Raphanus sativus_ which
have small roots yield numerous seed containing much oil, whilst those
with large roots are not productive in oil; and so it is with _Brassica
asperifolia._ The varieties of _Cucurbita pepo_ which bear large fruit
yield a small crop, according to Naudin; whilst those producing small
fruit yield a vast number. Lastly, I have endeavoured to show in the
eighteenth chapter that with many cultivated plants unnatural treatment
checks the full and proper action of the reproductive organs, and they
are thus rendered more or less sterile; consequently, in the way of
compensation, the fruit becomes greatly enlarged, and, in double
flowers, the petals are greatly increased in number.

With animals, it has been found difficult to produce cows which yield
much milk, and are afterwards capable of fattening well. With fowls
which have large top-knots and beards the comb and wattles are
generally much reduced in size; though there are exceptions to this
rule. Perhaps the entire absence of the oil-gland in fantail pigeons
may be connected with the great development of their tails.

_Mechanical Pressure as a Cause of Modifications._—In some few cases
there is reason to believe that mere mechanical pressure has affected
certain structures. Vrolik and Weber[9] maintain that the shape of the
human head is influenced by the shape of the mother’s pelvis. The
kidneys in different birds differ much in form, and St. Ange[10]
believes that this is determined by the form of the pelvis, which
again, no doubt, stands in close relation with their power of
locomotion. In snakes, the viscera are curiously displaced, in
comparison with their position in other vertebrates; and this has been
attributed by some authors to the elongation of their bodies; but here,
as in so many previous cases, it is impossible to disentangle a direct
result of this kind from that consequent on natural selection. Godron
has argued[11] that the abortion of the spur on the inner side of the
flowers in Corydalis, is caused by the buds at a very early period of
growth whilst underground being closely pressed against one another and
against the stem. Some botanists believe that the singular difference
in the shape both of the seed and corolla, in the interior and exterior
florets in certain Compositous and Umbelliferous plants, is due to the
pressure to which the inner florets are subjected; but this conclusion
is doubtful.

The facts just given do not relate to domesticated productions, and
therefore do not strictly concern us. But here is a more appropriate
case: H. Müller[12] has shown that in shortfaced races of the dog some
of the molar teeth are placed in a slightly different position to that
which they occupy in other dogs, especially in those having elongated
muzzles; and as he remarks, any inherited change in the arrangement of
the teeth deserves notice, considering their classificatory importance.
This difference in position is due to the shortening of certain facial
bones and the consequent want of space; and the shortening results from
a peculiar and abnormal state of the embryonal cartilages of the bones.

      _Relative Position of Flowers with respect to the Axis, and of
      Seeds in the Ovary, as inducing Variation._

In the thirteenth chapter various peloric flowers were described, and
their production was shown to be due either to arrested development, or
to reversion to a primordial condition. Moquin-Tandon has remarked that
the flowers which stand on the summit of the main stem or of a lateral
branch are more liable to become peloric than those on the sides;[13]
and he adduces, amongst other instances, that of _Teucrium
campanulatum._ In another Labiate plant grown by me, viz., the
_Galeobdolon luteum,_ the peloric flowers were always produced on the
summit of the stem, where flowers are not usually borne. In
Pelargonium, a _single_ flower in the truss is frequently peloric, and
when this occurs I have during several years invariably observed it to
be the central flower. This is of such frequent occurrence that one
observer[14] gives the names of ten varieties flowering at the same
time, in every one of which the central flower was peloric.
Occasionally more than one flower in the truss is peloric, and then of
course the additional ones must be lateral. These flowers are
interesting as showing how the whole structure is correlated. In the
common Pelargonium the upper sepal is produced into a nectary which
coheres with the flower-peduncle; the two upper petals differ a little
in shape from the three lower ones, and are marked with dark shades of
colour; the stamens are graduated in length and upturned. In the
peloric flowers, the nectary aborts; all the petals become alike both
in shape and colour; the stamens are generally reduced in number and
become straight, so that the whole flower resembles that of the allied
genus Erodium. The correlation between these changes is well shown when
one of the two upper petals alone loses its dark mark, for in this case
the nectary does not entirely abort, but is usually much reduced in
length.[15]

Morren has described[16] a marvellous flask-shaped flower of the
Calceolaria, nearly four inches in length, which was almost completely
peloric; it grew on the summit of the plant, with a normal flower on
each side; Prof. Westwood also has described[17] three similar peloric
flowers, which all occupied a central position on the flower-branches.
In the Orchideous genus, Phalænopsis, the terminal flower has been seen
to become peloric.

In a Laburnum-tree I observed that about a fourth part of the racemes
produced terminal flowers which had lost their papilionaceous
structure. These were produced after almost all the other flowers on
the same racemes had withered. The most perfectly pelorised examples
had six petals, each marked with black striae like those on the
standard-petal. The keel seemed to resist the change more than the
other petals. Dutrochet has described[18] an exactly similar case in
France, and I believe these are the only two instances of pelorism in
the laburnum which have been recorded. Dutrochet remarks that the
racemes on this tree do not properly produce a terminal flower, so that
(as in the case of the Galeobdolon) their position as well as structure
are both anomalies, which no doubt are in some manner related. Dr.
Masters has briefly described another leguminous plant,[19] namely, a
species of clover, in which the uppermost and central flowers were
regular or had lost their papilionaceous structure. In some of these
plants the flower-heads were also proliferous.

Lastly, Linaria produces two kinds of peloric flowers, one having
simple petals, and the other having them all spurred. The two forms, as
Naudin remarks,[20] not rarely occur on the same plant, but in this
case the spurred form almost invariably stands on the summit of the
spike.

The tendency in the terminal or central flower to become peloric more
frequently than the other flowers, probably results from “the bud which
stands on the end of a shoot receiving the most sap; it grows out into
a stronger shoot than those situated lower down.”[21] I have discussed
the connection between pelorism and a central position, partly because
some few plants are known normally to produce a terminal flower
different in structure from the lateral ones; but chiefly on account of
the following case, in which we see a tendency to variability or to
reversion connected with the same position. A great judge of
Auriculas[22] states that when one throws up a side bloom it is pretty
sure to keep its character; but that if it grows from the centre or
heart of the plant, whatever the colour of the edging ought to be, “it
is just as likely to come in any other class as in the one to which it
properly belongs.” This is so notorious a fact, that some florists
regularly pinch off the central trusses of flowers. Whether in the
highly improved varieties the departure of the central trusses from
their proper type is due to reversion, I do not know. Mr. Dombrain
insists that, whatever may be the commonest kind of imperfection in
each variety, this is generally exaggerated in the central truss. Thus
one variety “sometimes has the fault of producing a little green floret
in the centre of the flower,” and in central blooms these become
excessive in size. In some central blooms, sent to me by Mr. Dombrain,
all the organs of the flower were rudimentary in structure, of minute
size, and of a green colour, so that by a little further change all
would have been converted into small leaves. In this case we clearly
see a tendency to prolification—a term which I may explain, for those
who have never attended to botany, to mean the production of a branch
or flower, or head of flowers, out of another flower. Now Dr.
Masters[23] states that the central or uppermost flower on a plant is
generally the most liable to prolification. Thus, in the varieties of
the Auricula, the loss of their proper character and a tendency to
prolification, also a tendency to prolification with pelorism, are all
connected together, and are due either to arrested development, or to
reversion to a former condition.

The following is a more interesting case; Metzger[24] cultivated in
Germany several kinds of maize brought from the hotter parts of
America, and he found, as previously described, that in two or three
generations the grains became greatly changed in form, size, and
colour; and with respect to two races he expressly states that in the
first generation, whilst the lower grains on each head retained their
proper character, the uppermost grains already began to assume that
character which in the third generation all the grains acquired. As we
do not know the aboriginal parent of the maize, we cannot tell whether
these changes are in any way connected with reversion.

In the two following cases, reversion comes into play and is determined
by the position of the seed in the capsule. The Blue Imperial pea is
the offspring of the Blue Prussian, and has larger seed and broader
pods than its parent. Now Mr. Masters, of Canterbury, a careful
observer and a raiser of new varieties of the pea, states[25] that the
Blue Imperial always has a strong tendency to revert to its
parent-stock, and the reversion “occurs in this manner: the last (or
uppermost) pea in the pod is frequently much smaller than the rest; and
if these small peas are carefully collected and sown separately, very
many more, in proportion, will revert to their origin, than those taken
from the other parts of the pod.” Again, M. Chaté[26] says that in
raising seedling stocks he succeeds in getting eighty per cent to bear
double flowers, by leaving only a few of the secondary branches to
seed; but in addition to this, “at the time of extracting the seeds,
the upper portion of the pod is separated and placed aside, because it
has been ascertained that the plants coming from the seeds situated in
this portion of the pod, give eighty per cent of single flowers.” Now
the production of single-flowering plants from the seed of
double-flowering plants is clearly a case of reversion. These latter
facts, as well as the connection between a central position and
pelorism and prolification, show in an interesting manner how small a
difference—namely, a little greater or less freedom in the flow of sap
towards one part of the plant—determines important changes of
structure.

_Analogous or Parallel Variation._—By this term I mean that similar
characters occasionally make their appearance in the several varieties
or races descended from the same species, and more rarely in the
offspring of widely distinct species. We are here concerned, not as
hitherto with the causes of variation, but with the results; but this
discussion could not have been more conveniently introduced elsewhere.
The cases of analogous variation, as far as their origin is concerned,
may be grouped, disregarding minor subdivisions, under two main heads;
firstly, those due to unknown causes acting on similarly constituted
organisms, and which consequently have varied in a similar manner; and
secondly, those due to the reappearance of characters which were
possessed by a more or less remote progenitor. But these two main
divisions can often be separated only conjecturally, and graduate, as
we shall presently see, into each other.

Under the first head of analogous variations, not due to reversion, we
have the many cases of trees belonging to quite different orders which
have produced pendulous and fastigiate varieties. The beech, hazel, and
barberry have given rise to purple-leaved varieties; and, as Bernhardi
remarks,[27] a multitude of plants, as distinct as possible, have
yielded varieties with deeply-cut or laciniated leaves. Varieties
descended from three distinct species of Brassica have their stems, or
so-called roots, enlarged into globular masses. The nectarine is the
offspring of the peach; and the varieties of peaches and nectarines
offer a remarkable parallelism in the fruit being white, red, or yellow
fleshed—in being clingstones or freestones—in the flowers being large
or small—in the leaves being serrated or crenated, furnished with
globose or reniform glands, or quite destitute of glands. It should be
remarked that each variety of the nectarine has not derived its
character from a corresponding variety of the peach. The several
varieties also of a closely allied genus, namely the apricot, differ
from one another in nearly the same parallel manner. There is no reason
to believe that any of these varieties have merely reacquired long-lost
characters; and in most of them this certainly is not the case.

Three species of Cucurbita have yielded a multitude of races which
correspond so closely in character that, as Naudin insists, they may be
arranged in almost strictly parallel series. Several varieties of the
melon are interesting from resembling, in important characters, other
species, either of the same genus or of allied genera; thus, one
variety has fruit so like, both externally and internally, the fruit of
a perfectly distinct species, namely, the cucumber, as hardly to be
distinguished from it; another has long cylindrical fruit twisting
about like a serpent; in another the seeds adhere to portions of the
pulp; in another the fruit, when ripe, suddenly cracks and falls into
pieces; and all these highly remarkable peculiarities are
characteristic of species belonging to allied genera. We can hardly
account for the appearance of so many unusual characters by reversion
to a single ancient form; but we must believe that all the members of
the family have inherited a nearly similar constitution from an early
progenitor. Our cereal and many other plants offer similar cases.

With animals we have fewer cases of analogous variation, independently
of direct reversion. We see something of the kind in the resemblance
between the short-muzzled races of the dog, such as the pug and
bull-dog; in feather-footed races of the fowl, pigeon, and canary-bird;
in horses of the most different races presenting the same range of
colour; in all black-and-tan dogs having tan-coloured eye-spots and
feet, but in this latter case reversion may possibly have played a
part. Low has remarked[28] that several breeds of cattle are
“sheeted,”—that is, have a broad band of white passing round their
bodies like a sheet; this character is strongly inherited, and
sometimes originates from a cross; it may be the first step in
reversion to an early type, for, as was shown in the third chapter,
white cattle with dark ears, dark feet and tip of tail, formerly
existed, and now exist in feral or semi-feral condition in several
quarters of the world.

Under our second main division, namely, of analogous variations due to
reversion, the best cases are afforded by pigeons. In all the most
distinct breeds, sub-varieties occasionally appear coloured exactly
like the parent rock-pigeon, with black wing-bars, white loins, banded
tail, etc.; and no one can doubt that these characters are due to
reversion. So with minor details; turbits properly have white tails,
but occasionally a bird is born with a dark-coloured and banded tail;
pouters properly have their primary wing-feathers white, but not rarely
a “sword-flighted” bird appears, that is, one with the few first
primaries dark-coloured; and in these cases we have characters proper
to the rock-pigeon, but new to the breed, evidently appearing from
reversion. In some domestic varieties the wing-bars, instead of being
simply black, as in the rock-pigeon, are beautifully edged with
different zones of colour, and they then present a striking analogy
with the wing-bars in certain natural species of the same family, such
as _Phaps chalcoptera_; and this may probably be accounted for by all
the species of the family being descended from the same remote
progenitor and having a tendency to vary in the same manner. Thus,
also, we can perhaps understand the fact of some Laugher-pigeons cooing
almost like turtle-doves, and for several races having peculiarities in
their flight, since certain natural species (viz., _C. torquatrix_ and
_palumbus_), display singular vagaries in this respect. In other cases
a race, instead of imitating a distinct species, resembles some other
race; thus, certain runts tremble and slightly elevate their tails,
like fantails; and turbits inflate the upper part of their oesophagus,
like pouter-pigeons.

It is a common circumstance to find certain coloured marks persistently
characterising all the species of a genus, but differing much in tint;
and the same thing occurs with the varieties of the pigeon: thus,
instead of the general plumage being blue, with the wing-bars black,
there are snow-white varieties with red bars, and black varieties with
white bars; in other varieties the wing-bars, as we have seen, are
elegantly zoned with different tints. The Spot pigeon is characterised
by the whole plumage being white, excepting a spot on the forehead and
the tail; but these parts may be red, yellow, or black. In the
rock-pigeon and in many varieties the tail is blue, with the outer
edges of the outer feathers white; but in the sub-variety of the
monk-pigeon we have a reversed style of coloration, for the tail is
white, except the outer edges of the outer feathers, which are
black.[29]

With some species of birds, for instance with gulls, certain coloured
parts appear as if almost washed out, and I have observed exactly the
same appearance in the terminal dark tail-bar in certain pigeons, and
in the whole plumage of certain varieties of the duck. Analogous facts
in the vegetable kingdom could be given.

Many sub-varieties of the pigeon have reversed and somewhat lengthened
feathers on the back part of their heads, and this is certainly not due
to reversion to the parent-species, which shows no trace of such
structure: but when we remember that sub-varieties of the fowl, turkey,
canary-bird, duck, and goose, all have either topknots or reversed
feathers on their heads; and when we remember that scarcely a single
large natural group of birds can be named, in which some members have
not a tuft of feathers on their heads, we may suspect that reversion to
some extremely remote form has come into action.

Several breeds of the fowl have either spangled or pencilled feathers;
and these cannot be derived from the parent-species, the _Gallus
bankiva_; though of course it is possible that one early progenitor of
this species may have been spangled, and another pencilled. But, as
many gallinaceous birds are either spangled or pencilled, it is a more
probable view that the several domestic breeds of the fowl have
acquired this kind of plumage from all the members of the family
inheriting a tendency to vary in a like manner. The same principle may
account for the ewes in certain breeds of sheep being hornless, like
the females of some other hollow-horned ruminants; it may account for
certain domestic cats having slightly-tufted ears, like those of the
lynx; and for the skulls of domestic rabbits often differing from one
another in the same characters by which the skulls of the various
species of the genus Lepus differ.

I will only allude to one other case, already discussed. Now that we
know that the wild parent of the ass commonly has striped legs, we may
feel confident that the occasional appearance of stripes on the legs of
the domestic ass is due to reversion; but this will not account for the
lower end of the shoulder-stripe being sometimes angularly bent or
slightly forked. So, again, when we see dun and other coloured horses
with stripes on the spine, shoulders, and legs, we are led, from
reasons formerly given, to believe that they reappear through reversion
to the wild parent-horse. But when horses have two or three
shoulder-stripes, with one of them occasionally forked at the lower
end, or when they have stripes on their faces, or are faintly striped
as foals over nearly their whole bodies, with the stripes angularly
bent one under the other on the forehead, or irregularly branched in
other parts, it would be rash to attribute such diversified characters
to the reappearance of those proper to the aboriginal wild horse. As
three African species of the genus are much striped, and as we have
seen that the crossing of the unstriped species often leads to the
hybrid offspring being conspicuously striped—bearing also in mind that
the act of crossing certainly causes the reappearance of long-lost
characters—it is a more probable view that the above-specified stripes
are due to reversion, not to the immediate wild parent-horse, but to
the striped progenitor of the whole genus.

I have discussed this subject of analogous variation at considerable
length, because it is well known that the varieties of one species
frequently resemble distinct species—a fact in perfect harmony with the
foregoing cases, and explicable on the theory of descent. Secondly,
because these facts are important from showing, as remarked in a former
chapter, that each trifling variation is governed by law, and is
determined in a much higher degree by the nature of the organisation,
than by the nature of the conditions to which the varying being has
been exposed. Thirdly, because these facts are to a certain extent
related to a more general law, namely, that which Mr. B. D. Walsh[30]
has called the “Law of _Equable Variability,_” or, as he explains it,
“if any given character is very variable in one species of a group, it
will tend to be variable in allied species; and if any given character
is perfectly constant in one species of a group, it will tend to be
constant in allied species.”

This leads me to recall a discussion in the chapter on Selection, in
which it was shown that with domestic races, which are now undergoing
rapid improvement, those parts or characters vary the most, which are
the most valued. This naturally follows from recently selected
characters continually tending to revert to their former less improved
standard, and from their being still acted on by the same agencies,
whatever these may be, which first caused the characters in question to
vary. The same principle is applicable to natural species, for, as
stated in my ‘Origin of Species’ generic characters are less variable
than specific characters; and the latter are those which have been
modified by variation and natural selection, since the period when all
the species belonging to the genus branched off from a common
progenitor, whilst generic characters are those which have remained
unaltered from a much more remote epoch, and accordingly are now less
variable. This statement makes a near approach to Mr. Walsh’s law of
Equable Variability. Secondary sexual characters, it may be added,
rarely serve to characterise distinct genera, for they usually differ
much in the species of the same genus, and they are highly variable in
the individuals of the same species; we have also seen in the earlier
chapters of this work how variable secondary sexual characters become
under domestication.

      _Summary of the three previous Chapters on the Laws of
      Variation._

In the twenty-third chapter we saw that changed conditions
occasionally, or even often, act in a definite manner on the
organisation, so that all, or nearly all, the individuals thus exposed
become modified in the same manner. But a far more frequent result of
changed conditions, whether acting directly on the organisation or
indirectly through the reproductive system, is indefinite and
fluctuating variability. In the three last chapters, some of the laws
by which such variability is regulated have been discussed.

Increased use adds to the size of muscles, together with the
blood-vessels, nerves, ligaments, the crests of bone and the whole
bones, to which they are attached. Increased functional activity
increases the size of various glands, and strengthens the sense-organs.
Increased and intermittent pressure thickens the epidermis. A change in
the nature of the food sometimes modifies the coats of the stomach, and
augments or decreases the length of the intestines. Continued disuse,
on the other hand, weakens and diminishes all parts of the
organisation. Animals which during many generations have taken but
little exercise, have their lungs reduced in size, and as a consequence
the bony fabric of the chest and the whole form of the body become
modified. With our anciently domesticated birds, the wings have been
little used, and they are slightly reduced; with their decrease, the
crest of the sternum, the scapulae, coracoids, and furculum, have all
been reduced.

With domesticated animals, the reduction of a part from disuse is never
carried so far that a mere rudiment is left; whereas we have reason to
believe that this has often occurred under nature; the effects of
disuse in this latter case being aided by economy of growth, together
with the intercrossing of many varying individuals. The cause of this
difference between organisms in a state of nature, and under
domestication, probably is that in the latter case there has not been
time sufficient for any very great change, and that the principle of
economy of growth does not come into action. On the contrary,
structures which are rudimentary in the parent-species, sometimes
become partially redeveloped in our domesticated productions. Such
rudiments as occasionally make their appearance under domestication,
seem always to be the result of a sudden arrest of development;
nevertheless they are of interest, as showing that rudiments are the
relics of organs once perfectly developed.

Corporeal, periodical, and mental habits, though the latter have been
almost passed over in this work, become changed under domestication,
and the changes are often inherited. Such changed habits in an organic
being, especially when living a free life, would often lead to the
augmented or diminished use of various organs, and consequently to
their modification. From long-continued habit, and more especially from
the occasional birth of individuals with a slightly different
constitution, domestic animals and cultivated plants become to a
certain extent acclimatised or adapted to a climate different from that
proper to the parent-species.

Through the principle of correlated variability, taken in its widest
sense, when one part varies other parts vary, either simultaneously, or
one after the other. Thus, an organ modified during an early embryonic
period affects other parts subsequently developed. When an organ, such
as the beak, increases or decreases in length, adjoining or correlated
parts, as the tongue and the orifice of the nostrils, tend to vary in
the same manner. When the whole body increases or decreases in size,
various parts become modified; thus, with pigeons the ribs increase or
decrease in number and breadth. Homologous parts which are identical
during their early development and are exposed to similar conditions,
tend to vary in the same or in some connected manner,—as in the case of
the right and left sides of the body, and of the front and hind limbs.
So it is with the organs of sight and hearing; for instance, white cats
with blue eyes are almost always deaf. There is a manifest relation
throughout the body between the skin and various dermal appendages,
such as hair, feathers, hoofs, horns, and teeth. In Paraguay, horses
with curly hair have hoofs like those of a mule; the wool and the horns
of sheep often vary together; hairless dogs are deficient in their
teeth; men with redundant hair have abnormal teeth, either by
deficiency or excess. Birds with long wing-feathers usually have long
tail-feathers. When long feathers grow from the outside of the legs and
toes of pigeons, the two outer toes are connected by membrane; for the
whole leg tends to assume the structure of the wing. There is a
manifest relation between a crest of feathers on the head and a
marvellous amount of change in the skull of various fowls; and in a
lesser degree, between the greatly elongated, lopping ears of rabbits
and the structure of their skulls. With plants, the leaves, various
parts of the flower, and the fruit, often vary together to a correlated
manner.

In some cases we find correlation without being able even to conjecture
what is the nature of the connection, as with various monstrosities and
diseases. This is likewise the case with the colour of the adult
pigeon, in connection with the presence of down on the young bird.
Numerous curious instances have been given of peculiarities of
constitution, in correlation with colour, as shown by the immunity of
individuals of one colour from certain diseases, from the attacks of
parasites and from the action of certain vegetable poisons.

Correlation is an important subject; for with species, and in a lesser
degree with domestic races, we continually find that certain parts have
been greatly modified to serve some useful purpose; but we almost
invariably find that other parts have likewise been more or less
modified, without our being able to discover any advantage in the
change. No doubt great caution is necessary with respect to this latter
point, for it is difficult to overrate our ignorance on the use of
various parts of the organisation; but from what we have seen, we may
believe that many modifications are of no direct service, having arisen
in correlation with other and useful changes.

Homologous parts during their early development often become fused
together. Multiple and homologous organs are especially liable to vary
in number and probably in form. As the supply of organised matter is
not unlimited, the principle of compensation sometimes comes into
action; so that, when one part is greatly developed, adjoining parts
are apt to be reduced; but this principle is probably of much less
importance than the more general one of the economy of growth. Through
mere mechanical pressure hard parts occasionally affect adjoining
parts. With plants the position of the flowers on the axis, and of the
seeds in the ovary, sometimes leads, through a more or less free flow
of sap, to changes of structure; but such changes are often due to
reversion. Modifications, in whatever manner caused, will be to a
certain extent regulated by that co-ordinating power, or so-called
_nisus formativus,_ which is in fact a remnant of that simple form of
reproduction, displayed by many lowly organised beings in their power
of fissiparous generation and budding. Finally, the effects of the laws
which directly or indirectly govern variability, may be largely
regulated by man’s selection, and will so far be determined by natural
selection that changes advantageous to any race will be favoured, and
disadvantageous changes will be checked.

Domestic races descended from the same species, or from two or more
allied species, are liable to revert to characters derived from their
common progenitor; and, as they inherit a somewhat similar
constitution, they are liable to vary in the same manner. From these
two causes analogous varieties often arise. When we reflect on the
several foregoing laws, imperfectly as we understand them, and when we
bear in mind how much remains to be discovered, we need not be
surprised at the intricate and to us unintelligible manner in which our
domestic productions have varied, and still go on varying.

REFERENCES

 [1] ‘Hist. des Anomalies,’ 1832, tom. i. pp. 22, 537-556; tom. iii. p.
 462.

 [2] ‘Comptes Rendus,’ 1855, pp. 855, 1039.

 [3] ‘Catalogue of the Teratological Series in the Museum of the R.
 Coll. of Surgeons,’ 1872, p. 16.

 [4] ‘Archives de Zoolog. Exper.,’ Jan. 1874, p. 78.

 [5] ‘Tératologie Vég.,’ 1841, livre iii.

 [6] ‘Hist. des Anomalies,’ tom. iii. pp. 4, 5, 6.

 [7] ‘Tératologie Vég.,’ p. 156. _See also_ my book on ‘The Movements
 and Habits of Climbing Plants,’ 2nd edit., 1875, p. 202.

 [8] ‘Mémoires du Muséum,’ etc., tom. viii. p. 178.

 [9] Prichard, ‘Phys. Hist. of Mankind,’ 1851, vol. i. p. 324.

 [10] ‘Annales des Sc. Nat.,’ 1st series, tom. xix. p. 327.

 [11] ‘Comptes Rendus,’ Dec. 1864, p. 1039.

 [12] “Ueber fötale Rachites,” ‘Würzburger Medicin. Zeitschrift,’ 1860,
 B. i. s. 265.

 [13] ‘Tératologie Vég.,’ p. 192.

 [14] ‘Journal of Horticulture,’ July 2nd, 1861, p. 253.

 [15] It would be worth trial to fertilise with the same pollen the
 central and lateral flowers of the pelargonium, or of other highly
 cultivated plants, protecting them of course from insects: then to sow
 the seed separately, and observe whether the one or the other lot of
 seedlings varied the most.

 [16] Quoted in ‘Journal of Horticulture,’ Feb. 24th, 1863, p. 152.

 [17] ‘Gardener’s Chronicle,’ 1866, p. 612. For the Phalænopsis, _see_
 ibid., 1867, p. 211.

 [18] ‘Mémoires . . . des Végétaux,’ 1837, tom. ii. p. 170.

 [19] ‘Journal of Horticulture,’ July 23rd, 1861, p. 311.

 [20] ‘Nouvelles Archives du Muséum,’ tom. i. p. 137.

 [21] Hugo von Mohl, ‘The Vegetable Cell,’ Eng. translat., 1852, p. 76.

 [22] The Rev. H. H. Dombrain, in ‘Journal of Horticulture,’ 1861, June
 4th, p. 174; and June 25th, p. 234; 1862, April 29th, p. 83.

 [23] ‘Transact. Linn. Soc.,’ vol. xxiii. 1861, p. 360.

 [24] ‘Die Getreidearten,’ 1845, s. 208, 209.

 [25] ‘Gardener’s Chronicle,’ 1850, p. 198.

 [26] Quoted in ‘Gardener’s Chronicle,’ 1866, p. 74.

 [27] ‘Ueber den Begriff der Pflanzenart,’ 1834, s. 14.

 [28] ‘Domesticated Animals,’ 1845, p. 351.

 [29] Bechstein, ‘Naturgeschichte Deutschlands,’ B. iv. 1795, s. 31.

 [30] ‘Proc. Entomolog. Soc. of Philadelphia,’ Oct. 1863, p. 213.




CHAPTER XXVII. PROVISIONAL HYPOTHESIS OF PANGENESIS.

PRELIMINARY REMARKS—FIRST PART: THE FACTS TO BE CONNECTED UNDER A
SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS OF
REPRODUCTION—RE-GROWTH OF AMPUTATED PARTS—GRAFT-HYBRIDS—THE DIRECT
ACTION OF THE MALE ELEMENT ON THE FEMALE—DEVELOPMENT—THE FUNCTIONAL
INDEPENDENCE OF THE UNITS OF THE
BODY—VARIABILITY—INHERITANCE—REVERSION—SECOND PART: STATEMENT OF THE
HYPOTHESIS—HOW FAR THE NECESSARY ASSUMPTIONS ARE IMPROBABLE—EXPLANATION
BY AID OF THE HYPOTHESIS OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN
THE FIRST PART—CONCLUSION.


In the previous chapters large classes of facts, such as those bearing
on bud-variation, the various forms of inheritance, the causes and laws
of variation, have been discussed; and it is obvious that these
subjects, as well as the several modes of reproduction, stand in some
sort of relation to one another. I have been led, or rather forced, to
form a view which to a certain extent connects these facts by a
tangible method. Every one would wish to explain to himself, even in an
imperfect manner, how it is possible for a character possessed by some
remote ancestor suddenly to reappear in the offspring; how the effects
of increased or decreased use of a limb can be transmitted to the
child; how the male sexual element can act not solely on the ovules,
but occasionally on the mother-form; how a hybrid can be produced by
the union of the cellular tissue of two plants independently of the
organs of generation; how a limb can be reproduced on the exact line of
amputation, with neither too much nor too little added; how the same
organism may be produced by such widely different processes, as budding
and true seminal generation; and, lastly, how of two allied forms, one
passes in the course of its development through the most complex
metamorphoses, and the other does not do so, though when mature both
are alike in every detail of structure. I am aware that my view is
merely a provisional hypothesis or speculation; but until a better one
be advanced, it will serve to bring together a multitude of facts which
are at present left disconnected by any efficient cause. As Whewell,
the historian of the inductive sciences, remarks:—“Hypotheses may often
be of service to science, when they involve a certain portion of
incompleteness, and even of error.” Under this point of view I venture
to advance the hypothesis of Pangenesis, which implies that every
separate part of the whole organisation reproduces itself. So that
ovules, spermatozoa, and pollen-grains,—the fertilised egg or seed, as
well as buds,—include and consist of a multitude of germs thrown off
from each separate part or unit.[1]

In the First Part I will enumerate as briefly as I can the groups of
facts which seem to demand connection; but certain subjects, not
hitherto discussed, must be treated at disproportionate length. In the
Second Part the hypothesis will be given; and after considering how far
the necessary assumptions are in themselves improbable, we shall see
whether it serves to bring under a single point of view the various
facts.

PART I.

Reproduction may be divided into two main classes, namely, sexual and
asexual. The latter is effected in many ways—by the formation of buds
of various kinds, and by fissiparous generation, that is by spontaneous
or artificial division. It is notorious that some of the lower animals,
when cut into many pieces, reproduce so many perfect individuals:
Lyonnet cut a Nais or freshwater worm into nearly forty pieces, and
these all reproduced perfect animals.[2] It is probable that
segmentation could be carried much further in some of the protozoa; and
with some of the lowest plants each cell will reproduce the
parent-form. Johannes Müller thought that there was an important
distinction between gemmation and fission; for in the latter case the
divided portion, however small, is more fully developed than a bud,
which also is a younger formation; but most physiologists are now
convinced that the two processes are essentially alike.[3] Prof. Huxley
remarks, “fission is little more than a peculiar mode of budding,” and
Prof. H. J. Clark shows in detail that there is sometimes “a compromise
between self-division and budding.” When a limb is amputated, or when
the whole body is bisected, the cut extremities are said to bud
forth;[4] and as the papilla, which is first formed, consists of
undeveloped cellular tissue like that forming an ordinary bud, the
expression is apparently correct. We see the connection of the two
processes in another way; for Trembley observed with the hydra, that
the reproduction of the head after amputation was checked as soon as
the animal put forth reproductive gemmæ.[5]

Between the production, by fissiparous generation, of two or more
complete individuals, and the repair of even a very slight injury,
there is so perfect a gradation, that it is impossible to doubt that
the two processes are connected. As at each stage of growth an
amputated part is replaced by one in the same state of development, we
must also follow Sir J. Paget in admitting, “that the powers of
development from the embryo, are identical with those exercised for the
restoration from injuries: in other words, that the powers are the same
by which perfection is first achieved, and by which, when lost, it is
recovered.”[6] Finally, we may conclude that the several forms of
budding, fissiparous generation, the repair of injuries, and
development, are all essentially the results of one and the same power.

_Sexual Generation._—The union of the two sexual elements seems at
first sight to make a broad distinction between sexual and asexual
generation. But the conjugation of algæ, by which process the contents
of two cells unite into a single mass capable of development,
apparently gives us the first step towards sexual union: and
Pringsheim, in his memoir on the pairing of Zoospores,[7] shows that
conjugation graduates into true sexual reproduction. Moreover, the now
well-ascertained cases of Parthenogenesis prove that the distinction
between sexual and asexual generation is not nearly so great as was
formerly thought; for ova occasionally, and even in some cases
frequently, become developed into perfect beings, without the concourse
of the male. With most of the lower animals and even with mammals, the
ova show a trace of parthenogenetic power, for without being fertilised
they pass through the first stages of segmentation.[8] Nor can pseudova
which do not need fertilisation, be distinguished from true ova, as was
first shown by Sir J. Lubbock, and is now admitted by Siebold. So,
again, the germ-balls in the larvæ of Cecidomyia are said by
Leuckart[9] to be formed within the ovarium, but they do not require to
be fertilised. It should also be observed that in sexual generation,
the ovules and the male element have equal power of transmitting every
single character possessed by either parent to their offspring. We see
this clearly when hybrids are paired _inter se,_ for the characters of
both grandparents often appear in the progeny, either perfectly or by
segments. It is an error to suppose that the male transmits certain
characters and the female other characters; although no doubt, from
unknown causes, one sex sometimes has a much stronger power of
transmission than the other.

It has, however, been maintained by some authors that a bud differs
essentially from a fertilised germ, in always reproducing the perfect
character of the parent-stock; whilst fertilised germs give birth to
variable beings. But there is no such broad distinction as this. In the
eleventh chapter numerous cases were advanced showing that buds
occasionally grow into plants having quite new characters; and the
varieties thus produced can be propagated for a length of time by buds,
and occasionally by seed. Nevertheless, it must be admitted that beings
produced sexually are much more liable to vary than those produced
asexually; and of this fact a partial explanation will hereafter be
attempted. The variability in both cases is determined by the same
general causes, and is governed by the same laws. Hence new varieties
arising from buds cannot be distinguished from those arising from seed.
Although bud-varieties usually retain their character during successive
bud-generations, yet they occasionally revert, even after a long series
of bud-generations, to their former character. This tendency to
reversion in buds, is one of the most remarkable of the several points
of agreement between the offspring from bud and seminal reproduction.

But there is one difference between organisms produced sexually and
asexually, which is very general. The former pass in the course of
their development from a very low stage to their highest stage, as we
see in the metamorphoses of insects and of many other animals, and in
the concealed metamorphoses of the vertebrata. Animals propagated
asexually by buds or fission, on the other hand, commence their
development at that stage at which the budding or self-dividing animal
may happen to be, and therefore do not pass through some of the lower
developmental stages.[10] Afterwards, they often advance in
organisation, as we see in the many cases of “alternate generation.” In
thus speaking of alternate generation, I follow those naturalists who
look at this process as essentially one of internal budding or of
fissiparous generation. Some of the lower plants, however, such as
mosses and certain algæ, according to Dr. L. Radlkofer,[11] when
propagated asexually, do undergo a retrogressive metamorphosis. As far
as the final cause is concerned, we can to a certain extent understand
why beings propagated by buds should not pass through all the early
stages of development; for with each organism the structure acquired at
each stage must be adapted to its peculiar habits; and if there are
places for the support of many individuals at some one stage, the
simplest plan will be that they should be multiplied at this stage, and
not that they should first retrograde in their development to an
earlier or simpler structure, which might not be fitted for the then
surrounding conditions.

From the several foregoing considerations we may conclude that the
difference between sexual and asexual generation is not nearly so great
as at first appears; the chief difference being that an ovule cannot
continue to live and to be fully developed unless it unites with the
male element; but even this difference is far from invariable, as shown
by the many cases of parthenogenesis. We are therefore naturally led to
inquire what the final cause can be of the necessity in ordinary
generation for the concourse of the two sexual elements.

Seeds and ova are often highly serviceable as the means of
disseminating plants and animals, and of preserving them during one or
more seasons in a dormant state; but unimpregnated seeds or ova, and
detached buds, would be equally serviceable for both purposes. We can,
however, indicate two important advantages gained by the concourse of
the two sexes, or rather of two individuals belonging to opposite
sexes; for, as I have shown in a former chapter, the structure of every
organism appears to be especially adapted for the concurrence, at least
occasionally, of two individuals. When species are rendered highly
variable by changed conditions of life, the free intercrossing of the
varying individuals tends to keep each form fitted for its proper place
in nature; and crossing can be effected only by sexual generation; but
whether the end thus gained is of sufficient importance to account for
the first origin of sexual intercourse is extremely doubtful. Secondly,
I have shown from a large body of facts, that, as a slight change in
the conditions of life is beneficial to each creature, so, in an
analogous manner, is the change effected in the germ by sexual union
with a distinct individual; and I have been led, from observing the
many widely-extended provisions throughout nature for this purpose, and
from the greater vigour of crossed organisms of all kinds, as proved by
direct experiments, as well as from the evil effects of close
interbreeding when long continued, to believe that the advantage thus
gained is very great.

Why the germ, which before impregnation undergoes a certain amount of
development, ceases to progress and perishes, unless it be acted on by
the male element; and why conversely the male element, which in the
case of some insects is enabled to keep alive for four or five years,
and in the case of some plants for several years, likewise perishes,
unless it acts on or unites with the germ, are questions which cannot
be answered with certainty. It is, however, probable that both sexual
elements perish, unless brought into union, simply from including too
little formative matter for independent development. Quatrefages has
shown in the case of the Teredo,[12] as did formerly Prevost and Dumas
with other animals, that more than one spermatozoon is requisite to
fertilise an ovum. This has likewise been shown by Newport,[13] who
proved by numerous experiments, that, when a very small number of
spermatozoa are applied to the ova of Batrachians, they are only
partially impregnated, and an embryo is never fully developed. The rate
also of the segmentation of the ovum is determined by the number of the
spermatozoa. With respect to plants, nearly the same results were
obtained by Kölreuter and Gärtner. This last careful observer, after
making successive trials on a Malva with more and more pollen-grains,
found,[14] that even thirty grains did not fertilise a single seed; but
when forty grains were applied to the stigma, a few seeds of small size
were formed. In the case of Mirabilis the pollen grains are
extraordinarily large, and the ovarium contains only a single ovule;
and these circumstances led Naudin[15] to make the following
experiments: a flower was fertilised by three grains and succeeded
perfectly; twelve flowers were fertilised by two grains, and seventeen
flowers by a single grain, and of these one flower alone in each lot
perfected its seed: and it deserves especial notice that the plants
produced by these two seeds never attained their proper dimensions, and
bore flowers of remarkably small size. From these facts we clearly see
that the quantity of the peculiar formative matter which is contained
within the spermatozoa and pollen-grains is an all-important element in
the act of fertilisation, not only for the full development of the
seed, but for the vigour of the plant produced from such seed. We see
something of the same kind in certain cases of parthenogenesis, that
is, when the male element is wholly excluded; for M. Jourdan[16] found
that, out of about 58,000 eggs laid by unimpregnated silk-moths, many
passed through their early embryonic stages, showing that they were
capable of self-development, but only twenty-nine out of the whole
number produced caterpillars. The same principle of quantity seems to
hold good even in artificial fissiparous reproduction, for Hackel[17]
found that by cutting the segmented and fertilised ova or larva of
Siphonophoræ (jelly-fishes) into pieces, the smaller the pieces were,
the slower was the rate of development, and the larvæ thus produced
were by so much the more imperfect and inclined to monstrosity. It
seems, therefore, probable that with the separate sexual elements
deficient quantity of formative matter is the main cause of their not
having the capacity for prolonged existence and development, unless
they combine and thus increase each other’s bulk. The belief that it is
the function of the spermatozoa to communicate life to the ovule seems
a strange one, seeing that the unimpregnated ovule is already alive and
generally undergoes a certain amount of independent development. Sexual
and asexual reproduction are thus seen not to differ essentially; and
we have already shown that asexual reproduction, the power of re-growth
and development are all parts of one and the same great law.

_Re-growth of amputated parts._—This subject deserves a little further
discussion. A multitude of the lower animals and some vertebrates
possess this wonderful power. For instance, Spallanzani cut off the
legs and tail of the same salamander six times successively, and
Bonnet[18] did so eight times; and on each occasion the limbs were
reproduced on the exact line of amputation, with no part deficient or
in excess. An allied animal, the axolotl, had a limb bitten off, which
was reproduced in an abnormal condition, but when this was amputated it
was replaced by a perfect limb.[19] The new limbs in these cases bud
forth, and are developed in the same manner as during the regular
development of a young animal. For instance, with the _Amblystoma
lurida,_ three toes are first developed, then the fourth, and on the
hind-feet the fifth, and so it is with a reproduced limb.[20]

The power of re-growth is generally much greater during the youth of an
animal or during the earlier stages of its development than during
maturity. The larvæ or tadpoles of the Batrachians are capable of
reproducing lost members, but not so the adults.[21] Mature insects
have no power of re-growth, excepting in one order, whilst the larvæ of
many kinds have this power. Animals low in the scale are able, as a
general rule, to reproduce lost parts far more easily than those which
are more highly organised. The myriapods offer a good illustration of
this rule; but there are some strange exceptions to it—thus Nemerteans,
though lowly organised, are said to exhibit little power of re-growth.
With the higher vertebrata, such as birds and mammals, the power is
extremely limited.[22]

In the case of those animals which may be bisected or chopped into
pieces, and of which every fragment will reproduce the whole, the power
of re-growth must be diffused throughout the whole body. Nevertheless
there seems to be much truth in the view maintained by Prof.
Lessona,[23] that this capacity is generally a localised and special
one, serving to replace parts which are eminently liable to be lost in
each particular animal. The most striking case in favour of this view,
is that the terrestrial salamander, according to Lessona, cannot
reproduce lost parts, whilst another species of the same genus, the
aquatic salamander, has extraordinary powers of re-growth, as we have
just seen; and this animal is eminently liable to have its limbs, tail,
eyes and jaws bitten off by other tritons.[24] Even with the aquatic
salamander the capacity is to a certain extent localised, for when M.
Philipeaux[25] extirpated the entire fore limb together with the
scapula, the power of re-growth was completely lost. It is also a
remarkable fact, standing in opposition to a very general rule, that
the young of the aquatic salamander do not possess the power of
repairing their limbs in an equal degree with the adults[26] but I do
not know that they are more active, or can otherwise better escape the
loss of their limbs, than the adults. The walking-stick insect,
_Diapheromera femorata,_ like other insects of the same order, can
reproduce its legs in the mature state, and these from their great
length must be liable to be lost: but the capacity is localised (as in
the case of the salamander), for Dr. Scudder found,[27] that if the
limb was removed within the trochanto-femoral articulation, it was
never renewed. When a crab is seized by one of its legs, this is thrown
off at the basal joint, being afterwards replaced by a new leg; and it
is generally admitted that this is a special provision for the safety
of the animal. Lastly, with gasteropod molluscs, which are well known
to have the power of reproducing their heads, Lessona shows that they
are very liable to have their heads bitten off by fishes; the rest of
the body being protected by the shell. Even with plants we see
something of the same kind, for non-deciduous leaves and young stems
have no power of re-growth, these parts being easily replaced by growth
from new buds; whilst the bark and subjacent tissues of the trunks of
trees have great power of re-growth, probably on account of their
increase in diameter, and of their liability to injury from being
gnawed by animals.

_Graft-hybrids._—It is well known from innumerable trials made in all
parts of the world, that buds may be inserted into a stock, and that
the plants thus raised are not affected in a greater degree than can be
accounted for by changed nutrition. Nor do the seedlings raised from
such inserted buds partake of the character of the stock, though they
are more liable to vary than are seedlings from the same variety
growing on its own roots. A bud, also, may sport into a new and
strongly-marked variety without any other bud on the same plant being
in the least degree affected. We may therefore infer, in accordance
with the common view, that each bud is a distinct individual, and that
its formative elements do not spread beyond the parts subsequently
developed from it. Nevertheless, we have seen in the abstract on
graft-hybridisation in the eleventh chapter that buds certainly include
formative matter, which can occasionally combine with that included in
the tissues of a distinct variety or species; a plant intermediate
between the two parent-forms being thus produced. In the case of the
potato we have seen that the tubers produced from a bud of one kind
inserted into another are intermediate in colour, size, shape and state
of surface; that the stems, foliage, and even certain constitutional
peculiarities, such as precocity, are likewise intermediate. With these
well-established cases, the evidence that graft-hybrids have also been
produced with the laburnum, orange, vine, rose, etc., seems sufficient.
But we do not know under what conditions this rare form of reproduction
is possible. From these several cases we learn the important fact that
formative elements capable of blending with those of a distinct
individual (and this is the chief characteristic of sexual generation),
are not confined to the reproductive organs, but are present in the
buds and cellular tissue of plants; and this is a fact of the highest
physiological importance.

_Direct Action of the Male Element on the Female._—In the eleventh
chapter, abundant proofs were given that foreign pollen occasionally
affects in a direct manner the mother-plant. Thus, when Gallesio
fertilised an orange-flower with pollen from the lemon, the fruit bore
stripes of perfectly characterised lemon-peel. With peas, several
observers have seen the colour of the seed-coats and even of the pod
directly affected by the pollen of a distinct variety. So it has been
with the fruit of the apple, which consists of the modified calyx and
upper part of the flower-stalk. In ordinary cases these parts are
wholly formed by the mother-plant. We here see that the formative
elements included within the male element or pollen of one variety can
affect and hybridise, not the part which they are properly adapted to
affect, namely, the ovules, but the partially-developed tissues of a
distinct variety or species. We are thus brought half-way towards a
graft-hybrid, in which the formative elements included within the
tissues of one individual combine with those included in the tissues of
a distinct variety or species, thus giving rise to a new and
intermediate form, independently of the male or female sexual organs.

With animals which do not breed until nearly mature, and of which all
the parts are then fully developed, it is hardly possible that the male
element should directly affect the female. But we have the analogous
and perfectly well-ascertained case of the male element affecting (as
with the quagga and Lord Morton’s mare) the female or her ova, in such
a manner that when she is impregnated by another male her offspring are
affected and hybridised by the first male. The explanation would be
simple if the spermatozoa could keep alive within the body of the
female during the long interval which has sometimes elapsed between the
two acts of impregnation; but no one will suppose that this is possible
with the higher animals.

_Development._—The fertilised germ reaches maturity by a vast number of
changes: these are either slight and slowly effected, as when the child
grows into the man, or are great and sudden, as with the metamorphoses
of most insects. Between these extremes we have every gradation, even
within the same class; thus, as Sir J. Lubbock has shown[28] there is
an Ephemerous insect which moults above twenty times, undergoing each
time a slight but decided change of structure; and these changes, as he
further remarks, probably reveal to us the normal stages of
development, which are concealed and hurried through or suppressed in
most other insects. In ordinary metamorphoses, the parts and organs
appear to become changed into the corresponding parts in the next stage
of development; but there is another form of development, which has
been called by Professor Owen metagenesis. In this case “the new parts
are not moulded upon the inner surface of the old ones. The plastic
force has changed its course of operation. The outer case, and all that
gave form and character to the precedent individual, perish and are
cast off; they are not changed into the corresponding parts of the new
individual. These are due to a new and distinct developmental process,”
etc.[29] Metamorphosis, however, graduates so insensibly, into
metagenesis, that the two processes cannot be distinctly separated. For
instance, in the last change which Cirripedes undergo, the alimentary
canal and some other organs are moulded on pre-existing parts; but the
eyes of the old and the young animal are developed in entirely
different parts of the body; the tips of the mature limbs are formed
within the larval limbs, and may be said to be metamorphosed from them;
but their basal portions and the whole thorax are developed in a plane
at right angles to the larval limbs and thorax; and this may be called
metagenesis. The metagenetic process is carried to an extreme point in
the development of some Echinoderms, for the animal in the second stage
of development is formed almost like a bud within the animal of the
first stage, the latter being then cast off like an old vestment, yet
sometimes maintaining for a short period an independent vitality.[30]

If, instead of a single individual, several were to be thus developed
metagenetically within a pre-existing form, the process would be called
one of alternate generation. The young thus developed may either
closely resemble the encasing parent-form, as with the larvæ of
Cecidomyia, or may differ to an astonishing degree, as with many
parasitic worms and jelly-fishes; but this does not make any essential
difference in the process, any more than the greatness or abruptness of
the change in the metamorphoses of insects.

The whole question of development is of great importance for our
present subject. When an organ, the eye, for instance, is
metagenetically formed in a part of the body where during the previous
stage of development no eye existed, we must look at it as a new and
independent growth. The absolute independence of new and old
structures, although corresponding in structure and function, is still
more obvious when several individuals are formed within a previous
form, as in the cases of alternate generation. The same important
principle probably comes largely into play even in the case of
apparently continuous growth, as we shall see when we consider the
inheritance of modifications at corresponding ages.

We are led to the same conclusion, namely, the independence of parts
successively developed, by another and quite distinct group of facts.
It is well known that many animals belonging to the same order, and
therefore not differing widely from each other, pass through an
extremely different course of development. Thus certain beetles, not in
any way remarkably different from others of the same order, undergo
what has been called a hyper-metamorphosis—that is, they pass through
an early stage wholly different from the ordinary grub-like larva. In
the same sub-order of crabs, namely, the Macroura, as Fritz Müller
remarks, the river cray-fish is hatched under the same form which it
ever afterwards retains; the young lobster has divided legs, like a
Mysis; the Palæmon appears under the form of a Zoea, and Peneus under
the Nauplius-form; and how wonderfully these larval forms differ from
one another, is known to every naturalist.[31] Some other crustaceans,
as the same author observes, start from the same point and arrive at
nearly the same end, but in the middle of their development are widely
different from one another. Still more striking cases could be given
with respect to the Echinodermata. With the Medusæ or jelly-fishes
Professor Allman observes, “The classification of the Hydroida would be
a comparatively simple task if, as has been erroneously asserted,
generically-identical medusoids always arose from generically-identical
polypoids; and, on the other hand, that generically-identical polypoids
always gave origin to generically-identical medusoids.” So again, Dr.
Strethill Wright remarks, “In the life-history of the Hydroidæ any
phase, planuloid, polypoid, or medusoid, may be absent.”[32]

According to the belief now generally accepted by our best naturalists,
all the members of the same order or class, for instance, the Medusæ or
the Macrourous crustaceans, are descended from a common progenitor.
During their descent they have diverged much in structure, but have
retained much in common; and this has occurred, though they have passed
through and still pass through marvellously different metamorphoses.
This fact well illustrates how independent each structure is from that
which precedes and that which follows it in the course of development.

_The Functional Independence of the Elements or Units of the
Body._—Physiologists agree that the whole organism consists of a
multitude of elemental parts, which are to a great extent independent
of one another. Each organ, says Claude Bernard,[33] has its proper
life, its autonomy; it can develop and reproduce itself independently
of the adjoining tissues. A great German authority, Virchow,[34]
asserts still more emphatically that each system consists of an
“enormous mass of minute centres of action. . . . Every element has its
own special action, and even though it derive its stimulus to activity
from other parts, yet alone effects the actual performance of duties. .
. . Every single epithelial and muscular fibre-cell leads a sort of
parasitical existence in relation to the rest of the body. . . . Every
single bone-corpuscle really possesses conditions of nutrition peculiar
to itself.” Each element, as Sir J. Paget remarks, lives its appointed
time and then dies, and is replaced after being cast off or
absorbed.[35] I presume that no physiologist doubts that, for instance,
each bone-corpuscle of the finger differs from the corresponding
corpuscle in the corresponding joint of the toe; and there can hardly
be a doubt that even those on the corresponding sides of the body
differ, though almost identical in nature. This near approach to
identity is curiously shown in many diseases in which the same exact
points on the right and left sides of the body are similarly affected;
thus Sir J. Paget[36] gives a drawing of a diseased pelvis, in which
the bone has grown into a most complicated pattern, but “there is not
one spot or line on one side which is not represented, as exactly as it
would be in a mirror, on the other.”

Many facts support this view of the independent life of each minute
element of the body. Virchow insists that a single bone-corpuscle or a
single cell in the skin may become diseased. The spur of a cock, after
being inserted into the ear of an ox, lived for eight years, and
acquired a weight of 396 grammes (nearly fourteen ounces), and the
astonishing length of twenty-four centimetres, or about nine inches; so
that the head of the ox appeared to bear three horns.[37] The tail of a
pig has been grafted into the middle of its back, and reacquired
sensibility. Dr. Ollier[38] inserted a piece of periosteum from the
bone of a young dog under the skin of a rabbit, and true bone was
developed. A multitude of similar facts could be given. The frequent
presence of hairs and of perfectly developed teeth, even teeth of the
second dentition, in ovarian tumours,[39] are facts leading to the same
conclusion. Mr. Lawson Tait refers to a tumour in which “over 300 teeth
were found, resembling in many respects milk-teeth;” and to another
tumour, “full of hair which had grown and been shed from one little
spot of skin not bigger than the tip of my little finger. The amount of
hair in the sac, had it grown from a similarly sized area of the scalp,
would have taken almost a lifetime to grow and be shed.”

Whether each of the innumerable autonomous elements of the body is a
cell or the modified product of a cell, is a more doubtful question,
even if so wide a definition be given to the term, as to include
cell-like bodies without walls and without nuclei.[40] The doctrine of
_omnis cellula e cellulâ_ is admitted for plants, and widely prevails
with respect to animals.[41] Thus Virchow, the great supporter of the
cellular theory, whilst allowing that difficulties exist, maintains
that every atom of tissue is derived from cells, and these from
pre-existing cells, and these primarily from the egg, which he regards
as a great cell. That cells, still retaining the same nature, increase
by self-division or proliferation, is admitted by every one. But when
an organism undergoes great changes of structure during development,
the cells, which at each stage are supposed to be directly derived from
previously existing cells, must likewise be greatly changed in nature;
this change is attributed by the supporters of the cellular doctrine to
some inherent power which the cells possess, and not to any external
agency. Others maintain that cells and tissues of all kinds may be
formed, independently of pre-existing cells, from plastic lymph or
blastema. Whichever view may be correct, every one admits that the body
consists of a multitude of organic units, all of which possess their
own proper attributes, and are to a certain extent independent of all
others. Hence it will be convenient to use indifferently the terms
cells or organic units, or simply units.

_Variability and Inheritance._—We have seen in the twenty-second
chapter that variability is not a principle co-ordinate with life or
reproduction, but results from special causes, generally from changed
conditions acting during successive generations. The fluctuating
variability thus induced is apparently due in part to the sexual system
being easily affected, so that it is often rendered impotent; and when
not so seriously affected, it often fails in its proper function of
transmitting truly the characters of the parents to the offspring. But
variability is not necessarily connected with the sexual system, as we
see in the cases of bud-variation. Although we are seldom able to trace
the nature of the connection, many deviations of structure no doubt
result from changed conditions acting directly on the organisation,
independently of the reproductive system. In some instances we may feel
sure of this, when all, or nearly all the individuals which have been
similarly exposed are similarly and definitely affected, of which
several instances have been given. But it is by no means clear why the
offspring should be affected by the exposure of the parents to new
conditions, and why it is necessary in most cases that several
generations should have been thus exposed.

How, again, can we explain the inherited effects of the use or disuse
of particular organs? The domesticated duck flies less and walks more
than the wild duck, and its limb-bones have become diminished and
increased in a corresponding manner in comparison with those of the
wild duck. A horse is trained to certain paces, and the colt inherits
similar consensual movements. The domesticated rabbit becomes tame from
close confinement; the dog, intelligent from associating with man; the
retriever is taught to fetch and carry; and these mental endowments and
bodily powers are all inherited. Nothing in the whole circuit of
physiology is more wonderful. How can the use or disuse of a particular
limb or of the brain affect a small aggregate of reproductive cells,
seated in a distant part of the body, in such a manner that the being
developed from these cells inherits the characters of either one or
both parents? Even an imperfect answer to this question would be
satisfactory.

In the chapters devoted to inheritance it was shown that a multitude of
newly acquired characters, whether injurious or beneficial, whether of
the lowest or highest vital importance, are often faithfully
transmitted—frequently even when one parent alone possesses some new
peculiarity; and we may on the whole conclude that inheritance is the
rule, and non-inheritance the anomaly. In some instances a character is
not inherited, from the conditions of life being directly opposed to
its development; in many instances, from the conditions incessantly
inducing fresh variability, as with grafted fruit-trees and
highly-cultivated flowers. In the remaining cases the failure may be
attributed to reversion, by which the child resembles its grandparents
or more remote progenitors, instead of its parents.

Inheritance is governed by various laws. Characters which first appear
at any particular age tend to reappear at a corresponding age. They
often become associated with certain seasons of the year, and reappear
in the offspring at a corresponding season. If they appear rather late
in life in one sex, they tend to reappear exclusively in the same sex
at the same period of life.

The principle of reversion, recently alluded to, is one of the most
wonderful of the attributes of Inheritance. It proves to us that the
transmission of a character and its development, which ordinarily go
together and thus escape discrimination, are distinct powers; and these
powers in some cases are even antagonistic, for each acts alternately
in successive generations. Reversion is not a rare event, depending on
some unusual or favourable combination of circumstances, but occurs so
regularly with crossed animals and plants, and so frequently with
uncrossed breeds, that it is evidently an essential part of the
principle of inheritance. We know that changed conditions have the
power of evoking long-lost characters, as in the case of animals
becoming feral. The act of crossing in itself possesses this power in a
high degree. What can be more wonderful than that characters, which
have disappeared during scores, or hundreds, or even thousands of
generations, should suddenly reappear perfectly developed, as in the
case of pigeons and fowls, both when purely bred and especially when
crossed; or as with the zebrine stripes on dun-coloured horses, and
other such cases? Many monstrosities come under this same head, as when
rudimentary organs are redeveloped, or when an organ which we must
believe was possessed by an early progenitor of the species, but of
which not even a rudiment is left, suddenly reappears, as with the
fifth stamen in some Scrophulariaceæ. We have already seen that
reversion acts in bud-reproduction; and we know that it occasionally
acts during the growth of the same individual animal, especially, but
not exclusively, if of crossed parentage,—as in the rare cases
described of fowls, pigeons, cattle, and rabbits, which have reverted
to the colours of one of their parents or ancestors as they advanced in
years.

We are led to believe, as formerly explained, that every character
which occasionally reappears is present in a latent form in each
generation, in nearly the same manner as in male and female animals the
secondary characters of the opposite sex lie latent and ready to be
evolved when the reproductive organs are injured. This comparison of
the secondary sexual characters which lie latent in both sexes, with
other latent characters, is the more appropriate from the case recorded
of a Hen, which assumed some of the masculine characters, not of her
own race, but of an early progenitor; she thus exhibited at the same
time the redevelopment of latent characters of both kinds. In every
living creature we may feel assured that a host of long-lost characters
lie ready to be evolved under proper conditions. How can we make
intelligible and connect with other facts, this wonderful and common
capacity of reversion,—this power of calling back to life long-lost
characters?

PART II.

I have now enumerated the chief facts which every one would desire to
see connected by some intelligible bond. This can be done, if we make
the following assumptions, and much may be advanced in favour of the
chief one. The secondary assumptions can likewise be supported by
various physiological considerations. It is universally admitted that
the cells or units of the body increase by self-division or
proliferation, retaining the same nature, and that they ultimately
become converted into the various tissues and substances of the body.
But besides this means of increase I assume that the units throw off
minute granules which are dispersed throughout the whole system; that
these, when supplied with proper nutriment, multiply by self-division,
and are ultimately developed into units like those from which they were
originally derived. These granules may be called gemmules. They are
collected from all parts of the system to constitute the sexual
elements, and their development in the next generation forms a new
being; but they are likewise capable of transmission in a dormant state
to future generations and may then be developed. Their development
depends on their union with other partially developed or nascent cells
which precede them in the regular course of growth. Why I use the term
union, will be seen when we discuss the direct action of pollen on the
tissues of the mother-plant. Gemmules are supposed to be thrown off by
every unit, not only during the adult state, but during each stage of
development of every organism; but not necessarily during the continued
existence of the same unit. Lastly, I assume that the gemmules in their
dormant state have a mutual affinity for each other, leading to their
aggregation into buds or into the sexual elements. Hence, it is not the
reproductive organs or buds which generate new organisms, but the units
of which each individual is composed. These assumptions constitute the
provisional hypothesis which I have called Pangenesis. Views in many
respects similar have been propounded by various authors.[42]

Before proceeding to show, firstly, how far these assumptions are in
themselves probable, and secondly, how far they connect and explain the
various groups of facts with which we are concerned, it may be useful
to give an illustration, as simple as possible, of the hypothesis. If
one of the Protozoa be formed, as it appears under the microscope, of a
small mass of homogeneous gelatinous matter, a minute particle or
gemmule thrown off from any part and nourished under favourable
circumstances would reproduce the whole; but if the upper and lower
surfaces were to differ in texture from each other and from the central
portion, then all three parts would have to throw off gemmules, which
when aggregated by mutual affinity would form either buds or the sexual
elements, and would ultimately be developed into a similar organism.
Precisely the same view may be extended to one of the higher animals;
although in this case many thousand gemmules must be thrown off from
the various parts of the body at each stage of development; these
gemmules being developed in union with pre-existing nascent cells in
due order of succession.

Physiologists maintain, as we have seen, that each unit of the body,
though to a large extent dependent on others, is likewise to a certain
extent independent or autonomous, and has the power of increasing by
self-division. I go one step further, and assume that each unit casts
off free gemmules which are dispersed throughout the system, and are
capable under proper conditions of being developed into similar units.
Nor can this assumption be considered as gratuitous and improbable. It
is manifest that the sexual elements and buds include formative matter
of some kind, capable of development; and we now know from the
production of graft-hybrids that similar matter is dispersed throughout
the tissues of plants, and can combine with that of another and
distinct plant, giving rise to a new being, intermediate in character.
We know also that the male element can act directly on the partially
developed tissues of the mother-plant, and on the future progeny of
female animals. The formative matter which is thus dispersed throughout
the tissues of plants, and which is capable of being developed into
each unit or part, must be generated there by some means; and my chief
assumption is that this matter consists of minute particles or gemmules
cast off from each unit or cell.[43]

But I have further to assume that the gemmules in their undeveloped
state are capable of largely multiplying themselves by self-division,
like independent organisms. Delpino insists that to “admit of
multiplication by fissiparity in corpuscles, analogous to seeds or buds
. . . is repugnant to all analogy.” But this seems a strange objection,
as Thuret[44] has seen the zoospore of an alga divide itself, and each
half germinated. Haeckel divided the segmented ovum of a siphonophora
into many pieces, and these were developed. Nor does the extreme
minuteness of the gemmules, which can hardly differ much in nature from
the lowest and simplest organisms, render it improbable that they
should grow and multiply. A great authority, Dr. Beale,[45] says “that
minute yeast cells are capable of throwing off buds or gemmules, much
less than the 1/100000 of an inch in diameter;” and these he thinks are
“capable of subdivision practically ad infinitum.”

A particle of small-pox matter, so minute as to be borne by the wind,
must multiply itself many thousandfold in a person thus inoculated; and
so with the contagious matter of scarlet fever.[46] It has recently
been ascertained[47] that a minute portion of the mucous discharge from
an animal affected with rinderpest, if placed in the blood of a healthy
ox, increases so fast that in a short space of time “the whole mass of
blood, weighing many pounds, is infected, and every small particle of
that blood contains enough poison to give, within less than forty-eight
hours, the disease to another animal.”

The retention of free and undeveloped gemmules in the same body from
early youth to old age will appear improbable, but we should remember
how long seeds lie dormant in the earth and buds in the bark of a tree.
Their transmission from generation to generation will appear still more
improbable; but here again we should remember that many rudimentary and
useless organs have been transmitted during an indefinite number of
generations. We shall presently see how well the long-continued
transmission of undeveloped gemmules explains many facts.

As each unit, or group of similar units, throughout the body, casts off
its gemmules, and as all are contained within the smallest ovule, and
within each spermatozoon or pollen-grain, and as some animals and
plants produce an astonishing number of pollen-grains and ovules,[48]
the number and minuteness of the gemmules must be something
inconceivable. But considering how minute the molecules are, and how
many go to the formation of the smallest granule of any ordinary
substance, this difficulty with respect to the gemmules is not
insuperable. From the data arrived at by Sir W. Thomson, my son George
finds that a cube of 1/10000 of an inch of glass or water must consist
of between 16 million millions, and 131 thousand million million
molecules. No doubt the molecules of which an organism is formed are
larger, from being more complex, than those of an inorganic substance,
and probably many molecules go to the formation of a gemmule; but when
we bear in mind that a cube of 1/10000 of an inch is much smaller than
any pollen-grain, ovule or bud, we can see what a vast number of
gemmules one of these bodies might contain.

The gemmules derived from each part or organ must be thoroughly
dispersed throughout the whole system. We know, for instance, that even
a minute fragment of a leaf of a Begonia will reproduce the whole
plant; and that if a fresh-water worm is chopped into small pieces,
each will reproduce the whole animal. Considering also the minuteness
of the gemmules and the permeability of all organic tissues, the
thorough dispersion of the gemmules is not surprising. That matter may
be readily transferred without the aid of vessels from part to part of
the body, we have a good instance in a case recorded by Sir J. Paget of
a lady, whose hair lost its colour at each successive attack of
neuralgia and recovered it again in the course of a few days. With
plants, however, and probably with compound animals, such as corals,
the gemmules do not ordinarily spread from bud to bud, but are confined
to the parts developed from each separate bud; and of this fact no
explanation can be given.

The assumed elective affinity of each gemmule for that particular cell
which precedes it in due order of development is supported by many
analogies. In all ordinary cases of sexual reproduction, the male and
female elements certainly have a mutual affinity for each other: thus,
it is believed that about ten thousand species of Compositæ exist, and
there can be no doubt that if the pollen of all these species could be
simultaneously or successively placed on the stigma of any one species,
this one would elect with unerring certainty its own pollen. This
elective capacity is all the more wonderful, as it must have been
acquired since the many species of this great group of plants branched
off from a common progenitor. On any view of the nature of sexual
reproduction, the formative matter of each part contained within the
ovules and the male element act on each other by some law of special
affinity, so that corresponding parts affect one another; thus, a calf
produced from a short-horned cow by a long-horned bull has its horns
affected by the union of the two forms, and the offspring from two
birds with differently coloured tails have their tails affected.

The various tissues of the body plainly show, as many physiologists
have insisted,[49] an affinity for special organic substances, whether
natural or foreign to the body. We see this in the cells of the kidneys
attracting urea from the blood; in curare affecting certain nerves;
_Lytta vesicatoria_ the kidneys; and the poisonous matter of various
diseases, as small-pox, scarlet-fever, hooping-cough, glanders, and
hydrophobia, affecting certain definite parts of the body.

It has also been assumed that the development of each gemmule depends
on its union with another cell or unit which has just commenced its
development, and which precedes it in due order of growth. That the
formative matter within the pollen of plants, which by our hypothesis
consists of gemmules, can unite with and modify the partially developed
cells of the mother-plant, we have clearly seen in the section devoted
to this subject. As the tissues of plants are formed, as far as is
known, only by the proliferation of pre-existing cells, we must
conclude that the gemmules derived from the foreign pollen do not
become developed into new and separate cells, but penetrate and modify
the nascent cells of the mother-plant. This process may be compared
with what takes place in the act of ordinary fertilisation, during
which the contents of the pollen-tubes penetrate the closed embryonic
sac within the ovule, and determine the development of the embryo.
According to this view, the cells of the mother-plant may almost
literally be said to be fertilised by the gemmules derived from the
foreign pollen. In this case and in all others the proper gemmules must
combine in due order with pre-existing nascent cells, owing to their
elective affinities. A slight difference in nature between the gemmules
and the nascent cells would be far from interfering with their mutual
union and development, for we well know in the case of ordinary
reproduction that such slight differentiation in the sexual elements
favours in a marked manner their union and subsequent development, as
well as the vigour of the offspring thus produced.

Thus far we have been able by the aid of our hypothesis to throw some
obscure light on the problems which have come before us; but it must be
confessed that many points remain altogether doubtful. Thus it is
useless to speculate at what period of development each unit of the
body casts off its gemmules, as the whole subject of the development of
the various tissues is as yet far from clear. We do not know whether
the gemmules are merely collected by some unknown means at certain
seasons within the reproductive organs, or whether after being thus
collected they rapidly multiply there, as the flow of blood to these
organs at each breeding season seems to render probable. Nor do we know
why the gemmules collect to form buds in certain definite places,
leading to the symmetrical growth of trees and corals. We have no means
of deciding whether the ordinary wear and tear of the tissues is made
good by means of gemmules, or merely by the proliferation of
pre-existing cells. If the gemmules are thus consumed, as seems
probable from the intimate connection between the repair of waste,
re-growth, and development, and more especially from the periodical
changes which many male animals undergo in colour and structure, then
some light would be thrown on the phenomena of old age, with its
lessened power of reproduction and of the repair of injuries, and on
the obscure subject of longevity. The fact of castrated animals, which
do not cast off innumerable gemmules in the act of reproduction, not
being longer-lived than perfect males, seems opposed to the belief that
gemmules are consumed in the ordinary repair of wasted tissues; unless
indeed the gemmules after being collected in small numbers within the
reproductive organs are there largely multiplied.[50]

That the same cells or units may live for a long period and continue
multiplying without being modified by their union with free gemmules of
any kind, is probable from such cases as that of the spur of a cock
which grew to an enormous size when grafted into the ear of an ox. How
far units are modified during their normal growth by absorbing peculiar
nutriment from the surrounding tissues, independently of their union
with gemmules of a distinct nature, is another doubtful point.[51] We
shall appreciate this difficulty by calling to mind what complex yet
symmetrical growths the cells of plants yield when inoculated by the
poison of a gall-insect. With animals various polypoid excrescences and
tumours are generally admitted[52] to be the direct product, through
proliferation, of normal cells which have become abnormal. In the
regular growth and repair of bones, the tissues undergo, as Virchow
remarks,[53] a whole series of permutations and substitutions. “The
cartilage cells may be converted by a direct transformation into
marrow-cells, and continue as such; or they may first be converted into
osseous and then into medullary tissue; or lastly, they may first be
converted into marrow and then into bone. So variable are the
permutations of these tissues, in themselves so nearly allied, and yet
in their external appearance so completely distinct.” But as these
tissues thus change their nature at any age, without any obvious change
in their nutrition, we must suppose in accordance with our hypothesis
that gemmules derived from one kind of tissue combine with the cells of
another kind, and cause the successive modifications.

We have good reason to believe that several gemmules are requisite for
the development of one and the same unit or cell; for we cannot
otherwise understand the insufficiency of a single or even of two or
three pollen-grains or spermatozoa. But we are far from knowing whether
the gemmules of all the units are free and separate from one another,
or whether some are from the first united into small aggregates. A
feather, for instance, is a complex structure, and, as each separate
part is liable to inherited variations, I conclude that each feather
generates a large number of gemmules; but it is possible that these may
be aggregated into a compound gemmule. The same remark applies to the
petals of flowers, which are sometimes highly complex structures, with
each ridge and hollow contrived for a special purpose, so that each
part must have been separately modified, and the modifications
transmitted; consequently, separate gemmules, according to our
hypothesis, must have been thrown off from each cell or unit. But, as
we sometimes see half an anther or a small portion of a filament
becoming petali-form, or parts or mere stripes of the calyx assuming
the colour and texture of the corolla, it is probable that with petals
the gemmules of each cell are not aggregated together into a compound
gemmule, but are free and separate. Even in so simple a case as that of
a perfect cell, with its protoplasmic contents, nucleus, nucleolus, and
walls, we do not know whether or not its development depends on a
compound gemmule derived from each part.[54]

Having now endeavoured to show that the several foregoing assumptions
are to a certain extent supported by analogous facts, and having
alluded to some of the most doubtful points, we will consider how far
the hypothesis brings under a single point of view the various cases
enumerated in the First Part. All the forms of reproduction graduate
into one another and agree in their product; for it is impossible to
distinguish between organisms produced from buds, from self-division,
or from fertilised germs; such organisms are liable to variations of
the same nature and to reversions of the same kind; and as, according
to our hypothesis, all the forms of reproduction depend on the
aggregation of gemmules derived from the whole body, we can understand
this remarkable agreement. Parthenogenesis is no longer wonderful, and
if we did not know that great good followed from the union of the
sexual elements derived from two distinct individuals, the wonder would
be that parthenogenesis did not occur much oftener than it does. On any
ordinary theory of reproduction the formation of graft-hybrids, and the
action of the male element on the tissues of the mother-plant, as well
as on the future progeny of female animals, are great anomalies; but
they are intelligible on our hypothesis. The reproductive organs do not
actually create the sexual elements; they merely determine the
aggregation and perhaps the multiplication of the gemmules in a special
manner. These organs, however, together with their accessory parts,
have high functions to perform. They adapt one or both elements for
independent temporary existence, and for mutual union. The stigmatic
secretion acts on the pollen of a plant of the same species in a wholly
different manner to what it does on the pollen of one belonging to a
distinct genus or family. The spermatophores of the Cephalopoda are
wonderfully complex structures, which were formerly mistaken for
parasitic worms; and the spermatozoa of some animals possess attributes
which, if observed in an independent animal, would be put down to
instinct guided by sense-organs,—as when the spermatozoa of an insect
find their way into the minute micropyle of the egg.

The antagonism which has long been observed,[55] with certain
exceptions, between growth and the power of sexual
reproduction[56]—between the repair of injuries and gemmation—and with
plants, between rapid increase by buds, rhizomes, etc., and the
production of seed, is partly explained by the gemmules not existing in
sufficient numbers for these processes to be carried on simultaneously.

Hardly any fact in physiology is more wonderful than the power of
re-growth; for instance, that a snail should be able to reproduce its
head, or a salamander its eyes, tail, and legs, exactly at the points
where they have been cut off. Such cases are explained by the presence
of gemmules derived from each part, and disseminated throughout the
body. I have heard the process compared with that of the repair of the
broken angles of a crystal by re-crystallisation; and the two processes
have this much in common, that in the one case the polarity of the
molecules is the efficient cause, and in the other the affinity of the
gemmules for particular nascent cells. But we have here to encounter
two objections which apply not only to the re-growth of a part, or of a
bisected individual, but to fissiparous generation and budding. The
first objection is that the part which is reproduced is in the same
stage of development as that of the being which has been operated on or
bisected; and in the case of buds, that the new beings thus produced
are in the same stage as that of the budding parent. Thus a mature
salamander, of which the tail has been cut off, does not reproduce a
larval tail; and a crab does not reproduce a larval leg. In the case of
budding it was shown in the first part of this chapter that the new
being thus produced does not retrograde in development,—that is, does
not pass through those earlier stages, which the fertilised germ has to
pass through. Nevertheless, the organisms operated on or multiplying
themselves by buds must, by our hypothesis, include innumerable
gemmules derived from every part or unit of the earlier stages of
development; and why do not such gemmules reproduce the amputated part
or the whole body at a corresponding early stage of development?

The second objection, which has been insisted on by Delpino, is that
the tissues, for instance, of a mature salamander or crab, of which a
limb has been removed, are already differentiated and have passed
through their whole course of development; and how can such tissues in
accordance with our hypothesis attract and combine with the gemmules of
the part which is to be reproduced? In answer to these two objections
we must bear in mind the evidence which has been advanced, showing that
at least in a large number of cases the power of re-growth is a
localised faculty, acquired for the sake of repairing special injuries
to which each particular creature is liable; and in the case of buds or
fissiparous generation, for the sake of quickly multiplying the
organism at a period of life when it can be supported in large numbers.
These considerations lead us to believe that in all such cases a stock
of nascent cells or of partially developed gemmules are retained for
this special purpose either locally or throughout the body, ready to
combine with the gemmules derived from the cells which come next in due
succession. If this be admitted we have a sufficient answer to the
above two objections. Anyhow, pangenesis seems to throw a considerable
amount of light on the wonderful power of re-growth.

It follows, also, from the view just given, that the sexual elements
differ from buds in not including nascent cells or gemmules in a
somewhat advanced stage of development, so that only the gemmules
belonging to the earliest stages are first developed. As young animals
and those which stand low in the scale generally have a much greater
capacity for re-growth than older and higher animals, it would also
appear that they retain cells in a nascent state, or partially
developed gemmules, more readily than do animals which have already
passed through a long series of developmental changes. I may here add
that although ovules can be detected in most or all female animals at
an extremely early age, there is no reason to doubt that gemmules
derived from parts modified during maturity can pass into the ovules.

With respect to hybridism, pangenesis agrees well with most of the
ascertained facts. We must believe, as previously shown, that several
gemmules are requisite for the development of each cell or unit. But
from the occurrence of parthenogenesis, more especially from those
cases in which an embryo is only partially formed, we may infer that
the female element generally includes gemmules in nearly sufficient
number for independent development, so that when united with the male
element the gemmules are superabundant. Now, when two species or races
are crossed reciprocally, the offspring do not commonly differ, and
this shows that the sexual elements agree in power, in accordance with
the view that both include the same gemmules. Hybrids and mongrels are
also generally intermediate in character between the two parent-forms,
yet occasionally they closely resemble one parent in one part and the
other parent in another part, or even in their whole structure: nor is
this difficult to understand on the admission that the gemmules in the
fertilised germ are superabundant in number, and that those derived
from one parent may have some advantage in number, affinity, or vigour
over those derived from the other parent. Crossed forms sometimes
exhibit the colour or other characters of either parent in stripes or
blotches; and this occurs in the first generation, or through reversion
in succeeding bud and seminal generations, of which fact several
instances were given in the eleventh chapter. In these cases we must
follow Naudin[57] and admit that the “essence” or “element” of the two
species,—terms which I should translate into the gemmules,—have an
affinity for their own kind, and thus separate themselves into distinct
stripes or blotches; and reasons were given, when discussing in the
fifteenth chapter the incompatibility of certain characters to unite,
for believing in such mutual affinity. When two forms are crossed, one
is not rarely found to be prepotent in the transmission of its
characters over the other; and this we can explain by again assuming
that the one form has some advantage over the other in the number,
vigour, or affinity of its gemmules. In some cases, however, certain
characters are present in the one form and latent in the other; for
instance, there is a latent tendency in all pigeons to become blue,
and, when a blue pigeon is crossed with one of any other colour, the
blue tint is generally prepotent. The explanation of this form of
prepotency will be obvious when we come to the consideration of
Reversion.

When two distinct species are crossed, it is notorious that they do not
yield the full or proper number of offspring; and we can only say on
this head that, as the development of each organism depends on such
nicely-balanced affinities between a host of gemmules and nascent
cells, we need not feel at all surprised that the commixture of
gemmules derived from two distinct species should lead to partial or
complete failure of development. With respect to the sterility of
hybrids produced from the union of two distinct species, it was shown
in the nineteenth chapter that this depends exclusively on the
reproductive organs being specially affected; but why these organs
should be thus affected we do not know, any more than why unnatural
conditions of life, though compatible with health, should cause
sterility; or why continued close interbreeding, or the illegitimate
unions of heterostyled plants, induce the same result. The conclusion
that the reproductive organs alone are affected, and not the whole
organisation, agrees perfectly with the unimpaired or even increased
capacity in hybrid plants for propagation by buds; for this implies,
according to our hypothesis, that the cells of the hybrids throw off
hybridised gemmules, which become aggregated into buds, but fail to
become aggregated within the reproductive organs, so as to form the
sexual elements. In a similar manner many plants, when placed under
unnatural conditions, fail to produce seed, but can readily be
propagated by buds. We shall presently see that pangenesis agrees well
with the strong tendency to reversion exhibited by all crossed animals
and plants.

Each organism reaches maturity through a longer or shorter course of
growth and development: the former term being confined to mere increase
of size, and development to changed structure. The changes may be small
and insensibly slow, as when a child grows into a man, or many, abrupt,
and slight, as in the metamorphoses of certain ephemerous insects, or,
again, few and strongly-marked, as with most other insects. Each newly
formed part may be moulded within a previously existing and
corresponding part, and in this case it will appear, falsely as I
believe, to be developed from the old part; or it may be formed within
a distinct part of the body, as in the extreme cases of metagenesis. An
eye, for instance, may be developed at a spot where no eye previously
existed. We have also seen that allied organic beings in the course of
their metamorphoses sometimes attain nearly the same structure after
passing through widely different forms; or conversely, after passing
through nearly the same early forms, arrive at widely different mature
forms. In these cases it is very difficult to accept the common view
that the first-formed cells or units possess the inherent power,
independently of any external agency, of producing new structures
wholly different in form, position, and function. But all these cases
become plain on the hypothesis of pangenesis. The units, during each
stage of development, throw off gemmules, which, multiplying, are
transmitted to the offspring. In the offspring, as soon as any
particular cell or unit becomes partially developed, it unites with
(or, to speak metaphorically, is fertilised by) the gemmule of the next
succeeding cell, and so onwards. But organisms have often been
subjected to changed conditions of life at a certain stage of their
development, and in consequence have been slightly modified; and the
gemmules cast off from such modified parts will tend to reproduce parts
modified in the same manner. This process may be repeated until the
structure of the part becomes greatly changed at one particular stage
of development, but this will not necessarily affect other parts,
whether previously or subsequently formed. In this manner we can
understand the remarkable independence of structure in the successive
metamorphoses, and especially in the successive metageneses of many
animals. In the case, however, of diseases which supervene during old
age, subsequently to the ordinary period of procreation, and which,
nevertheless, are sometimes inherited, as occurs with brain and heart
complaints, we must suppose that the organs were affected at an early
age and threw off at this period affected gemmules; but that the
affection became visible or injurious only after the prolonged growth,
in the strict sense of the word, of the part. In all the changes of
structure which regularly supervene during old age, we probably see the
effects of deteriorated growth, and not of true development.

The principle of the independent formation of each part, owing to the
union of the proper gemmules with certain nascent cells, together with
the superabundance of the gemmules derived from both parents, and the
subsequent self-multiplication of the gemmules, throws light on a
widely different group of facts, which on any ordinary view of
development appears very strange. I allude to organs which are
abnormally transposed or multiplied. For instance, a curious case has
been recorded by Dr. Elliott Coues[58] of a monstrous chicken with a
perfect additional _right_ leg articulated to the _left_ side of the
pelvis. Gold-fish often have supernumerary fins placed on various parts
of their bodies. When the tail of a lizard is broken off, a double tail
is sometimes reproduced; and when the foot of the salamander was
divided longitudinally by Bonnet, additional digits were occasionally
formed. Valentin injured the caudal extremity of an embryo, and three
days afterwards it produced rudiments of a double pelvis and of double
hind-limbs.[59] When frogs, toads, etc., are born with their limbs
doubled, as sometimes happens, the doubling, as Gervais remarks,[60]
cannot be due to the complete fusion of two embryos, with the exception
of the limbs, for the larvæ are limbless. The same argument is
applicable[61] to certain insects produced with multiple legs or
antennæ, for these are metamorphosed from apodal or antennæ-less larvæ.
Alphonse Milne-Edwards[62] has described the curious case of a
crustacean in which one eye-peduncle supported, instead of a complete
eye, only an imperfect cornea, and out of the centre of this a portion
of an antenna was developed. A case has been recorded[63] of a man who
had during both dentitions a double tooth in place of the left second
incisor, and he inherited this peculiarity from his paternal
grandfather. Several cases are known[64] of additional teeth having
been developed in the orbit of the eye, and, more especially with
horses, in the palate. Hairs occasionally appear in strange situations,
as “within the substance of the brain.”[65] Certain breeds of sheep
bear a whole crowd of horns on their foreheads. As many as five spurs
have been seen on both legs of certain Game-fowls. In the Polish fowl
the male is ornamented with a topknot of hackles like those on his
neck, whilst the female has a top-knot formed of common feathers. In
feather-footed pigeons and fowls, feathers like those on the wing arise
from the outer side of the legs and toes. Even the elemental parts of
the same feather may be transposed; for in the Sebastopol goose,
barbules are developed on the divided filaments of the shaft. Imperfect
nails sometimes appear on the stumps of the amputated fingers of
man[66] and it is an interesting fact that with the snake-like
Saurians, which present a series with more and more imperfect limbs,
the terminations of the phalanges first disappear, “the nails becoming
transferred to their proximal remnants, or even to parts which are not
phalanges.”[67]

Analogous cases are of such frequent occurrence with plants that they
do not strike us with sufficient surprise. Supernumerary petals,
stamens, and pistils, are often produced. I have seen a leaflet low
down in the compound leaf of _Vicia sativa_ replaced by a tendril; and
a tendril possesses many peculiar properties, such as spontaneous
movement and irritability. The calyx sometimes assumes, either wholly
or by stripes, the colour and texture of the corolla. Stamens are so
frequently converted into petals, more or less completely, that such
cases are passed over as not deserving notice; but as petals have
special functions to perform, namely, to protect the included organs,
to attract insects, and in not a few cases to guide their entrance by
well-adapted contrivances, we can hardly account for the conversion of
stamens into petals merely by unnatural or superfluous nourishment.
Again, the edge of a petal may occasionally be found including one of
the highest products of the plant, namely, pollen; for instance, I have
seen the pollen-mass of an Ophrys, which is a very complex structure,
developed in the edge of an upper petal. The segments of the calyx of
the common pea have been observed partially converted into carpels,
including ovules, and with their tips converted into stigmas. Mr.
Salter and Dr. Maxwell Masters have found pollen within the ovules of
the passion-flower and of the rose. Buds may be developed in the most
unnatural positions, as on the petal of a flower. Numerous analogous
facts could be given.[68]

I do not know how physiologists look at such facts as the foregoing.
According to the doctrine of pangenesis, the gemmules of the transposed
organs become developed in the wrong place, from uniting with wrong
cells or aggregates of cells during their nascent state; and this would
follow from a slight modification in their elective affinities. Nor
ought we to feel much surprise at the affinities of cells and gemmules
varying, when we remember the many curious cases given in the
seventeenth chapter, of plants which absolutely refuse to be fertilised
by their own pollen, though abundantly fertile with that of any other
individual of the same species, and in some cases only with that of a
distinct species. It is manifest that the sexual elective affinities of
such plants—to use the term employed by Gärtner—have been modified. As
the cells of adjoining or homologous parts will have nearly the same
nature, they will be particularly liable to acquire by variation each
other’s elective affinities; and we can thus understand to a certain
extent such cases as a crowd of horns on the heads of certain sheep, of
several spurs on the legs of fowls, hackle-like feathers on the heads
of the males of other fowls, and with the pigeon wing-like feathers on
their legs and membrane between their toes, for the leg is the
homologue of the wing. As all the organs of plants are homologous and
spring from a common axis, it is natural that they should be eminently
liable to transposition. It ought to be observed that when any compound
part, such as an additional limb or an antenna, springs from a false
position, it is only necessary that the few first gemmules should be
wrongly attached; for these whilst developing would attract other
gemmules in due succession, as in the re-growth of an amputated limb.
When parts which are homologous and similar in structure, as the
vertebræ of snakes or the stamens of polyandrous flowers, etc., are
repeated many times in the same organism, closely allied gemmules must
be extremely numerous, as well as the points to which they ought to
become united; and, in accordance with the foregoing views, we can to a
certain extent understand Isid. Geoffroy Saint-Hilaire’s law, that
parts, which are already multiple, are extremely liable to vary in
number.

Variability often depends, as I have attempted to show, on the
reproductive organs being injuriously affected by changed conditions;
and in this case the gemmules derived from the various parts of the
body are probably aggregated in an irregular manner, some superfluous
and others deficient. Whether a superabundance of gemmules would lead
to the increased size of any part cannot be told; but we can see that
their partial deficiency, without necessarily leading to the entire
abortion of the part, might cause considerable modifications; for in
the same manner as plants, if their own pollen be excluded, are easily
hybridised, so, in the case of cells, if the properly succeeding
gemmules were absent, they would probably combine easily with other and
allied gemmules, as we have just seen with transposed parts.

In variations caused by the direct action of changed conditions, of
which several instances have been given, certain parts of the body are
directly affected by the new conditions, and consequently throw off
modified gemmules, which are transmitted to the offspring. On any
ordinary view it is unintelligible how changed conditions, whether
acting on the embryo, the young or the adult, can cause inherited
modifications. It is equally or even more unintelligible on any
ordinary view, how the effects of the long-continued use or disuse of a
part, or of changed habits of body or mind, can be inherited. A more
perplexing problem can hardly be proposed; but on our view we have only
to suppose that certain cells become at last structurally modified; and
that these throw off similarly modified gemmules. This may occur at any
period of development, and the modification will be inherited at a
corresponding period; for the modified gemmules will unite in all
ordinary cases with the proper preceding cells, and will consequently
be developed at the same period at which the modification first arose.
With respect to mental habits or instincts, we are so profoundly
ignorant of the relation between the brain and the power of thought
that we do not know positively whether a fixed habit induces any change
in the nervous system, though this seems highly probable; but when such
habit or other mental attribute, or insanity, is inherited, we must
believe that some actual modification is transmitted;[69] and this
implies, according to our hypothesis, that gemmules derived from
modified nerve-cells are transmitted to the offspring.

It is generally necessary that an organism should be exposed during
several generations to changed conditions or habits, in order that any
modification thus acquired should appear in the offspring. This may be
partly due to the changes not being at first marked enough to catch
attention, but this explanation is insufficient; and I can account for
the fact only by the assumption, which we shall see under the head of
reversion is strongly supported, that gemmules derived from each
unmodified unit or part are transmitted in large numbers to successive
generations, and that the gemmules derived from the same unit after it
has been modified go on multiplying under the same favourable
conditions which first caused the modification, until at last they
become sufficiently numerous to overpower and supplant the old
gemmules.

A difficulty may be here noticed; we have seen that there is an
important difference in the frequency, though not in the nature, of the
variations in plants propagated by sexual and asexual generation. As
far as variability depends on the imperfect action of the reproductive
organs under changed conditions, we can at once see why plants
propagated asexually should be far less variable than those propagated
sexually. With respect to the direct action of changed conditions, we
know that organisms produced from buds do not pass through the earlier
phases of development; they will therefore not be exposed, at that
period of life when structure is most readily modified, to the various
causes inducing variability in the same manner as are embryos and young
larval forms; but whether this is a sufficient explanation I know not.

With respect to variations due to reversion, there is a similar
difference between plants propagated from buds and seeds. Many
varieties can be propagated securely by buds, but generally or
invariably revert to their parent-forms by seed. So, also, hybridised
plants can be multiplied to any extent by buds, but are continually
liable to reversion by seed,—that is, to the loss of their hybrid or
intermediate character. I can offer no satisfactory explanation of
these facts. Plants with variegated leaves, phloxes with striped
flowers, barberries with seedless fruit, can all be securely propagated
by buds taken from the stem or branches; but buds from the roots of
these plants almost invariably lose their character and revert to their
former condition. This latter fact is also inexplicable, unless buds
developed from the roots are as distinct from those on the stem, as is
one bud on the stem from another, and we know that these latter behave
like independent organisms.

Finally, we see that on the hypothesis of pangenesis variability
depends on at least two distinct groups of causes. Firstly, the
deficiency, superabundance, and transposition of gemmules, and the
redevelopment of those which have long been dormant; the gemmules
themselves not having undergone any modification; and such changes will
amply account for much fluctuating variability. Secondly, the direct
action of changed conditions on the organisation, and of the increased
use or disuse of parts; and in this case the gemmules from the modified
units will be themselves modified, and, when sufficiently multiplied,
will supplant the old gemmules and be developed into new structures.

Turning now to the laws of Inheritance. If we suppose a homogeneous
gelatinous protozoon to vary and assume a reddish colour, a minute
separated particle would naturally, as it grew to full size, retain the
same colour; and we should have the simplest form of inheritance.[70]
Precisely the same view may be extended to the infinitely numerous and
diversified units of which the whole body of one of the higher animals
is composed; the separated particles being our gemmules. We have
already sufficiently discussed by implication, the important principle
of inheritance at corresponding ages. Inheritance as limited by sex and
by the season of the year (for instance with animals becoming white in
winter) is intelligible if we may believe that the elective affinities
of the units of the body are slightly different in the two sexes,
especially at maturity, and in one or both sexes at different seasons,
so that they unite with different gemmules. It should be remembered
that, in the discussion on the abnormal transposition of organs, we
have seen reason to believe that such elective affinities are readily
modified. But I shall soon have to recur to sexual and seasonal
inheritance. These several laws are therefore explicable to a large
extent through pangenesis, and on no other hypothesis which has as yet
been advanced.

But it appears at first sight a fatal objection to our hypothesis that
a part or organ may be removed during several successive generations,
and if the operation be not followed by disease, the lost part
reappears in the offspring. Dogs and horses formerly had their tails
docked during many generations without any inherited effect; although,
as we have seen, there is some reason to believe that the tailless
condition of certain sheep-dogs is due to such inheritance.
Circumcision has been practised by the Jews from a remote period, and
in most cases the effects of the operation are not visible in the
offspring; though some maintain that an inherited effect does
occasionally appear. If inheritance depends on the presence of
disseminated gemmules derived from all the units of the body, why does
not the amputation or mutilation of a part, especially if effected on
both sexes, invariably affect the offspring? The answer in accordance
with our hypothesis probably is that gemmules multiply and are
transmitted during a long series of generations—as we see in the
reappearance of zebrine stripes on the horse—in the reappearance of
muscles and other structures in man which are proper to his lowly
organised progenitors, and in many other such cases. Therefore the
long-continued inheritance of a part which has been removed during many
generations is no real anomaly, for gemmules formerly derived from the
part are multiplied and transmitted from generation to generation.

We have as yet spoken only of the removal of parts, when not followed
by morbid action: but when the operation is thus followed, it is
certain that the deficiency is sometimes inherited. In a former chapter
instances were given, as of a cow, the loss of whose horn was followed
by suppuration, and her calves were destitute of a horn on the same
side of their heads. But the evidence which admits of no doubt is that
given by Brown-Séquard with respect to guinea-pigs, which after their
sciatic nerves had been divided, gnawed off their own gangrenous toes,
and the toes of their offspring were deficient in at least thirteen
instances on the corresponding feet. The inheritance of the lost part
in several of these cases is all the more remarkable as only one parent
was affected; but we know that a congenital deficiency is often
transmitted from one parent alone—for instance, the offspring of
hornless cattle of either sex, when crossed with perfect animals, are
often hornless. How, then, in accordance with our hypothesis can we
account for mutilations being sometimes strongly inherited, if they are
followed by diseased action? The answer probably is that all the
gemmules of the mutilated or amputated part are gradually attracted to
the diseased surface during the reparative process, and are there
destroyed by the morbid action.

A few words must be added on the complete abortion of organs. When a
part becomes diminished by disuse prolonged during many generations,
the principle of economy of growth, together with intercrossing, will
tend to reduce it still further as previously explained, but this will
not account for the complete or almost complete obliteration of, for
instance, a minute papilla of cellular tissue representing a pistil, or
of a microscopically minute nodule of bone representing a tooth. In
certain cases of suppression not yet completed, in which a rudiment
occasionally reappears through reversion, dispersed gemmules derived
from this part must, according to our view, still exist; we must
therefore suppose that the cells, in union with which the rudiment was
formerly developed, fail in their affinity for such gemmules, except in
the occasional cases of reversion. But when the abortion is complete
and final, the gemmules themselves no doubt perish; nor is this in any
way improbable, for, though a vast number of active and long-dormant
gemmules are nourished in each living creature, yet there must be some
limit to their number; and it appears natural that gemmules derived
from reduced and useless parts would be more liable to perish than
those freshly derived from other parts which are still in full
functional activity.

The last subject that need be discussed, namely, Reversion, rests on
the principle that transmission and development, though generally
acting in conjunction, are distinct powers; and the transmission of
gemmules with their subsequent development shows us how this is
possible. We plainly see the distinction in the many cases in which a
grandfather transmits to his grandson, through his daughter, characters
which she does not, or cannot, possess. But before proceeding, it will
be advisable to say a few words about latent or dormant characters.
Most, or perhaps all, of the secondary characters, which appertain to
one sex, lie dormant in the other sex; that is, gemmules capable of
development into the secondary male sexual characters are included
within the female; and conversely female characters in the male: we
have evidence of this in certain masculine characters, both corporeal
and mental, appearing in the female, when her ovaria are diseased or
when they fail to act from old age. In like manner female characters
appear in castrated males, as in the shape of the horns of the ox, and
in the absence of horns in castrated stags. Even a slight change in the
conditions of life due to confinement sometimes suffices to prevent the
development of masculine characters in male animals, although their
reproductive organs are not permanently injured. In the many cases in
which masculine characters are periodically renewed, these are latent
at other seasons; inheritance as limited by sex and season being here
combined. Again, masculine characters generally lie dormant in male
animals until they arrive at the proper age for reproduction. The
curious case formerly given of a Hen which assumed the masculine
characters, not of her own breed but of a remote progenitor,
illustrates the close connection between latent sexual characters and
ordinary reversion.

With those animals and plants which habitually produce several forms,
as with certain butterflies described by Mr. Wallace, in which three
female forms and one male form co-exist, or, as with the trimorphic
species of Lythrum and Oxalis, gemmules capable of reproducing these
different forms must be latent in each individual.

Insects are occasionally produced with one side or one quarter of their
bodies like that of the male, with the other half or three-quarters
like that of the female. In such cases the two sides are sometimes
wonderfully different in structure, and are separated from each other
by a sharp line. As gemmules derived from every part are present in
each individual of both sexes, it must be the elective affinities of
the nascent cells which in these cases differ abnormally on the two
sides of the body. Almost the same principle comes into play with those
animals, for instance, certain gasteropods and Verruca amongst
cirripedes, which normally have the two sides of the body constructed
on a very different plan; and yet a nearly equal number of individuals
have either side modified in the same remarkable manner.

Reversion, in the ordinary sense of the word, acts so incessantly, that
it evidently forms an essential part of the general law of inheritance.
It occurs with beings, however propagated, whether by buds or seminal
generation, and sometimes may be observed with advancing age even in
the same individual. The tendency to reversion is often induced by a
change of conditions, and in the plainest manner by crossing. Crossed
forms of the first generation are generally nearly intermediate in
character between their two parents; but in the next generation the
offspring commonly revert to one or both of their grandparents, and
occasionally to more remote ancestors. How can we account for these
facts? Each unit in a hybrid must throw off, according to the doctrine
of pangenesis, an abundance of hybridised gemmules, for crossed plants
can be readily and largely propagated by buds; but by the same
hypothesis dormant gemmules derived from both pure parent-forms are
likewise present; and as these gemmules retain their normal condition,
they would, it is probable, be enabled to multiply largely during the
lifetime of each hybrid. Consequently the sexual elements of a hybrid
will include both pure and hybridised gemmules; and when two hybrids
pair, the combination of pure gemmules derived from the one hybrid with
the pure gemmules of the same parts derived from the other, would
necessarily lead to complete reversion of character; and it is,
perhaps, not too bold a supposition that unmodified and undeteriorated
gemmules of the same nature would be especially apt to combine. Pure
gemmules in combination with hybridised gemmules would lead to partial
reversion. And lastly, hybridised gemmules derived from both
parent-hybrids would simply reproduce the original hybrid form.[71] All
these cases and degrees of reversion incessantly occur.

It was shown in the fifteenth chapter that certain characters are
antagonistic to each other or do not readily blend; hence, when two
animals with antagonistic characters are crossed, it might well happen
that a sufficiency of gemmules in the male alone for the reproduction
of his peculiar characters, and in the female alone for the
reproduction of her peculiar characters, would not be present; and in
this case dormant gemmules derived from the same part in some remote
progenitor might easily gain the ascendancy, and cause the reappearance
of the long-lost character. For instance, when black and white pigeons,
or black and white fowls, are crossed,—colours which do not readily
blend,—blue plumage in the one case, evidently derived from the
rock-pigeon, and red plumage in the other case, derived from the wild
jungle-cock, occasionally reappear. With uncrossed breeds the same
result follows, under conditions which favour the multiplication and
development of certain dormant gemmules, as when animals become feral
and revert to their pristine character. A certain number of gemmules
being requisite for the development of each character, as is known to
be the case from several spermatozoa or pollen-grains being necessary
for fertilisation, and time favouring their multiplication, will
perhaps account for the curious cases, insisted on by Mr. Sedgwick, of
certain diseases which regularly appear in alternate generations. This
likewise holds good, more or less strictly, with other weakly inherited
modifications. Hence, as I have heard it remarked, certain diseases
appear to gain strength by the intermission of a generation. The
transmission of dormant gemmules during many successive generations is
hardly in itself more improbable, as previously remarked, than the
retention during many ages of rudimentary organs, or even only of a
tendency to the production of a rudiment; but there is no reason to
suppose that dormant gemmules can be transmitted and propagated for
ever. Excessively minute and numerous as they are believed to be, an
infinite number derived, during a long course of modification and
descent, from each unit of each progenitor, could not be supported or
nourished by the organism. But it does not seem improbable that certain
gemmules, under favourable conditions, should be retained and go on
multiplying for a much longer period than others. Finally, on the view
here given, we certainly gain some insight into the wonderful fact that
the child may depart from the type of both its parents, and resemble
its grandparents, or ancestors removed by many hundreds of generations.

      _Conclusion._

The hypothesis of Pangenesis, as applied to the several great classes
of facts just discussed, no doubt is extremely complex, but so are the
facts. The chief assumption is that all the units of the body, besides
having the universally admitted power of growing by self-division,
throw off minute gemmules which are dispersed through the system. Nor
can this assumption be considered as too bold, for we know from the
cases of graft-hybridisation that formative matter of some kind is
present in the tissues of plants, which is capable of combining with
that included in another individual, and of reproducing every unit of
the whole organism. But we have further to assume that the gemmules
grow, multiply, and aggregate themselves into buds and the sexual
elements; their development depending on their union with other nascent
cells or units. They are also believed to be capable of transmission in
a dormant state, like seeds in the ground, to successive generations.

In a highly-organised animal, the gemmules thrown off from each
different unit throughout the body must be inconceivably numerous and
minute. Each unit of each part, as it changes during development, and
we know that some insects undergo at least twenty metamorphoses, must
throw off its gemmules. But the same cells may long continue to
increase by self-division, and even become modified by absorbing
peculiar nutriment, without necessarily throwing off modified gemmules.
All organic beings, moreover, include many dormant gemmules derived
from their grandparents and more remote progenitors, but not from all
their progenitors. These almost infinitely numerous and minute gemmules
are contained within each bud, ovule, spermatozoon, and pollen-grain.
Such an admission will be declared impossible; but number and size are
only relative difficulties. Independent organisms exist which are
barely visible under the highest powers of the microscope, and their
germs must be excessively minute. Particles of infectious matter, so
small as to be wafted by the wind or to adhere to smooth paper, will
multiply so rapidly as to infect within a short time the whole body of
a large animal. We should also reflect on the admitted number and
minuteness of the molecules composing a particle of ordinary matter.
The difficulty, therefore, which at first appears insurmountable, of
believing in the existence of gemmules so numerous and small as they
must be according to our hypothesis, has no great weight.

The units of the body are generally admitted by physiologists to be
autonomous. I go one step further and assume that they throw off
reproductive gemmules. Thus an organism does not generate its kind as a
whole, but each separate unit generates its kind. It has often been
said by naturalists that each cell of a plant has the potential
capacity of reproducing the whole plant; but it has this power only in
virtue of containing gemmules derived from every part. When a cell or
unit is from some cause modified, the gemmules derived from it will be
in like manner modified. If our hypothesis be provisionally accepted,
we must look at all the forms of asexual reproduction, whether
occurring at maturity or during youth, as fundamentally the same, and
dependent on the mutual aggregation and multiplication of the gemmules.
The re-growth of an amputated limb and the healing of a wound is the
same process partially carried out. Buds apparently include nascent
cells, belonging to that stage of development at which the budding
occurs, and these cells are ready to unite with the gemmules derived
from the next succeeding cells. The sexual elements, on the other hand,
do not include such nascent cells; and the male and female elements
taken separately do not contain a sufficient number of gemmules for
independent development, except in the cases of parthenogenesis. The
development of each being, including all the forms of metamorphosis and
metagenesis, depends on the presence of gemmules thrown off at each
period of life, and on their development, at a corresponding period, in
union with preceding cells. Such cells may be said to be fertilised by
the gemmules which come next in due order of development. Thus the act
of ordinary impregnation and the development of each part in each being
are closely analogous processes. The child, strictly speaking, does not
grow into the man, but includes germs which slowly and successively
become developed and form the man. In the child, as well as in the
adult, each part generates the same part. Inheritance must be looked at
as merely a form of growth, like the self-division of a lowly-organised
unicellular organism. Reversion depends on the transmission from the
forefather to his descendants of dormant gemmules, which occasionally
become developed under certain known or unknown conditions. Each animal
and plant may be compared with a bed of soil full of seeds, some of
which soon germinate, some lie dormant for a period, whilst others
perish. When we hear it said that a man carries in his constitution the
seeds of an inherited disease, there is much truth in the expression.
No other attempt, as far as I am aware, has been made, imperfect as
this confessedly is, to connect under one point of view these several
grand classes of facts. An organic being is a microcosm—a little
universe, formed of a host of self-propagating organisms, inconceivably
minute and numerous as the stars in heaven.

REFERENCES

 [1] This hypothesis has been severely criticised by many writers, and
 it will be fair to give references to the more important articles. The
 best essay which I have seen is by Prof. Delpino, entitled ‘Sulla
 Darwiniana Teoria della Pangenesi, 1869,’ of which a translation
 appeared in ‘Scientific Opinion,’ Sept. 29th, 1869, and the succeeding
 numbers. He rejects the hypothesis, but criticises it fairly, and I
 have found his criticisms very useful. Mr. Mivart (‘Genesis of
 Species,’ 1871, chap. x.) follows Delpino, but adds no new objections
 of any weight. Dr. Bastian (‘The Beginnings of Life,’ 1872, vol. ii.
 p. 98) says that the hypothesis “looks like a relic of the old rather
 than a fitting appanage of the new evolution philosophy.” He shows
 that I ought not to have used the term “pangenesis,” as it had been
 previously used by Dr. Gros in another sense. Dr. Lionel Beale
 (‘Nature,’ May 11th, 1871, p. 26) sneers at the whole doctrine with
 much acerbity and some justice. Prof. Wigand (‘Schriften der Gesell.
 der gesammt. Naturwissen. zu Marburg,’ B. ix. 1870) considers the
 hypothesis as unscientific and worthless. Mr. G. H. Lewes
 (‘Fortnightly Review,’ Nov. 1st, 1868, p. 503) seems to consider that
 it may be useful: he makes many good criticisms in a perfectly fair
 spirit. Mr. F. Galton, after describing his valuable experiments
 (‘Proc. Royal Soc.,’ vol. xix. p. 393) on the intertransfusion of the
 blood of distinct varieties of the rabbit, concludes by saying that in
 his opinion the results negative beyond all doubt the doctrine of
 Pangenesis. He informs me that subsequently to the publication of his
 paper he continued his experiments on a still larger scale for two
 more generations, without any sign of mongrelism showing itself in the
 very numerous offspring. I certainly should have expected that
 gemmules would have been present in the blood, but this is no
 necessary part of the hypothesis, which manifestly applies to plants
 and the lowest animals. Mr. Galton, in a letter to ‘Nature’ (April
 27th, 1871, p. 502), also criticises various incorrect expressions
 used by me. On the other hand, several writers have spoken favourably
 of the hypothesis, but there would be no use in giving references to
 their articles. I may, however, refer to Dr. Ross’ work, ‘The Graft
 Theory of Disease; being an application of Mr. Darwin’s hypothesis of
 Pangenesis,’ 1872, as he gives several original and ingenious
 discussions.

 [2] Quoted by Paget, ‘Lectures on Pathology,’ 1853, p. 159.

 [3] Dr. Lachmann, also, observes (‘Annals and Mag. of Nat. History,’
 2nd series, vol. xix. 1857, p. 231) with respect to infusoria, that
 “fissation and gemmation pass into each other almost imperceptibly.”
 Again, Mr. W. C. Minor (‘Annals and Mag. of Nat. Hist.,’ 3rd series,
 vol. xi. p. 328) shows that with Annelids the distinction that has
 been made between fission and budding is not a fundamental one. _See
 also_ Professor Clark’s work ‘Mind in Nature,’ New York, 1865, pp. 62,
 94.

 [4] _See_ Bonnet, ‘Œuvres d’Hist. Nat.,’ tom. v., 1781, p. 339, for
 remarks on the budding-out of the amputated limbs of Salamanders.

 [5] Paget, ‘Lectures on Pathology,’ 1853, p. 158.

 [6] Ibid., pp. 152, 164.

 [7] Translated in ‘Annals and Mag. of Nat. Hist.,’ April 1870, p. 272.

 [8] Bischoff, as quoted by von Siebold, “Ueber Parthenogenesis,”
 ‘Sitzung der math. phys. Classe.’ Munich, Nov. 4th, 1871, p. 240. _See
 also_ Quatrefages, ‘Annales des Sc. Nat. Zoolog.,’ 3rd series, 1850,
 p. 138.

 [9] ‘On the Asexual Reproduction of Cecidomyide Larvæ,’ translated in
 ‘Annals and Mag. of Nat. Hist.,’ March 1866, pp. 167, 171.

 [10] Prof. Allman speaks (‘Transact. R. Soc. of Edinburgh,’ vol.
 xxvi., 1870, p. 102) decisively on this head with respect to the
 Hydroida: he says, “It is a universal law in the succession of zooids,
 that no retrogression ever takes place in the series.”

 [11] ‘Annals and Mag. of Nat. Hist.,’ 2nd series, vol. xx., 1857, pp.
 153-455.

 [12] ‘Annales des Sc. Nat.,’ 3rd series, 1850, tom. xiii.

 [13] ‘Transact. Phil. Soc.,’ 1851, pp. 196, 208, 210; 1853 pp. 245,
 247.

 [14] ‘Beitrage zur Kenntniss,’ etc., 1844, s. 345.

 [15] ‘Nouvelles Archives du Muséum,’ tom. i. p. 27.

 [16] As quoted by Sir J. Lubbock in ‘Nat. Hist. Review,’ 1862, p. 345.
 Weijenbergh also raised (‘Nature,’ Dec. 21st, 1871, p. 149) two
 successive generations from unimpregnated females of another
 lepidopterous insect, _Liparis dispar._ These females did not produce
 at most one-twentieth of their full complement of eggs, and many of
 the eggs were worthless. Moreover the caterpillars raised from these
 unfertilised eggs “possessed far less vitality” than those from
 fertilised eggs. In the third parthenogenetic generation not a single
 egg yielded a caterpillar.

 [17] ‘Entwickelungsgeschichte der Siphonophora,’ 1869, p. 73.

 [18] Spallanzani, ‘An Essay on Animal Reproduction,’ translated by Dr.
 Maty, 1769, p. 79. Bonnet, ‘Œuvres d’Hist. Nat.,’ tom. v., part i.,
 4to. edit., 1781, pp. 343, 350.

 [19] Vulpian, as quoted by Prof. Faivre, ‘La Variabilité des Espèces,’
 1868, p. 112.

 [20] Dr. P. Hoy, ‘The American Naturalist,’ Sept. 1871, p. 579.

 [21] Dr. Gunther, in Owen’s ‘Anatomy of Vertebrates,’ vol. i., 1866,
 p. 567. Spallanzani has made similar observations.

 [22] A thrush was exhibited before the British Association at Hull in
 1853 which had lost its tarsus, and this member, it was asserted, had
 been thrice reproduced; having been lost, I presume, each time by
 disease. Sir J. Paget informs me that he feels some doubt about the
 facts recorded by Sir J. Simpson (‘Monthly Journal of Medical
 Science,’ Edinburgh, 1848, new series, vol. ii., p. 890) of the
 re-growth of limbs in the womb in the case of man.

 [23] ‘Atti della Soc. Ital. di Sc. Nat.,’ vol. xi., 1869, p. 493.

 [24] Lessona states that this is so in the paper just referred to.
 _See also_ ‘The American Naturalist,’ Sept. 1871, p. 579.

 [25] ‘Comptes Rendus,’ Oct. 1st, 1866, and June, 1867.

 [26] Bonnet, ‘Oeuvres Hist. Nat.,’ vol. v., p. 294, as quoted by Prof.
 Rolleston in his remarkable address to the 36th annual meeting of the
 British Medical Association.

 [27] ‘Proc. Boston Soc. of Nat. Hist.,’ vol. xii., 1868-69, p. 1.

 [28] ‘Transact. Linn. Soc.,’ vol. xxiv., 1863, p. 62.

 [29] ‘Parthenogenesis,’ 1849, pp. 25, 26. Prof. Huxley has some
 excellent remarks (‘Medical Times,’ 1856, p. 637) on this subject in
 reference to the development of star-fishes, and shows how curiously
 metamorphosis graduates into gemmation or zoid-formation, which is in
 fact the same as metagenesis.

 [30] Prof. J. Reay Greene, in Günther’s ‘Record of Zoolog. Lit.,’
 1865, p. 625.

 [31] Fritz Müller, ‘Für Darwin,’ 1864, s. 65, 71. The highest
 authority on crustaceans, Prof. Milne-Edwards, insists (‘Annal. des
 Sci. Nat.,’ 2nd series, Zoolog., tom. iii., p. 322) on the difference
 in the metamorphosis of closely-allied genera.

 [32] Prof. Allman, in ‘Annals and Mag. of Nat. Hist.,’ 3rd series,
 vol. xiii., 1864, p. 348; Dr. S. Wright, ibid., vol. viii., 1861, p.
 127. _See also_ p. 358 for analogous statements by Sars.

 [33] ‘Tissus Vivants,’ 1866, p. 22.

 [34] ‘Cellular Pathology,’ translated by Dr. Chance, 1860, pp. 14, 18,
 83, 460.

 [35] Paget, ‘Surgical Pathology,’ vol. i., 1853, pp. 12-14.

 [36] Ibid., p. 19.

 [37] _See_ Prof. Mantegazza’s interesting work, ‘Degli innesti
 Animali,’ etc., Milano, 1865, p. 51, tab. 3.

 [38] ‘De la Production Artificielle des Os,’ p. 8.

 [39] Isidore Geoffroy Saint-Hilaire, ‘Hist. des Anomalies,’ tom. ii.,
 pp. 549, 560, 562; Virchow, ibid., p. 484. Lawson Tait, ‘The Pathology
 of Diseases of the Ovaries,’ 1874, pp. 61, 62.

 [40] For the most recent classification of cells, _see_ Ernst Hackel,
 ‘Generelle Morpholog.,’ B. ii., 1866, s. 275.

 [41] Dr. W. Turner, ‘The Present Aspect of Cellular Pathology,’
 ‘Edinburgh Medical Journal,’ April 1863.

 [42] Mr. G. H. Lewes (‘Fortnightly Review,’ Nov. 1st, 1868, p. 506)
 remarks on the number of writers who have advanced nearly similar
 views. More than two thousand years ago Aristotle combated a view of
 this kind, which, as I hear from Dr. W. Ogle, was held by Hippocrates
 and others. Ray, in his ‘Wisdom of God’ (2nd edit., 1692, p. 68), says
 that “every part of the body seems to club and contribute to the
 seed.” The “organic molecules” of Buffon (‘Hist. Nat. Gen.,’ edit. of
 1749, tom. ii., pp. 54, 62, 329, 333, 420, 425) appear at first sight
 to be the same as the gemmules of my hypothesis, but they are
 essentially different. Bonnet (‘Œuvres d’Hist. Nat.,’ tom. v., part
 i., 1781, 4to edit., p. 334) speaks of the limbs having germs adapted
 for the reparation of all possible losses; but whether these germs are
 supposed to be the same with those within buds and the sexual organs
 is not clear. Prof. Owen says (‘Anatomy of Vertebrates,’ vol. iii.,
 1868, p. 813) that he fails to see any fundamental difference between
 the views which he propounded in his ‘Parthenogenesis’ (1849, pp.
 5-8), and which he now considers as erroneous, and my hypothesis of
 pangenesis: but a reviewer (‘Journal of Anat. and Phys.,’ May 1869, p.
 441) shows how different they really are. I formerly thought that the
 “physiological units” of Herbert Spencer (‘Principles of Biology,’
 vol. i., chaps. iv. and viii., 1863-64) were the same as my gemmules,
 but I now know that this is not the case. Lastly, it appears from a
 review of the present work by Prof. Mantegazza (‘Nuova Antologia,
 Maggio,’ 1868), that he (in his ‘Elementi di Igiene,’ Ediz. iii., p.
 540) clearly foresaw the doctrine of pangenesis.

 [43] Mr. Lowne has observed (‘Journal of Queckett Microscopical Club,’
 Sept. 23rd, 1870) certain remarkable changes in the tissues of the
 larva of a fly, which makes him believe “it possible that organs and
 organisms are sometimes developed by the aggregation of excessively
 minute gemmules, such as those which Mr. Darwin’s hypothesis demands.”

 [44] ‘Annales des Sc. Nat.,’ 3rd series, Bot., tom. xiv., 1850, p.
 244.

 [45] ‘Disease Germs,’ p. 20.

 [46] _See_ some very interesting papers on this subject by Dr. Beale,
 in ‘Medical Times and Gazette,’ Sept. 9th, 1865, pp. 273, 330.

 [47] Third Report of the R. Comm. on the Cattle Plague, as quoted in
 ‘Gardener’s Chronicle,’ 1866, p. 446.

 [48] Mr. F. Buckland found 6,867,840 eggs in a cod-fish (‘Land and
 Water,’ 1868, p. 62). An Ascaris produces about 64,000,000 eggs
 (Carpenter’s ‘Comp. Phys.,’ 1854, p. 590). Mr. J. Scott, of the Royal
 Botanic Garden of Edinburgh, calculated, in the same manner as I have
 done for some British Orchids (‘Fertilisation of Orchids,’ p. 344),
 the number of seeds in a capsule of an Acropera and found the number
 to be 371,250. Now this plant produces several flowers on a raceme,
 and many racemes during a season. In an allied genus, Gongora, Mr.
 Scott has seen twenty capsules produced on a single raceme; ten such
 racemes on the Acropera would yield above seventy-four millions of
 seed.

 [49] Paget, ‘Lectures on Pathology,’ p. 27; Virchow, ‘Cellular
 Pathology,’ translated by Dr. Chance, pp. 123, 126, 294. Claude
 Bernard, ‘Des Tissus Vivants,’ pp. 177, 210, 337; Müller,
 ‘Physiology,’ Eng. translat., p. 290.

 [50] Prof. Ray Lankester has discussed several of the points here
 referred to as bearing on pangenesis, in his interesting essay, ‘On
 Comparative Longevity in Man and the Lower Animals,’ 1870, pp. 33, 77,
 etc.

 [51] Dr. Ross refers to this subject in his ‘Graft Theory of Disease,’
 1872, p. 53.

 [52] Virchow, ‘Cellular Pathology,’ translated by Dr. Chance, 1860,
 pp. 60, 162, 245, 441, 454.

 [53] Ibid., pp. 412-426.

 [54] _See_ some good criticisms on this head by Delpino and by Mr. G.
 H. Lewes in the ‘Fortnightly Review,’ Nov. 1st, 1868, p. 509.

 [55] Mr. Herbert Spencer (‘Principles of Biology,’ vol. ii., p. 430)
 has fully discussed this antagonism.

 [56] The male salmon is known to breed at a very early age. The Triton
 and Siredon, whilst retaining their larval branchiæ, according to
 Filippi and Duméril (‘Annals and Mag. of Nat. Hist.,’ 3rd series,
 1866, p. 157) are capable of reproduction. Ernst Haeckel has recently
 (‘Monatsbericht Akad. Wiss. Berlin,’ Feb. 2nd, 1865) observed the
 surprising case of a medusa, with its reproductive organs active,
 which produces by budding a widely different form of medusa; and this
 latter also has the power of sexual reproduction. Krohn has shown
 (‘Annals and Mag. of Nat. Hist.,’ 3rd series, vol. xix., 1862, p. 6)
 that certain other medusæ, whilst sexually mature, propagate by gemmæ.
 _See also_ Kolliker, ‘Morphologie und Entwickelungsgeschichte des
 Pennatulidenstammes,’ 1872, p. 12.

 [57] _See_ his excellent discussion on this subject in ‘Nouvelles
 Archives du Museum,’ tom. i., p. 151.

 [58] ‘Proc. Boston Soc. of Nat. Hist.,’ republished in ‘Scientific
 Opinion,’ Nov. 10th, 1869, p. 488.

 [59] Todd’s ‘Cyclop. of Anat. and Phys.,’ vol. iv., 1849-52, p. 975.

 [60] ‘Compte Rendus,’ Nov. 14th, 1865, p. 800.

 [61] As previously remarked by Quatrefages, in his ‘Métamorphoses de
 l’Homme,’ etc., 1862, p. 129.

 [62] Günther’s ‘Zoological Record,’ 1864, p. 279.

 [63] Sedgwick, ‘Medico-Chirurg. Review,’ April 1863, p. 454.

 [64] Isid. Geoffroy Saint-Hilaire, ‘Hist. des Anomalies,’ tom. i.,
 1832, pp. 435, 657; and tom. ii., p. 560.

 [65] Virchow, ‘Cellular Pathology,’ 1860, p. 66.

 [66] Müller’s ‘Phys.,’ Eng. Translat., vol. i., 1833, p. 407. A case
 of this kind has lately been communicated to me.

 [67] Dr. Fürbringer, ‘Die Knochen etc. bei den schlangenähnlichen
 Sauriern,’ as reviewed in ‘Journal of Anat. and Phys.,’ May 1870, p.
 286.

 [68] Moquin-Tandon, ‘Tératologie Vég.,’ 1841, pp. 218, 220, 353. For
 the case of the pea, _see_ ‘Gardener’s Chronicle,’ 1866, p. 897. With
 respect to pollen within ovules, _see_ Dr. Masters in ‘Science
 Review,’ Oct. 1873, p. 369. The Rev. J. M. Berkeley describes a bud
 developed on a petal of a Clarkia, in ‘Gardener’s Chronicle,’ April
 28th, 1866.

 [69] _See_ some remarks to this effect by Sir H. Holland in his
 ‘Medical Notes,’ 1839, p. 32.

 [70] This is the view taken by Prof. Haeckel, in his ‘Generelle
 Morphologie’ (B. ii. s. 171), who says: “Lediglich die partielle
 Identität der specifisch constituirten Materie im elterlichen und im
 kindlichen Organismus, die Theilung dieser Materie bei der
 Fortpflanzung, ist die Ursache der Erblichkeit.”

 [71] In these remarks I, in fact, follow Naudin, who speaks of the
 elements or essences of the two species which are crossed. _ See_ his
 excellent memoir in the ‘Nouvelles Archives du Muséum,’ tom. i., p.
 151.




CHAPTER XXVIII. CONCLUDING REMARKS.

DOMESTICATION—NATURE AND CAUSES OF VARIABILITY—SELECTION—DIVERGENCE AND
DISTINCTNESS OF CHARACTER—EXTINCTION OF RACES—CIRCUMSTANCES FAVOURABLE
TO SELECTION BY MAN—ANTIQUITY OF CERTAIN RACES—THE QUESTION WHETHER
EACH PARTICULAR VARIATION HAS BEEN SPECIALLY PREORDAINED.


As summaries have been added to nearly all the chapters, and as, in the
chapter on pangenesis, various subjects, such as the forms of
reproduction, inheritance, reversion, the causes and laws of
variability, etc., have been recently discussed, I will here only make
a few general remarks on the more important conclusions which may be
deduced from the multifarious details given throughout this work.

Savages in all parts of the world easily succeed in taming wild
animals; and those inhabiting any country or island, when first visited
by man, would probably have been still more easily tamed. Complete
subjugation generally depends on an animal being social in its habits,
and on receiving man as the chief of the herd or family. In order that
an animal should be domesticated it must be fertile under changed
conditions of life, and this is far from being always the case. An
animal would not have been worth the labour of domestication, at least
during early times, unless of service to man. From these circumstances
the number of domesticated animals has never been large. With respect
to plants, I have shown in the ninth chapter how their varied uses were
probably first discovered, and the early steps in their cultivation.
Man could not have known, when he first domesticated an animal or
plant, whether it would flourish and multiply when transported to other
countries, therefore he could not have been thus influenced in his
choice. We see that the close adaptation of the reindeer and camel to
extremely cold and hot countries has not prevented their domestication.
Still less could man have foreseen whether his animals and plants would
vary in succeeding generations and thus give birth to new races; and
the small capacity of variability in the goose has not prevented its
domestication from a remote epoch.

With extremely few exceptions, all animals and plants which have been
long domesticated have varied greatly. It matters not under what
climate, or for what purpose they are kept, whether as food for man or
beast, for draught or hunting, for clothing or mere pleasure,—under all
these circumstances races have been produced which differ more from one
another than do the forms which in a state of nature are ranked as
different species. Why certain animals and plants have varied more
under domestication than others we do not know, any more than why some
are rendered more sterile than others under changed conditions of life.
But we have to judge of the amount of variation which our domestic
productions have undergone, chiefly by the number and amount of
difference between the races which have been formed, and we can often
clearly see why many and distinct races have not been formed, namely,
because slight successive variations have not been steadily
accumulated; and such variations will never be accumulated if an animal
or plant be not closely observed, much valued, and kept in large
numbers.

The fluctuating, and, as far as we can judge, never-ending variability
of our domesticated productions,—the plasticity of almost their whole
organisation,--is one of the most important lessons which we learn from
the numerous details given in the earlier chapters of this work. Yet
domesticated animals and plants can hardly have been exposed to greater
changes in their conditions of life than have many natural species
during the incessant geological, geographical, and climatal changes to
which the world has been subject; but domesticated productions will
often have been exposed to more sudden changes and to less continuously
uniform conditions. As man has domesticated so many animals and plants
belonging to widely different classes, and as he certainly did not
choose with prophetic instinct those species which would vary most, we
may infer that all natural species, if exposed to analogous conditions,
would, on an average, vary to the same degree. Few men at the present
day will maintain that animals and plants were created with a tendency
to vary, which long remained dormant, in order that fanciers in after
ages might rear, for instance, curious breeds of the fowl, pigeon, or
canary-bird.

From several causes it is difficult to judge of the amount of
modification which our domestic productions have undergone. In some
cases the primitive parent-stock has become extinct; or it cannot be
recognised with certainty, owing to its supposed descendants having
been so much modified. In other cases two or more closely-allied forms,
after being domesticated, have crossed; and then it is difficult to
estimate how much of the character of the present descendants ought to
be attributed to variation, and how much to the influence of the
several parent-stocks. But the degree to which our domesticated breeds
have been modified by the crossing of distinct species has probably
been much exaggerated by some authors. A few individuals of one form
would seldom permanently affect another form existing in greater
numbers; for, without careful selection, the stain of the foreign blood
would soon be obliterated, and during early and barbarous times, when
our animals were first domesticated, such care would seldom have been
taken.

There is good reason to believe in the case of the dog, ox, pig, and of
some other animals, that several of our races are descended from
distinct wild prototypes; nevertheless the belief in the multiple
origin of our domesticated animals has been extended by some few
naturalists and by many breeders to an unauthorised extent. Breeders
refuse to look at the whole subject under a single point of view; I
have heard it said by a man, who maintained that our fowls were
descended from at least half-a-dozen aboriginal species, that the
evidence of the common origin of pigeons, ducks and rabbits, was of no
avail with respect to fowls. Breeders overlook the improbability of
many species having been domesticated at an early and barbarous period.
They do not consider the improbability of species having existed in a
state of nature which, if they resembled our present domestic breeds,
would have been highly abnormal in comparison with all their congeners.
They maintain that certain species, which formerly existed, have become
extinct, or are now unknown, although formerly known. The assumption of
so much recent extinction is no difficulty in their eyes; for they do
not judge of its probability by the facility or difficulty of the
extinction of other closely-allied wild forms. Lastly, they often
ignore the whole subject of geographical distribution as completely as
if it were the result of chance.

Although from the reasons just assigned it is often difficult to judge
accurately of the amount of change which our domesticated productions
have undergone, yet this can be ascertained in the cases in which all
the breeds are known to be descended from a single species,—as with the
pigeon, duck, rabbit, and almost certainly with the fowl; and by the
aid of analogy this can be judged of to a certain extent with
domesticated animals descended from several wild stocks. It is
impossible to read the details given in the earlier chapters and in
many published works, or to visit our various exhibitions, without
being deeply impressed with the extreme variability of our domesticated
animals and cultivated plants. No part of the organisation escapes the
tendency to vary. The variations generally affect parts of small vital
or physiological importance, but so it is with the differences which
exist between closely-allied species. In these unimportant characters
there is often a greater difference between the breeds of the same
species than between the natural species of the same genus, as Isidore
Geoffroy has shown to be the case with size, and as is often the case
with the colour, texture, form, etc., of the hair, feathers, horns, and
other dermal appendages.

It has often been asserted that important parts never vary under
domestication, but this is a complete error. Look at the skull of the
pig in any one of the highly improved breeds, with the occipital
condyles and other parts greatly modified; or look at that of the niata
ox. Or, again, in the several breeds of the rabbit, observe the
elongated skull, with the differently shaped occipital foramen, atlas,
and other cervical vertebrae. The whole shape of the brain, together
with the skull, has been modified in Polish fowls; in other breeds of
the fowl the number of the vertebrae and the forms of the cervical
vertebrae have been changed. In certain pigeons the shape of the lower
jaw, the relative length of the tongue, the size of the nostrils and
eyelids, the number and shape of the ribs, the form and size of the
oesophagus, have all varied. In certain quadrupeds the length of the
intestines has been much increased or diminished. With plants we see
wonderful differences in the stones of various fruits. In the
Cucurbitaceae several highly important characters have varied, such as
the sessile position of the stigmas on the ovarium, the position of the
carpels, and the projection of the ovarium out of the receptacle. But
it would be useless to run through the many facts given in the earlier
chapters.

It is notorious how greatly the mental disposition, tastes, habits,
consensual movements, loquacity or silence, and tone of voice have
varied and been inherited in our domesticated animals. The dog offers
the most striking instance of changed mental attributes, and these
differences cannot be accounted for by descent from distinct wild
types.

New characters may appear and old ones disappear at any stage of
development, being inherited at a corresponding stage. We see this in
the difference between the eggs, the down on the chickens and the first
plumage of the various breeds of the fowl; and still more plainly in
the differences between the caterpillars and cocoons of the various
breeds of the silk-moth. These facts, simple as they appear, throw
light on the differences between the larval and adult states of allied
natural species, and on the whole great subject of embryology. New
characters first appearing late in life are apt to become attached
exclusively to that sex in which they first arose, or they may be
developed in a much higher degree in this than in the other sex; or
again, after having become attached to one sex, they may be transferred
to the opposite sex. These facts, and more especially the circumstance
that new characters seem to be particularly liable, from some unknown
cause, to become attached to the male sex, have an important bearing on
the acquirement of secondary sexual characters by animals in a state of
nature.

It has sometimes been said that our domestic races do not differ in
constitutional peculiarities, but this cannot be maintained. In our
improved cattle, pigs, etc., the period of maturity, including that of
the second dentition, has been much hastened. The period of gestation
varies much, and has been modified in a fixed manner in one or two
cases. In some breeds of poultry and pigeons the period at which the
down and the first plumage are acquired, differs. The number of moults
through which the larvae of silk-moths pass, varies. The tendency to
fatten, to yield much milk, to produce many young or eggs at a birth or
during life, differs in different breeds. We find different degrees of
adaptation to climate, and different tendencies to certain diseases, to
the attacks of parasites, and to the action of certain vegetable
poisons. With plants, adaptation to certain soils, the power of
resisting frost, the period of flowering and fruiting, the duration of
life, the period of shedding the leaves or of retaining them throughout
the winter, the proportion and nature of certain chemical compounds in
the tissues or seeds, all vary.

There is, however, one important constitutional difference between
domestic races and species; I refer to the sterility which almost
invariably follows, in a greater or less degree, when species are
crossed, and to the perfect fertility of the most distinct domestic
races, with the exception of a very few plants, when similarly crossed.
It is certainly a most remarkable fact that many closely-allied
species, which in appearance differ extremely little, should yield when
crossed only a few more or less sterile offspring, or none at all;
whilst domestic races which differ conspicuously from each other are,
when united, remarkably fertile, and yield perfectly fertile offspring.
But this fact is not in reality so inexplicable as it at first appears.
In the first place, it was clearly shown in the nineteenth chapter that
the sterility of crossed species does not depend chiefly on differences
in their external structure or general constitution, but on differences
in the reproductive system, analogous to those which cause the lessened
fertility of the illegitimate unions of dimorphic and trimorphic
plants. In the second place, the Pallasian doctrine, that species after
having been long domesticated lose their natural tendency to sterility
when crossed, has been shown to be highly probable or almost certain.
We cannot avoid this conclusion when we reflect on the parentage and
present fertility of the several breeds of the dog, of the Indian or
humped and European cattle, and of the two chief kinds of pigs. Hence
it would be unreasonable to expect that races formed under
domestication should acquire sterility when crossed, whilst at the same
time we admit that domestication eliminates the normal sterility of
crossed species. Why with closely-allied species their reproductive
systems should almost invariably have been modified in so peculiar a
manner as to be mutually incapable of acting on each other—though in
unequal degrees in the two sexes, as shown by the difference in
fertility between reciprocal crosses of the same species—we do not
know, but may with much probability infer the cause to be as follows.
Most natural species have been habituated to nearly uniform conditions
of life for an incomparably longer time than have domestic races; and
we positively know that changed conditions exert an especial and
powerful influence on the reproductive system. Hence this difference
may well account for the difference in the power of reproduction
between domestic races when crossed and species when crossed. It is
probably in chief part owing to the same cause that domestic races can
be suddenly transported from one climate to another, or placed under
widely different conditions, and yet retain in most cases their
fertility unimpaired; whilst a multitude of species subjected to lesser
changes are rendered incapable of breeding.

The offspring of crossed domestic races and of crossed species resemble
each other in most respects, with the one important exception of
fertility; they often partake in the same unequal degree of the
characters of their parents, one of which is often prepotent over the
other; and they are liable to reversion of the same kind. By successive
crosses one species may be made to absorb completely another, and so it
notoriously is with races. The latter resemble species in many other
ways. They sometimes inherit their newly-acquired characters almost or
even quite as firmly as species. The conditions leading to variability
and the laws governing its nature appear to be the same in both.
Varieties can be classed in groups under groups, like species under
genera, and these under families and orders; and the classification may
be either artificial,—that is, founded on any arbitrary character,—or
natural. With varieties a natural classification is certainly founded,
and with species is apparently founded, on community of descent,
together with the amount of modification which the forms have
undergone. The characters by which domestic varieties differ from one
another are more variable than those distinguishing species, though
hardly more so than with certain polymorphic species; but this greater
degree of variability is not surprising, as varieties have generally
been exposed within recent times to fluctuating conditions of life, and
are much more liable to have been crossed; they are also in many cases
still undergoing, or have recently undergone, modification by man’s
methodical or unconscious selection.

Domestic varieties as a general rule certainly differ from one another
in less important parts than do species; and when important differences
occur, they are seldom firmly fixed; but this fact is intelligible, if
we consider man’s method of selection. In the living animal or plant he
cannot observe internal modifications in the more important organs; nor
does he regard them as long as they are compatible with health and
life. What does the breeder care about any slight change in the molar
teeth of his pigs, or for an additional molar tooth in the dog; or for
any change in the intestinal canal or other internal organ? The breeder
cares for the flesh of his cattle being well marbled with fat, and for
an accumulation of fat within the abdomen of his sheep, and this he has
effected. What would the floriculturist care for any change in the
structure of the ovarium or of the ovules? As important internal organs
are certainly liable to numerous slight variations, and as these would
probably be transmitted, for many strange monstrosities are inherited,
man could undoubtedly effect a certain amount of change in these
organs. When he has produced any modification in an important part, he
has generally done so unintentionally, in correlation with some other
conspicuous part. For instance, he has given ridges and protuberances
to the skulls of fowls, by attending to the form of the comb, or to the
plume of feathers on the head. By attending to the external form of the
pouter-pigeon, he has enormously increased the size of the oesophagus,
and has added to the number of the ribs, and given them greater
breadth. With the carrier-pigeon, by increasing through steady
selection the wattles on the upper mandible, he has greatly modified
the form of the lower mandible; and so in many other cases. Natural
species, on the other hand, have been modified exclusively for their
own good, to fit them for infinitely diversified conditions of life, to
avoid enemies of all kinds, and to struggle against a host of
competitors. Hence, under such complex conditions, it would often
happen that modifications of the most varied kinds, in important as
well as in unimportant parts, would be advantageous or even necessary;
and they would slowly but surely be acquired through the survival of
the fittest. Still more important is the fact that various indirect
modifications would likewise arise through the law of correlated
variation.

Domestic breeds often have an abnormal or semi-monstrous character, as
amongst dogs, the Italian greyhound, bulldog, Blenheim spaniel, and
bloodhound,—some breeds of cattle and pigs,—several breeds of the
fowl,—and the chief breeds of the pigeon. In such abnormal breeds,
parts which differ but slightly or not at all in the allied natural
species, have been greatly modified. This may be accounted for by man’s
often selecting, especially at first, conspicuous and semi-monstrous
deviations of structure. We should, however, be cautious in deciding
what deviations ought to be called monstrous: there can hardly be a
doubt that, if the brush of horse-like hair on the breast of the
turkey-cock had first appeared in the domesticated bird, it would have
been considered as a monstrosity; the great plume of feathers on the
head of the Polish cock has been thus designated, though plumes are
common on the heads of many kinds of birds; we might call the wattle or
corrugated skin round the base of the beak of the English
carrier-pigeon a monstrosity, but we do not thus speak of the globular
fleshy excrescence at the base of the beak of the _Carpophaga
oceanica._

Some authors have drawn a wide distinction between artificial and
natural breeds; although in extreme cases the distinction is plain, in
many other cases it is arbitrary; the difference depending chiefly on
the kind of selection which has been applied. Artificial breeds are
those which have been intentionally improved by man; they frequently
have an unnatural appearance, and are especially liable to lose their
characters through reversion and continued variability. The so-called
natural breeds, on the other hand, are those which are found in
semi-civilised countries, and which formerly inhabited separate
districts in nearly all the European kingdoms. They have been rarely
acted on by man’s intentional selection; more frequently by unconscious
selection, and partly by natural selection, for animals kept in
semi-civilised countries have to provide largely for their own wants.
Such natural breeds will also have been directly acted on by the
differences, though slight, in the surrounding conditions.

There is a much more important distinction between our several breeds,
namely, in some having originated from a strongly-marked or
semi-monstrous deviation of structure, which, however, may subsequently
have been augmented by selection; whilst others have been formed in so
slow and insensible a manner, that if we could see their early
progenitors we should hardly be able to say when or how the breed first
arose. From the history of the racehorse, greyhound, gamecock, etc.,
and from their general appearance, we may feel nearly confident that
they were formed by a slow process of improvement; and we know that
this has been the case with the carrier-pigeon, as well as with some
other pigeons. On the other hand, it is certain that the ancon and
mauchamp breeds of sheep, and almost certain that the niata cattle,
turnspit, and pug-dogs, jumper and frizzled fowls, short-faced tumbler
pigeons, hook-billed ducks, etc., suddenly appeared in nearly the same
state as we now see them. So it has been with many cultivated plants.
The frequency of these cases is likely to lead to the false belief that
natural species have often originated in the same abrupt manner. But we
have no evidence of the appearance, or at least of the continued
procreation, under nature, of abrupt modifications of structure; and
various general reasons could be assigned against such a belief.

On the other hand, we have abundant evidence of the constant occurrence
under nature of slight individual differences of the most diversified
kinds; and we are thus led to conclude that species have generally
originated by the natural selection of extremely slight differences.
This process may be strictly compared with the slow and gradual
improvement of the racehorse, greyhound, and gamecock. As every detail
of structure in each species has to be closely adapted to its habits of
life, it will rarely happen that one part alone will be modified; but,
as was formerly shown, the co-adapted modifications need not be
absolutely simultaneous. Many variations, however, are from the first
connected by the law of correlation. Hence it follows that even
closely-allied species rarely or never differ from one another by one
character alone; and the same remark is to a certain extent applicable
to domestic races; for these, if they differ much, generally differ in
many respects.

Some naturalists boldly insist[1] that species are absolutely distinct
productions, never passing by intermediate links into one another;
whilst they maintain that domestic varieties can always be connected
either with one another or with their parent-forms. But if we could
always find the links between the several breeds of the dog, horse,
cattle, sheep, pigs, etc., there would not have been such incessant
doubts whether they were descended from one or several species. The
greyhound genus, if such a term may be used, cannot be closely
connected with any other breed, unless, perhaps, we go back to the
ancient Egyptian monuments. Our English bulldog also forms a very
distinct breed. In all these cases crossed breeds must of course be
excluded, for distinct natural species can thus be likewise connected.
By what links can the Cochin fowl be closely united with others? By
searching for breeds still preserved in distant lands, and by going
back to historical records, tumbler-pigeons, carriers, and barbs can be
closely connected with the parent rock-pigeon; but we cannot thus
connect the turbit or the pouter. The degree of distinctness between
the various domestic breeds depends on the amount of modification which
they have undergone, and more especially on the neglect and final
extinction of intermediate and less-valued forms.

It has often been argued that no light is thrown on the changes which
natural species are believed to undergo from the admitted changes of
domestic races, as the latter are said to be mere temporary
productions, always reverting, as soon as they become feral, to their
pristine form. This argument has been well combated by Mr. Wallace[2]
and full details were given in the thirteenth chapter, showing that the
tendency to reversion in feral animals and plants has been greatly
exaggerated, though no doubt it exists to a certain extent. It would be
opposed to all the principles inculcated in this work, if domestic
animals, when exposed to new conditions and compelled to struggle for
their own wants against a host of foreign competitors, were not
modified in the course of time. It should also be remembered that many
characters lie latent in all organic beings, ready to be evolved under
fitting conditions; and in breeds modified within recent times, the
tendency to reversion is particularly strong. But the antiquity of some
of our breeds clearly proves that they remain nearly constant as long
as their conditions of life remain the same.

It has been boldly maintained by some authors that the amount of
variation to which our domestic productions are liable is strictly
limited; but this is an assertion resting on little evidence. Whether
or not the amount of change in any particular direction is limited, the
tendency to general variability is, as far as we can judge, unlimited.
Cattle, sheep, and pigs have varied under domestication from the
remotest period, as shown by the researches of Rutimeyer and others;
yet these animals have been improved to an unparalleled degree, within
quite recent times, and this implies continued variability of
structure. Wheat, as we know from the remains found in the Swiss
lake-dwellings, is one of the most anciently cultivated plants, yet at
the present day new and better varieties frequently arise. It may be
that an ox will never be produced of larger size and finer proportions,
or a racehorse fleeter, than our present animals, or a gooseberry
larger than the London variety; but he would be a bold man who would
assert that the extreme limit in these respects has been finally
attained. With flowers and fruit it has repeatedly been asserted that
perfection has been reached, but the standard has soon been excelled. A
breed of pigeons may never be produced with a beak shorter than that of
the present short-faced tumbler, or with one longer than that of the
English carrier, for these birds have weak constitutions and are bad
breeders; but shortness and length of beak are the points which have
been steadily improved during the last 150 years, and some of the best
judges deny that the goal has yet been reached. From reasons which
could be assigned, it is probable that parts which have now reached
their maximum development, might, after remaining constant during a
long period, vary again in the direction of increase under new
conditions of life. But there must be, as Mr. Wallace has remarked with
much truth,[3] a limit to change in certain directions both with
natural and domestic productions; for instance, there must be a limit
to the fleetness of any terrestrial animal, as this will be determined
by the friction to be overcome, the weight to be carried, and the power
of contraction in the muscular fibres. The English racehorse may have
reached this limit; but it already surpasses in fleetness its own wild
progenitor and all other equine species. The short-faced tumbler-pigeon
has a beak shorter, and the carrier a beak longer, relatively to the
size of their bodies, than that of any natural species of the family.
Our apples, pears and gooseberries bear larger fruit than those of any
natural species of the same genera; and so in many other cases.

It is not surprising, seeing the great difference between many domestic
breeds, that some few naturalists have concluded that each is descended
from a distinct aboriginal stock, more especially as the principle of
selection has been ignored, and the high antiquity of man, as a breeder
of animals, has only recently become known. Most naturalists, however,
freely admit that our various breeds, however dissimilar, are descended
from a single stock, although they do not know much about the art of
breeding, cannot show the connecting links, nor say where and when the
breeds arose. Yet these same naturalists declare, with an air of
philosophical caution, that they will never admit that one natural
species has given birth to another until they behold all the
transitional steps. Fanciers use exactly the same language with respect
to domestic breeds; thus, an author of an excellent treatise on pigeons
says he will never allow that the carrier and fantail are the
descendants of the wild rock-pigeon, until the transitions have
“actually been observed, and can be repeated whenever man chooses to
set about the task.” No doubt it is difficult to realise that slight
changes added up during long centuries can produce such great results;
but he who wishes to understand the origin of domestic breeds or of
natural species must overcome this difficulty.

The causes which excite and the laws which govern variability have been
discussed so lately, that I need here only enumerate the leading
points. As domesticated organisms are much more liable to slight
deviations of structure and to monstrosities than species living under
their natural conditions, and as widely-ranging species generally vary
more than those which inhabit restricted areas, we may infer that
variability mainly depends on changed conditions of life. We must not
overlook the effects of the unequal combination of the characters
derived from both parents, or reversion to former progenitors. Changed
conditions have an especial tendency to render the reproductive organs
more or less impotent, as shown in the chapter devoted to this subject;
and these organs consequently often fail to transmit faithfully the
parental characters. Changed conditions also act directly and
definitely on the organisation, so that all or nearly all the
individuals of the same species thus exposed become modified in the
same manner; but why this or that part is especially affected we can
seldom or ever say. In most cases, however, a change in the conditions
seems to act indefinitely, causing diversified variations in nearly the
same manner as exposure to cold or the absorption of the same poison
affects different individuals in different ways. We have reason to
suspect that an habitual excess of highly-nutritious food, or an excess
relatively to the wear and tear of the organisation from exercise, is a
powerful exciting cause of variability. When we see the symmetrical and
complex outgrowths, caused by a minute drop of the poison of a
gall-insect, we may believe that slight changes in the chemical nature
of the sap or blood would lead to extraordinary modifications of
structure.

The increased use of a muscle with its various attached parts, and the
increased activity of a gland or other organ, lead to their increased
development. Disuse has a contrary effect. With domesticated
productions, although their organs sometimes become rudimentary through
abortion, we have no reason to suppose that this has ever followed
solely from disuse. With natural species, on the contrary, many organs
appear to have been rendered rudimentary through disuse, aided by the
principle of the economy of growth together with intercrossing.
Complete abortion can be accounted for only by the hypothesis given in
the last chapter, namely, the final destruction of the germs or
gemmules of useless parts. This difference between species and domestic
varieties may be partly accounted for by disuse having acted on the
latter for an insufficient length of time, and partly from their
exemption from any severe struggle for existence entailing rigid
economy in the development of each part, to which all species under
nature are subjected. Nevertheless the law of compensation or
balancement, which likewise depends on the economy of growth,
apparently has affected to a certain extent our domesticated
productions.

As almost every part of the organisation becomes highly variable under
domestication, and as variations are easily selected both consciously
and unconsciously, it is very difficult to distinguish between the
effects of the selection of indefinite variations and the direct action
of the conditions of life. For instance, it is possible that the feet
of our water-dogs and of the American dogs which have to travel much
over the snow, may have become partially webbed from the stimulus of
widely extending their toes; but it is more probable that the webbing,
like the membrane between the toes of certain pigeons, spontaneously
appeared and was afterwards increased by the best swimmers and the best
snow-travellers being preserved during many generations. A fancier who
wished to decrease the size of his bantams or tumbler-pigeons would
never think of starving them, but would select the smallest individuals
which spontaneously appeared. Quadrupeds are sometimes born destitute
of hair and hairless breeds have been formed, but there is no reason to
believe that this is caused by a hot climate. Within the tropics heat
often causes sheep to lose their fleeces; on the other hand, wet and
cold act as a direct stimulus to the growth of hair; but who will
pretend to decide how far the thick fur of arctic animals, or their
white colour, is due to the direct action of a severe climate, and how
far to the preservation of the best-protected individuals during a long
succession of generations?

Of all the laws governing variability, that of correlation is one of
the most important. In many cases of slight deviations of structure as
well as of grave monstrosities, we cannot even conjecture what is the
nature of the bond of connexion. But between homologous parts—between
the fore and hind limbs—between the hair, hoofs, horns, and teeth—which
are closely similar during their early development and which are
exposed to similar conditions, we can see that they would be eminently
liable to be modified in the same manner. Homologous parts, from having
the same nature, are apt to blend together, and, when many exist, to
vary in number.

Although every variation is either directly or indirectly caused by
some change in the surrounding conditions, we must never forget that
the nature of the organisation which is acted on, is by far the more
important factor in the result. We see this in different organisms,
which when placed under similar conditions vary in a different manner,
whilst closely-allied organisms under dissimilar conditions often vary
in nearly the same manner. We see this, in the same modification
frequently reappearing in the same variety at long intervals of time,
and likewise in the several striking cases given of analogous or
parallel variations. Although some of these latter cases are due to
reversion, others cannot thus be accounted for.

From the indirect action of changed conditions on the organisation,
owing to the reproductive organs being thus affected—from the direct
action of such conditions, and these will cause the individuals of the
same species either to vary in the same manner, or differently in
accordance with slight differences in their constitution—from the
effects of the increased or decreased use of parts—and from
correlation,—the variability of our domesticated productions is
complicated to an extreme degree. The whole organisation becomes
slightly plastic. Although each modification must have its own exciting
cause, and though each is subjected to law, yet we can so rarely trace
the precise relation between cause and effect, that we are tempted to
speak of variations as if they arose spontaneously. We may even call
them accidental, but this must be only in the sense in which we say
that a fragment of rock dropped from a height owes its shape to
accident.

It may be worth while briefly to consider the result of the exposure to
unnatural conditions of a large number of animals of the same species
and allowed to cross freely with no selection of any kind, and
afterwards to consider the result when selection is brought into play.
Let us suppose that 500 wild rock-pigeons were confined in their native
land in an aviary and fed in the same manner as pigeons usually are;
and that they were not allowed to increase in number. As pigeons
propagate so rapidly, I suppose that a thousand or fifteen hundred
birds would have to be annually killed. After several generations had
been thus reared, we may feel sure that some of the young birds would
vary, and the variations would tend to be inherited; for at the present
day slight deviations of structure often occur and are inherited. It
would be tedious even to enumerate the multitude of points which still
go on varying or have recently varied. Many variations would occur in
correlation with one another, as the length of the wing and tail
feathers—the number of the primary wing-feathers, as well as the number
and breadth of the ribs, in correlation with the size and form of the
body—the number of the scutellae with the size of the feet—the length
of the tongue with the length of the beak—the size of the nostrils and
eyelids and the form of lower jaw in correlation with the development
of wattle—the nakedness of the young with the future colour of the
plumage—the size of the feet with that of the beak, and other such
points. Lastly, as our birds are supposed to be confined in an aviary,
they would use their wings and legs but little, and certain parts of
the skeleton, such as the sternum, scapulae and feet, would in
consequence become slightly reduced in size.

As in our assumed case many birds have to be indiscriminately killed
every year, the chances are against any new variety surviving long
enough to breed. And as the variations which arise are of an extremely
diversified nature, the chances are very great against two birds
pairing which have varied in the same manner; nevertheless, a varying
bird even when not thus paired would occasionally transmit its
character to its young; and these would not only be exposed to the same
conditions which first caused the variation in question to appear, but
would in addition inherit from their modified parent a tendency again
to vary in the same manner. So that, if the conditions decidedly tended
to induce some particular variation, all the birds might in the course
of time become similarly modified. But a far commoner result would be,
that one bird would vary in one way and another bird in another way;
one would be born with a beak a little longer, and another with a
shorter beak; one would gain some black feathers, another some white or
red feathers. And as these birds would be continually intercrossing,
the final result would be a body of individuals differing from each
other in many ways, but only slightly; yet more than did the original
rock-pigeons. But there would not be the least tendency towards the
formation of several distinct breeds.

If two separate lots of pigeons were treated in the manner just
described, one in England and the other in a tropical country, the two
lots being supplied with different kinds of food, would they after many
generations differ? When we reflect on the cases given in the
twenty-third chapter, and on such facts as the difference in former
times between the breeds of cattle, sheep, etc., in almost every
district of Europe, we are strongly inclined to admit that the two lots
would be differently modified through the influence of climate and
food. But the evidence on the definite action of changed conditions is
in most cases insufficient; and, with respect to pigeons, I have had
the opportunity of examining a large collection of domesticated kinds,
sent to me by Sir W. Elliot from India, and they varied in a remarkably
similar manner with our European birds.

If two distinct breeds were mingled together in equal numbers, there is
reason to suspect that they would to a certain extent prefer pairing
with their own kind; but they would often intercross. From the greater
vigour and fertility of the crossed offspring, the whole body would by
this means become interblended sooner than would otherwise have
occurred. From certain breeds being prepotent over others, it does not
follow that the interblended progeny would be strictly intermediate in
character. I have, also, proved that the act of crossing in itself
gives a strong tendency to reversion, so that the crossed offspring
would tend to revert to the state of the aboriginal rock-pigeon; and in
the course of time they would probably be not much more heterogeneous
in character than in our first case, when birds of the same breed were
confined together.

I have just said that the crossed offspring would gain in vigour and
fertility. From the facts given in the seventeenth chapter there can be
no doubt of this fact; and there can be little doubt, though the
evidence on this head is not so easily acquired, that long-continued
close interbreeding leads to evil results. With hermaphrodites of all
kinds, if the sexual elements of the same individual habitually acted
on each other, the closest possible interbreeding would be perpetual.
But we should bear in mind that the structure of all hermaphrodite
animals, as far as I can learn, permits and frequently necessitates a
cross with a distinct individual. With hermaphrodite plants we
incessantly meet with elaborate and perfect contrivances for this same
end. It is no exaggeration to assert that, if the use of the talons and
tusks of a carnivorous animal, or of the plumes and hooks on a seed,
may be safely inferred from their structure, we may with equal safety
infer that many flowers are constructed for the express purpose of
ensuring a cross with a distinct plant. From these various
considerations, not to mention the result of a long series of
experiments which I have tried, the conclusion arrived at in the
chapter just referred to—namely, that great good of some kind is
derived from the sexual concourse of distinct individuals—must be
admitted.

To return to our illustration: we have hitherto assumed that the birds
were kept down to the same number by indiscriminate slaughter; but if
the least choice be permitted in their preservation, the whole result
will be changed. Should the owner observe any slight variation in one
of his birds, and wish to obtain a breed thus characterised, he would
succeed in a surprisingly short time by careful selection. As any part
which has once varied generally goes on varying in the same direction,
it is easy, by continually preserving the most strongly marked
individuals, to increase the amount of difference up to a high,
predetermined standard of excellence. This is methodical selection.

If the owner of the aviary, without any thought of making a new breed,
simply admired, for instance, short-beaked more than long-beaked birds,
he would, when he had to reduce the number, generally kill the latter;
and there can be no doubt that he would thus in the course of time
sensibly modify his stock. It is improbable, if two men were to keep
pigeons and act in this manner, that they would prefer exactly the same
characters; they would, as we know, often prefer directly opposite
characters, and the two lots would ultimately come to differ. This has
actually occurred with strains or families of cattle, sheep, and
pigeons, which have been long kept and carefully attended to by
different breeders, without any wish on their part to form new and
distinct sub-breeds. This unconscious kind of selection will more
especially come into action with animals which are highly serviceable
to man; for every one tries to get the best dogs, horses, cows, or
sheep, without thinking about their future progeny, yet these animals
would transmit more or less surely their good qualities to their
offspring. Nor is any one so careless as to breed from his worst
animals. Even savages, when compelled from extreme want to kill some of
their animals, would destroy the worst and preserve the best. With
animals kept for use and not for mere amusement, different fashions
prevail in different districts, leading to the preservation, and
consequently to the transmission, of all sorts of trifling
peculiarities of character. The same process will have been pursued
with our fruit-trees and vegetables, for the best will always have been
the most largely cultivated, and will occasionally have yielded
seedlings better than their parents.

The different strains, just alluded to, which have been actually
produced by breeders without any wish on their part to obtain such a
result, afford excellent evidence of the power of unconscious
selection. This form of selection has probably led to far more
important results than methodical selection, and is likewise more
important under a theoretical point of view from closely resembling
natural selection. For during this process the best or most valued
individuals are not separated and prevented from crossing with others
of the same breed, but are simply preferred and preserved; yet this
inevitably leads to their gradual modification and improvement; so that
finally they prevail, to the exclusion of the old parent-form.

With our domesticated animals natural selection checks the production
of races with any injurious deviation of structure. In the case of
animals which, from being kept by savages or semi-civilised people,
have to provide largely for their own wants under different
circumstances, natural selection will have played a more important
part. Hence it probably is that they often closely resemble natural
species.

As there is no limit to man’s desire to possess animals and plants more
and more useful in any respect, and as the fancier always wishes, owing
to fashions running into extremes, to produce each character more and
more strongly pronounced, there is, through the prolonged action of
methodical and unconscious selection, a constant tendency in every
breed to become more and more different from its parent-stock; and when
several breeds have been produced and are valued for different
qualities, to differ more and more from each other. This leads to
Divergence of Character. As improved sub-varieties and races are slowly
formed, the older and less improved breeds are neglected and decrease
in number. When few individuals of any breed exist within the same
locality, close interbreeding, by lessening their vigour and fertility,
aids in their final extinction. Thus the intermediate links are lost,
and the remaining breeds gain in Distinctness of Character.

In the chapters on the Pigeon, it was proved by historical evidence and
by the existence of connecting sub-varieties in distant lands that
several breeds have steadily diverged in character, and that many old
and intermediate sub-breeds have been lost. Other cases could be
adduced of the extinction of domestic breeds, as of the Irish wolf-dog,
the old English hound, and of two breeds in France, one of which was
formerly highly valued.[4] Mr. Pickering remarks[5] that “the sheep
figured on the most ancient Egyptian monuments is unknown at the
present day; and at least one variety of the bullock, formerly known in
Egypt, has in like manner become extinct.” So it has been with some
animals and with several plants cultivated by the ancient inhabitants
of Europe during the neolithic period. In Peru, Von Tschudi[6] found in
certain tombs, apparently prior to the dynasty of the Incas, two kinds
of maize not now known in the country. With our flowers and culinary
vegetables, the production of new varieties and their extinction has
incessantly recurred. At the present time improved breeds sometimes
displace older breeds at an extraordinarily rapid rate; as has recently
occurred throughout England with pigs. The Longhorn cattle in their
native home were “suddenly swept away as if by some murderous
pestilence,” by the introduction of Shorthorns.[7]

What grand results have followed from the long-continued action of
methodical and unconscious selection, regulated to a certain extent by
natural selection, we see on every side of us. Compare the many animals
and plants which are displayed at our exhibitions with their
parent-forms when these are known, or consult old historical records
with respect to their former state. Most of our domesticated animals
have given rise to numerous and distinct races, but those which cannot
be easily subjected to selection must be excepted—such as cats, the
cochineal insect, and the hive-bee. In accordance with what we know of
the process of selection, the formation of our many races has been slow
and gradual. The man who first observed and preserved a pigeon with its
oesophagus a little enlarged, its beak a little longer, or its tail a
little more expanded than usual, never dreamed that he had made the
first step in the creation of a pouter, carrier, and fantail-pigeon.
Man can create not only anomalous breeds, but others having their whole
structure admirably co-ordinated for certain purposes, such as the
racehorse and dray-horse, or the greyhound and bulldog. It is by no
means necessary that each small change of structure throughout the
body, leading towards excellence, should simultaneously arise and be
selected. Although man seldom attends to differences in organs which
are important under a physiological point of view, yet he has so
profoundly modified some breeds, that assuredly, if found wild, they
would be ranked as distinct genera.

The best proof of what selection has effected is perhaps afforded by
the fact that whatever part or quality in any animal, and more
especially in any plant, is most valued by man, that part or quality
differs most in the several races. This result is well seen by
comparing the amount of difference between the fruits produced by the
several varieties of fruit-trees, between the flowers of our
flower-garden plants, between the seeds, roots, or leaves of our
culinary and agricultural plants, in comparison with the other and not
valued parts of the same varieties. Striking evidence of a different
kind is afforded by the fact ascertained by Oswald Heer[8] namely, that
the seeds of a large number of plants,—wheat, barley, oats, peas,
beans, lentils, poppies,—cultivated for their seed by the ancient
Lake-inhabitants of Switzerland, were all smaller than the seeds of our
existing varieties. Rütimeyer has shown that the sheep and cattle which
were kept by the earlier Lake-inhabitants were likewise smaller than
our present breeds. In the middens of Denmark, the earliest dog of
which the remains have been found was the weakest; this was succeeded
during the Bronze age by a stronger kind, and this again during the
Iron age by one still stronger. The sheep of Denmark during the Bronze
period had extraordinarily slender limbs, and the horse was smaller
than our present animal.[9] No doubt in most of these cases the new and
larger breeds were introduced from foreign lands by the immigration of
new hordes of men. But it is not probable that each larger breed, which
in the course of time has supplanted a previous and smaller breed, was
the descendant of a distinct and larger species; it is far more
probable that the domestic races of our various animals were gradually
improved in different parts of the great Europaeo-Asiatic continent,
and thence spread to other countries. This fact of the gradual increase
in size of our domestic animals is all the more striking as certain
wild or half-wild animals, such as red-deer, aurochs, park-cattle, and
boars[10] have within nearly the same period decreased in size.

The conditions favourable to selection by man are,—the closest
attention to every character,—long-continued perseverance,—facility in
matching or separating animals,—and especially a large number being
kept, so that the inferior individuals may be freely rejected or
destroyed, and the better ones preserved. When many are kept there will
also be a greater chance of the occurrence of well-marked deviations of
structure. Length of time is all-important; for as each character, in
order to become strongly pronounced, has to be augmented by the
selection of successive variations of the same kind, this can be
effected only during a long series of generations. Length of time will,
also, allow any new feature to become fixed by the continued rejection
of those individuals which revert or vary, and by the preservation of
those which still inherit the new character. Hence, although some few
animals have varied rapidly in certain respects under new conditions of
life, as dogs in India and sheep in the West Indies, yet all the
animals and plants which have produced strongly marked races were
domesticated at an extremely remote epoch, often before the dawn of
history. As a consequence of this, no record has been preserved of the
origin of our chief domestic breeds. Even at the present day new
strains or sub-breeds are formed so slowly that their first appearance
passes unnoticed. A man attends to some particular character, or merely
matches his animals with unusual care, and after a time a slight
difference is perceived by his neighbours;—the difference goes on being
augmented by unconscious and methodical selection, until at last a new
sub-breed is formed, receives a local name, and spreads; but by this
time its history is almost forgotten. When the new breed has spread
widely, it gives rise to new strains and sub-breeds, and the best of
these succeed and spread, supplanting other and older breeds; and so
always onwards in the march of improvement.

When a well-marked breed has once been established, if not supplanted
by still further improved sub-breeds, and if not exposed to greatly
changed conditions of life inducing further variability or reversion to
long-lost characters, it may apparently last for an enormous period. We
may infer that this is the case from the high antiquity of certain
races; but some caution is necessary on this head, for the same
variation may appear independently after long intervals of time, or in
distant places. We may safely assume that this has occurred with the
turnspit-dog, of which one is figured on the ancient Egyptian
monuments—with the solid-hoofed swine[11] mentioned by Aristotle—with
five-toed fowls described by Columella—and certainly with the
nectarine. The dogs represented on the Egyptian monuments, about 2000
B.C., show us that some of the chief breeds then existed, but it is
extremely doubtful whether any are identically the same with our
present breeds. A great mastiff sculptured on an Assyrian tomb, 640
B.C., is said to be the same with the dog still imported from Thibet
into the same region. The true greyhound existed during the Roman
classical period. Coming down to a later period, we have seen that,
though most of the chief breeds of the pigeon existed between two and
three centuries ago, they have not all retained exactly the same
character to the present day; but this has occurred in certain cases in
which no improvement was desired, for instance, in the case of the Spot
and Indian ground-tumbler.

De Candolle[12] has fully discussed the antiquity of various races of
plants; he states that the black seeded poppy was known in the time of
Homer, the white-seeded sesamum by the ancient Egyptians, and almonds
with sweet and bitter kernels by the Hebrews; but it does not seem
improbable that some of these varieties may have been lost and
reappeared. One variety of barley and apparently one of wheat, both of
which were cultivated at an immensely remote period by the
Lake-inhabitants of Switzerland, still exist. It is said[13] that
“specimens of a small variety of gourd which is still common in the
market of Lima were exhumed from an ancient cemetery in Peru.” De
Candolle remarks that, in the books and drawings of the sixteenth
century, the principal races of the cabbage, turnip, and gourd can be
recognised: this might have been expected at so late a period, but
whether any of these plants are absolutely identical with our present
sub-varieties is not certain. It is, however, said that the Brussels
sprout, a variety which in some places is liable to degeneration, has
remained genuine for more than four centuries in the district where it
is believed to have originated.[14]

In accordance with the views maintained by me in this work and
elsewhere, not only the various domestic races, but the most distinct
genera and orders within the same great class—for instance, mammals,
birds, reptiles, and fishes—are all the descendants of one common
progenitor, and we must admit that the whole vast amount of difference
between these forms has primarily arisen from simple variability. To
consider the subject under this point of view is enough to strike one
dumb with amazement. But our amazement ought to be lessened when we
reflect that beings almost infinite in number, during an almost
infinite lapse of time, have often had their whole organisation
rendered in some degree plastic, and that each slight modification of
structure which was in any way beneficial under excessively complex
conditions of life has been preserved, whilst each which was in any way
injurious has been rigorously destroyed. And the long-continued
accumulation of beneficial variations will infallibly have led to
structures as diversified, as beautifully adapted for various purposes
and as excellently co-ordinated, as we see in the animals and plants
around us. Hence I have spoken of selection as the paramount power,
whether applied by man to the formation of domestic breeds, or by
nature to the production of species. I may recur to the metaphor given
in a former chapter: if an architect were to rear a noble and
commodious edifice, without the use of cut stone, by selecting from the
fragments at the base of a precipice wedge-formed stones for his
arches, elongated stones for his lintels, and flat stones for his roof,
we should admire his skill and regard him as the paramount power. Now,
the fragments of stone, though indispensable to the architect, bear to
the edifice built by him the same relation which the fluctuating
variations of organic beings bear to the varied and admirable
structures ultimately acquired by their modified descendants.

Some authors have declared that natural selection explains nothing,
unless the precise cause of each slight individual difference be made
clear. If it were explained to a savage utterly ignorant of the art of
building, how the edifice had been raised stone upon stone, and why
wedge-formed fragments were used for the arches, flat stones for the
roof, etc.; and if the use of each part and of the whole building were
pointed out, it would be unreasonable if he declared that nothing had
been made clear to him, because the precise cause of the shape of each
fragment could not be told. But this is a nearly parallel case with the
objection that selection explains nothing, because we know not the
cause of each individual difference in the structure of each being.

The shape of the fragments of stone at the base of our precipice may be
called accidental, but this is not strictly correct; for the shape of
each depends on a long sequence of events, all obeying natural laws; on
the nature of the rock, on the lines of deposition or cleavage, on the
form of the mountain, which depends on its upheaval and subsequent
denudation, and lastly on the storm or earthquake which throws down the
fragments. But in regard to the use to which the fragments may be put,
their shape may be strictly said to be accidental. And here we are led
to face a great difficulty, in alluding to which I am aware that I am
travelling beyond my proper province. An omniscient Creator must have
foreseen every consequence which results from the laws imposed by Him.
But can it be reasonably maintained that the Creator intentionally
ordered, if we use the words in any ordinary sense, that certain
fragments of rock should assume certain shapes so that the builder
might erect his edifice? If the various laws which have determined the
shape of each fragment were not predetermined for the builder’s sake,
can it be maintained with any greater probability that He specially
ordained for the sake of the breeder each of the innumerable variations
in our domestic animals and plants;—many of these variations being of
no service to man, and not beneficial, far more often injurious, to the
creatures themselves? Did He ordain that the crop and tail-feathers of
the pigeon should vary in order that the fancier might make his
grotesque pouter and fantail breeds? Did He cause the frame and mental
qualities of the dog to vary in order that a breed might be formed of
indomitable ferocity, with jaws fitted to pin down the bull for man’s
brutal sport? But if we give up the principle in one case,—if we do not
admit that the variations of the primeval dog were intentionally guided
in order that the greyhound, for instance, that perfect image of
symmetry and vigour, might be formed,—no shadow of reason can be
assigned for the belief that variations, alike in nature and the result
of the same general laws, which have been the groundwork through
natural selection of the formation of the most perfectly adapted
animals in the world, man included, were intentionally and specially
guided. However much we may wish it, we can hardly follow Professor Asa
Gray in his belief “that variation has been led along certain
beneficial lines,” like a stream “along definite and useful lines of
irrigation.” If we assume that each particular variation was from the
beginning of all time preordained, then that plasticity of
organisation, which leads to many injurious deviations of structure, as
well as the redundant power of reproduction which inevitably leads to a
struggle for existence, and, as a consequence, to the natural selection
or survival of the fittest, must appear to us superfluous laws of
nature. On the other hand, an omnipotent and omniscient Creator ordains
everything and foresees everything. Thus we are brought face to face
with a difficulty as insoluble as is that of free will and
predestination.

REFERENCES

 [1] Godron, ‘De l’Espèce,’ 1859, tom. ii. p. 44, etc.

 [2] ‘Journal Proc. Linn. Soc.,’ 1858, vol. iii. p. 60.

 [3] ‘The Quarterly Journal of Science,’ Oct. 1867, p. 486.

 [4] M. Rufz de Lavison, in ‘Bull. Soc. Imp. d’Acclimat.,’ Dec. 1862,
 p. 1009.

 [5] ‘Races of Man,’ 1850, p. 315.

 [6] ‘Travels in Peru,’ Eng. translat., p. 177.

 [7] Youatt on Cattle, 1834, p. 200. On Pigs, _see_ ‘Gardener’s
 Chronicle,’ 1854, p. 410.

 [8] ‘Die Pflanzen der Pfahlbauten,’ 1865.

 [9] Morlot, ‘Soc. Vaud. des Scien. Nat.,’ Mars, 1860, p. 298.

 [10] Rütimeyer, ‘Die Fauna der Pfahlbauten,’ 1861, s. 30.

 [11] Godron,’De l’Espèce,’ tom. i., 1859, p. 368.

 [12] ‘Geographie Botan.,’ 1855, p. 989.

 [13] Pickering, ‘Races of Man,’ 1850, p. 318.

 [14] ‘Journal of a Horticultural Tour,’ by a Deputation of the
 Caledonian Hist. Soc., 1823, p. 293.




INDEX


ABBAS PACHA, a fancier of fantailed pigeons, 6.

ABBEY, Mr., on grafting, 18 (2);

    —on mignonette, 21.

ABBOTT, Mr. Keith, on the Persian tumbler pigeon, 5.

ABBREVIATION of the facial bones, 3.

ABORTION of organs, 24, 27.

ABSORPTION of minority in crossed races, 15, 19.

ABUTILON, graft hybridisation of, 11.

ACCLIMATISATION, 24;

    —of maize, 9.

ACERBI, on the fertility of domestic animals in Lapland, 16.

_Achatinella,_ 13.

_Achillea millefolium,_ bud variation in, 11.

_Aconitum napellus,_ roots of, innocuous in cold climates, 23.

_Acorus calamus,_ sterility of, 18.

ACOSTA, on fowls in South America at its discovery, 7.

_Acropera,_ number of seeds in, 27.

ADAM, M., origin of _Cytisus adami,_ 11.

ADAM, W., on consanguineous marriages, 17.

ADAMS, on hereditary diseases, 12.

ADVANCEMENT in scale of organisation, Introduction.

_Ægilops triticoides,_ observations of Fabre and Godron on, 9;

    —increasing fertility of hybrids of, with wheat, 16.

_Æsculus pavia,_ tendency of, to become double, 18.

_Æthusa cynapium,_ 25.

AFFINITY, sexual elective, 19.

AFRICA, white bull from, 3;

    —feral cattle in, 3;

    —food-plants of savages of, 9;

    —South, diversity of breeds of cattle in, 3;

    —West, change in fleece of sheep in, 3.

_Agave vivipara,_ seeding of, in poor soil, 18.

AGE, changes in trees, dependent on, 11.

——, as bearing on pangenesis, 27.

AGOUTI, fertility of, in captivity, 18.

AGRICULTURE, antiquity of, 21.

_Agrostis,_ seeds of, used as food, 9.

AGUARA, 1.

AINSWORTH, Mr., on the change in the hair of animals at Angora, 24.

AKBAR KHAN, his fondness for pigeons, 6; 20.

_Alauda arvensis,_ 18.

ALBIN, on “Golden Hamburgh” fowls, 7;

    —figure of the hook-billed duck, 8.

ALBINISM, 4, 12.

ALBINO, negro, attacked by insects, 21.

ALBINOES, heredity of, 12.

ALBINUS, thickness of the epidermis on the palms of the hands in man,
24.

ALCO, 1, 15.

ALDROVANDI, on rabbits, 4;

    —description of the nun pigeon, 5;

    —on the fondness of the Dutch for pigeons in the seventeenth
    century, 6;

    —notice of several varieties of pigeons, 6;

    —on the breeds of fowls, 7;

    —on the origin of the domestic duck, 8.

ALEFIELD, Dr., on the varieties of peas and their specific unity, 9;

    —on the varieties of beans, 9.

ALEXANDER the Great, his selection of Indian cattle, 20.

ALGÆ, retrogressive metamorphosis in, 27;

    —division of zoospores of, 27.

ALLEN, J., birds in United States, 23.

ALLEN, W., on feral fowls, 7, 13.

ALLMAN, Professor, on a monstrous _Saxifraga geum,_ 18;

    —on the Hydroida, 27 (2).

ALMOND, 10;

    —antiquity of, 28;

    —bitter, not eaten by mice, 21.

_Alnus glutinosa,_ and _incana,_ hybrids of, 17.

ALPACA, selection of, 20.

_Althæa rosea,_ 11, 16.

_Amaryllis,_ 17.

_Amaryllis vittata,_ effect of foreign pollen on, 5.

AMAUROSIS, hereditary, 12.

_Amblystoma lurida,_ 27.

AMERICA, limits within which no useful plants have been furnished by,
9;

    —colours of feral horses in, 2;

    —North, native cultivated plants of, 9;

    —skin of feral pig from, 3;

    —South, variations in cattle of, 3.

AMMON, on the persistency of colour in horses, 12.

_Amygdalus persica,_ 10, 11.

_Anagallis arvensis,_ 19.

ANALOGOUS variation, 5, 22;

    —in horses, 5;

    —in the horse and ass, 2;

    —in fowls, 7.

_Anas boschas,_ 8, 13;

    —skull of, figured, 8.

“ANCON” sheep of Massachusetts, 3, 15.

ANDALUSIAN fowls, 7.

ANDALUSIAN rabbits, 4.

ANDERSON, J., on the origin of British sheep, 4;

    —on the selection of qualities in cattle, 20;

    —on a one-eared breed of rabbits, 4;

    —on the inheritance of characters from a one-eared rabbit, and
    three-legged bitch, 12;

    —on the persistency of varieties of peas, 9;

    —on the production of early peas by selection, 20;

    —on the varieties of the potato, 9;

    —on crossing varieties of the melon, 11;

    —on reversion in the barberry, 11.

ANDERSON, Mr., on the reproduction of the weeping ash by seed, 12.

    —on the cultivation of the tree pæony in China, 20.

ANDERSSON, Mr., on the Damara, Bechuana, and Namaqua cattle, 3;

    —on the cows of the Damaras, 24;

    —selection practised by the Damaras and Namaquas, 20;

    —on the use of grass-seeds and the roots of reeds as food in South
    Africa, 9.

_Anemone coronaria,_ doubled by selection, 20.

ANGINA pectoris, hereditary, occurring at a certain age, 14.

ANGLESEA, cattle of, 3.

ANGOLA sheep, 3.

ANGORA, change in hair of animals at, 23;

    —cats of, 1 (2);

    —rabbits of, 4 (2).

ANIMALS, domestication of, facilitated by fearlessness of man, 1;

    —refusal of wild, to breed in captivity, 18;

    —compound, individual peculiarities of, reproduced by budding, 11;

    —variation by selection in useful qualities of, 20.

ANNUAL plants, rarity of bud-variation in, 11.

ANOMALIES in the osteology of the horse, 2.

ANOMALOUS breeds of pigs, 3;

    —of cattle, 3.

_Anser albifrons,_ characters of, reproduced in domestic geese, 8.

_Anser ægyptiacus,_ 8, 14.

_Anser canadensis,_ 18. _Anser ferus,_ the original of the domestic
goose, 8;

    —fertility of cross of, with domestic goose, 8.

ANSON, on feral fowls in the Ladrones, 7.

ANTAGONISM between growth and reproduction, 27.

_Anthemis nobilis,_ bud-variation in flowers of, 11;

    —becomes single in poor soil, 18.

ANTHERS, contabescence of, 18.

ANTIGUA, cats of, 5;

    —changed fleece of sheep in, 3.

_Antirrhinum majus,_ peloric, 10, 13 (2), 18;

    —double-flowered, 18;

    —bud-variation in, 11.

ANTS, individual recognition of, 22.

APHIDES, attacking pear-trees, 21;

    —development of, 27.

APOPLEXY, hereditary, occurring at a certain age, 14.

APPLE, 10;

    —fruit of, in Swiss lake-dwellings, 9;

    —rendered fastigiate by heat in India, 10;

    —bud-variation in the, 11;

    —with dimidiate fruit, 11 (2);

    —with two kinds of fruit on the same branch, 11;

    —artificial fecundation of, 11;

    —St. Valéry, 11, 18;

    —reversion in seedlings of, 13;

    —crossing of varieties of, 17;

    —growth of the, in Ceylon, 21;

    —winter majetin, not attacked by _ coccus,_ 21;

    —flower-buds of, attacked by bullfinches, 21;

    —American, change of, when grown in England, 23.

APRICOT, 10 (2);

    —glands on the leaves of, 21;

    —analogous variation in the, 26.

_Aquila fusca,_ copulating in captivity, 18.

_Aquilegia vulgaris,_ 10, 25.

ARAB boarhound, described by Harcourt, 1.

_Arabis blepharophylla_ and _A. soyeri,_ effects of crossing, 11.

_Aralia trifoliata,_ bud-variation in leaves of, 11.

ARAUCARIAS, young, variable resistance of, to frost, 24.

ARCHANGEL pigeon, 21.

ARCTIC regions, variability of plants and shells of, 22.

_Aria vestita,_ grafted on thorns, 11.

ARISTOPHANES, fowls mentioned by, 7.

ARISTOTLE, on solid-hoofed pigs, 3;

    —domestic duck unknown to, 8;

    —on the assumption of male characters by old hens, 13.

ARNI, domestication of the, 3.

ARNOLD, Mr., experiments of pollen on the maize, 11.

ARRESTS of development, 24.

ARTERIES, increase of anastomosing branches of, when tied, 24.

ARU Islands, wild pig of, 3.

ARUM, Polynesian varieties of, 22.

_Ascaris,_ number of eggs of, 27.

ASH, varieties of the, 10;

    —weeping, 10;

    —simple-leaved, 10;

    —bud-variation in, 11;

    —effects of graft upon the stock in the, 11;

    —production of the blotched Breadalbane, 11;

    —weeping, capricious reproduction of, by seed, 12.

_Asinus burchellii,_ 2.

_Asinus hemionus,_ 13.

_Asinus indicus,_ 13 (2).

_Asinus quagga,_ 2.

_Asinus tæniopus,_ the original of the domestic ass, 2.

ASPARAGUS, increased fertility of cultivated, 16.

ASS, early domestication of the, 2;

    —breeds of, 2;

    —small size of, in India, 2;

    —stripes of, 2 (2);

    —dislike of, to cross water, 6;

    —reversion in, 13 (3);

    —hybrid of the, with mare and zebra, 13;

    —prepotency of the, over the horse, 14;

    —crossed with wild ass, 20;

    —variation and selection of the, 21.

ASSYRIAN sculpture of a mastiff, 1.

ASTERS, 12, 24.

ASTHMA, hereditary, 12, 14.

ATAVISM. _See_ Reversion.

ATHELSTAN, his care of horses, 20.

ATKINSON, Mr., on the sterility of the Tarroo silk-moth in confinement,
18.

AUBERGINE, 15.

AUDUBON, on feral hybrid ducks, 6, 13;

    —on the domestication of wild ducks on the Mississippi, 8;

    —on the wild cock turkey visiting domestic hens, 8;

    —fertility of _Fringilla ciris_ in captivity, 18;

    —fertility of _Columba migratoria_ and _leucocephala_ in captivity,
    18;

    —breeding of _Anser canadensis_ in captivity, 18.

AUDUBON and Bachman, on the change of coat in _Ovis montana,_ 3;

    —sterility of _Sciurus cinerea_ in confinement, 18.

AURICULA, effect of seasonal conditions on the, 23;

    —blooming of, 26.

AUSTRALIA, no generally useful plants derived from, 9;

    —useful plants of, enumerated by Hooker, 9.

AUSTRIA, heredity of character in emperors of, 14.

AUTENRIETH, on persistency of colour in horses, 12.

AVA, horses of, 2.

_Avena fatua,_ cultivability of, 9.

‘AYEEN Akbery,’ pigeons mentioned in the, 5 (2), 6 (4).

AYRES, W. P., on bud-variation in pelargoniums, 11.

_Azalea indica,_ bud-variation in, 11.

AZARA, on the feral dogs of La Plata, 1;

    —on the crossing of domestic with wild cats in Paraguay, 1;

    —on hornlike processes in horses, 2;

    —on curled hair in horses, 2;

    —on the colours of feral horses, 2;

    —on the cattle of Paraguay and La Plata, 3 (3), 22;

    —on a hornless bull, 20;

    —on the increase of cattle in South America, 17;

    —on the growth of horns in the hornless cattle of Corrientes, 13;

    —on the “Niata” cattle, 3;

    —on naked quadrupeds, 23;

    —on a race of black-skinned fowls in South America, 7, 20;

    —on a variety of maize, 9.

BABINGTON, C. C., on the origin of the plum, 10;

    —British species of the genus _ Rosa,_ 10;

    —distinctness of _Viola lutea_ and _tricolor,_ 10.

BACHMANN, Mr., on the turkey, 22.

    _See also_ Audubon. BADGER, breeding in confinement, 18.

“BAGADOTTEN-TAUBE,” 5.

BAILY, Mr., on the effect of selection on fowls, 20;

    —on Dorking fowls, 21.

BAIRD, S., on the origin of the turkey, 8.

BAKER, Mr., on heredity in the horse, 12;

    —on the degeneration of the horse by neglect, 21;

    —orders of Henrys VII. and VIII. for the destruction of undersized
    mares, 20.

BAKEWELL, change in the sheep effected by, 20.

BALANCEMENT, 26 (2);

    —of growth, law of, 26.

BALDHEAD (pigeon), 5.

BALDNESS, in man, inherited, 25;

    —with deficiency in teeth, 25 (2).

BALLANCE, Mr., on the effects of interbreeding on fowls, 17;

    —on variation in the eggs of fowls, 7.

_Ballota nigra,_ transmission of variegated leaves in, 11.

BAMBOO, varieties of the, 22.

BANANA, variation of the, 10, 22;

    —bud-variation in the, 11;

    —sterility of the, 22.

BANTAM fowls, 7;

    —Sebright, origin of, 15;

    —sterility of, 16.

BARB (pigeon), 5 (2), 6, 21;

    —figure of, 5;

    —figure of lower jaw of, 5.

BARBS, of wheat, 9.

BARBERRY, dark or red-leaved variety, 10, 12;

    —reversion in suckers of seedless variety, 11.

BARBUT, J., on the dogs of Guinea, 1;

    —on the domestic pigeons in Guinea, 6;

    —fowls not native in Guinea, 7.

BARKING, acquisition of the habit of, by various dogs, 1.

BARLEY, wild, 9;

    —of the lake-dwellings, 9;

    —ancient variety of, 28.

BARNES, Mr., production of early peas by selection, 20.

BARNET, Mr., on the intercrossing of strawberries, 10;

    —diœciousness of the hautbois strawberry, 10;

    —on the Scarlet American strawberry, 20.

BARTH, Dr., use of grass-seeds as food in Central Africa, 9.

BARTLETT, A. D., on the origin of “Himalayan” rabbits by intercrossing,
4;

    —on the feral rabbits of Porto Santo, 4;

    —on geese with reversed feathers on the head and neck, 8;

    —on the young of the black-shouldered peacock, 8;

    —on a variety of the turkey, 8;

    —size of hybrids, 17;

    —on the breeding of the Felidæ in captivity, 18;

    —so-called hybrids, 25.

BARTRAM, on the black wolf-dog of Florida, 1.

BATES, H. W., refusal of wild animals to breed in captivity, 18 (2);

    —sterility of American monkeys in captivity, 18;

    —sterility of tamed guans, 18.

BATRACHIA, regeneration of lost parts in, 27.

BEACH, raised, in Peru, containing heads of maize, 9.

BEAK, variability of, in fowls, 7;

    —individual differences of, in pigeons, 5;

    —correlation of, with the feet in pigeons, 5.

BEALE, Lionel, on the contents of cells, 27;

    —on the multiplication of infectious atoms, 27.

BEANS, 9;

    —of Swiss lake-dwellings, 9;

    —varieties of, produced by selection, 20;

    —French and scarlet, variable resistance of, to frost, 24 (2);

    —superiority of native seed of, 24;

    —a symmetrical variation of scarlet, 27;

    —experiments on kidney, 8;

    —with monstrous stipules and abortive leaflets, 26.

BEARD pigeon, 5.

BEARS, breeding in captivity, 18.

BEASLEY, J., reversion in crossed cattle, 13.

BEATON, D., effect of soil upon strawberries, 10;

    —on varieties of pelargonium, 10, 23 (2);

    —bud-variation in _Gladiolus colvilii,_ 11;

    —cross between Scotch kail and cabbage, 15;

    —hybrid gladiolus, 17;

    —constant occurrence of new forms among seedlings, 21;

    —on the doubling of the Compositæ, 24.

BECHUANA cattle, 3.

BECHSTEIN, on the burrowing of wolves, 1;

    —Spitz Dog, 1;

    —origin of the Newfoundland dog, 1;

    —crossing of domestic and wild swine, 3;

    —on the Jacobin pigeon, 5, 6;

    —notice of swallow-pigeons, 5;

    —on a fork-tailed pigeon, 5;

    —variations in the colour of the croup in pigeons, 6;

    —on the German dovecot pigeon, 6;

    —fertility of mongrel-pigeons, 6;

    —on hybrid turtle-doves, 6;

    —on crossing the pigeon with _ Columba œnas, C. palumbus, Turtur
    risoria,_ and _T. vulgaris,_ 6;

    —development of spurs in the silk hen, 7;

    —on Polish fowls, 7 (2);

    —on crested birds, 7;

    —on the canary-bird, 8, 12, 18;

    —German superstition about the turkey, 8;

    —occurrence of horns in hornless breeds of sheep, 13;

    —hybrids of the horse and ass, 14;

    —crosses of tailless fowls, 15;

    —difficulty of pairing dove-cot and fancy pigeons, 16;

    —fertility of tame ferrets and rabbits, 16;

    —fertility of wild sow, 16;

    —difficulty of breeding caged birds, 18;

    —comparative fertility of _ Psittacus erithacus_ in captivity, 18;

    —on changes of plumage in captivity, 18;

    —liability of light-coloured cattle to the attacks of flies, 21;

    —want of exercise a cause of variability, 22;

    —effect of privation of light upon the plumage of birds, 23;

    —on a sub-variety of the monk-pigeon, 26.

BECK, Mr., constitutional differences in pelargoniums, 10.

BECKMANN, on changes in the odours of plants, 23.

BEDDOE, Dr., correlation of complexion with consumption, 25.

BEE, persistency of character of, 21, 22;

    —intercrossing, 17;

    —conveyance of pollen of peas by, 9.

BEE OPHRYS, self-fertilisation of, 15.

BEECH, dark-leaved, 10, 12;

    —fern-leaved, reversion of, 11;

    —weeping, non-production of, by seed, 12.

BEECHEY, horses of Loochoo Islands, 2.

BEET, 9;

    —increase of sugar in, by selection, 20.

_Begonia frigida,_ singular variety of, 10;

    —sterility of, 18.

BELGIAN rabbit, 4.

BELL, T., statement that white cattle have coloured ears, 3.

BELL, W., bud-variation in _Paritium tricuspis,_ 11.

BELLINGERI, observations on gestation in the dog, 1

    —on the fertility of dogs and cats, 16.

BELON, on high-flying pigeons in Paphlagonia, 6;

    —varieties of the goose, 8.

BENGUELA, cattle of, 3.

BENNETT, Dr. G., pigs of the Pacific Islands, 3, 15;

    —dogs of the Pacific Islands, 15;

    —varieties of cultivated plants in Tahiti, 22.

BENNETT, Mr., on the fallow deer, 16.

BENTHAM, G., number and origin of cultivated plants, 9;

    —on Phaseolus, 9;

    —cereals all cultivated varieties, 9;

    —species of the orange group, 10;

    —distinctions of almond and peach, 10;

    —British species of _Rosa,_ 10;

    —identity of _Viola lutea_ and _tricolor,_ 10.

_Berberis vulgaris,_ 11, 12.

_Berberis wallichii,_ indifference of, to climate, 18.

BERJEAU, on the history of the dog, 1 (2).

BERKELEY, G. F., production of hen-cocks in a strain of game-fowls, 7.

BERKELEY, M. J., crossing of varieties of the pea, 11;

    —effect of foreign pollen on grapes, 11;

    —on hybrid plants, 17;

    —analogy between pollen of highly-cultivated plants and hybrids,
    22;

    —on Hungarian kidney-beans, 23;

    —failure of Indian wheat in England, 24.

BERNARD, inheritance of disease in the horse, 12.

BERNARD, C., independence of the organs of the body, 27;

    —special affinities of the tissues, 27.

BERNHARDI, varieties of plants with laciniated leaves, 26.

_Bernicla antarctica,_ 8.

BERTERO, on feral pigeons in Juan Fernandez, 6.

_Betula alba,_ 12.

BEWICK, on the British wild cattle, 3.

BIANCONI, Prof., on the skulls of dogs, 1.

BIBLE, reference to breeding studs of horses in, 2;

    —references to domestic pigeons in the, 6;

    —indications of selection of sheep in the, 20;

    —notice of mules in the, 20.

BIDWELL, Mr., on self-impotence in _Amaryllis,_ 17.

_Bignonia,_ self-sterility of, 17.

BIRCH, weeping, 11, 12.

BIRCH, Dr. S., on the ancient domestication of the pigeon in Egypt, 6;

    —notice of bantam fowls in a Japanese encyclopædia, 7 (2).

BIRCH, WYRLEY, on silver-grey rabbits, 4 (2).

BIRDS, sterility caused in, by change of conditions, 18.

BLADDER-NUT, tendency of the, to become double, 18.

BLAINE, Mr., on wry-legged terriers, 21.

BLAINVILLE, origin and history of the dog, 1;

    —variations in the number of teeth in dogs, 1;

    —variations in the number of toes in dogs, 1;

    —on mummies of cats, 1;

    —on the osteology of solid-hoofed pigs, 3;

    —on feral Patagonian and N. American pigs, 3.

“BLASS-TAUBE,” 5

BLEEDING, hereditary, 12;

    —sexual limitation of excessive, 14.

BLENDING of crossed races, time occupied by the, 15.

BLINDNESS, hereditary, 12;

    —at a certain age, 14;

    —associated with colour of hair, 25.

BLOODHOUNDS, degeneration of, caused by interbreeding, 17.

BLUMENBACH, on the protuberance of the skull in Polish fowls, 7;

    —on the effect of circumcision, 12;

    —inheritance of a crooked finger, 12;

    —on badger-dogs and other varieties of the dog, 20;

    —on _Hydra,_ 24;

    —on the “nisus formativus,” 24.

BLYTH, E., on the pariah dog, 1;

    —hybrids of dog and jackal, 1;

    —early domestication of cats in India, 1;

    —origin of domestic cat, 1;

    —crossing of domestic and wild cats, 1;

    —on Indian cats resembling _Felis chaus,_ 1;

    —on striped Burmese ponies, 2;

    —on the stripes of the ass, 2;

    —on Indian wild pigs, 3;

    —on humped cattle, 3;

    —occurrence of _Bos frontosus_ in Irish crannoges, 3;

    —fertile crossing of zebus and common cattle, 3;

    —on the species of sheep, 3;

    —on the fat-tailed Indian sheep, 3;

    —origin of the goat, 3;

    —on rabbits breeding in India, 4;

    —number of tail-feathers in fantails, 5;

    —Lotan tumbler pigeons, 5;

    —number of tail-feathers in _ Ectopistes,_ 2;

    —on _Columba affinis,_ 6;

    —pigeons roosting in trees, 6;

    —on _Columba leuconota,_ 6;

    —on _Columba intermedia_ of Strickland, 6;

    —variation in colour of croup in pigeons, 6 (3);

    —voluntary domestication of rock-pigeons in India, 6;

    —feral pigeons on the Hudson, 6;

    —occurrence of sub-species of pigeons, 6;

    —notice of pigeon-fanciers in Delhi, etc., 6;

    —hybrids of _Gallus sonneratii_ and the domestic hen, 7;

    —supposed hybridity of _Gallus temminckii,_ 7;

    —variations and domestication of _ Gallus bankiva,_ 7 (2);

    —crossing of wild and tame fowls in Burmah, 7;

    —restricted range of the larger gallinaceous birds, 7;

    —feral fowls in the Nicobar Islands, 7;

    —black-skinned fowls occurring near Calcutta, 7;

    —weight of _Gallus bankiva,_ 7;

    —degeneration of the turkey in India, 8, 23;

    —on the colour of gold-fish, 8;

    —reversion from a cross, 13;

    —on the Ghor-Khur (_Asinus indicus_), 13;

    —on _Asinus hemionus,_ 13;

    —number of eggs of _Gallus bankiva,_ 16;

    —on the breeding of birds in captivity, 18;

    —co-existence of large and small breeds in the same country, 23;

    —on the drooping ears of the elephant, 24;

    —homology of leg and wing feathers, 25.

BOETHIUS on Scotch wild cattle, 3.

BOITARD and Corbié, on the breeds of pigeons, 5;

    —Lille pouter pigeon, 5;

    —notice of a gliding pigeon, 5;

    —variety of the pouter pigeon, 5;

    —dove-cot pigeon, 6;

    —crossing pigeons, 6, 15, 17;

    —sterility of hybrids of turtle-doves, 6;

    —reversion of crossed pigeons, 6, 13;

    —on the fantail, 6, 14;

    —on the trumpeter, 14;

    —prepotency of transmission in silky fantail, 14 (2);

    —secondary sexual characters in pigeons, 14;

    —crossing of white and coloured turtle-doves, 15;

    —fertility of pigeons, 16.

BOMBYCIDÆ, wingless females of, 24.

_Bombyx hesperus,_ 24.

_Bombyx huttoni,_ 8.

_Bombyx mori,_ 8.

BONAFOUS, on maize, 9. BONAPARTE, number of species of Columbidæ, 5;

    —number of tail-feathers in pigeons, 5;

    —size of the feet in Columbidæ, 5;

    —on _Columba guinea,_ 6;

    —_Columba turricola, rupestris_ and _schimperi,_ 6.

_Bonatea speciosa,_ development of ovary of, 11.

BONAVIA, Dr., growth of cauliflowers in India, 24.

BONER, Mr., semi-feral sheep, 13.

BONES, removal of portions of, 24;

    —regeneration of, 24;

    —growth and repair of, 27.

BONIZZI, on pigeons, 5 (2).

BONNET, on the salamander, 27;

    —theory of reproduction, 27 (2).

BORCHMEYER, experiments with the seeds of the weeping ash, 12.

BORECOLE, 9.

BORELLI, on Polish fowls, 7.

BORNEO, fowls of, with tail-bands, 7.

BORNET, E., condition of the ovary in hybrid _Cisti,_ 11;

    —self-impotence of hybrid _ Cisti,_ 17.

BORROW, G., on pointers, 1.

BORY DE SAINT-VINCENT, on gold-fish, 8.

_Bos,_ probable origin of European domestic cattle from three species
of, 3.

_Bos frontosus,_ 3.

_Bos indicus,_ 3.

_Bos longifrons,_ 3 (3).

_Bos primigenius,_ 3 (2), 17. _Bos sondaicus,_ 20.

_Bos taurus,_ 3.

_Bos trochoceros,_ 3.

BOSC, heredity in foliage-varieties of the elm, 10.

BOSSE, production of double flowers from old seed, 18.

BOSSI, on breeding dark-coloured silkworms, 8.

BOSMAN, on dogs of Guinea, 1.

BOUCHARDAT, on the vine disease, 10.

BOUDIN, on local diseases, 23;

    —resistance to cold of dark-complexioned men, 25.

“BOULANS,” 5.

“BOUTON d’Alep,” 23.

BOWEN, Prof., doubts as to the importance of inheritance, 12.

BOWMAN, Mr., hereditary peculiarities in the human eye, 12;

    —hereditary cataract, 14.

BRACE, Mr., on Hungarian cattle, 3.

_Brachycome iberidifolia,_ 22.

BRACTS, unusual development of, in gooseberries, 10.

BRADLEY, Mr., effect of grafts upon the stock in the ash, 11;

    —effect of foreign pollen upon apples, 11;

    —on change of soil, 18.

“BRAHMA Pootras,” a new breed of fowls, 7.

BRAIN, proportion of, in hares and rabbits, 4.

BRANDT, Dr., origin of the goat, 3;

    —correlation of teeth and hair, 25.

_Brassica,_ varieties of, with enlarged stems, 26.

_Brassica asperifolia,_ 26.

_Brassica napus,_ 9.

_Brassica oleracea,_ 9.

_Brassica rapa,_ 9, 18.

BRAUN, A., bud-variation in the vine, 11;

    —in the currant, 11;

    —in _Mirabilis jalapa_, 11;

    —in _Cytisus adami,_ 11;

    —on reversion in the foliage of trees, 11;

    —spontaneous production of _Cytisus purpureo-elongatus,_ 11;

    —reversion of flowers by stripes and blotches, 13;

    —excess of nourishment a source of variability, 22.

BRAZIL, cattle of, 3.

BREAD-FRUIT, varieties of, 22;

    —sterility and variability of, 22.

BREE, W. T., bud-variation in _Geranium pratense_ and _ Centaurea
cyanus,_ 11;

    —by tubers in the dahlia, 11;

    —on the deafness of white cats with blue eyes, 25.

BREEDING, high, dependent on inheritance, 12 (2).

BREEDS, domestic, persistency of, 21;

    —artificial and natural, 28 (2);

    —extinction of, 28;

    —of domestic cats, 1;

    —of pigs produced by crossing, 3;

    —of cattle, 3 (2);

    —of goats, 3.

BREHM, on _Columba amaliæ,_ 6.

BRENT, B. P., number of mammæ in rabbits, 4;

    —habits of the tumbler pigeon, 5;

    —Laugher pigeon, 5;

    —colouring of the kite tumbler, 5;

    —crossing of the pigeon with _ Columba œnas,_ 6;

    —mongrels of the trumpeter pigeon, 14;

    —close interbreeding of pigeons, 17;

    —opinion on Aldrovandi’s fowls, 7;

    —on stripes in chickens, 7;

    —on the combs of fowls, 7;

    —double-spurred Dorking fowls, 7;

    —effect of crossing on colour of plumage in fowls, 7;

    —-incubatory instinct of mongrels between non-setting varieties of
    fowls, 13;

    —origin of the domestic duck, 8;

    —fertility of the hook-billed duck, 8;

    —occurrence of the plumage of the wild duck in domestic breeds, 8;

    —voice of ducks, 8;

    —occurrence of a short upper mandible in crosses of hook-billed and
    common ducks, 8;

    —reversion in ducks produced by crossing, 13;

    —variation of the canary-bird, 8;

    —fashion in the canary, 21;

    —hybrids of canary and finches, 13.

BRICKELL, on raising nectarines from seed, 4;

    —on the horses of North Carolina, 24.

BRIDGES, Mr., on the dogs of Tierra del Fuego, 1;

    —on the selection of dogs by the Fuegians, 20.

BRIDGMAN, W. K., reproduction of abnormal ferns, 11.

BROCA, P., on the intercrossing of dogs, 1 (2);

    —on hybrids of hare and rabbit, 4;

    —on the rumpless fowl, 7;

    —on the character of half-castes, 13;

    —degree of fertility of mongrels, 16;

    —sterility of descendants of wild animals bred in captivity, 18.

BROCCOLI, 9;

    —rudimentary flowers in, 24;

    —tenderness of, 24.

BROMEHEAD, W., doubling of the Canterbury Bell by selection, 20.

BROOMFIELD, Dr., sterility of the ivy and _Acorus calamus,_ 18.

_Bromus secalinus,_ 9.

BRONN, H. G., bud variation in _Anthemis,_ 11;

    —effects of cross-breeding on the female, 11;

    —on heredity in a one-horned cow, 12;

    —propagation of a pendulous peach by seed, 12;

    —absorption of the minority in crossed races, 15;

    —on the crossing of horses, 15;

    —fertility of tame rabbits and sheep, 16;

    —changes of plumage in captivity, 18;

    —on the dahlia, 22.

BRONZE period, dog of, 1.

BROWN, C. M., prepotency of a greyhound, 14.

BROWN, G., variations in the dentition of the horse, 2.

BROWN-SÉQUARD, Dr., inheritance of artificially-produced epilepsy in
the guinea-pig, 12;

    —inherited effects of injuries, 12.

_Brunswigia,_ 17.

BRUSSELS sprouts, 9, 28.

_Bubo maximus,_ 18.

BUCKLAND, F., on oysters, 23;

    —number of eggs in a codfish, 27.

BUCKLE, Mr., doubts as to the importance of inheritance, 12.

BUCKLEY, Miss, carrier-pigeons roosting in trees, 6.

BUCKMAN, Prof., cultivation of _Avena fatua,_ 9;

    —cultivation of the wild parsnip, 9, 20, 23;

    —reversion in the parsnip, 13.

BUCKWHEAT, injurious when in flower to white pigs, 25.

BUD and seed, close analogy of, 11.

BUD-REVERSION, 13.

BUDS, adventitious, 27.

BUD-VARIATION, 11, 22, 23 (3);

    —contrasted with seminal reproduction, 11;

    —peculiar to plants, 11;

    —in the peach, 10;

    —in plums, 11;

    —in the cherry, 11;

    —in grapes, 11;

    —in the gooseberry and currant, 11;

    —pear and apple, 11;

    —and in the banana, camellia, hawthorn, _Azalea indica,_ and
    _Paritium tricuspis,_ 11;

    —in the hollyhock and pelargonium, 11;

    —in _Geranium pratense_ and the chrysanthemum, 11;

    —in roses, 10, 11;

    —in sweet williams, carnations, pinks, stocks, and snapdragons, 11
    (2);

    —in wall-flowers, cyclamen, _ Œnothera biennis, Gladiolus
    colvillii,_ fuchsias, and _ Mirabilis jalapa,_ 11;

    —in foliage of various trees, 11;

    —cryptogamic plants, 11;

    —by suckers in _Phlox_ and barberry, 11;

    —by tubers in the potato, 11;

    —in the dahlia, 11;

    —by bulbs in hyacinths, _ Imatophyllum miniatum,_ and tulips, 11;

    —in _Tigridia conchiflora,_ 11;

    —in _Hemerocallis,_ 11;

    —doubtful cases, 11;

    —in _Cytisus adami,_ 11;

    —summary of observations on, 11.

BUFFON, on crossing the wolf and dog, 1;

    —increase of fertility by domestication, 16;

    —improvement of plants by unconscious selection, 20;

    —theory of reproduction, 27.

_Bulimus,_ 13.

BULL, apparent influence of, on offspring, 14.

BULLACE, 10.

BULLDOG, degeneration of, in India, 1;

    —recent modifications of, 1.

BULLFINCH, breeding in captivity, 18;

    —attacking flower-buds, 21.

BULT, Mr., on the length of pouter pigeons, 6.

“BUNDTNERSCHWEIN,” 3.

BUNTING, reed, in captivity, 18.

BURDACH, crossing of domestic and wild animals, 3;

    —aversion of the wild boar to barley, 24.

BURKE, Mr., inheritance in the horse, 12.

_Burlingtonia,_ 17.

BURMAH, cats of, 1.

BURMESE ponies, striped, 2.

BURNES, Sir A., on the Karakool sheep, 3, 23;

    —varieties of the vine in Cabool, 10;

    —hawks, trained in Scinde, 18;

    —pomegranates producing seed, 18.

BURR, FEARING, potato-grafting, 11.

BURTON CONSTABLE, wild cattle at, 3.

“BURZEL-TAUBEN,” 5.

BUSSORAH carrier, 5.

_Buteo vulgaris,_ copulation of, in captivity, 18.

BUTTERFLIES, polymorphic, 27.

BUXTON, Mr., parrots breeding in Norfolk, 18.

BUZAREINGUES, GIROU DE, inheritance of tricks, 12.

CABANIS, pears grafted on the quince, 22.

CABBAGE, 9;

    —varieties of, 9;

    —unity of character in flowers and seeds of, 9;

    —cultivated by ancient Celts, 9;

    —classification of varieties of, 9;

    —ready crossing of, 9, 15 (2), 17;

    —origin of, 9;

    —increased fertility of, when cultivated, 16;

    —growth of, in tropical countries, 23.

CABOOL, vines of, 10.

CABRAL, on early cultivation in Brazil, 9.

CACTUS, growth of cochineal on, in India, 23.

CÆSAR, _Bos primigenius_ wild in Europe in the time of, 3;

    —notice of fowls in Britain, 7;

    —notice of the importation of horses by the Celts, 20.

CAFFRE fowls, 7.

CAFFRES, different kinds of cattle possessed by the, 3.

“CÁGIAS” a breed of sheep, 3.

_Cairina moschata,_ 6.

CALCEOLARIAS, 10, 18;

    —effects of seasonal conditions on, 23;

    —peloric flowers in, 26.

CALDWELL, J., sporting of sugar-cane, 11.

“CALONGOS,” a Columbian breed of cattle, 3.

CALVER, Mr., on a seedling peach producing both peaches and nectarines,
10.

CALYX, segments of the, converted into carpels, 27.

CAMEL, its dislike to crossing water, 6.

_Camellia,_ bud-variations in, 11;

    —recognition of varieties of, 22;

    —variety in, hardiness of, 24.

CAMERON, D, on the cultivation of Alpine plants, 18.

CAMERONN, Baron, value of English blood in racehorses, 12.

_Campanula medium,_ 20.

CANARY-BIRD, 8;

    —conditions of inheritance in, 12;

    —hybrids of, 13;

    —period of perfect plumage in, 14;

    —diminished fertility of, 18;

    —standard of perfection in, 20;

    —analogous variation in, 26.

CANCER, heredity of, 12, 14.

CANFIELD, Dr., on horses with curled hair, 2;

    —on feral horses in North America, 2.

CANINE teeth, development of the, in mares, 24.

_Canis alopex,_ 1.

_Canis antarcticus,_ 1.

_Canis argentatus,_ 18.

_Canis aureus,_ 1.

_Canis cancrivorus,_ domesticated and crossed in Guiana, 1.

_Canis cinereo-variegatus,_ 1.

_Canis fulvus,_ 1.

_Canis ingæ,_ the naked Peruvian dog, 1.

_Canis latrans,_ 1;

    —resemblance of, to the Hare Indian dog, 1;

    —one of the original stocks, 1.

_Canis lupaster,_ 1.

_Canis lupus,_ var. _occidentalis,_ resemblance of, to North American
dogs, 1;

    —crossed with dogs, 1;

    —one of the original stocks, 1.

_Canis mesomelas,_ 1 (2).

_Canis primævus,_ tamed by Mr. Hodgson, 1.

_Canis sabbar,_ 1.

_Canis simensis,_ possible original of greyhounds, 1.

_Canis thaleb,_ 1.

_Canis variegatus,_ 1.

CANNING, A. S. G., the japanned peacock, 8.

CANTERBURY Bell, doubled by selection, 20.

CAPE of Good Hope, different kinds of cattle at the, 3;

    —no useful plants derived from the, 9.

CAPERCAILZIE, breeding in captivity, 18.

_Capra ægagrus_ and _C. falconeri,_ probable parents of domestic goat,
3.

CAPSICUM, 10.

CARDAN, on a variety of the walnut, 10;

    —on grafted walnuts, 22.

CARDOON, 13.

_Carex rigida,_ local sterility of the, 18.

CARLIER, early selection of sheep, 20.

CARLISLE, Sir A., inheritance of peculiarities, 12 (2).

    —of polydactylism, 12.

“CARME” pigeon, 5.

CARNATION, bud-variation in, 11;

    —variability of, 10;

    —striped, produced by crossing red and white, 12;

    —effect of conditions of life on the, 23.

CARNIVORA, general fertility of, in captivity, 18.

CAROLINE Archipelago, cats of, 1.

CARP, 21.

CARPELS, variation of, in cultivated Cucurbitaceæ, 10.

CARPENTER, W. B., regeneration of bone, 24;

    —number of eggs in an _Ascaris,_ 27.

_Carpinus betulus,_ 27.

_Carpophaga oceanica,_ 28.

CARR, Mr., effect of changed conditions, 17.

CARRIER pigeon, 5;

    —English, 5;

    —figured, 5;

    —skull figured, 5;

    —history of the, 6;

    —Persian, 5;

    —Bussorah, 5;

    —Bagadotten, skull figured, 5;

    —lower jaw figured, 5.

CARRIÈRE, origin of radish, 9;

    —intermediate form between the almond and the peach, 10;

    —glands of peach-leaves, 10;

    —bud-variation in the vine, 11;

    —bud-variation in the rose, 11;

    —inheritance in purple-leaved trees, 12;

    —on variation, 11 (3);

    —grafts of _Aria vestita_ upon thorns, 11;

    —variability of hybrids of _ Erythrina,_ 22.

CARROT, wild, effects of cultivation on the, 9;

    —reversion in the, 13;

    —run wild, 13;

    —increased fertility of cultivated, 16;

    —experiments on the, 23;

    —acclimatisation of the, in India, 24.

_Carthamus,_ abortion of the pappus in, 24.

CARTIER, cultivation of native plants in Canada, 9.

CARYOPHYLLACEÆ, frequency of contabescence in the, 18.

CASPARY, bud-variation in the moss-rose, 11;

    —on the ovules and pollen of _ Cytisus,_ 11;

    —crossing of _Cytisus purpureus_ and _C. laburnum,_ 11;

    —trifacial orange, 11;

    —differently-coloured flowers in the wild _Viola lutea,_ 11;

    —sterility of the horse-radish, 18.

CASTELNAU, on Brazilian cattle, 3.

CASTRATION, assumption of female characters caused by, 13 (2).

_Casuarius bennettii,_ 18.

CAT, domestic, 1;

    —early domestication and probable origin of the, 1 (2);

    —intercrossing of, with wild species, 1 (2);

    —variations of, 1;

    —feral, 1, 13;

    —anomalous, 1;

    —polydactylism in, 12;

    —black, indications of stripes in young, 13;

    —tortoiseshell, 14;

    —effects of crossing in, 15;

    —fertility of, 16;

    —difficulty of selection in, 21 (2);

    —length of intestines in, 24;

    —white with blue eyes, deafness of, 25;

    —with tufted ears, 26.

CATARACT, hereditary, 12, 14.

CATERPILLARS, effect of changed food on, 23.

_Catleya leopoldii,_ 11.

CATLIN, G., colour of feral horses in North America, 2.

CATON, Judge, wild turkey, 16.

CATTLE, European, their probable origin from three original species, 3;

    —humped, or zebus, 3;

    —intercrossing of, 3 (3);

    —wild, of Chillingham, Hamilton, Chartley, Burton Constable, and
    Gisburne, 1, 17;

    —colour of feral, 3, 20;

    —British breeds of, 3 (2);

    —South African breeds of, 3;

    —South American breeds of, 3, 20;

    —Niata, 3 (2), 20 (2), 25;

    —effects of food and climate on, 3;

    —effects of selection on, 3 (2);

    —Dutch-buttocked, 12;

    —hornless, production of horns in, 25;

    —reversion in, when crossed, 13;

    —wildness of hybrid, 13;

    —short-horned, prepotency of, 14;

    —wild, influence of crossing and segregation on, 15;

    —crosses of, 15, 16, 17;

    —of Falkland Islands, 16;

    —mutual fertility of all varieties of, 16;

    —effects of interbreeding on, 17 (2);

    —shorthorn, sterility of, 17;

    —effects of careful selection on, 20 (2);

    —naked, of Columbia, 20;

    —crossed with wild banteng in Java, 20;

    —with reversed hair in Banda Oriental, 20;

    —selection of trifling characters in, 20;

    —fashion in, 20;

    —similarity of best races of, 21;

    —unconscious selection in, 20;

    —effects of natural selection on anomalous breeds of, 21 (2);

    —light-coloured, attacked by flies, 21, 25;

    —Jersey, rapid improvement of, 21;

    —effects of disuse of parts in, 24;

    —rudimentary horns in, 24;

    —supposed influence of humidity on the hair of, 25;

    —white spots of, liable to disease, 25;

    —supposed analogous variation in, 26;

    —displacement of long-horned by short-horned, 28.

CAULIFLOWER, 9;

    —free-seeding of, in India, 21;

    —rudimentary flowers in, 24.

CAVALIER pigeon, 15.

_Cavia aperea,_ 18.

CAY (_Cebus azaræ_), sterility of, in confinement, 18.

_Cebus azaræ,_ 18.

_Cecidomyia,_ larval development of, 23, 27 (2);

    —and _Misocampus,_ Introduction.

CEDARS of Lebanon and Atlas, 10.

CELERY, turnip-rooted, 9;

    —run wild, 13.

CELL-THEORY, 27.

_Celosia cristata,_ 10.

CELSUS, on the selection of seed-corn, 9, 20.

CELTS, early cultivation of the cabbage by the, 9;

    —selection of cattle and horses by the, 20.

_Cenchrus,_ seeds of a, used as food, 9.

_Centaurea cyanus,_ bud-variation in, 11.

CEPHALOPODA, spermatophores of, 27.

_Cerasus padus,_ yellow-fruited, 12.

_Cercoleptes,_ sterility of, in captivity, 18.

_Cercopithecus,_ breeding of a species of, in captivity, 18.

CEREALS, 9 (2);

    —of the Neolithic period in Switzerland, 9;

    —adaptation of, to soils, 24.

_Cereus,_ 13.

_Cereus speciosissimus_ and _phyllanthus,_ reversion in hybrids of, 11.

_Cervus canadensis,_ 18.

_Cervus dama,_ 17.

CETACEA, correlation of dermal system and teeth in the, 25.

CEYLON, cats of, 1;

    —pigeon-fancying in, 6.

CHAMISSO, on seeding bread-fruit, 18.

CHANNEL Islands, breeds of cattle in, 3.

CHAPMAN, Professor, peach-trees producing nectarines, 10.

CHAPUIS, F., sexual peculiarities in pigeons, 5;

    —effect produced by first male upon the subsequent progeny of the
    female, 11;

    —sterility of the union of some pigeons, 18.

CHARACTERS, fixity of, 21;

    —latent, 13, 27 (2);

    —continued divergence of, 21;

    —antagonistic, 27.

CHARDIN, abundance of pigeons in Persia, 6.

CHARLEMAGNE, orders as to the selection of stallions, 20.

CHARTLEY, wild cattle of, 3.

CHATÉ, reversion of the upper seeds in the pods of stocks, 26.

CHAUNDY, Mr., crossed varieties of cabbage, 17.

CHEETAH, general sterility of, in captivity, 18.

_Cheiranthus cheiri,_ 11.

CHERRIES, 10 (2);

    —bud-variation in, 11;

    —white Tartarian, 21;

    —variety of, with curled petals, 21;

    —period of vegetation of, changed by forcing, 24.

CHEVREUL, on crossing fruit-trees, 17.

CHICKENS, differences in characters of, 7 (2);

    —white, liable to gapes, 21, 25.

CHIGOE, 23.

CHILE, sheep of, 3.

CHILLINGHAM cattle, identical with _Bos primigenius,_ 3;

    —characters of, 3.

CHILOE, half-castes of, 13.

CHINA, cats of, with drooping ears, 1;

    —horses of, 2;

    —striped ponies of, 2;

    —asses of, 2;

    —notice of rabbits in, by Confucius, 4;

    —breeds of pigeons reared in, 6;

    —breeds of fowls of, in fifteenth century, 7 (2).

CHINCHILLA, fertility of, in captivity, 18.

CHINESE, selection practised by the, 20;

    —preference of the, for hornless rams, 20;

    —recognition of the value of native breeds by the, 24.

CHINESE, or Himalayan rabbit, 4.

“CHIVOS,” a breed of cattle in Paraguay, 3.

CHOUX-RAVES, 9.

CHRIST, H., on the plants of the Swiss Lake-dwellings, 9 (2);

    —intermediate forms between _Pinus sylvestris_ and _montana,_ 10.

CHRYSANTHEMUM, 11.

_Chrysotis festiva,_ 23.

CINERARIA, effects of selection on the, 20.

CIRCASSIA, horses of, 16.

CIRCUMCISION, 12.

CIRRIPEDES, metagenesis in, 27.

_Cistus,_ intercrossing and hybrids of, 10, 12, 17.

CITRONS, 10 (2).

“_Citrus aurantium fructu variabili,_” 10 _Citrus decumana,_ 10.

_Citrus lemonum,_ 10.

_Citrus medica,_ 10 (2).

CLAPHAM, A., bud-variation in the hawthorn, 11.

“CLAQUANT” (pigeons), 5.

“CLAQUERS” (pigeons), 5.

CLARK, G., on the wild dogs of Juan de Nova, 1;

    —on striped Burmese and Javanese ponies, 2;

    —breeds of goats imported into the Mauritius, 3;

    —variations in the mammæ of goats, 3;

    —bilobed scrotum of Muscat goat, 3.

CLARK, H. J., on fission and gemmation, 27.

CLARKE, R. T., intercrossing of strawberries, 10.

CLARKE, T., hybridisation of stocks, 11, 15.

CLARKSON, Mr., prize-cultivation of the gooseberry, 10.

CLASSIFICATION, explained by the theory of natural selection,
Introduction.

CLEFT palate, inheritance of, 12.

CLEMENTE, on wild vines in Spain, 10.

CLERMONT-TONNERRE, on the St. Valéry apple, 11.

CLIMATE, effect of, upon breeds of dogs, 1;

    —on horses, 2 (2);

    —on cattle, 3 (2);

    —on the fleece of sheep, 3 (2);

    —on seeds of wheat, 9;

    —on cultivated cabbages, 9;

    —adaptation of maize to, 9.

CLIMATE and pasture, adaptation of breeds of sheep to, 3 (2).

CLIMATE and soil, effects of, upon strawberries, 10.

CLINE, Mr., on the skull in horned and hornless rams, 25.

CLOS, on sterility in _Ranunculus ficaria,_ 18.

CLOTZSCH, hybrids of various trees, 17.

CLOVER, pelorism in, 26.

COATE, Mr., on interbreeding pigs, 17.

COCCUS of apple-trees, 21.

COCHIN fowls, 7 (5);

    —occipital foramen of, figured, 7;

    —section of skull of, figured, 7;

    —cervical vertebra of, figured, 7.

COCHINEAL, persistence of, 21;

    —preference of, for a particular cactus, 23.

_Cochlearia armoracia,_ 18.

COCK, game, natural selection in, 21;

    —spur of, grafted on the comb, 24;

    —spur of, inserted into the ear of an ox, 27;

    —effect of castration upon the, 13.

COCK’S-COMB, varieties of the, 10.

COCOONS of silkworms, variations in, 8.

CODFISH, bulldog, 3;

    —number of eggs in the, 27.

_Coelogenys paca,_ 18.

COLIN, prepotency of the ass over the horse, 14;

    —on cross-breeding, 15;

    —on change of diet, 24.

COLLINSON, PETER, peach-tree producing a nectarine, 10.

COLORATION in pigeons, an evidence of unity of descent, 6.

COLOUR, correlation of, in dogs, 1;

    —persistence of, in horses, 2;

    —inheritance and diversity of, in horses, 2;

    —variations of, in the ass, 5;

    —of wild or feral cattle, 5;

    —transmission of, in rabbits, 4;

    —peculiarities of, in Himalayan rabbits, 4;

    —influence of, 21;

    —correlation of, in head and limbs, 25;

    —correlated with constitutional peculiarities, 25.

COLOUR and odour, correlation of, 25.

COLOUR-BLINDNESS, hereditary, 12;

    —more common in men than in women, 14 (2);

    —associated with inability to distinguish musical sounds, 25.

COLOURS, sometimes not blended by crossing, 15.

_Columba affinis,_ Blyth, a variety of _C. livia,_ 6.

_Columba amaliæ,_ Brehm, a variety of _C. livia,_ 6.

_Columba guinea,_ 6.

_Columba gymnocyclus,_ Gray, a form of _C. livia,_ 6.

_Columba gymnophthalmos,_ hybrids of, with _C. œnas,_ 6;

    —with _C. maculosa,_ 6.

_Columba intermedia,_ Strickland, a variety of _C. livia,_ 6.

_Columba leucocephala,_ 18.

_Columba leuconota,_ 6 (2).

_Columba littoralis,_ 6.

_Columba livia,_ 13 (2);

    —the parent of domestic breeds of pigeons, 6;

    —measurements of, 5;

    —figured, 5;

    —skull figured, 5;

    —lower jaw figured, 5;

    —scapula figured, 5.

_Columba luctuosa,_ 6.

_Columba migratoria_ and _leucocephala,_ diminished fertility of, in
captivity, 18.

_Columba œnas,_ 6;

    —crossed with common pigeon and _C. gymnophthalmos,_ 6.

_Columba palumbus,_ 6, 26.

_Columba rupestris,_ 6 (3).

_Columba schimperi,_ 6.

_Columba torquatrix,_ 26.

_Columba turricola,_ 6.

COLUMBIA, cattle of, 6. COLUMBINE, double, 10, 25.

COLUMBUS, on West Indian dogs, 1.

COLUMELLA, on Italian shepherd dogs, 1;

    —on domestic fowls, 7 (2), 20, 28;

    —on the keeping of ducks, 8;

    —on the selection of seed-corn, 9;

    —on the benefits of change of soil to plants, 18;

    —on the value of native breeds, 24.

COLZA, 9.

COMB, in fowls, variations of, 7;

    —sometimes rudimentary, 24.

COMPENSATION, law of, 7.

COMPENSATION of growth, 26.

COMPLEXION, connection of, with constitution, 25.

COMPOSITÆ, double flowers of, 10, 18, 24.

CONCEPTION, earlier in Alderney and Zetland cows than in other breeds,
3.

CONDITIONS of life, changed, effect of, 28;

    —on horses, 2;

    —upon variation in pigeons, 6;

    —upon wheat, 9;

    —upon trees, 10;

    —in producing bud-variation, 11;

    —advantages of, 18;

    —sterility caused by, 18;

    —conducive to variability, 22;

    —accumulative action of, 22;

    —direct action of, 23.

CONDOR, breeding in captivity, 18.

CONFINEMENT, effect of, upon the cock, 17.

CONFUCIUS, on the breeding of rabbits in China, 4.

CONOLLY, Mr., on Angora goats, 25.

CONSTITUTIONAL differences in sheep, 3;

    —in varieties of apples, 10;

    —in pelargoniums, 10;

    —in dahlias, 10.

CONSTITUTIONAL peculiarities in strawberries, 10;

    —in roses, 10.

CONSUMPTION, hereditary, 12;

    —period of appearance of, 14;

    —correlated with complexion, 25.

CONTABESCENCE, 18 (2).

_Convolvulus batatas,_ 18, 24.

_Convolvulus tricolor,_ bud-variation in, 11.

COOPER, Mr., improvement of vegetables by selection, 20.

COOPER, WHITE, hereditary peculiarities of vision, 12;

    —association of affections of the eyes with those of other systems,
    25.

CORALS, bud-variation in, 11;

    —non-diffusion of cell-gemmules in, 27.

CORBIÉ, _See_ Boitard.

CORDEMOZ, Dr., seedless plants, 18.

CORNEA, opacity of, inherited, 12.

_Cornus mascula,_ yellow-fruited, 12.

CORRELATION, 25;

    —of neighbouring parts, 25;

    —of change in the whole body, and in some of its parts, 25;

    —of homologous parts, 25;

    —inexplicable, 25, 26, 27;

    —commingling of, with the effects of other agencies, 25.

CORRELATION of skull and limbs in swine, 3;

    —of tusks and bristles in swine, 3;

    —of multiplicity of horns and coarseness of wool in sheep, 3;

    —of beak and feet in pigeons, 5 (2);

    —between nestling down and colour of plumage in pigeons, 6;

    —of changes in silkworms, 8;

    —in plants, 20;

    —in maize, 9;

    —in pigeons, 5;

    —in fowls, 7.

CORRESPONDING periods, inheritance at, 14.

CORRIENTES, dwarf cattle of, 3.

CORRINGHAM, Mr., influence of selection on pigs, 20.

CORSICA, ponies of, 2.

“CORTBECK” (pigeon) of Aldrovandi, 6.

_Corvus corone,_ and _C. cornix,_ hybrids of, 15.

_Corydalis,_ flower of, 26.

_Corydalis cava,_ 17 (2).

_Corydalis solida,_ sterile when peloric, 18.

_Corydalis tuberosa,_ peloric by reversion, 13.

_Corylus avellana,_ 10.

COSTA, A., on shells transferred from England to the Mediterranean, 23.

COUES, Dr. E., on a monstrous chicken, 27.

COWPER, Mr. WHITE, defective development of the dental system, 25.

“COUVE TRONCHUDA,” 9 COW, inheritance of loss of one horn in the, 12;

    —amount of milk furnished by the, 24;

    —development of six mammæ in, 24.

COWSLIP, 12.

CRACIDÆ, sterility of the, in captivity, 18.

CRANES, fertility of, in captivity, 18.

_Cratægus oxyacantha,_ 10, 11, 21, 22, 12.

_Cratægus monogyna,_ 10.

_Cratægus sibirica,_ 10.

CRAWFURD, J., Malasian cats, 1;

    —horses of the Malay Archipelago, 2;

    —horses of Japan, 2;

    —occurrence of stripes in young wild pigs of Malacca, 3;

    —on a Burmese hairy family with deficient teeth, 14, 25;

    —Japanese origin of the bantam, 7;

    —game fowls of the Philippine Islands, 22;

    —hybrids of _Gallus varius_ and domestic fowl, 7;

    —domestication of _Gallus bankiva,_ 7;

    —feral fowls in the Pellew Islands, 7;

    —history of the fowl, 7;

    —history of the domestic duck, 8;

    —domestication of the goose, 8;

    —cultivated plants of New Zealand, 9;

    —breeding of tame elephants in Ava, 18;

    —sterility of _Goura coronata_ in confinement, 18;

    —geese of the Philippine Islands, 18.

CREEPERS, a breed of fowls, 7.

CRESTED fowl, 7;

    —figured, 7.

“CRÈVE-CŒUR,” a French sub-breed of fowls, 7.

CRISP, Dr., on the brains of the hare and rabbit, 4.

CROCKER, C. W., singular form of _Begonia frigida,_ 10, 18;

    —sterility in _Ranunculus ficaria,_ 18.

CROCUS, 18.

CROSS-BREEDING, permanent effect of, on the female, 11.

CROSSING, 15, 16, 17, 19;

    —a cause of uniformity, 15;

    —occurs in all organised beings, 15;

    —some characters not blended by, 15, 19;

    —modifications and new races produced by, 15;

    —causes which check, 16;

    —domestication and cultivation favourable to, 16, 19;

    —beneficial effects of, 17, 19;

    —necessary in some plants, 17, 19;

    —summary of subject of, 17;

    —of dogs with wolves in North America, 1 (2);

    —with _Canis cancrivorus_ in Guiana, 1;

    —of dog with wolf, described by Pliny and others, 1;

    —characters furnished by, brought out by reversion in the progeny,
    13;

    —a direct cause of reversion, 13 (2);

    —a cause of variability, 22.

CRUSTACEA, macrourous, differences in the development of the, 27.

CRUSTACEAN with an antenna-like development of the eye-peduncle, 27.

CRYPTOGAMIC plants, bud-variation in, 11.

CUBA, wild dogs of, 1.

“CUCKOO,” sub-breeds of fowls, 7.

CUCUMBER, variation in number of carpels of, 10;

    —supposed crossing of varieties of the, 11.

_Cucumis momordica,_ 10.

_Cucumis sativa,_ 10.

_Cucurbita,_ dwarf, correlation of leaves in, 25.

_Cucurbita maxima,_ 10 (2).

_Cucurbita moschata,_ 10 (2).

_Cucurbita pepo_ 10;

    —varieties of, 10;

    —relation in size and number of fruit of, 26.

CUCURBITACEÆ, 10;

    —supposed crossing of, 11;

    —Naudin’s observations on hybrids of, 18;

    —acclimatisation of, 24.

“CULBUTANTS” (pigeons), 5.

CULTIVATION of plants, origin of, among savages, 9 (2);

    —fertility increased by, 16.

CUNIER, on hereditary night-blindness, 12.

CUPPLES, Mr., pairing of deer-hounds, 17.

CURRANTS, of Tierra del Fuego, 9;

    —bud-variation in, 11.

CURTIS, Mr., bud-variation in the rose, 11.

CUVIER, on the gestation of the wolf, 1;

    —the odour of the jackal, an obstacle to domestication, 1;

    —differences of the skull in dogs, 1;

    —external characters of dogs, 1;

    —elongation of the intestines in domestic pigs, 3, 24;

    —fertility of the hook-billed duck, 8;

    —hybrid of ass and zebra, 13;

    —breeding of animals in the Jardin des Plantes, 18;

    —sterility of predaceous birds in captivity, 18;

    —facility of hybridisation in confinement, 18.

CYANOSIS, affection of fingers in, 25.

CYCLAMEN, bud-variation in, 11.

_Cynara cardunculus,_ 13.

_Cynips fecundatrix,_ 23.

_Cynocephalus hamadryas,_ 18.

_Cyprinus auratus,_ 8.

_Cyrtanthus,_ 17.

_Cyrtopodium,_ 17.

_Cytisus adami,_ its bud-variation, 11;

    —seedlings from, 11;

    —different views of its origin, 11;

    —experiments in crossing _C. purpureus_ and _laburnum_ to produce,
    11;

    —its production by M. Adam, 11;

    —discussion of origin of, 11.

_Cytisus alpino-laburnum,_ ovules and pollen of, 11;

    —origin of, 11.

_Cytisus alpinus,_ 11.

_Cytisus laburnum,_ 11 (3).

_Cytisus purpureo-elongatus,_ ovules and pollen of, 11;

    —production of, 11.

_Cytisus purpureus,_ 11.

DAHLBOHM, effects of food on hymenoptera, 23.

DAHLIA, 10;

    —bud-variation by tubers in the, 11;

    —improvement of, by selection, 20;

    —steps in cultivation of, 22;

    —effect of conditions of life on, 23;

    —correlation of form and colour in, 25.

DAISY, hen-and-chicken, 10;

    —Swan River, 22.

DALBRET, varieties of wheat, 9.

DALIBERT, changes in the odours of plants, 23.

DALLY, Dr., on consanguineous marriages, 17.

DALTONISM, hereditary, 12.

DAMARAS, cattle of, 3, 20 (2).

DAMSON, 10.

DANDOLO, Count, on silkworms, 8.

DANIELL, fertility of English dogs in Sierra Leone, 18.

DANISH Middens, remains of dogs in, 1.

DAPPLING in horses, asses, and hybrids, 2.

DARESTE, C., on the skull of the Polish fowl, 7;

    —causes of variability, 22;

    —on the production of monstrous chickens, 23;

    —co-existence of anomalies, 25;

    —production of double monsters, 26.

DARVILL, Mr., heredity of good qualities in horses, 12.

DARWIN, C., on _Lepus magellanicus,_ 4;

    —on the wild potato, 9;

    —dimorphism in the polyanthus and primrose, 12.

DARWIN, Dr., improvement of vegetables by selection, 20.

DARWIN, Sir F., wildness of crossed pigs, 13.

DARWIN, G., consanguineous marriages, 17.

D’ASSO, monogynous condition of the hawthorn in Spain, 10.

_Dasyprocta aguti,_ 18.

DATE-PALM, varieties of the, 22.

_Datura,_ 13;

    —variability in, 22.

_Datura lævis_ and _stramonium,_ reversion in hybrids of, 11.

_Datura stramonium,_ 14.

DAUBENTON, variations in the number of mammæ in dogs, 1;

    —proportions of intestines in wild and domestic cats, 1, 24.

DAUDIN, on white rabbits, 21.

DAVY, Dr., on sheep in the West Indies, 3.

DAWKINS, W. BOYD, history of the dog, 1;

    —origin of cattle, 3;

    —early domestication of _Bos longifrons_ in Britain, 3.

DEAF-MUTES, non-heredity in, 12.

DEAFNESS, inheritance of, 14.

DEAN, potato-grafting, 11.

DEBY, wild hybrids of common and musk ducks, 13.

DE CANDOLLE, ALPH., number and origin of cultivated plants, 9 (2), 10;

    —regions which have furnished no useful plants, 9;

    —wild wheat, 9 (2);

    —wild rye and oats, 9;

    —antiquity of varieties of wheat, 9;

    —apparent inefficacy of selection in wheat, 9;

    —origin and cultivation of maize, 9, 25;

    —colours of seeds of maize, 9;

    —varieties and origin of the cabbage, 9 (2);

    —origin of the garden-pea, 9;

    —on the vine, 10, 24;

    —cultivated species of the orange group, 10;

    —Chinese origin of the peach, 10;

    —on the peach and nectarine, 10 (2);

    —varieties of the peach, 10;

    —origin of the apricot, 10;

    —origin and varieties of the plum, 10;

    —origin of the cherry, 10;

    —varieties of the gooseberry, 10;

    —selection practised with forest-trees, 10;

    —wild fastigiate oak, 10;

    —dark-leaved varieties of trees, 10;

    —conversion of stamens into pistils in the poppy, 10;

    —variegated foliage, 10;

    —heredity of white hyacinths, 10, 12;

    —changes in oaks dependent on age, 11;

    —inheritance of anomalous characters, 12;

    —variation of plants in their native countries, 22;

    —deciduous bushes becoming evergreen in hot climates, 24;

    —antiquity of races of plants, 28.

DE CANDOLLE, P., non-variability of monotypic genera, 22;

    —relative development of root and seed in _Raphanus sativus,_ 26.

DECAISNE, on the cultivation of the wild carrot, 9;

    —varieties of the pear, 10;

    —intercrossing of strawberries, 10;

    —fruit of the apple, 11;

    —sterility of _Lysimachia nummularia,_ 18;

    —tender variety of the peach, 24.

DEER, assumption of horns by female, 13;

    —imperfect development of horns in a, on a voyage, 18.

DEER, fallow, 16.

DEERHOUND, Scotch, difference in size of the sexes of, 14;

    —deterioration of, 17.

DEGENERATION of high-bred races, under neglect, 21.

DE JONGHE, J., on strawberries, 10;

    —soft-barked pears, 21;

    —on accumulative variation, 22;

    —resistance of blossoms to frost, 24.

DELAMER, E. S., on rabbits, 4 (2).

_Delphinium ajacis,_ 12.

_Delphinium consolida,_ 12 (2).

DELPINO on Pangenesis, 27 (2).

_Dendrocygna viduata,_ 18.

DENNY, H., lice of Aperea, 18.

DENTITION, variations of, in the horse, 2.

DEODAR, 10.

DESMAREST, distribution of white on dogs, 1;

    —cat from the Cape of Good Hope, 1;

    —cats of Madagascar, 1;

    —occurrence of striped young in Turkish pigs, 3;

    —French breeds of cattle, 3;

    —horns of goats, 3;

    —on hornless goats, 24.

DESPORTES, number of varieties of roses, 10.

DEVAY, Dr., singular case of albinism, 12;

    —on the marriage of cousins, 17;

    —on the effects of close interbreeding, 22.

DEVELOPMENT and metamorphosis, 27 (2).

DEVELOPMENT, arrests of, 24.

DEVELOPMENT, embryonic, 27.

D’HERVEY-SAINT-DENYS, L., on the Yami, or imperial race of the Chinese,
20.

DHOLE, fertility of the, in captivity, 18.

DIABETES, occurrence of, in three brothers, 12.

_Dianthus,_ contabescent plants of, 18 (2);

    —hybrid varieties of, 22.

_Dianthus armeria_ and _deltoides,_ hybrids of, 15.

_Dianthus barbatus,_ 11.

_Dianthus caryophyllus,_ 11.

_Dianthus japonicus,_ contabescence of female organs in, 18.

_Diapheromera femorata,_ 27.

DICHOGAMOUS plants, 15.

DICKSON, Mr., on “running” in carnations, 11;

    —on the colours of tulips, 11.

_Dicotyles torquatus_ and _labiatus,_ 18.

DIEFFENBACH, dog of New Zealand, 1;

    —feral cats in New Zealand, 1;

    —polydactylism in Polynesia, 12.

_Dielytra,_ 13.

DIET, change of, 24 (2).

_Digitalis,_ properties of, affected by culture, 23.

DIGITS, supernumerary, 12;

    —analogy of, with embryonic conditions, 13;

    —fusion of, 26.

DIMORPHIC plants, 17;

    —conditions of reproduction in, 19.

DIMORPHISM, reciprocal, 15.

DINGO, 1;

    —variation of, in colour 1;

    —half-bred, attempting to burrow 1;

    —attraction of foxes by a female, 1;

    —variations of, in confinement, 22.

DIOECIOUSNESS of strawberries, 10.

DISEASES, inheritance of, 12 (2);

    —inherited at corresponding periods of life, 14;

    —peculiar to localities and climates, 23;

    —obscure correlations in, 25 (2);

    —affecting certain parts of the body, 27;

    —occurring in alternate generations, 27.

DISTEMPER, fatal to white terriers, 21.

DISUSE and use of parts, effects of, 24, 26 (2), 28 (2);

    —in the skeleton of rabbits, 4;

    —in pigeons, 5;

    —in fowls, 7;

    —in ducks, 8;

    —in the silk-moth, 8.

DIVERGENCE, influence of, in producing breeds of pigeons, 6.

DIXON, E. S., on the musk duck, 6;

    —on feral ducks, 6;

    —on feral pigeons in Norfolk Island, 6;

    —crossing of pigeons, 6;

    —origin of domestic fowls, 7;

    —crossing of _Gallus sonneratii_ and common fowl, 7;

    —occurrence of white in the young chicks of black fowls, 7;

    —Paduan fowl of Aldrovandi, 7;

    —peculiarities of the eggs of fowls, 7;

    —chickens, 7 (2);

    —late development of the tail in Cochin cocks, 7;

    —comb of lark-crested fowls, 7;

    —development of webs in Polish fowls, 7;

    —on the voice of fowls, 7;

    —origin of the duck, 8;

    —ducks kept by the Romans, 8;

    —domestication of the goose, 8;

    —gander frequently white, 8;

    —breeds of turkeys, 8;

    —incubatory instinct of mongrels of non-sitting races of fowls, 13;

    —aversion of the dove-cot pigeon to pair with fancy birds, 16;

    —fertility of the goose, 16;

    —general sterility of the guans in captivity, 18;

    —fertility of geese in captivity, 18;

    —white pea-fowl, 25.

DOBELL, H., inheritance of anomalies of the extremities, 12;

    —non-reversion to a malformation, 13.

DOBRIZHOFFER, abhorrence of incest by the Abipones, 17.

DOGS, origin of, 1;

    —ancient breeds of, 1, 28;

    —of Neolithic, Bronze and Iron periods in Europe, 1 (2), 28;

    —resemblance of, to various species of Canidæ, 1;

    —of North America compared with wolves, 1 (2);

    —of the West Indies, South America, and Mexico, 1 (2);

    —of Guiana, 1 (2);

    —naked dogs of Paraguay and Peru, 1 (2);

    —dumb, on Juan Fernandez, 1;

    —of Juan de Nova, 1;

    —of La Plata, 1;

    —of Cuba, 1;

    —of St. Domingo, 1;

    —correlation of colour in, 1 (2);

    —gestation of, 1 (2);

    —hairless Turkish, 1, 21;

    —inter-crossing of different breeds of, 1;

    —characters of different breeds of, discussed, 1;

    —degeneration of European, in warm climates, 1 (2), 23;

    —liability to certain diseases in different breeds of, 1 (2);

    —causes of differences of breeds discussed, 1;

    —catching fish and crabs in New Guinea and Tierra del Fuego, 1;

    —webbing of the feet in, 1;

    —influence of selection in producing different breeds of, 1 (2);

    —retention of original habits by, 6;

    —inheritance of polydactylism in, 12;

    —feral, 13;

    —reversion in fourth generation of, 13;

    —of the Pacific Islands, 15, 20, 27;

    —mongrel, 15;

    —comparative facility of crossing different breeds of, 16;

    —fertility of, 16, 18;

    —interbreeding of, 17;

    —selection of, among the Greeks, 20 (2);

    —among savages, 17 (2);

    —unconscious selection of, 20 (2);

    —valued by the Fuegians, 20 (2);

    —climatal changes in hair of, 23;

    —production of drooping ears in, 24;

    —rejection of bones of game by, 24;

    —inheritance of rudiments of limbs in, 24;

    —development of fifth toe in, 24;

    —hairless, deficiency of teeth in, 25;

    —short-faced, teeth of, 26;

    —probable analogous variation in, 26;

    —extinction of breeds of, 28.

DOMBRAIN, H. H., on the auricula, 26.

DOMESTICATION, essential points in, 28 (2);

    —favourable to crossing, 16, (2);

    —fertility increased by, 16, 19.

DOMESTICATED animals, origin of, 18 (2);

    —occasional sterility of, under changed conditions, 18 (2).

DONDERS, Dr., hereditary hypermetropia, 12.

DORKING fowl, 7 (2);

    —furculum of, figured, 7.

DORMOUSE, 18.

DOUBLE flowers, 18 (4);

    —produced by selection, 20.

DOUBLEDAY, H., cultivation of the filbert pine strawberry, 10.

DOUGLAS, J., crossing of white and black game-fowls, 15.

DOWNING, Mr., wild varieties of the hickory, 9;

    —peaches and nectarines from seed, 10 (2);

    —origin of the Boston nectarine, 10;

    —American varieties of the peach, 10;

    —North American apricot, 10;

    —varieties of the plum, 10;

    —origin and varieties of the cherry, 10 (2);

    —“twin-cluster pippins,” 10;

    —varieties of the apple, 10;

    —on strawberries, 10 (2);

    —fruit of the wild gooseberry, 10;

    —effects of grafting upon the seed, 12;

    —diseases of plum and peach tree, 21;

    —injury done to stone fruit in America by the “weevil,” 21;

    —grafts of the plum and peach, 22;

    —wild varieties of pears, 22;

    —varieties of fruit-trees suitable to different climates, 24.

DOWNING, Mr. J., sterility of shorthorns, 17.

_Draba sylvestris_ 18.

DRAGON (pigeon), 5 (2).

“DRAIJER” (pigeon), 5.

DRINKING, effects of, in different climates, 23.

DROMEDARY, selection of, 20.

DRUCE, Mr., interbreeding, 17;

    —value of cross breed of pigs, 17.

DU CHAILLU, fruit-trees in West Africa, 9.

DUCHESNE, on _Fragaria vesca,_ 10 (2).

DUFOUR, LEON, on _Cecidomyia_ and _Misocampus,_ Introduction.

DUCK, musk, retention of perching habit by the, 6;

    —feral hybrid of, 6.

DUCK, penguin, hybrid of, with Egyptian goose, 14.

Duck, wild, difficulty of rearing, 21;

    —effects of domestication on, 23.

DUCKS, breeds of, 8 (2);

    —origin of, 8;

    —history of, 8;

    —wild, easily tamed, 8 (2);

    —fertility of breeds of, when crossed, 8;

    —with the plumage of _Anas boschas,_ 8;

    —Malayan penguin, identical in plumage with English, 8;

    —characters of the breeds of, 8;

    —eggs of, 8;

    —effects of use and disuse in, 8, 24;

    —feral, in Norfolk, 6;

    —Aylesbury, inheritance of early hatching by, 12;

    —reversion in, produced by crossing, 13;

    —wildness of half-bred wild, 13;

    —hybrids of, with the musk duck, 13 (2);

    —assumption of male plumage by, 13;

    —crossing of Labrador and penguin, 15;

    —increased fertility of, by domestication, 16;

    —general fertility of, in confinement, 18;

    —increase of size of, by care in breeding, 20;

    —change produced by domestication in, 22.

DUMÉRIL, AUG., breeding of _Siredon_ in the branchiferous stage, 27.

DUN-COLOURED horses, origin of, 2.

DUREAU DE LA MALLE, feral pigs in Louisiana, 13;

    —feral fowls in Africa, 13;

    —bud-variation in the pear, 11;

    —production of mules among the Romans, 16.

_Dusicyon silvestris,_ 1.

DUTCH rabbit, 4.

DUTCH roller pigeon, 5.

DUTROCHET, pelorism in the laburnum, 26.

DUVAL, growth of pears in woods in France, 22.

DUVAL-JOUVE, on _Leersia oryzoides,_ 15.

DUVERNOY, self-impotence in _Lilium candidum,_ 17.

DZIERZON, variability in the characters and habits of bees, 8.

EARLE, Dr., on colour-blindness, 14, 25.

EARS, of fancy rabbits, 4;

    —deficiency of, in breeds of rabbits, 4;

    —rudimentary, in Chinese sheep, 24;

    —drooping, 24;

    —fusion of, 26.

EATON, J. M., on fancy pigeons, 5, (2);

    —variability of characters in breeds of pigeons, 5;

    —reversion of crossed pigeons to coloration of _Columba livia,_ 6;

    —on pigeon-fancying, 6 (3);

    —on tumbler-pigeons, 6, 21;

    —carrier-pigeon, 6;

    —effects of interbreeding on pigeons, 17;

    —properties of pigeons, 20;

    —death of short-faced tumblers in the egg, 21;

    —Archangel-pigeon, 21.

ECHINODERMATA, metagenesis in, 27.

_Ectopistes,_ specific difference in number of tail-feathers in, 5.

_Ectopistes migratorius,_ sterile hybrids of, with _Turtur vulgaris,_
6.

EDENTATA, correlation of dermal system and teeth in the, 25.

EDGEWORTH, Mr., use of grass-seeds as food in the Punjab, 9.

EDMONSTON, Dr., on the stomach in _Larus argentatus_ and the raven, 24.

EDWARDS and Colin, on English wheat in France, 24.

EDWARDS, W. F., absorption of the minority in crossed races, 15.

EDWARDS, W. W., occurrence of stripes in a nearly thoroughbred horse,
2;

    —in foals of racehorses, 2.

EGGS, of fowls, characters of, 7;

    —variations of, in ducks, 8;

    —of the silk-moth, 8.

EGYPT, ancient dogs of, 1 (2);

    —ancient domestication of the pigeon in, 6;

    —absence of the fowl in ancient, 7.

EGYPTIAN goose, hybrids of, with penguin duck, 8.

EHRENBERG, Prof., multiple origin of the dog, 1;

    —dogs of Lower Egypt, 1;

    —mummies of _Felis maniculata,_ 1.

ELEMENTS of the body, functional independence of the, 27.

ELEPHANT, its sterility in captivity,18.

ELK, Irish, correlations in the, 25 (2).

ELLIOT, Sir WALTER, on cats in India, 1;

    —on striped horses, 2;

    —Indian domestic and wild swine, 3;

    —pigeons from Cairo and Constantinople, 5;

    —fantail pigeons, 5;

    —Lotan tumbler pigeons, 5;

    —a pigeon uttering the sound “Yahu,” 5;

    —_Gallus bankiva_ in Pegu, 7.

ELLIS, Mr., varieties of cultivated plants in Tahiti, 22.

ELM, nearly evergreen Cornish variety of the, 10, 24;

    —foliage-varieties of the, 10.

ELM, weeping, 10;

    —not reproduced by seed, 12.

_Emberiza passerina,_ 18.

EMBRYOS, similarity of, 1;

    —fusion of, 26.

ENGEL, on _Laurus sassafras,_ 23.

ENGLAND, domestication of _Bos longifrons_ in, 3;

    —selection of horses in, in mediæval times, 20;

    —laws against the early slaughter of rams in, 20.

EPHEMERIDÆ, development of the, 27.

_Epidendrum cinnabarinum,_ 11;

    —and _E. zebra,_ 17.

EPILEPSY, hereditary, 12, 14.

_Equus burchellii,_ 2.

_Equus quagga,_ 2.

_Equus indicus,_ 1 (2).

_Equus tæniopus,_ 2 (2), 13.

ERDT, disease of the white parts of cattle, 25.

ERICACEÆ, frequency of contabescence in the, 18.

ERICHTHONIUS, an improver of horses by selection, 20.

ERMAN, on the fat-tailed Kirghisian sheep, 3, 23;

    —on the dogs of the Ostyaks, 20.

_Erodium,_ 13.

_Erythrina crista-galli_ and _E. herbacea,_ hybrids of, 22.

_Eschscholtzia californica,_ self-sterile in England, 17.

ESQUILANT, Mr., on the naked young of dun-coloured pigeons, 5.

ESQUIMAUX dogs, their resemblance to wolves, 1;

    —selection of, 20.

ESQUIROL, on hereditary insanity, 2.

EUDES-DESLONGCHAMPS, on appendages under the jaw of pigs, 3.

_Euonymus japonicus,_ 11.

_Euphorbia maculata,_ 23.

EUROPEAN cultivated plants, still wild in Europe, 9.

EVANS, Mr., on the Lotan tumbler pigeon, 5.

EVELYN, pansies grown in his garden, 10.

EVEREST, R., on the Newfoundland dog in India, 1, 24;

    —degeneration of setters in India, 1;

    —Indian wild boars, 3.

EWES, hornless, 26.

EXTINCTION of domestic races, 6.

EYES, hereditary peculiarities of the, 12;

    —loss of, causing microphthalmia in children, 12;

    —modification of the structure of, by natural selection, 20 (2).

EYEBROWS, hereditary elongation of hairs in, 12.

EYELIDS, inherited peculiarities of the, 12.

EYTON, Mr., on gestation in the dog, 1;

    —variability in number of vertebræ in the pig, 3;

    —individual sterility, 18.

_Faba vulgaris,_ 9.

FABRE, observations on _Ægilops triticoides,_ 9.

_Fagus sylvatica,_ 12.

FAIRWEATHER, Mr., production of double flowers from old seed, 18.

FAIVRE, on the _Primula sinensis,_ 10, 25.

_Falco albidus,_ resumption of young plumage by, in captivity, 18.

_Falco ossifragus,_ 21.

_Falco subbuteo,_ copulating in captivity, 18.

_Falco tinnunculus,_ breeding in captivity, 18.

FALCONER, Dr., sterility of English bulldogs in India, 1;

    —resemblance between _ Sivatherium_ and Niata cattle, 3;

    —selection of the silkworm in India, 8;

    —fastigiate apple-trees in Calcutta, 10;

    —reproduction of a supernumerary thumb after amputation, 12;

    —fertility of the dhole in captivity, 18;

    —fertility of English dogs in India, 18;

    —sterility of the tiger in captivity, 18;

    —turkeys at Delhi, 18;

    —on Indian cultivated plants, 18;

    —Thibet mastiff and goat, 23.

FALCONS, sterility of, in captivity, 18.

FALKLAND Islands, horses of the, 2 (2);

    —feral pigs of the, 3;

    —feral cattle of the, 3 (2);

    —feral rabbits of the, 4.

FALLOW deer, 16, 17.

FANTAIL pigeons, 5, 21;

    —figured, 5;

    —furculum of, figured, 5;

    —history of, 6;

    —absence of oil-gland in, 26.

FAROE Islands, pigeons of the, 6.

FASHION, influence of, in breeding, 21.

FASTIGIATE trees, 23, 26.

FAUNAS, geographical differences of, 1.

“FAVOURITE” bull, 14, 17.

FEATHERS, homologous variation in, 25.

FEET, of pigeons, individual differences of, 5;

    —correlations of external characters in, 5.

FEET and beak, correlation of, in pigeons, 5.

FELIDÆ, fertility of, in captivity, 18.

_Felis bubastes,_ 1.

_Felis caffra,_ 1.

_Felis caligulata,_ 1.

_Felis chaus,_ 1.

_Felis jubata,_ 18.

_Felis lybica,_ 1.

_Felis maniculata,_ 1.

_Felis manul,_ 1.

_Felis ornata,_ 1.

_Felis sylvestris,_ 1.

_Felis torquata,_ 1.

FEMALE, affected by male element, 27 (2).

FEMALE flowers, in male panicle of maize, 9.

FENN, Mr., grafting potatoes, 11.

FENNEL, Italian variety of, 9.

FERAL cats, 1;

    —cattle, 3;

    —rabbits, 4 (2);

    —Guinea fowl, 8;

    —animals and plants, reversion in, 13 (3).

FERGUSON, Mr., supposed plurality of origin of domestic fowls, 7;

    —chickens of black game-fowls, 7;

    —relative size of eggs of fowls, 7;

    —yolk of eggs of game-fowls, 7;

    —early pugnacity of game-cocks, 7;

    —voice of the Malay fowl, 7;

    —effects of interbreeding on fowls, 17;

    —selection in Cochin-China fowls, 20;

    —on fashion in poultry, 21.

FERNANDEZ, on Mexican dogs, 1.

FERNS, reproduction of abnormal forms of, by spores, 11;

    —non-diffusion of cell-gemmules in, 27.

FERRETS, 16, 18, 20.

FERTILISATION, artificial, of the St. Valéry apple, 10 (2).

FERTILITY, various degrees of, in sheep, 3;

    —unlimited mutual, of breeds of pigeons, 6;

    —comparative, of mongrels and hybrids, 16 (2), 19;

    —influence of nourishment on, 16;

    —diminished by close interbreeding, 17, 19;

    —reduced, of Chillingham wild cattle, 17;

    —of domesticated varieties when crossed, 19.

_Festuca,_ species of, propagated by bulblets, 18.

FILBERTS, spared by tomtits, 21.

FILIPPI, on the breeding of branchiferous tritons, 27.

FINCHES, general sterility of, in captivity, 18.

FINNIKIN (pigeon), 5.

FINNOCCHIO, 9.

FIR, Scotch, acclimatisation of, 24.

FISH, Mr., advantage of change of soil to plants, 18.

FISHES, regeneration of portions of fins of, 13;

    —variability of, when kept in tanks, 22;

    —marine, living in fresh water, 24;

    —double monsters of, 26.

FISSION and gemmation, 27.

FITCH, Mr., persistency of a variety of the pea, 9.

FITTEST, survival of the, 1.

FITZINGER, origin of sheep, 3;

    —African maned sheep, 3.

FITZPATRICK, Mr., potato-grafting, 11.

FIXEDNESS of character, conditions of, discussed, 14.

FLAX, found in the Swiss lake-dwellings, 9;

    —climatal difference in products of, 23.

FLEECE, fineness of, in Austrian merinos, 20.

FLEISCHMANN, on German sheep crossed with merinos, 15.

“FLORENTINER-TAUBE,” 5 (2).

FLOUNDER, 1.

FLOURENS, crossing of wolf and dog, 1;

    —prepotency of the jackal over the dog, 14;

    —hybrids of the horse and ass, 14;

    —breeding of monkeys in Europe, 18.

FLOWER-GARDEN, earliest known, in Europe, 20.

FLOWERS, capricious transmission of colour-varieties in, 12 (2);

    —tendency to uniformity in striped, 14;

    —scorching of, dependent on colour, 21;

    —change in, caused by conditions of life, 23;

    —rudimentary, 24;

    —relative position of, to the axis, 26.

FŒTATION, abdominal, 24.

FOLEY, Mr., wild varieties of pears, 22.

FOLIAGE, inherited peculiarities of, 10;

    —variegation of, 10;

    —bud-variation in, 11.

FOOD, influence of, on the pig, 3;

    —on cattle, 3;

    —excess of, a cause of variability, 22.

FORBES, D., on Chilian sheep, 3;

    —on the horses of Spain, Chili, and the Pampas, 2.

_Formica rufa,_ 22.

FORTUNE, R., sterility of the sweet potato in China, 18;

    —development of axillary bulbs in the yam, 18.

FOWL, common, breeds of, 7;

    —supposed plurality of origin, 7;

    —early history of, 7;

    —causes of production of breeds of, 7;

    —origin of, from _Gallus bankiva,_ 7 (2);

    —feral, notices of, 7 (2);

    —reversion and analogous variation in, 7, 13 (2), 26 (2);

    —“cuckoo” sub-breeds of, 7;

    —history of, 7;

    —structural characters of, 7;

    —sexual peculiarities of, 7, 14;

    —external differences of, 7;

    —differences of breeds of, from _G. bankiva,_ 7;

    —osteological characters of, 7;

    —effects of disuse of parts in, 7, 24;

    —feral, 6, 13;

    —polydactylism in, 12;

    —fertility of, increased by domestication, 16, 18;

    —sterility of, under certain conditions, 18;

    —influence of selection on, 20 (3);

    —evils of close interbreeding of, 17 (2);

    —crossing of, 15;

    —prepotency of transmission in, 14;

    —rudimentary organs in, 24;

    —crossing of non-sitting varieties of, 13 (2);

    —homology of wing and leg feathers in, 25;

    —hybrids of, with pheasants and _ Gallus sonneratii,_ 13;

    —black-skinned, 20;

    —black, preyed upon by the osprey in Ireland, 21;

    —five-toed, mentioned by Columella, 28;

    —rumpless, tailed chickens produced by, 13;

    —Dorking, crosses of, 15;

    —form of comb and colour of plumage in, 21;

    —game, crossing of white and black, 15;

    —five-spurred, 27;

    —Spanish, liable to suffer from frost, 24;

    —Polish, peculiarities of skull of, 25.

FOX, sterility of, in captivity, 18.

FOX, S. BEVAN, races of bees, 8.

FOX, W. DARWIN, gestation of the dog, 1;

    —“Negro” cat, 1;

    —reversion of sheep in colour, 13;

    —period of gestation in the pig, 3;

    —young of the Himalayan rabbit, 4;

    —crossing of wild and domestic turkeys, 8;

    —reversion in crossed musk ducks, 13;

    —spontaneous segregation of varieties of geese, 16;

    —effects of close interbreeding upon bloodhounds, 17;

    —deafness of white cats with blue eyes, 25.

FOXHOUNDS, 1, 17.

_Fragaria chiloensis,_ 10.

_Fragaria collina,_ 10.

_Fragaria dioica_ of Duchesne, 10.

_Fragaria elatior,_ 10.

_Fragaria grandiflora,_ 10.

_Fragaria vesca,_ 10.

_Fragaria virginiana,_ 10.

_Fraxinus excelsior,_ 10, 11, 12.

_Fraxinus lentiscifolia,_ 12.

FRIESLAND cattle, probably descended from _Bos primigenius,_ 3.

FRILLBACK pigeon, 5;

    —Indian, 5.

_Fringilla ciris,_ 18.

_Fringilla spinus,_ 18.

FRIZZLED fowls, 7;

    —horses, 2.

FROG, polydactylism in the, 12.

FRUIT, seedless, 18.

FRUIT-TREES, varieties of, occurring wild, 9.

FRY, Mr., on fertile hybrid cats, 1;

    —on feral fowls in Ascension, 7.

FUCHSIAS, origin of, 10;

    —bud-variation in,11.

_Fuchsia coccinea_ and _fulgens,_ twin seed produced by crossing, 11.

FUEGIANS, their superstition about killing young water-fowl, 9;

    —selection of dogs by the, 20;

    —their comparative estimation of dogs and old women, 20;

    —their power of distant vision, 20.

FUNGI, parasitic, 23 (2).

FÜRBRINGER, Dr., on nails of Saurians, 27.

FURCULUM, characters and variations of the, in pigeons, 5;

    —alteration of, by disuse, in pigeons, 5;

    —characters of, in fowls, 7.

FUSION of homologous parts, 27.

GAIT, inheritance of peculiarities of, 12.

GALAPAGOS Archipelago, its peculiar fauna and flora, Introduction

_Galeobdolon luteum,_ pelorism in, 13, 26.

GALLS, 13 (2).

GALL-GNATS, 23.

GALL-LIKE excrescences not inherited, 13.

GALLINACEOUS birds, restricted range of large, 7;

    —general fertility of, in captivity, 18.

_Gallinula chloropus,_ 5.

_Gallinula nesiotis,_ 8.

GALLESIO, species of oranges, 10;

    —hybridisation of oranges, 10;

    —persistency of races in the peach, 10;

    —supposed specific distinctions of peach and nectarine10;

    —bizzarria orange, 11;

    —crossing of red and white carnations, 11;

    —crossing of the orange and lemon, 11, 27;

    —effect of foreign pollen on maize, 4;

    —spontaneous crossing of oranges, 15;

    —monstrosities a cause of sterility in plants, 18;

    —seeding of ordinarily seedless fruits, 18;

    —sterility of the sugar-cane, 18;

    —tendency of male flowers to become double, 18;

    —effects of selection in enlarging fruit, etc., 20;

    —variation of the orange-tree in North Italy, 22;

    —naturalisation of the orange in Italy, 24.

_Gallus æneus,_ a hybrid of _G. varius_ and the domestic fowl, 7.

_Gallus bankiva,_ probable original of domestic fowls, 7 (3);

    —game-fowl, nearest to, 7;

    —crossed with _G. sonneratii,_ 7;

    —its character and habits, 7, 16;

    —differences of various breeds of fowls from, 7;

    —occipital foramen of, figured, 7;

    —skull of, figured, 7;

    —cervical vertebra of, figured, 7;

    —furculum of, figured, 7;

    —reversion to, in crossed fowls, 13 (2);

    —hybrid of, with _G. varius,_ 7, 13;

    —number of eggs of, 16.

_Gallus ferrugineus,_ 7.

_Gallus furcatus,_ 7.

_Gallus giganteus,_ 7.

_Gallus sonneratii,_ characters and habits of, 7;

    —hybrids of, 7, 13

_Gallus stanleyi,_ hybrids of, 7.

_Gallus temminckii,_ probably a hybrid, 7.

_Gallus varius,_ characters and habits of, 7;

    —hybrids and probable hybrids of, 7.

GALTON, Mr., fondness of savages for taming animals, 1;

    —cattle of Benguela, 3;

    —on hereditary talent, 12;

    —on Pangenesis, 27.

GAMBIER, Lord, his early cultivation of the pansy, 10.

GAME-FOWL, 7 (2).

GAPES, 21.

GARCILAZO DE LA VEGA, annual hunts of the Peruvian Incas, 20.

GARNETT, Mr., migratory propensities of hybrid ducks, 13.

GARROD, Dr., on hereditary gout, 12.

GÄRTNER, on the sterility of hybrids, 6, 16, 19;

    —acquired sterility of varieties of plants when crossed, 10;

    —sterility in transplanted plants, and in the lilac in Germany, 18;

    —mutual sterility of blue and red flowers of the pimpernel, 19;

    —supposed rules of transmission in crossing plants, 14;

    —on crossing plants, 15, 17 (3);

    —on repeated crossing, 22;

    —absorption of one species by another, when crossed, 15;

    —crossing of varieties of the pea, 11;

    —crossing maize, 16;

    —crossing of species of _ Verbascum,_ 15, 16;

    —reversion in hybrids, 13 (3);

    —of _Cereus,_ 11;

    —of _Tropæolum majus_ and _minus,_ 11;

    —variability of hybrids, 22;

    —variable hybrids from one variable parent, 22;

    —graft hybrid produced by inoculation in the vine, 11;

    —effect produced by grafts on the stock, 11, 23;

    —tendency of hybrid plants to produce double flowers, 18;

    —production of perfect fruit by sterile hybrids, 18;

    —sexual elective affinity, 19;

    —self-impotence in _Lobelia, Verbascum, Lilium,_ and _Passiflora,_
    17 (2);

    —on the action of pollen, 16;

    —fertilisation of _Malva,_ 11, 27;

    —prepotency of pollen, 19;

    —prepotency of transmission in species of _Nicotiana,_ 14;

    —bud-variation in _Pelargonium zonale,_ 11;

    —in _Œnothera biennis,_ 11;

    —in _Achillæa millefolium,_ 11;

    —effect of manure on the fertility of plants, 18;

    —on contabescence, 18;

    —inheritance of plasticity, 21;

    —villosity of plants, 23.

GASPARINI, a genus of pumpkins, founded on stigmatic characters, 10.

GAUDICHAUD, bud-variation in the pear, 11;

    —apple-tree with two kinds of fruit on branch, 11.

GAY, on _Fragaria grandiflora,_ 10;

    —on _Viola lutea_ and _ tricolor,_ 10;

    —on the nectary of _Viola grandiflora,_ 10.

GAYAL, domestication of the, 3.

GAYOT. _See_ Moll.

GEESE (_anseres_), general fertility of, in captivity, 18.

GEMMATION and fission, 27.

GEMMULES, or cell-gemmules, 27 (3).

GENERATION, alternate, 27 (3).

GENERATION, sexual, 27.

GENET, fertility of the, in captivity, 18. GENIUS, inheritance of, 12.

_Gentiana amarella,_ 18.

GEOFFROY SAINT-HILAIRE, production of monstrous chickens, 23;

    —“_Loi de l’affinite de soi pour soi,_” 26;

    —compensation of growth, 26.

GEOFFROY SAINT-HILAIRE, ISID., origin of the dog, 1;

    —barking of a jackal, 1;

    —period of gestation and odour of the jackal, 1;

    —anomalies in the teeth of dogs, 1;

    —variations in the proportions of dogs, 1;

    —webbed feet of Newfoundland dogs, 1;

    —crossing of domestic and wild cats, 1;

    —domestication of the arni, 3;

    —supposed introduction of cattle into Europe from the East, 3;

    —absence of interdigital pits in sheep, 3;

    —origin of the goat, 3;

    —feral geese, 6;

    —ancient history of the fowl, 7;

    —skull of the Polish fowl, 7;

    —preference of the Romans for the liver of white geese, 8;

    —polydactylism, 12;

    —assumption of male characters by female bird, 13;

    —transmission and blending of characters in hybrids, 15;

    —refusal of animals to breed in captivity, 18;

    —on the Guinea-pig, 18;

    —silkworms producing white cocoons, 20;

    —on the carp, 21;

    —on _Helix lactea,_ 23;

    —on monstrosities, 22;

    —injury to the embryo a cause of monstrosity, 22;

    —alteration in the coat of horses in coal-mines, 23;

    —length of the intestines in wild and tame animals, 24 (2);

    —inheritance of rudimentary limbs in the dog, 24;

    —correlation in monstrosities, 25;

    —supernumerary digits in man, 25;

    —co-existence of anomalies, 25;

    —presence of hairs and teeth in ovarian tumours, 27;

    —development of teeth on the palate in the horse, 27.

GEOGRAPHICAL differences of faunas, Introduction.

GEOLOGICAL succession of organisms, Introduction.

_Geranium,_ 13.

_Geranium phæum_ and _pyrenaicum,_ 22.

_Geranium pratense,_ 11.

GERARD, asserted climatal change in Burgundian bees, 8.

GERARDE, on varieties of the hyacinth, 10.

GERSTÄCKER, on hive-bees, 8.

GERVAIS, Prof., origin of the dog, 1;

    —resemblance of dogs and jackals, 1;

    —taming of the jackal, 1;

    —number of teeth in dogs, 1;

    —breeds of dogs, 1;

    —on tertiary horses, 2;

    —Biblical notices of horses, 2;

    —species of _Ovis,_ 3;

    —wild and domestic rabbits, 4;

    —rabbits from Mount Sinai and Algeria, 4;

    —earless rabbits, 4;

    —batrachia with doubled limbs, 27.

GESTATION, period of, in the dog, wolf, etc., 1;

    —in the pig, 3 (2);

    —in cattle, 3, 25;

    —in sheep, 3.

GESTURES, inheritance of peculiarities in, 12.

“GHOONDOOKS” a sub-breed of fowls, 7.

GHOR-KHUR, 13.

GILES, Mr., effect of cross-breeding in the pig, 11.

GIRAFFE, co-ordination of structure of, 20.

GIRARD, period of appearance of permanent teeth in dogs, 1.

GIRAUD-TEULON, cause of short sight, 12.

GIROU DE BUZAREINGUES, inheritance in the horse, 12;

    —reversion by age in cattle, 13;

    —prepotency of transmission of character in sheep and cattle, 14;

    —on crossing gourds, 16.

GISBURNE, wild cattle at, 3.

_Gladiolus,_ 10;

    —self-impotence of hybrids of, 17.

_Gladiolus colvillii,_ bud-variation in, 11.

GLANDS, compensatory development of, 24.

GLASTONBURY thorn, 10.

GLENNY, Mr., on the _Cineraria,_ 20.

GLOEDE, F., on strawberries, 10.

GLOGER, on the wings of ducks, 24.

“GLOUGLOU” (pigeon), 5.

_Gloxiniæ,_ peloric, 10, 18.

GMELIN, on red cats, at Tobolsk, 1.

GOAT, 3 (2);

    —polydactylism in the, 12;

    —sexual differences in horns of, 14;

    —valued by South Africans, 20;

    —Thibet, 23;

    —amount of milk and development of udders in the, 24;

    —hornless, rudimentary bony cores in, 24;

    —Angora, 25.

GODINE, on prepotency of transmission., 14

GODRON, odour of the hairless Turkish dog, 1;

    —differences in the skull of dogs, 1;

    —increase of breeds of horses, 2;

    —crossing of domestic and wild swine, 3;

    —on goats, 3 (2);

    —colour of the skin in fowls, 7;

    —bees of north and south of France, 8;

    —introduction of the silkworm into Europe, 8;

    —variability in the silkworm, 8;

    —supposed species of wheat, 9 (2);

    —on _Ægilops triticoides,_, 9;

    —variable presence of barbs in grasses, 9;

    —colours of the seeds of maize, 9;

    —unity of character in cabbages, 9;

    —correlation of colour and odour, 9;

    —effect of heat and moisture on the cabbage, 9;

    —on the cultivated species of _ Brassica,_ 9;

    —on the Rouncival and sugar peas, 9;

    —variation in the numbers of peas in the same pod, 9;

    —wild vines in Spain, 10;

    —on raising peaches from seed, 10;

    —supposed specific distinctness of peach and nectarine, 10;

    —nectarine producing peaches, 10;

    —on the flower of _Corydalis,_ 26;

    —origin and variations of the plum, 10;

    —origin of the cherry, 10;

    —reversion of single-leaved strawberries, 10;

    —five-leaved variety of _Fragaria collina,_ 10;

    —supposed immutability of specific characters, 10 (2);

    —varieties of _Robinia,_ 10;

    —permanency of the simple-leaved ash, 10;

    —non-inheritance of certain mutilations, 12;

    —wild turnips, carrots, and celery, 13;

    —peloria, 13;

    —prepotency of a goat-like ram, 14;

    —benefit of change of soil to plants, 18;

    —fertility of peloric flowers of _ Corydalis solida,_ 18;

    —seeding of ordinarily seedless fruit, 18;

    —sexual sterility of plants propagated by buds, etc., 18;

    —increase of sugar in beet-root, 20;

    —effects of selection in enlarging particular parts of plants, 20;

    —growth of the cabbage in the tropics, 23;

    —rejection of bitter almonds by mice, 21;

    —influence of marshy pasture on the fleece of sheep, 23;

    —on the ears of ancient Egyptian pigs, 24;

    —primitive distinctness of species, 28;

    —solid-hoofed swine, 28.

GOETHE, on compensation of growth, 26.

GOLD-FISH, 8 (2), 21.

GOMARA, on South American cats, 1.

GONGORA, number of seeds in the, 27.

GOODMAN, three-toed cows, 12.

GOOSE, ancient domestication of, 8;

    —sacred to Juno in Rome, 8;

    —inflexibility of organisation of, 8;

    —skull perforated in tufted, 8;

    —characters of breeds and sub-breeds of, 8 (2);

    —variety of, from Sebastopol, 8, 27;

    —feral, in La Plata, 6;

    —Egyptian, hybrid of, with penguin duck, 14;

    —spontaneous segregation of varieties of, 16;

    —fertility of, increased by domestication, 16;

    —decreased fertility of, in Bogota, 18;

    —sterility of, in the Philippine Islands, 18;

    —selection of, 20;

    —white, preference of the Romans for the liver of, 20;

    —persistency of character in, 22;

    —Egyptian, change in breeding season of, 24.

GOOSEBERRY, 10;

    —bud-variation in the, 11;

    —Whitesmith’s, 21.

GÖPPERT, on monstrous poppies, 18.

GOSSE, P. H., feral dogs in Jamaica, 1;

    —feral pigs of Jamaica, 3;

    —feral rabbits of Jamaica, 4;

    —on _Columba leucocephala,_ 6;

    —feral Guinea fowl in Jamaica, 6;

    —reproduction of individual peculiarities by gemmation in a coral,
    11;

    —frequency of striped legs in mules, 13.

GOULD, Dr., on hereditary hæmorrhage, 12.

GOULD, JOHN, origin of the turkey, 8.

_Goura coronata_ and _Victoriæ,_ hybrids of, 6, 18.

GOURDS, 10;

    —crossing of varieties of, 16;

    —ancient Peruvian variety of, 28.

GOUT, inheritance of, 12;

    —period of appearance of, 14.

GRABA, on the pigeon of the Faroe Islands, 6.

GRAFTING, 18;

    —effects of, 22 (2);

    —upon the stock, 11;

    —upon the variability of trees, 22;

    —changes analogous to bud-variation produced by, 11 (2).

GRAFT-HYBRIDS, 11 (2), 27.

GRAPES, bud-variation in, 11;

    —cross of white and purple, 11;

    —green, liable to disease, 25;

    —effect of foreign pollen on, 11.

GRASSES, seeds of, used as food by savages, 9.

GRAY, ASA, superior wild varieties of fruit-trees, 9;

    —cultivated native plants of North America, 9, 10;

    —non-variation of weeds, 9;

    —supposed spontaneous crossing of Cucurbitaceæ, 11;

    —pre-ordination of variation, 11;

    —progeny of husked form of maize, 9;

    —wild intermediate forms of strawberries, 10.

GRAY, G. R., on _Columba gymnocyclus,_, 6.

GRAY, J. E., on _Sus pliciceps,_ 3;

    —on a variety of the gold-fish, 8;

    —hybrids of the ass and zebra, 13 (2);

    —on the breeding of animals at Knowsley, 18;

    —on the breeding of birds in captivity, 18.

GREENE, J. REAY, on the development of the echinodermata, 27.

GREENHOW, Mr., on a Canadian web-footed dog, 1.

GREENING, Mr., experiments on _Abraxas grossulariata,_ 23.

GREGSON, Mr., experiments on _Abraxas grossulariata,_ 23.

GREY, Sir GEORGE, preservation of seed-bearing plants by the Australian
savages, 9;

    —detestation of incest by Australian savages, 17.

GREYHOUNDS, sculptured on Egyptian monuments, and in the Villa of
Antoninus, 1;

    —modern breed of, 1;

    —crossed with the bulldog, by Lord Orford, 3;

    —close interbreeding of, 17;

    —co-ordination of structure of, due to selection, 20 (2);

    —Italian, 21.

GREYNESS, inherited at corresponding periods of life, 14.

GRIEVE, Mr., on early-flowering dahlias, 10.

GRIGOR, Mr., acclimatisation of the Scotch fir, 24.

GRÖNLAND, hybrids of _Ægilops_ and wheat, 16.

GROOM-NAPIER, C. O., on the webbed feet of the otter-hound, 1.

GROS, on Pangenesis, 27.

“GROSSES-GORGES” (pigeons), 5.

GROUND-TUMBLER, Indian, 5.

GROUSE, fertility of, in captivity, 18.

_Grus montigresia, cinerea,_ and _antigone,_ 18.

GUANACOS, selection of, 20.

GUANS, general fertility of, in captivity, 18.

GUELDER-ROSE, 19.

GUELDERLAND fowls, 6.

GUIANA, selection of dogs by the Indians of, 20.

GUINEA fowl, 8;

    —feral, in Ascension and Jamaica, 6, 13;

    —indifference of, to change of climate, 18.

GUINEA pig, 12, 18.

GÜLDENSTADT, on the jackal, 1.

GULL, herring, breeding in confinement, 18.

GULLS, general sterility of, in captivity, 18.

_Gulo,_ sterility of, in captivity, 18.

GÜNTHER, A., on tufted ducks and geese, 7;

    —on the regeneration of lost parts in batrachia, 27.

GURNEY, Mr., owls breeding in captivity, 18;

    —appearance of “black-shouldered” among ordinary peacocks, 8.

HABIT, influence of, in acclimatisation, 24.

HÄCKEL, on fissiparous reproduction, 27;

    —on cells, 27;

    —on the double reproduction of medusæ, 27;

    —on inheritance, 27.

HACKLES, peculiarities of, in fowls, 7.

HAIR, on the face, inheritance of, in man, 12;

    —peculiar lock of, inherited, 12;

    —growth of, under stimulation of skin, 25;

    —homologous variation of, 25;

    —development of, in the brain, 27.

HAIR and teeth, correlation of, 25.

HAIRY family, corresponding period of inheritance in, 14.

HALF-CASTES, character of, 13.

HALF-LOP rabbits, figured and described, 4, (2);

    —skull of, 4.

_Haliætus leucocephalus,_ copulating in captivity, 18.

HALLAM, Col., on a two-legged race of pigs, 12.

HALLET, Major, selection in cereals, 5;

    —on pedigree wheat, 9.

HAMBURGH fowl, 7 (2);

    —figured, 7.

HAMILTON, wild cattle of, 3.

HAMILTON, Dr., on the assumption of male plumage by the hen pheasant,
13.

HAMILTON, F. BUCHANAN, on the shaddock, 10;

    —varieties of Indian cultivated plants, 22.

HANCOCK, Mr., sterility of tamed birds, 18 (2).

HANDWRITING, inheritance of peculiarities in, 12.

HANMER, Sir J., on selection of flower-seeds, 20.

HANSELL, Mr., inheritance of dark yolks in duck’s eggs, 8.

HARCOURT, E. V., on the Arab boar-hound, 1;

    —aversion of the Arabs to dun-coloured horses, 2.

HARDY, Mr., effect of excess of nourishment on plants, 22.

HARE, hybrids of, with rabbit, 4;

    —sterility of the, in confinement, 18;

    —preference of, for particular plants, 21.

HARE-LIP, inheritance of, 12.

HARLAN, Dr., on hereditary diseases, 12.

HARTMAN, on the wild ass, 2.

HARVEY, Mr., monstrous red and white African bull, 3.

HARVEY, Prof., singular form of _Begonia frigida,_ 10;

    —effects of cross-breeding on the female, 11;

    —monstrous saxifrage, 18.

HASORA wheat, 9.

HAUTBOIS strawberry, 10.

HAWKER, Col., on call or decoy ducks, 8.

HAWTHORN, varieties of, 10 (2);

    —pyramidal, 10;

    —pendulous hybridised, 12;

    —changes of, by age, 10, 11;

    —bud-variation in the, 11;

    —flower buds of, attacked by bullfinches, 21.

HAYES, Dr., character of Esquimaux dogs, 1.

HAYWOOD, W., on the feral rabbits of Porto Santo, 4.

HAZEL, purple-leaved, 10, 11, 25.

HEAD of wild boar and Yorkshire pig, figured, 3.

HEAD and limbs, correlated variability of, 25.

HEADACHE, inheritance of, 14.

HEARTSEASE, 10;

    —change produced in the, by transplantation, 11;

    —reversion in, 13 (2);

    —effects of selection on, 20;

    —scorching of, 21;

    —effects of seasonal conditions on the, 23;

    —annual varieties of the, 24.

HEAT, effect of, upon the fleece of sheep, 3.

HEBER, Bishop, on the breeding of the rhinoceros in captivity, 18.

HEBRIDES, cattle of the, 3;

    —pigeons of the, 6.

HEER, O., on the plants of the Swiss lake-dwellings, 9;

    —on the cereals, 9;

    —on the peas, 9;

    —on the vine growing in Italy in the Bronze age, 10.

HEIMANN, potato-grafting, 11.

_Helix lactea,_ 23.

_Hemerocallis fulva_ and _flava,_ interchanging by bud-variation, 11.

HEMLOCK, yields no conicine in Scotland, 23.

HEMP, differences of, in various parts of India, 18;

    —climatal difference in products of, 23.

HEMPSEED, effect of, upon the colour of birds, 23.

HERMAPHRODITE flowers, occurrence of, in maize, 9.

HEN, assumption of male characters by the, 13 (2);

    —development of spurs in the, 24.

“HENNIES,” or hen-like male fowls, 7.

HENRY, T. A., a variety of the ash produced by grafting, 11;

    —crossing of species of _ Rhododendron_ and _Arabis,_ 11.

HENSLOW, Prof., individual variation in wheat, 9;

    —bud-variation in the Austrian bramble rose, 11;

    —partial reproduction of the weeping ash by seed, 12.

HEPATICA, changed by transplantation, 11.

HERBERT, Dr., variations of _Viola grandiflora,_ 10;

    —bud-variation in camellias, 11;

    —seedlings from reverted _Cytisus adami,_, 11;

    —crosses of Swedish and other turnips, 15;

    —on hollyhocks, 20;

    —breeding of hybrids, 17;

    —self-impotence in hybrid hippeastrums, 17 (2);

    —hybrid _Gladiolus,_ 17;

    —on _Zephyranthes candida,_ 18;

    —fertility of the crocus, 18;

    —on contabescence, 18;

    —hybrid _Rhododendron,_ 22.

HERCULANEUM, figure of a pig found in, 3.

HERON, Sir R., appearance of “black-shouldered” among ordinary
peacocks, 8 (2);

    —non-inheritance of monstrous characters by gold-fish, 8;

    —crossing of white and coloured Angora rabbits, 15;

    —crosses of solid-hoofed pigs, 15.

_Herpestes fasciatus_ and _griseus,_ 18.

HEUSINGER, on the sheep of the Tarentino, 21;

    —on correlated constitutional peculiarities, 25.

HEWITT, Mr., reversion in bantam cocks, 7;

    —degeneration of silk fowls, 7;

    —partial sterility of hen-like male fowls, 7;

    —production of tailed chickens by rumpless fowls, 7;

    —on taming and rearing wild ducks, 8, 21, 22;

    —conditions of inheritance in laced Sebright bantams, 12;

    —reversion in rumpless fowls, 13;

    —reversion in fowls by age, 13;

    —hybrids of pheasant and fowl, 13, 14;

    —assumption of male characters by female pheasants, 13;

    —development of latent characters in a barren bantam hen, 13;

    —mongrels from the silk fowl, 14;

    —effects of close interbreeding on fowls, 17 (2);

    —on feather-legged bantams, 25.

HIBBERT, Mr., on the pigs of the Shetland Islands, 3.

HIBISCUS, _See Paritium._

HIGHLAND cattle, descended from _Bos longifrons,_ 3.

HILDEBRAND, Dr., on graft-hybrids with the potato, 11;

    —on the influence of pollen on the mother-plant, 11;

    —on the fertilisation of _ Orchideæ,_ 11 (2);

    —occasional necessary crossing of plants, 15;

    —on seeds not fitted for distribution, 9;

    —potato-grafting, 11;

    —crossing of varieties, 16;

    —on _Primula sinensis_ and _ Oxalis rosea,_ 17;

    —on _Corydalis cava,_ 17 (2).

HILL, R., on the Alco, 1;

    —feral rabbits in Jamaica, 4;

    —feral peacocks in Jamaica, 6;

    —variation of the Guinea fowl in Jamaica, 8;

    —sterility of tamed birds in Jamaica, 18 (2).

HIMALAYA, range of gallinaceous birds in the, 7.

HIMALAYAN rabbit, 4 (2);

    —skull of, 4.

HIMALAYAN sheep, 3.

HINDMARSH, Mr., on Chillingham cattle, 3.

“HINKEL-TAUBE,” 5 (2).

HINNY and mule, difference of, 14.

_Hipparion,_ anomalous resemblance to, in horses, 2.

_Hippeastrum,_ hybrids of, 17 (2).

HIVE-BEES, ancient domestication of, 8;

    —breeds of, 8;

    —smaller when produced in old combs, 8;

    —variability in, 8;

    —crossing of Ligurian and common, 8.

HOBBS, FISHER, on interbreeding pigs, 17.

“HOCKER-TAUBE,” 5.

HODGKIN, Dr., on the attraction of foxes by a female Dingo, 1;

    —origin of the Newfoundland dog, 1;

    —transmission of a peculiar lock of hair, 12.

HODGSON, Mr., domestication of _Canis primævus,_ 1;

    —development of a fifth digit in Thibet mastiffs, 1;

    —number of ribs in humped cattle, 3;

    —on the sheep of the Himalaya, 3;

    —presence of four mammæ in sheep, 3;

    —arched nose in sheep, 3;

    —measurements of the intestines of goats, 3;

    —presence of interdigital pits in goats, 3;

    —disuse a cause of drooping ears, 24.

HOFACKER, persistency of colour in horses, 2, 12;

    —production of dun horses from parents of different colours, 2;

    —inheritance of peculiarities in handwriting, 12;

    —heredity in a one horned stag, 12;

    —on consanguineous marriages, 17.

HOFFMAN, Prof., on _Raphanus,_ 9.

HOG, Red River, 18.

HOGG, Mr., retardation of breeding in cows by hard living, 16.

HOLLAND, Sir H., necessity of inheritance, 12;

    —on hereditary diseases, 12;

    —hereditary peculiarity in the eyelid, 12;

    —morbid uniformity in the same family, 12;

    —transmission of hydrocele through the female, 13;

    —inheritance of habits and tricks, 27.

HOLLY, varieties of the, 10 (2);

    —bud-reversion in, 11;

    —yellow-berried, 12, 21.

HOLLYHOCK, bud-variation in, 11;

    —non-crossing of double varieties of, 16;

    —tender variety of the, 24.

HOMER, notice of geese, 8;

    —breeding of the horses of Æneas, 20.

HOMOLOGOUS parts, correlated variability of, 25, 26 (2);

    —fusion of, 26;

    —affinity of, 26 (2).

HOOFS, correlated with hair in variation, 25.

HOOK-BILLED duck, skull figured, 8.

HOOKER, Dr. J. D., forked shoulder-stripe in Syrian asses, 2;

    —voice of the cock in Sikkim, 7;

    —use of Arum-roots as food, 9;

    —native useful plants of Australia, 9;

    —wild walnut of the Himalayas, 10;

    —variety of the plane-tree, 10;

    —production of _Thuja orientalis_ from seeds of _T. pendula,_ 10;

    —singular form of _Begonia frigida,_ 10;

    —reversion in plants run wild, 13;

    —on the sugar-cane, 18;

    —on Arctic plants, 22;

    —on the oak grown at the Cape of Good Hope, 23;

    —on _Rhododendron ciliatum,_ 23;

    —stock and mignonette perennial in Tasmania, 24.

HOPKIRK, Mr., bud-variation in the rose, 11;

    —in _Mirabilis jalapa,_ 11;

    —in _Convolvulus tricolor,_ 11.

HORNBEAM, heterophyllous, 10.

HORNED fowl, 7;

    —skull figured, 7.

HORNLESS cattle in Paraguay, 3.

HORNS of sheep, 3;

    —correlation of, with fleece in sheep, 25;

    —correlation of, with the skull, 25;

    —rudimentary in young polled cattle, 24;

    —of goats, 3.

HORSES, in Swiss lake-dwellings, 2;

    —different breeds of, in Malay Archipelago, 2;

    —anomalies in osteology and dentition of, 2;

    —mutual fertility of different breeds, 2;

    —feral, 2;

    —habit of scraping away snow, 2;

    —mode of production of breeds of, 2;

    —inheritance and diversity of colour in, 2;

    —dark stripes in, 2;

    —dun-coloured, origin of, 2;

    —colours of feral, 3 (2);

    —effect of fecundation by a quagga on the subsequent progeny of,
    11;

    —inheritance of peculiarities in, 12 (2);

    —polydactylism in, 12;

    —inheritance of colour in, 12;

    —inheritance of exostoses in legs of, 12;

    —reversion in, 13 (2);

    —hybrids of, with ass and zebra, 13;

    —prepotency of transmission in the sexes of, 14;

    —segregation of, in Paraguay, 16;

    —wild species of, breeding in captivity, 18;

    —curly, in Paraguay, 20, 25;

    —selection of, for trifling characters, 20;

    —unconscious selection of, 20 (2);

    —natural selection in Circassia, 21;

    —alteration of coat of, in coal-mines, 23;

    —degeneration of, in the Falkland Islands, 23;

    —diseases of, caused by shoeing, 24;

    —feeding on meat, 24;

    —white and white-spotted, poisoned by mildewed vetches, 25;

    —analogous variations in the colour of, 26;

    —teeth developed on palate of, 27;

    —of Bronze period in Denmark, 28.

HORSE-CHESTNUT, early, at the Tuileries, 10;

    —tendency to doubleness in, 18.

HORSE-RADISH, general sterility of the, 18.

“HOUDAN,” a French sub-breed of fowls, 7.

HOWARD, C., on an Egyptian monument, 1;

    —on crossing sheep, 3 (2).

HUC, on the Emperor Khang-hi, 20;

    —Chinese varieties of the bamboo, 22.

HUMBOLDT, A., character of the Zambos, 13;

    —parrot speaking in the language of an extinct tribe, 18;

    —on _Pulex penetrans,_ 23.

HUMIDITY, injurious effect of, upon horses, 2.

HUMPHREYS, Col., on Ancon sheep, 3.

HUNGARIAN cattle, 3.

HUNTER, JOHN, period of gestation in the dog, 1;

    —on secondary sexual characters, 3;

    —fertile crossing of _Anser ferus_ and the domestic goose, 8;

    —inheritance of peculiarities in gestures, voice, etc., 12;

    —assumption of male characters by the human female, 13;

    —period of appearance of hereditary diseases, 14;

    —graft of the spur of a cock upon its comb, 24;

    —on the stomach of _Larus tridentatus,_ 24.

HUNTER, W., evidence against the influence of imagination upon the
offspring, 22.

HUTH, Mr., close interbreeding of rabbits, 17;

    —consanguineous marriages, 17.

HUTTON, Capt., on the variability of the silk-moth, 8;

    —on the number of species of silkworms, 8;

    —markings of silkworms, 8;

    —domestication of the rock-pigeon in India, 6;

    —domestication and crossing of _ Gallus bankiva,_ 7;

    —reversion in goats from a cross, 13.

HUTCHINSON, Col., liability of dogs to distemper, 1.

HUXLEY, Prof., on the transmission of polydactylism, 12;

    —on unconscious selection, 20;

    —on correlation in the mollusca, 25;

    —on gemmation and fission, 27;

    —development of star-fishes, 27.

HYACINTHS, 10;

    —bud-variation in, 11;

    —graft-hybrid by union of half bulbs of, 11;

    —white, reproduced by seed, 12;

    —red, 21;

    —varieties of, recognisable by the bulb, 22.

HYACINTH, feather, 19, 24.

_Hyacinthus orientalis,_ 10.

_Hybiscus syriacus,_ 23.

HYBRIDS, of hare and rabbit, 6;

    —of various species of _Gallus,_ 7;

    —of almond, peach, and nectarine, 10;

    —naturally produced, of species of _Cytisus,_ 11;

    —from twin-seed of _Fuchsia coccinea_ and _fulgens,_ 11;

    —reversion of, 11 (2), 13 (2);

    —from mare, ass, and zebra, 13;

    —of tame animals, wildness of, 13 (2);

    —female instincts of sterile male, 13;

    —transmission and blending of characters in, 15;

    —breed better with parent species than with each other, 17;

    —self-impotence in, 17;

    —readily produced in captivity, 18.

HYBRIDISATION, singular effects of, in oranges, 10;

    —of cherries, 10;

    —difficulty of, in _ Cucurbitæ,_ 10;

    —of roses, 10.

HYBRIDISM, 19;

    —the cause of a tendency to double flowers, 18;

    —in relation to Pangenesis, 27.

HYBRIDITY in cats, 1 (2);

    —supposed, of peach and nectarine, 10.

_Hydra,_ 11, 24, 27.

HYDRANGEA, colour of flowers of, influenced by alum, 23.

HYDROCELE, 13.

HYDROCEPHALUS, 24.

_Hypericum calycinum,_ 18.

_Hypericum crispum,_ 21, 25.

HYPERMETAMORPHOSIS, 27.

HYPERMETROPIA, hereditary, 12.

ICHTHYOPTERYGIA, number of digits in the, 13.

_Ilex aquifolium,_ 12.

IMAGINATION, supposed effect of, on offspring, 22.

_Imatophyllum miniatum,_ bud-variation in, 11.

INCEST, abhorred by savages, 17.

INCUBATION, by crossed fowls of non-sitting varieties, 13.

INDIA, striped horses of, 2;

    —pigs of, 3 (2);

    —breeding of rabbits in, 4;

    —cultivation of pigeons in, 6.

INDIVIDUAL variability in pigeons, 5.

INGLEDEW, Mr., cultivation of European vegetables in India, 18.

“INDISCHE Taube,” 5.

INHERITANCE, 12, 27, (2);

    —doubts entertained of, by some writers, 12;

    —importance of, to breeders, 11, 12;

    —evidence of, derived from statistics of chances, 12;

    —of peculiarities in man, 12, (2);

    —of disease, 12 (3);

    —of peculiarities in the eye, 12;

    —of deviations from symmetry, 12;

    —of polydactylism, 12;

    —capriciousness of, 12;

    —of mutilations, 12;

    —of congenital monstrosities, 12;

    —causes of absence of, 12;

    —by reversion or atavism, 13;

    —its connection with fixedness of character, 14;

    —affected by prepotency of transmission of character, 14;

    —limited by sex, 14;

    —at corresponding periods of life, 14;

    —summary of the subject of, 14;

    —laws of, the same in seminal and bud varieties, 11;

    —of characters in the horse, 2;

    —in cattle, 3;

    —in rabbits, 4;

    —in the peach, 10;

    —in the nectarine, 10;

    —in plums, 10;

    —in apples, 10;

    —in pears, 10;

    —in the pansy, 10;

    —of primary characters of _Columba livia_ in crossed pigeons, 5;

    —of peculiarities of plumage in pigeons, 5;

    —of peculiarities of foliage in trees, 10;

    —effects of, in varieties of the cabbage, 9.

INSANITY, inheritance of, 12, 14.

INSECTS, regeneration of lost parts in, 10, 24;

    —agency of, in fecundation of larkspurs, 12;

    —effect of changed conditions upon, 18;

    —sterile neuter, 19;

    —monstrosities in, 22, 27.

INSTINCTS, defective, of silkworms, 8.

INTERBREEDING, close, ill effects of, 17, 19.

INTERCROSSING, of species, as a cause of variation, 6;

    —natural, of plants, 10;

    —of species of Canidæ and breeds of dogs, 1;

    —of domestic and wild cats, 1 (2);

    —of breeds of pigs, 3 (2);

    —of cattle, 3;

    —of varieties of cabbage, 9;

    —of peas, 9 (3);

    —of varieties of orange, 10;

    —of species of strawberries, 10 (2);

    —of _Cucurbitæ,_ 10 (2);

    —of flowering plants, 10;

    —of pansies, 10.

INTERDIGITAL pits, in goats, 3.

INTERMARRIAGES, close, 17 (2).

INTESTINES, elongation of, in pigs, 3;

    —relative measurement of parts of, in goats, 3;

    —effects of changed diet on, 24.

_Ipomœa purpurea,_ 17.

IRELAND, remains of _Bos frontosus_ and _longifrons_ found in, 3.

IRIS, hereditary absence of the, 12;

    —hereditary peculiarities of colour of the, 12;

    —variation of, 11.

_Iris xiphium,_ 11.

IRISH, ancient, selection practised by the, 20.

IRON period, in Europe, dog of, 1.

ISLANDS, oceanic, scarcity of useful plants on, 9.

ISLAY, pigeons of, 6.

ISOLATION, effect of, in favour of selection, 21 (2).

ITALY, vine-growing in, during the Bronze period, 10.

IVY, sterility of, in the north of Europe, 18.

JACK, Mr., effect of foreign pollen on grapes, 11.

JACKAL, 1 (3);

    —hybrids of, with the dog, 1;

    —prepotency of, over the dog, 1.

JACKSON, Mr., white-footed cats, 25.

JACOBIN pigeon, 5, 6.

JACQUEMET-BONNEFORT, on the mulberry, 10.

JAEGER, Prof., on reversion in pigs, from a cross, 13;

    —white pigeons killed by hawks, 21.

JAGUAR, with crooked legs, 1.

JAMAICA, feral dogs of, 1;

    —feral pigs of, 3;

    —feral rabbits of, 4.

JAMESON, Mr., on hybrid potatoes, 11.

JAPAN, horses of, 2.

JAPANESE pig (figured), 3.

JARDINE, Sir W., crossing of domestic and wild cats, 1.

JARVES, J., silkworm in the Sandwich Islands, 8.

JAVA, fantail pigeon in, 5.

JAVANESE ponies, 2 (2).

JEITTELES, history of the dog, 1;

    —history of the fowl, 7;

    —Hungarian sheep-dogs, 1;

    —crossing of domestic and wild cats, 1.

JEMMY BUTTON, 9.

JENYNS, L., whiteness of ganders, 8;

    —sunfish-like variety of the goldfish, 8.

JERDON, J. C., number of eggs laid by the pea-hen, 20;

    —origin of domestic fowl, 7.

JERSEY, arborescent cabbages of, 9.

JESSAMINE, 11.

JESSE, G. R., on the bulldog, 1.

JOHN, King, importation of stallions from Flanders by, 20.

JOHNSON, D., occurrence of stripes on young wild pigs in India, 3.

JORDAN, A., on Vibert’s experiments on the vine, 10;

    —origin of varieties of the apple, 10;

    —varieties of pears found wild in woods, 22.

JOURDAN, parthenogenesis in the silk-moth, 27.

JUAN DE NOVA, wild dogs on, 1.

JUAN FERNANDEZ, dumb dogs on, 1.

_Juglans regia,_ 10.

JUKES, Prof., origin of the Newfoundland dog, 1.

JULIEN, Stanislas, early domestication of pigs in China, 3;

    —antiquity of the domestication of the silkworm in China, 8.

JUMPERS, a breed of fowls, 7.

JUNIPER, variations of the, 10 (2).

_Juniperus suecica,_ 10.

_Jussiæa grandiflora,_ 18.

JUSSIEU, A. de, structure of the pappus in _Carthamus,_ 24.

KAIL, Scotch, reversion in, 13.

KALES, 9.

“KALI-PAR” pigeon, 5.

KALM, P., on maize, 9, 24;

    —introduction of wheat into Canada, 9;

    —sterility of trees growing in marshes and dense woods, 18.

“KALMI LOTAN” tumbler pigeon, 5.

KANE, Dr., on Esquimaux dogs, 1.

KARAKOOL sheep, 3.

KARKEEK, on inheritance in the horse, 12.

“KARMELITEN Taube,” 5.

KARSTEN on _Pulex penetrans,_ 23.

KATTYWAR horses, 2.

KEELEY, R., pelorism in _Galeobdolon luteum,_ 13.

KERNER, on the culture of Alpine plants, 18;

    —definite action of conditions, 23.

KESTREL, breeding in captivity, 18.

“KHANDÉSI,” 5.

KHANG-HI, selection of a variety of rice by, 20.

KIANG, 13.

KIDD, on the canary-bird, 8, 14.

KIDNEY bean, 10;

    —varieties of, 22, 23.

KIDNEYS, compensatory development of the, 24;

    —shape of, in birds influenced by the form of the pelvis, 26.

KING, Col., domestication of rock doves from the Orkneys, 6 (2).

KING, Dr., on _Paritium,_ 11.

KING, P. P., on the dingo, 1 (2).

KIRBY and Spence, on the growth of galls, 23.

KIRGHISIAN sheep, 3.

KITE, breeding in captivity, 18.

KLEINE, variability of bees, 8.

KNIGHT, ANDREW, on crossing horses of different breeds, 2;

    —crossing varieties of peas, 9, 17;

    —persistency of varieties of peas, 9;

    —origin of the peach, 10;

    —hybridisation of the morello by the Elton cherry, 10;

    —on seedling cherries, 10;

    —variety of the apple not attacked by coccus, 10;

    —intercrossing of strawberries, 10 (2);

    —broad variety of the cock’s-comb, 10;

    —bud variation in the cherry and plum, 11;

    —crossing of white and purple grapes, 11;

    —experiments in crossing apples, 11, 17;

    —hereditary disease in plants, 12;

    —on interbreeding, 17;

    —crossed varieties of wheat, 17;

    —necessity of intercrossing in plants, 19;

    —on variation, 22 (2);

    —effects of grafting, 11, 23;

    —bud-variation in a plum, 23;

    —correlated variation of head and limbs, 8.

KNOX, Mr., breeding of the eagle owl in captivity, 18.

KOCH, degeneracy in the turnip, 9.

KOHLRABI, 9.

KÖLREUTER, reversion in hybrids, 11, 13;

    —acquired sterility of crossed varieties of plants, 10, 16;

    —absorption of _Mirabilis vulgaris_ by _M. longiflora,_ 15;

    —crosses of species of _ Verbascum,_ 15, 16;

    —on the hollyhock, 16;

    —crossing varieties of tobacco, 16;

    —benefits of crossing plants, 17 (2), 19 (2);

    —sell-impotence in _Verbascum,_ 17 (2);

    —effects of conditions of growth upon fertility in _Mirabilis,_ 18;

    —great development of tubers in hybrid plants, 18;

    —inheritance of plasticity, 21;

    —variability of hybrids of _ Mirabilis,_ 22;

    —repeated crossing a cause of variation, 22;

    —number of pollen-grains necessary for fertilisation, 27.

“KRAUSESCHWEIN,” 3.

KROHN, on the double reproduction of Medusæ, 27.

“KROPF-TAUBEN,” 5.

LABAT, on the tusks of feral boars in the West Indies, 5;

    —on French wheat grown in the West Indies, 24;

    —on the culture of the vine in the West Indies, 24.

LABURNUM, Adam’s, _see Cytisus adami,_;

    —oak-leaved, reversion of, 11;

    —pelorism in the, 26;

    —Waterer’s, 11.

LACHMANN, on gemmation and fission, 27.

_Lachnanthes tinctoria,_ 21, 25.

LACTATION, imperfect, hereditary, 12;

    —deficient, of wild animals in captivity, 18.

LADRONE Islands, cattle of, 3.

LA GASCA, Prof., individual variation in wheat, 9.

LAING, Mr., resemblance of Norwegian and Devonshire cattle, 3.

LAKE-DWELLINGS, sheep of, 3;

    —cattle of, 3;

    —absence of the fowl in, 7;

    —cultivated plants of, 9, 28 (2);

    —cereals of, 9;

    —peas found in, 9;

    —beans found in, 9.

LAMARE-PIQUOT, observations on half-bred North American wolves, 1.

LAMBERT, A. B., on _Thuja pendula_ or _filiformis,_ 10.

LAMBERT family, 12, 14.

LAMBERTYE, on strawberries, 10 (2);

    —five-leaved variety of _Fragaria collina,_ 10.

LANDT, L., on sheep in the Faroe Islands, 16.

LANKESTER, RAY, on longevity, 27.

LA PLATA, wild dogs of, 1;

    —feral cat from, 1.

LARCH, 24.

LARKSPURS, insect agency necessary for the full fecundation of, 12.

_Larus argentatus,_ 18, 24.

_Larus tridactylus,_ 24.

LASTERYE, merino sheep in different countries, 3.

LATENT characters, 13.

LATHAM, on the fowl not breeding in the extreme north, 18.

_Lathyrus,_ 13.

_Lathyrus aphaca,_ 26.

_Lathyrus odoratus,_ 11 (2), 15 (2), 24.

LA TOUCHE, J. D., on a Canadian apple with dimidiate fruit, 11 (2).

“LATZ-TAUBE,” 5.

LAUGHER pigeon, 5, 6.

_Laurus sassafras,_ 23.

LAWRENCE, J., production of a new breed of foxhounds, 1;

    —occurrence of canines in mares, 2;

    —on three-parts-bred horses, 2;

    —on inheritance in the horse, 12 (2).

LAWSON, Mr., varieties of the potato, 9.

LAXTON, Mr., bud-variation in the gooseberry, 11;

    —crossing of varieties of the pea, 11 (2);

    —weakness of transmission in peas, 14;

    —double-flowered peas, 18.

LAYARD, E. L., resemblance of a Caffre dog to the Esquimaux breed, 1,
23;

    —crossing of the domestic cat with _Felis caffra,_ 1;

    —feral pigeons in Ascension, 6;

    —domestic pigeons of Ceylon, 6;

    —on _Gallus stanleyi,_ 7;

    —on black-skinned Ceylonese fowls, 7.

LE COMPTE family, blindness inherited in, 14.

LECOQ, bud-variation in _Mirabilis jalapa,_ 11;

    —hybrids of _Mirabilis,_ 11, 18, 22;

    —crossing in plants, 17;

    —fecundation of _Passiflora,_ 17;

    —hybrid _Gladiolus,_ 17;

    —sterility of _Ranunculus ficaria,_ 18;

    —villosity in plants, 23;

    —double asters, 24.

LE COUTEUR, J., varieties of wheat, 9;

    —acclimatisation of exotic wheat in Europe, 9;

    —adaptation of wheat to soil and climate, 9;

    —selection of seed-corn, 9;

    —evil from inter-breeding, 17;

    —on change of soil, 18;

    —selection of wheat, 20;

    —natural selection in wheat, 21;

    —cattle of Jersey, 21.

LEDGER, Mr., on the llama and alpaca, 20.

LEE, Mr., his early culture of the pansy, 10.

_Leersia oryzoides,_ 15.

LEFOUR, period of gestation in cattle, 3.

LEGRAIN, falsified experiments of, 17.

LEGS, of fowls, effects of disuse on, 7;

    —characters and variations of, in ducks, 24.

LEGUAT, cattle of the Cape of Good Hope, 3.

LEHMANN, occurrence of wild double-flowered plants near a hot spring,
18.

LEIGHTON, W. A., propagation of a weeping yew by seed, 12.

LEITNER, effects of removal of anthers, 18.

LEMMING, 18.

LEMOINE, variegated _Symphytum_ and _Phlox,_ 11.

LEMON, 10;

    —orange fecundated by pollen of the, 11.

LEMURS, hybrid, 4.

LEPORIDES, 18.

LEPSIUS, figures of ancient Egyptian dogs, 1;

    —domestication of pigeons in ancient Egypt, 6.

_Lepus glacialis,_ 4.

_Lepus magellanicus,_ 4.

_Lepus nigripes,_ 4.

_Lepus tibetanus,_ 4.

_Lepus variabilis,_ 4.

LEREBOULLET, double monsters of fishes, 26.

LESLIE, on Scotch wild cattle, 3.

LESSONA, on regrowth, 27;

    —on _Lepus magellanicus,_ 4.

LETHBRIDGE, previous impregnation, 11.

LEUCKART, on the larva of Cecidomyidæ, 27.

LEWES, G. H., on Pangenesis, 27.

LEWIS, G., cattle of the West Indies, 21.

LHERBETTE and Quatrefages, on the horses of Circassia, 16, 21.

LICHENS, sterility in, 18.

LICHTENSTEIN, resemblance of Bosjesman’s dogs to _Canis mesomelas,_ 1;

    —Newfoundland dog at the Cape of Good Hope, 1.

LIEBIG, differences in human blood, according to complexion, 23.

LIEBREICH, occurrence of pigmentary retinitis in deaf-mutes, 25.

LILACS, 18.

LILIACEÆ, contabescence in, 18.

_Lilium bulbiferum_ and _davuricum,_ 11.

_Lilium candidum,_ 17.

LIMBS, regeneration of, 27.

LIMBS and head, correlated variation of, 25.

LIME, effect of, upon shells of the mollusca, 23.

LIME-TREE, changes of, by age, 10, 11.

LIMITATION, sexual, 14.

LIMITATION, supposed, of variation, 28.

_Linaria,_ pelorism in, 13 (2), 14;

    —peloric, crossed with the normal form, 14;

    —sterility of, 18.

_Linaria vulgaris_ and _purpurea,_ hybrids of, 15.

LINDEMUTH, potato-grafting, 11.

LINDLEY, JOHN, classification of varieties of cabbages, 9;

    —origin of the peach, 10;

    —influence of soil on peaches and nectarines, 10;

    —varieties of the peach and nectarine, 10;

    —on the New Town pippin, 10;

    —freedom of the Winter Majetin apple from coccus, 10;

    —production of monœcious Hautbois strawberries by bud-selection,
    10;

    —origin of the large tawny nectarine, 11;

    —bud-variation in the gooseberry, 11;

    —hereditary disease in plants, 12;

    —on double flowers, 18;

    —seeding of ordinarily seedless fruits, 18;

    —sterility of _Acorus calamus,_ 18;

    —resistance of individual plants to cold, 24.

LINNÆUS, summer and winter wheat regarded as distinct species by, 9;

    —on the single-leaved strawberry, 10;

    —sterility of Alpine plants in gardens, 18;

    —recognition of individual reindeer by the Laplanders, 22;

    —growth of tobacco in Sweden, 24.

LINNET, 18.

_Linota cannabina,_ 18.

_Linum,_ 18.

LION, fertility of, in captivity, 18 (2).

LIPARI, feral rabbits of, 4.

LIVINGSTONE, Dr., striped young pigs on the Zambesi, 3;

    —domestic rabbits at Loanda, 4;

    —use of grass-seeds as food in Africa, 9;

    —planting of fruit-trees by the Batokas, 9;

    —character of half-castes, 13;

    —taming of animals among the Barotse, 18;

    —selection practised in South Africa, 20 (2).

LIVINGSTONE, Mr., disuse a cause of drooping ears, 24.

LIZARDS, reproduction of tail in, 24.

LLAMA, selection of, 20.

LLOYD, Mr., taming of the wolf, 1;

    —English dogs in northern Europe, 1;

    —fertility of the goose increased by domestication, 8;

    —number of eggs laid by the wild goose, 16;

    —breeding of the capercailzie in captivity, 18.

LOANDA, domestic rabbits at, 4.

_Loasa,_ hybrid of two species of, 15.

_Lobelia,_ reversion in hybrids of, 11;

    —contabescence in, 18.

_Lobelia fulgens, cardinalis,_ and _syphilitica,_ 17.

LOCKHART, Dr., on Chinese pigeons, 6.

LOCUST-TREE, 23.

LOISELEUR-DESLONGCHAMPS, originals of cultivated plants, 9;

    —Mongolian varieties of wheat, 9;

    —characters of the ear in wheat, 9;

    —acclimatisation of exotic wheat in Europe, 9;

    —effect of change of climate on wheat, 9;

    —on the supposed necessity of the coincident variation of weeds and
    cultivated plants, 9;

    —advantage of change of soil to plants, 18.

_Lolium temulentum,_ variable presence of barbs in, 9.

LONG-TAILED sheep, 3.

LOOCHOO Islands, horses of, 2.

LORD, J. K., on _Canis latrans,_ 1.

“LORI RAJAH,” how produced, 7.

_Lorius garrulus,_ 23.

“LOTAN” tumbler pigeon, 5.

LOUDON, J. W., varieties of the carrot, 9;

    —short duration of varieties of peas, 9;

    —on the glands of peach-leaves, 10;

    —presence of bloom on Russian apples, 10;

    —origin of varieties of the apple, 10;

    —varieties of the gooseberry, 10;

    —on the nut tree, 10;

    —varieties of the ash, 10;

    —fastigiate juniper (_J. suecica_), 10;

    —on _Ilex aquifolium ferox,_ 10;

    —varieties of the Scotch fir, 10 (2);

    —varieties of the hawthorn, 10;

    —variation in the persistency of leaves on the elm and Turkish oak,
    10;

    —importance of cultivated varieties, 10;

    —varieties of _Rosa spinosissima,_ 10;

    —variation of dahlias from the same seed, 10;

    —production of Provence roses from seeds of the moss-rose, 11;

    —effect of grafting the purple-leaved upon the common hazel, 11;

    —intercrossing melons, 17;

    —nearly evergreen Cornish variety of the elm, 24.

LOW, on the pigs of the Orkney Islands, 3.

LOW, Prof., pedigrees of greyhounds, 12;

    —origin of the dog, 1;

    —burrowing instinct of a half-bred dingo, 1;

    —inheritance of qualities in horses, 2;

    —comparative powers of English racehorses, Arabs, etc., 2;

    —British breeds of cattle, 3;

    —wild cattle of Chartley, 3;

    —effect of abundance of food on the size of cattle, 3;

    —effects of climate on the skin of cattle, 3, 25;

    —on interbreeding, 17;

    —selection in Hereford cattle, 20;

    —formation of new breeds, 21;

    —on “sheeted” cattle, 26.

LOWE, Mr., on hive bees, 8.

LOWE, Rev. Mr., on the range of _Pyrus malus_ and _P. acerba,_ 10.

LOWNE, Mr., monsters, 26;

    —on gemmules, 27.

“LOWTUN” tumbler pigeon, 5.

_Loxia pyrrhula,_ 5.

LUBBOCK, Sir J., developments of the Ephemeridæ, 27.

LUCAS, P., effects of cross-breeding on the female, 11;

    —hereditary diseases, 12, 14 (2);

    —hereditary affections of the eye, 12 (2);

    —inheritance of anomalies in the human eye and in that of the
    horse, 12;

    —inheritance of polydactylism, 12;

    —morbid uniformity in the same family, 12;

    —inheritance of mutilations, 12;

    —persistency of cross-reversion, 13;

    —persistency of character in breeds of animals in wild countries,
    14;

    —prepotency of transmission, 14 (2);

    —supposed rules of transmission in crossing animals, 14;

    —sexual limitations of transmission of peculiarities, 14 (2);

    —absorption of the minority in crossed races, 15;

    —crosses without blending of certain characters, 15;

    —on interbreeding, 17;

    —variability dependent on reproduction, 22;

    —period of action of variability, 22;

    —inheritance of deafness in cats, 25;

    —complexion and constitution, 25.

LUCAZE-DUTHIERS, structure and growth of galls, 23.

LUCAE, Prof., on the masked pig, 3;

    —on pigs, 24.

LUIZET, grafting of a peach-almond on a peach, 10.

LUTKE, cats of the Caroline Archipelago, 1.

LUXURIANCE, of vegetative organs, a cause of sterility in plants, 18
(2).

LYONNET, on the scission of _Nais,_ 27.

_Lysimachia nummularia,_ sterility of, 18.

_Lythrum,_ trimorphic species of, 27.

_Lythrum salicaria,_ 19;

    —contabescence in, 18.

_Lytta vesicatoria,_ affecting the kidneys, 27.

_Macacus,_ species of, bred in captivity, 18.

MACAULAY, Lord, improvement of the English horse, 20.

M’CLELLAND, Dr., variability of fresh-water fishes in India, 22.

M’COY, Prof., on the dingo, 1.

MACFAYDEN, influence of soil in producing sweet or bitter oranges from
the same seed, 10.

MACGILLIVRAY, domestication of the rock-dove, 6;

    —feral pigeons in Scotland, 6;

    —number of vertebræ in birds, 7;

    —on wild geese, 8;

    —number of eggs of wild and tame ducks, 16.

MACKENZIE, Sir G., peculiar variety of the potato, 9.

MACKENZIE, P., bud-variation in the currant, 11.

MACKINNON, Mr., horses of the Falkland Islands, 2;

    —feral cattle of the Falkland Islands, 3.

MACKNIGHT, C., on interbreeding cattle, 17.

MACNAB, Mr., on seedling weeping birches, 12;

    —non-production of the weeping beech by seed, 12.

MADAGASCAR, cats of, 1.

MADDEN, H., on interbreeding cattle, 17.

MADEIRA, rock pigeon of, 6.

_Magnolia grandiflora,_ 24.

MAGNUS, Herr, on potato-grafting, 11;

    —on graft-hybrids, 11 (2).

MAIZE, its unity of origin, 9;

    —antiquity of, 9;

    —with husked grains said to grow wild, 9;

    —variation of, 7;

    —irregularities in the flowers of, 9;

    —persistence of varieties, 9;

    —adaptation of, to climate, 9, 24;

    —acclimatisation of, 24, 26;

    —crossing of, 11, 16 (2);

    —extinct Peruvian varieties of, 28.

MALAY fowl, 7.

MALAY Archipelago, horses of, 2;

    —short-tailed cats of, 1;

    —striped young wild pigs of, 3;

    —ducks of, 8.

MALE, influence of, on the fecundated female, 11;

    —supposed influence of, on offspring, 14.

MALE flowers, appearance of, among female flowers in maize, 9.

MALFORMATIONS, hereditary, 14.

MALINGIÉ-NOUEL, on sheep, 3;

    —cross-breeding sheep, 14;

    —English sheep in France, 21.

MALM, eyes of flat fish, 13.

_Malva,_ fertilisation of, 11, 27.

_Mamestra suasa,_ 18.

MAMMÆ, variable in number in the pig, 3;

    —rudimentary, occasional full development of, in cows, 3, 24;

    —four present in some sheep, 3;

    —variable in number in rabbits, 4;

    —latent functions of, in male animals, 13, 24.

MANGLES, Mr., annual varieties of the heartsease, 24.

MANTEGAZZA, abnormal growth of spur of cock, 27;

    —on Pangenesis, 27.

MANTELL, Mr., taming of birds by the New Zealanders, 18.

MANU, domestic fowl noticed in the Institutes of, 7.

MANURE, effect of, on the fertility of plants, 18.

MANX cats, 1, 14.

MARCEL DE SERRES, fertility of the ostrich, 18.

MARIANNE Islands, varieties of _Pandanus_ in, 22.

MARKHAM, GERVASE, on rabbits, 4, 20.

MARKHOR, probably one of the parents of the goat, 3.

MARQUAND, cattle of the Channel Islands, 3.

MARRIMPOEY, inheritance in the horse, 12.

MARROW, vegetable, 10.

MARRYATT, Capt., breeding of asses in Kentucky, 21.

MARSDEN, notice of _Gallus giganteus,_ 7.

MARSHALL, Dr. W., on _Gallus sonneratii,_ 7.

MARSHALL, Mr., voluntary selection of pasture by sheep, 3;

    —adaptation of wheats to soil and climate, 9;

    —“Dutch-buttocked” cattle, 12;

    —segregation of herds of sheep, 16;

    —advantage of change of soil to wheat and potatoes, 18;

    —fashionable change in the horns of cattle, 20;

    —sheep in Yorkshire, 21.

MARTENS, E. VON, on _Achatinella,_ 13.

MARTIN, W. C. L., origin of the dog, 1;

    —Egyptian dogs, 1;

    —barking of a Mackenzie River dog, 1;

    —African hounds in the Tower menagerie, 3;

    —on dun horses and dappled asses, 2;

    —breeds of the horse, 2;

    —wild horses, 2;

    —Syrian breeds of asses, 2;

    —asses without stripes, 2;

    —effects of cross-breeding on the female in dogs, 11;

    —striped legs of mules, 13.

MARTINS, defective instincts of silkworms, 8.

MARTIUS, C., fruit-trees of Stockholm, 24.

MASON, W., bud-variation in the ash, 11.

MASTERS, Dr., on bud-variation and reversion, 11;

    —potato-grafting, 11;

    —on pollen within ovules, 27;

    —reversion in the spiral-leaved weeping willow, 11;

    —on peloric flowers, 13;

    —on _Opuntia,_ 23;

    —pelorism in a clover, 26;

    —position as a cause of pelorism, 26 (2).

MASTERS, Mr., persistence of varieties of peas, 9;

    —reproduction of colour in hyacinths, 12;

    —on hollyhocks, 16;

    —selection of peas for seed, 20;

    —on _Hibiscus syriacus,_ 23;

    —reversion by the terminal pea in the pod, 26.

MASTIFF, sculptured on an Assyrian monument, 1, 28;

    —Tibetan, 1, 23.

MATTHEWS, PATRICK, on forest trees, 21.

_Matthiola annua,_ 11 (2), 15.

_Matthiola incana,_ 11 (2).

MAUCHAMP merino sheep, 3.

MAUDUYT, crossing of wolves and dogs in the Pyrenees, 1.

MAUND, Mr., crossed varieties of wheat, 17.

MAUPERTUIS, axiom of “least action,” 1.

MAURITIUS, importation of goats into, 3.

MAW, G., effects of change of climate, 24;

    —correlation of contracted leaves and flowers in pelargoniums, 25
    (2).

MAWZ, fertility of _Brassica rapa,_ 18.

_Maxillaria,_ self-fertilised capsules of, 17.

_Maxillaria atro-rubens,_ fertilisation of, by _M. squalens,_ 17.

MAXIMOWICZ, direct action of pollen, 11.

MAYERS, on gold-fish in China, 8.

MAYES, M., self-impotence in _Amaryllis,_ 17.

MECKEL, on the number of digits, 12;

    —correlation of abnormal muscles in the leg and arm, 25.

MEDUSÆ, development of, 27 (2).

MEEHAN, Mr., weeping peach, 12;

    —effects of parasites, 23;

    —comparison of European and American trees, 23.

_Meles taxus,_ 18.

MELONS, 10 (2);

    —mongrel supposed to be produced from a twin-seed, 11;

    —crossing of varieties of, 11, 16, 17;

    —inferiority of, in Roman times, 20;

    —changes in, by culture and climate, 23;

    —serpent, correlation of variations in, 25;

    —analogous variations in, 26.

MEMBRANES, false, 24 (2).

MÉNÉTRIES, on the stomach of _Strix grallaria,_ 24.

MENINGITIS, tubercular, inherited, 14.

MERRICK, potato-grafting, 11.

METAGENESIS, 27.

METAMORPHOSIS, 27.

METAMORPHOSIS and development, 27 (2).

METZGER, on the supposed species of wheat, 9 (2);

    —tendency of wheat to vary, 9;

    —variation of maize, 9 (2);

    —cultivation of American maize in Europe, 9, 26;

    —on cabbages, 9;

    —acclimatisation of Spanish wheat in Germany, 12;

    —advantage of change of soil to plants, 18;

    —on rye, 22;

    —cultivation of different kinds of wheat, 22.

MEXICO, dog from, with tan spots on the eyes, 1;

    —colours of feral horses in, 2.

MEYEN, on seeding of bananas, 18.

MICE, grey and white, colours of, not blended by crossing, 15;

    —rejection of bitter almonds by, 21;

    —naked, 23.

MICHAUX, F., roan-coloured feral horses of Mexico, 2;

    —origin of domestic turkey, 8;

    —on raising peaches from seed, 10.

MICHEL, F., selection of horses in mediæval times, 20;

    —horses preferred on account of slight characters, 20.

MICHELY, effects of food on caterpillars, 23;

    —on _Bombyx hesperus,_ 25.

MICROPHTHALMIA, associated with defective teeth, 25.

MIDDENS, Danish, remains of dogs in, 1, 28.

MIGNONETTE, 21, 24.

MILLET, 10.

MILLS, J., diminished fertility of mares when first turned out to
grass, 18.

MILNE-EDWARDS, on the development of the crustacea, 27.

MILNE-EDWARDS, A., on a crustacean with a monstrous eye-peduncle, 27.

_Milvus niger,_ 18.

_Mimulus luteus,_ 17.

MINOR, W. C., gemmation and fission in annelids, 27.

_Mirabilis,_ fertilisation of, 27;

    —hybrids of, 17, 18, 22.

_Mirabilis jalapa,_ 11 (2).

_Mirabilis longiflora,_ 15.

_Mirabilis vulgaris,_ 15.

_Misocampus_ and _Cecidomyia,_ 1.

MITCHELL, Dr., effects of the poison of the rattlesnake, 23.

MITFORD, Mr., notice of the breeding of horses by Erichthonius, 20.

MIVART, Mr., rudimentary organs, 24.

MOCCAS Court, weeping oak at, 12.

MOGFORD, horses poisoned by fool’s parsley, 25.

MÖLLER, L., effects of food on insects, 23.

MOLE, white, 25.

MOLL and Gayot, on cattle, 3, 15, 20.

MOLLUSCA, change in shells of, 23.

MONKE, Lady, culture of the pansy by, 10.

MONKEYS, rarely fertile in captivity, 18.

MONNIER, identity of summer and winter wheat, 9.

MONSTERS, double, 26 (2).

MONSTROSITIES, occurrence of, in domesticated animals and cultivated
plants, 10, 22;

    —due to persistence of embryonic conditions, 13;

    —occurring by reversion, 13;

    —a cause of sterility, 18;

    —caused by injury to the embryo, 22.

MOOR, J. H., deterioration of the horse in Malasia, 2.

MOORCROFT, Mr., on Hasora wheat, 9;

    —selection of white-tailed yaks, 20;

    —melon of Kaschmir, 23;

    —varieties of the apricot cultivated in Ladakh, 10;

    —varieties of the walnut cultivated in Kaschmir, 27.

MOORE, Mr., on breeds of pigeons, 5 (2), 6 (3);

    —on ground tumblers, 6.

MOORUK, fertility of, in captivity, 18.

MOQUIN-TANDON, original form of maize, 9;

    —variety of the double columbine, 10;

    —peloric flowers, 13;

    —position as a cause of pelorism in flowers, 26;

    —tendency of peloric flowers to become irregular, 14;

    —on monstrosities, 22;

    —correlation in the axis and appendages of plants, 25;

    —fusion of homologous parts in plants, 26;

    —on a bean with monstrous stipules and abortive leaflets, 26;

    —conversion of parts of flowers, 27.

MORLOT, dogs of the Danish Middens, 1;

    —sheep and horse of the Bronze period, 28.

_Mormodes ignea,_ 13.

MOROCCO, estimation of pigeons in, 6.

MORREN, grafts of Abutilon, 11;

    —on pelorism, 13;

    —in _Calceolaria,_ 26;

    —non-coincidence of double flowers and variegated leaves, 18.

MORRIS, Mr., breeding of the kestrel in captivity, 18.

MORSE, Dr., digits of birds, 25.

MORTON, Lord, effect of fecundation by a quagga on an Arab mare, 11.

MORTON, Dr., origin of the dog, 1.

_Morus alba,_ 10.

MOSCOW, rabbits of, 4 (2);

    —effects of cold on pear-trees at, 24.

MOSSES, sterility in, 18;

    —retrogressive metamorphosis in, 27.

MOSS-ROSE, probable origin of, from _Rosa centifolia,_ 11;

    —Provence roses produced from seeds of, 11.

MOSTO, Cada, on the introduction of rabbits into Porto Santo, 4.

MOT-MOT, mutilation of feathers inherited, 12.

MOTTLING of fruits and flowers, 11.

MOUNTAIN-ASH, 21.

MOUSE, Barbary, 18.

“MÖVEN-TAUBE,” 5.

MOWBRAY, Mr., on the eggs of game fowls, 7;

    —early pugnacity of game cocks, 7;

    —diminished fecundity of the pheasant in captivity, 18.

MOWBRAY, Mr., reciprocal fecundation of _Passiflora alata_ and
_racemosa,_ 17.

MULATTOS, character of, 13.

MULBERRY, 10, 22.

MULE and hinny, differences in the, 14.

MULES, striped colouring of, 13;

    —obstinacy of, 13;

    —production of, among the Romans, 16;

    —noticed in the Bible, 20.

MÜLLER, FRITZ, reproduction of orchids, 17;

    —development of crustacea, 27;

    —direct action of pollen, 11;

    —self-sterile bignonia, 17.

MÜLLER, H., on the face and teeth in dogs, 1, 3, 26.

MÜLLER, J., tendency to variation, 22;

    —atrophy of the optic nerve consequent on destruction of the eye,
    24;

    —on gemmation and fission, 27;

    —identity of ovules and buds, 27;

    —special affinities of the tissues, 27.

MÜLLER, MAX, antiquity of agriculture, 21.

MULTIPLICITY of origin of pigeons, hypotheses of, discussed, 6.

MUNIZ, F., on Niata cattle, 3.

MUNRO, R., on the fertilisation of orchids, 17;

    —reproduction of _Passiflora alata,_ 17;

    —self-sterile Passiflora, 17.

“MURASSA” pigeon, 5.

MURIE, Dr., size of hybrids, 17.

MURPHY, J. J., the structure of the eye not producible by selection,
20.

_Mus alexandrinus,_ 15 (2).

_Musa sapientium, chinensis_ and _cavendishii,_ 11.

_Muscari comosum,_ 19, 24.

MUSCLES, effects of use on, 24.

MUSK duck, feral hybrid of, with the common duck, 6.

MUTILATIONS, inheritance or non-inheritance of, 12, 27 (2).

MYATT, on a five-leaved variety of the strawberry, 10.

MYOPIA, hereditary, 12.

MYRIAPODA, regeneration of lost parts in, 24, 27.

NAILS, growing on stumps of fingers, 27.

NAIS, scission of, 27.

NAMAQUAS, cattle of the, 3, 20.

NARCISSUS, double, becoming single in poor soil, 18.

NARVAEZ, on the cultivation of native plants in Florida, 9.

_Nasua,_ sterility of, in captivity, 18.

“NATAS” or Niatas, a South American breed of cattle, 3.

NATHUSIUS, H. VON, on striped horses, 2;

    —on the pigs of the Swiss lake-dwellings, 3;

    —on the races of pigs, 3;

    —convergence of character in highly-bred pigs, 3, 21;

    —causes of changes in the form of the pig’s skull, 3 (2);

    —changes in breeds of pigs by crossing, 3;

    —change of form in the pig, 23;

    —effects of disuse of parts in the pig, 24;

    —period of gestation in the pig, 3;

    —appendages to the jaw in pigs, 3;

    —on _Sus pliciceps,_ 3;

    —period of gestation in sheep, 3;

    —on Niata cattle, 3;

    —on shorthorn cattle, 17;

    —on interbreeding, 17;

    —in the sheep, 17;

    —in pigs, 17;

    —unconscious selection in cattle and pigs, 20;

    —variability of highly-selected races, 21.

NATO, P., on the Bizzarria orange, 11.

NATURAL selection, its general principles, Introduction.

NATURE, sense in which the term is employed, Introduction.

NAUDIN, supposed rules of transmission in crossing plants, 14;

    —on the nature of hybrids, 13 (2);

    —essences of the species in hybrids, 27 (2);

    —reversion of hybrids, 13 (3);

    —reversion in flowers by stripes and blotches, 13;

    —hybrids of _Linaria vulgaris_ and _purpurea,_ 15;

    —pelorism in _Linaria,_ 13, 14;

    —crossing of peloric _Linaria_ with the normal form, 14;

    —variability in _Datura,_ 22;

    —hybrids of _Datura laevis_ and _stramonium,_ 11;

    —prepotency of transmission of _ Datura stramonium_ when crossed,
    14;

    —on the pollen of _Mirabilis_ and of hybrids, 11;

    —fertilisation of _Mirabilis,_ 27;

    —cultivated Cucurbitaceæ, 10 (2), 16;

    —rudimentary tendrils in gourds, 24;

    —dwarf _Cucurbitæ,_ 25;

    —relation between the size and number of the fruit in _Cucurbita
    pepo,_ 26;

    —analogous variation in _ Cucurbitæ,_ 22;

    —acclimatisation of Cucurbitaceæ, 24;

    —production of fruit by sterile hybrid Cucurbitaceæ, 18;

    —on the melon, 10, 16, 23;

    —incapacity of the cucumber to cross with other species, 10.

NECTARINE, 10;

    —derived from the peach, 10 (2);

    —hybrids of, 10;

    —persistency of characters in seedling, 10;

    —origin of, 10;

    —produced on peach-trees, 10 (2);

    —producing peaches, 10;

    —variation in, 10 (2);

    —bud-variation in, 11;

    —glands in the leaves of the, 21;

    —analogous variation in, 26.

NECTARY, variations of, in pansies, 10.

NEES, on changes in the odour of plants, 23.

“NEGRO” cat, 1.

NEGROES, polydactylism in, 12;

    —selection of cattle practised by, 20.

NEOLITHIC period, domestication of _Bos longifrons_ and _ primigenius_
in the, 3;

    —cattle of the, distinct from the original species, 3;

    —domestic goat in the, 3;

    —cereals of the, 9.

NERVE, optic, atrophy of the, 24.

NEUBERT, potato-grafting, 11.

NEUMEISTER, on the Dutch and German pouter pigeons, 5;

    —on the Jacobin pigeon, 5;

    —duplication of the middle flight feather in pigeons, 5;

    —on a peculiarly coloured breed of pigeons, “Staarhalsige Taube,”
    5;

    —fertility of hybrid pigeons, 6;

    —mongrels of the trumpeter pigeon, 14;

    —period of perfect plumage in pigeons, 14;

    —advantage of crossing pigeons, 17.

NEURALGIA, hereditary, 14.

NEW ZEALAND, feral cats of, 1;

    —cultivated plants of, 9.

NEWFOUNDLAND dog, modification of, in England, 1.

NEWMAN, E., sterility of Sphingidæ under certain conditions, 18.

NEWPORT, G., non-copulation of _Vanessæ_ in confinement, 18;

    —fertilisation of the ovule in batrachia, 27.

NEWT, polydactylism in the, 12.

NEWTON, A., absence of sexual distinctions in the Columbidæ, 5;

    —production of a “black-shouldered” peahen among the ordinary kind,
    8;

    —on hybrid ducks, 18.

NGAMI, Lake, cattle of, 3.

“NIATA” cattle, 3;

    —resemblance of, to _ Sivatherium,_ 3;

    —prepotency of transmission of character by, 14.

“NICARD” rabbit, 4.

NICHOLSON, Dr., on the cats of Antigua, 1;

    —on the sheep of Antigua, 3.

_Nicotiana,_ crossing of varieties and species of, 3;

    —prepotency of transmission of characters in species of, 14;

    —contabescence of female organs in, 18.

_Nicotiana glutinosa,_ 16.

NIEBUHR, on the heredity of mental characteristics in some Roman
families, 14.

NIGHT-BLINDNESS, non-reversion to, 13.

NILSSON, Prof., on the barking of a young wolf, 1;

    —parentage of European breeds of cattle, 3 (2);

    —on _Bos frontosus_ in Scania, 3.

NIND, Mr., on the dingo, 1.

“NISUS formativus,” 24 (2), 26.

NITZSCH, on the absence of the oil-gland in certain Columbæ, 5.

NON-INHERITANCE, causes of, 12.

“NONNAIN” pigeon, 5.

NORDMANN, dogs of Awhasie, 1.

NORMANDY, pigs of, with appendages under the jaw, 3.

NORWAY, striped ponies of, 2.

NOTT and Gliddon, on the origin of the dog, 1;

    —mastiff represented on an Assyrian tomb, 1;

    —on Egyptian dogs, 1;

    —on the Hare Indian dog, 1.

_Notylia,_ 17.

NOURISHMENT, excess of, a cause of variability, 22.

NUMBER, importance of, in selection, 21.

_Numida ptilorhyncha,_ the original of the Guinea-fowl, 8.

NUN pigeon, 5;

    —known to Aldrovandi, 6.

NUTMEG-TREE, 21.

OAK, weeping, 10, 12, 21;

    —pyramidal, 10;

    —Hessian, 10;

    —late-leaved, 10;

    —valueless as timber at the Cape of Good Hope, 23;

    —changes in, dependent on age, 11;

    —galls of the, 23.

OATS, wild, 9;

    —in the Swiss lake-dwellings, 9.

OBERLIN, change of soil beneficial to the potato, 18.

ODART, Count, varieties of the vine, 10, 23;

    —bud-variation in the vine, 11.

_Œcidium,_ 23.

_Œnothera biennis,_ bud-variation in, 11.

OGLE, Dr. J. W., inherited deficient phalanges, 12;

    —resemblance of twins, 22 (2).

OIL-GLAND, absence of, in fantail pigeons, 5 (2).

OLDFIELD, Mr., estimation of European dogs among the natives of
Australia, 20.

OLEANDER, stock affected by grafting in the, 11.

OLLIER, Dr., insertion of the periosteum of a dog beneath the skin of a
rabbit, 27.

_Oncidium,_ reproduction of, 17, 18.

ONIONS, crossing of, 15;

    —white, liable to the attacks of fungi and disease, 21, 25.

_Ophrys apifera,_ self-fertilisation of, 15;

    —formation of pollen by a petal in, 27.

_Opuntia leucotricha,_ 23.

ORANGE, 10;

    —crossing of, 15;

    —with the lemon, 11, 27;

    —naturalisation of, in Italy, 24;

    —variation of, in North Italy, 22;

    —peculiar variety of, 25;

    —bizzarria, 11;

    —trifacial, 11.

ORCHIDS, reproduction of, 11 (2), 17.

ORFORD, Lord, crossing greyhounds with the bulldog, 1.

ORGANISMS, origin of, Introduction.

ORGANISATION, advancement in, Introduction.

ORGANS, rudimentary and aborted, 24;

    —multiplication of abnormal, 27.

ORIOLE, assumptions of hen-plumage by a male in confinement, 18.

ORKNEY Islands, pigs of, 3;

    —pigeons of, 6.

ORTHOPTERA, regeneration of hind legs in the, 24.

_Orthosia munda,_ 18.

ORTON, R., on the effects of cross-breeding on the female, 11;

    —on the Manx cat, 14;

    —on mongrels from the silk fowl, 14;

    —infertility of geese in Quito, 18.

OSBORNE, Dr., inherited mottling of the iris, 12.

OSPREY, preying on black fowls, 21.

OSTEN-SACKEN, Baron, on American oak-galls, 23.

OSTEOLOGICAL characters of pigs, 3 (4);

    —of rabbits, 4;

    —of pigeons, 5;

    —of ducks, 8.

OSTRICH, diminished fertility of the, in captivity, 18.

OSTYAKS, selection of dogs by the, 20.

OTTER, 18.

“OTTER” sheep of Massachusetts, 3.

OUDE, feral humped cattle in, 3.

OUISTITI, breed in Europe, 18.

OVARY, variation of, in _Cucurbita moschata,_ 10;

    —development of, independently of pollen, 11.

_Ovis montana,_ 3.

OVULES and buds, identity of nature of, 27.

OWEN, Capt., on stiff-haired cats at Mombas, 1.

OWEN, Prof. R., palæontological evidence as to the origin of dogs, 1;

    —on the skull of the “Niata” cattle, 3;

    —on fossil remains of rabbits, 3;

    —on the significance of the brain, 4;

    —on metagenesis, 27;

    —theory of reproduction and parthenogenesis, 27.

OWL, eagle, breeding in captivity, 18.

OWL pigeon, 5;

    —African, figured, 5;

    —known in 1735, 6.

_Oxalis,_ trimorphic species of, 27.

_Oxalis rosea,_ 17.

OXLEY, Mr., on the nutmeg-tree, 21.

OYSTERS, differences in the shells of, 23.

PACA, sterility of the, in confinement, 4.

PACIFIC Islands, pigs of the, 3.

PADUA, earliest known flower-garden at, 20.

PADUAN fowl of Aldrovandi, 7.

_Pæonia moutan,_ 20.

PÆONY-TREE, ancient cultivation of, in China, 20.

PAGET, on the Hungarian sheep-dog, 1.

PAGET, Sir J., inheritance of cancer, 12;

    —hereditary elongation of hairs in the eyebrow, 12;

    —regrowth of extra digits, 12;

    —circumcision, 12;

    —period of inheritance of cancer, 14;

    —on _Hydra,_ 24;

    —on the healing of wounds, 24;

    —on the reparation of bones, 24;

    —growth of hair near inflamed surfaces or fractures, 24;

    —on false membranes, 24;

    —compensatory development of the kidney, 24;

    —bronzed skin in disease of supra-renal capsules, 25;

    —unity of growth and gemmation, 27;

    —independence of the elements of the body, 27;

    —affinity of the tissues for special organic substances, 27.

PALLAS, on the influence of domestication upon the sterility of
intercrossed species, 1, 4, 6, 16;

    —hypothesis that variability is wholly due to crossing, 4, 8, 22
    (2);

    —on the origin of the dog, 1;

    —variation in dogs, 1;

    —crossing of dog and jackal, 1;

    —origin of domestic cats, 2;

    —origin of Angora cat, 1;

    —on wild horses, 2 (2);

    —on Persian sheep, 3;

    —on Siberian fat-tailed sheep, 23;

    —on Chinese sheep, 24;

    —on Crimean varieties of the vine, 10;

    —on a grape with rudimentary seeds, 24;

    —on feral musk-ducks, 13;

    —sterility of Alpine plants in gardens, 18;

    —selection of white-tailed yaks, 20.

PAMPAS, feral cattle on the, 3.

_Pandanus,_ 22.

PANGENESIS, hypothesis of, 27.

_Panicum,_ seeds of, used as food, 9;

    —found in the Swiss lake-dwellings, 9.

PANSY, 10.

PAPPUS, abortion of the, in _Carthamus,_ 24.

_Paradoxurus,_ sterility of species of, in captivity, 18.

PARAGUAY, cats of, 1;

    —cattle of, 3;

    —horses of, 3;

    —dogs of, 3;

    —black-skinned domestic fowl of, 7.

PARALLEL variation, 26.

PARAMOS, woolly pigs of, 3.

PARASITES, liability to attacks of, dependent on colour, 21.

PARIAH dog, with crooked legs, 1;

    —resembling the Indian wolf, 1.

PARISET, inheritance of handwriting, 13.

_Paritium tricuspis,_ bud-variation, 11.

PARKER, W. K., number of vertebræ in fowls, 7.

PARKINSON, Mr., varieties of the hyacinth, 10.

PARKYNS, MANSFIELD, on _Columba guinea,_ 6.

PARMENTIER, differences in the nidification of pigeons, 5;

    —on white pigeons, 21.

PARROTS, general sterility of, in confinement, 18;

    —alteration of plumage of, 23.

PARSNIP, reversion in, 13;

    —influence of selection on, 20;

    —experiments on, 23;

    —wild, enlargement of roots of, by cultivation, 9.

PARTHENOGENESIS, 27 (2).

PARTRIDGE, sterility of, in captivity, 18.

PARTURITION, difficult, hereditary, 12.

_Parus major,_ 21.

_Passiflora,_ self-impotence in species of, 17 (2);

    —contabescence of female organs in, 18.

_Passiflora alata,_ fertility of, when grafted, 19.

PASTRANA, Julia, peculiarities in the hair and teeth of, 25.

PASTURE and climate, adaptation of breeds of sheep to, 3 (2).

PATAGONIA, crania of pigs from, 3.

PATAGONIAN rabbit, 4.

PATERSON, R., on the Arrindy silk-moth, 24.

PAUL, W., on the hyacinth, 10 (2);

    —varieties of pelargoniums, 11;

    —weakness of transmission in hollyhocks, 14;

    —improvement of pelargoniums, 20.

_Pavo cristatus_ and _muticus,_ hybrids of, 8.

_Pavo nigripennis,_ 8.

“PAVODOTTEN-TAUBE,” 5.

PEACH, 10;

    —derived from the almond, 10;

    —stones of, figured, 10;

    —contrasted with almonds, 10;

    —double-flowering, 10 (3);

    —hybrids of, 10;

    —persistency of races of, 10;

    —trees producing nectarines, 10;

    —variation in, 10 (2);

    —bud-variation in, 11;

    —pendulous, 12;

    —variation by selection in, 20;

    —peculiar disease of the, 21;

    —glands on the leaves of the, 21;

    —antiquity of the, 24;

    —increased hardiness of the, 24;

    —varieties of, adapted for forcing, 24;

    —yellow-fleshed, liable to certain diseases, 25.

PEACH-ALMOND, 27.

PEAFOWL, origin of, 8;

    —japanned or black-shouldered, 8;

    —feral, in Jamaica, 6;

    —comparative fertility of, in wild and tame states, 16, 22;

    —white, 25.

PEARS, 10;

    —bud-variation in, 11;

    —reversion in seedling, 13;

    —inferiority of, in Pliny’s time, 20;

    —winter nelis, attacked by aphides, 21;

    —soft-barked varieties of, attacked by wood-boring beetles, 21;

    —origination of good varieties of, in woods, 22;

    —Forelle, resistance of, to frost, 24.

PEAS, 9;

    —origin of, 9;

    —varieties of, 9;

    —found in Swiss lake-dwellings, 9 (3);

    —fruit and seeds figured, 9;

    —persistency of varieties, 9;

    —intercrossing of varieties, 9, 11;

    —effect of crossing on the female organs in, 11;

    —double-flowered, 18;

    —maturity of, accelerated by selection, 20;

    —varieties of, produced by selection, 20;

    —thin-shelled, liable to the attacks of birds, 21;

    —reversion of, by the terminal seed in the pod, 26.

PECCARY, breeding of the, in captivity, 18.

PEDIGREES of horses, cattle, greyhounds, game-cocks, and pigs, 12.

PEGU, cats of, 1;

    —horses of, 2.

PELARGONIUMS, multiple origin of, 10;

    —zones of, 10;

    —bud-variation in, 11;

    —variegation in, accompanied by dwarfing, 11;

    —pelorism in, 18, 26;

    —by reversion, 13;

    —advantage of change of soil to, 18;

    —improvement of, by selection, 20;

    —scorching of, 21;

    —numbers of, raised from seed, 21;

    —effects of conditions of life on, 23;

    —stove-variety of, 24;

    —correlation of contracted leaves and flowers in, 25 (2).

_Pelargonium fulgidum,_ conditions of fertility in, 18.

“PELONES,” a Columbian breed of cattle, 3, 6.

PELORIC flowers, tendency of, to acquire the normal form, 14;

    —fertility or sterility of, 18 (2).

PELORIC races of _Gloxinia speciosa_ and _Antirrhinum majus,_ 10.

PELORISM, 13, 26 (2).

PELVIS, characters of, in rabbits, 4;

    —in pigeons, 5;

    —in fowls, 7;

    —in ducks, 8.

PEMBROKE cattle, 3.

PENDULOUS trees, 10, 26;

    —uncertainty of transmission of, 12 (2).

PENGUIN ducks, 8 (2);

    —hybrid of the, with the Egyptian goose, 8.

PENNANT, production of wolf-like curs at Fochabers, 1;

    —on the Duke of Queensberry’s wild cattle, 3.

_Pennisetum,_ seeds of, used as food in the Punjab, 9.

_Pennisetum distichum,_ seeds of, used as food in Central Africa, 9.

PERCIVAL, Mr., on inheritance in horses, 12;

    —on horn-like processes in horses, 2.

_Perdix rubra,_ occasional fertility of, in captivity, 18.

PERIOD of action of causes of variability, 22.

PERIOSTEUM of a dog, producing bone in a rabbit, 27.

PERIWINKLE, sterility of, in England, 19.

PERSIA, estimation of pigeons in, 6;

    —carrier pigeon of, 5;

    —tumbler pigeon of, 5;

    —cats of, 1;

    —sheep of, 3.

PERSISTENCE of colour in horses, 2;

    —of generic peculiarities, 4.

PERU, antiquity of maize in, 9;

    —peculiar potato from, 9;

    —selection of wild animals practised by the Incas of, 20 (2).

“PERUCKEN-TAUBE,” 5.

PETALS, rudimentary, in cultivated plants, 24;

    —producing pollen, 27.

PETUNIAS, multiple origin of, 10.

PEYRITSCH, Dr., vegetable teratology, 13.

“PFAUEN-TAUBE,” 5.

_Phalænopsis,_ pelorism in, 26.

PHALANGES, deficiency of, 14.

_Phaps chalcoptera,_ 26.

_Phaseolus multiflorus,_ 24, 25.

_Phaseolus vulgaris,_ 9, 24.

_Phasianus pictus,_ 7.

_Phasianus amherstiæ,_ 7.

PHEASANT, assumption of male plumage by the hen, 13;

    —wildness of hybrids of, with the common fowl, 13;

    —prepotency of the, over the fowl, 14;

    —diminished fecundity of the, in captivity, 18.

PHEASANTS, golden and Lady Amherst’s, 7.

PHEASANT-FOWLS, 7.

PHILIPEAUX, regeneration of limbs in the salamander, 27.

PHILIPPAR, on the varieties of wheat, 9.

PHILIPPINE Islands, named breeds of game fowl in the, 7.

PHILLIPS, Mr., on bud-variation in the potato, 11.

_Phlox,_ bud-variation by suckers in, 11.

PHTHISIS, affection of the fingers in, 25.

PHYLLOXERA, 10.

PICKERING, Dr., on the grunting voice of humped cattle, 3;

    —occurrence of the head of a fowl in an ancient Egyptian
    procession, 7;

    —seeding of ordinarily seedless fruits, 18;

    —extinction of ancient Egyptian breeds of sheep and oxen, 28;

    —on an ancient Peruvian gourd, 28.

PICOTEES, effect of conditions of life on, 23.

PICTET, A., oriental names of the pigeon, 6.

PICTET, Prof., origin of the dog, 1;

    —on fossil oxen, 3.

PIEBALDS, probably due to reversion, 13.

PIÉTREMENT, M., on the ribs of horses, 2.

PIGEAUX, hybrids of the hare and rabbit, 18.

PIGEON à cravate, 5.

PIGEON bagadais, 5 (2).

PIGEON coquille, 5.

PIGEON cygne, 5.

PIGEON heurté, 5.

PIGEON pattu plongeur, 5.

PIGEON polonais, 5.

PIGEON romain, 5 (2).

PIGEON tambour, 5.

PIGEON turc, 5.

PIGEONS, origin of, 5 (2), 6;

    —classified table of breeds of, 5;

    —pouter, 5;

    —carrier, 5;

    —runt, 5;

    —barbs, 5;

    —fantail, 5;

    —turbit and owl, 5;

    —tumbler, 5;

    —Indian frill-back, 5;

    —Jacobin, 5;

    —trumpeter, 5;

    —other breeds of, 5;

    —differences of, equal to generic, 5;

    —individual variations of, 5;

    —variability of peculiarities characteristic of breeds in, 5;

    —sexual variability in, 5 (2);

    —osteology of, 5;

    —correlation of growth in, 5, 25;

    —young of some varieties naked when hatched, 5, 25;

    —effects of disuse in, 5;

    —settling and roosting in trees, 6;

    —floating in the Nile to drink, 6;

    —dovecot, 6 (2);

    —arguments for unity of origin of, 6;

    —feral, in various places, 6, 13;

    —unity of coloration in, 6;

    —reversion of mongrel, to coloration of _C. livia,_ 6;

    —history of the cultivation of, 6;

    —history of the principal races of, 6;

    —mode of production of races of, 6;

    —reversion in, 13;

    —by age, 13;

    —produced by crossing in, 13 (2);

    —prepotency of transmission of characters in breeds of, 14 (2);

    —sexual differences in some varieties of, 14;

    —period of perfect plumage in, 14;

    —effect of segregation on, 15;

    —preferent pairing of, within the same breed, 16;

    —fertility of, increased by domestication, 16, 18;

    —effects of interbreeding and necessity of crossing, 17;

    —indifference of, to change of climate, 18;

    —selection of, 16, 20 (2);

    —among the Romans, 20;

    —unconscious selection of, 20 (2);

    —facility of selection of, 21;

    —white, liable to the attacks of hawks, 21;

    —effects of disuse of parts in, 24;

    —fed upon meat, 24;

    —effect of first male upon the subsequent progeny of the female,
    11;

    —homology of the leg and wing feathers in, 25;

    —union of two outer toes in feather-legged, 25;

    —correlation of beak, limbs, tongue, and nostrils, 25;

    —analogous variation in, 26 (2);

    —permanence of breeds of, 28.

PIGS, of Swiss lake-dwellings, 3;

    —types of, derived from _Sus scrofa_ and _Sus indicus,_ 3;

    —Japanese (_Sus pliciceps,_ Gray), figured, 3;

    —of Pacific Islands, 3, 15;

    —modifications of skull in, 3;

    —length of intestines in, 3, 24;

    —period of gestation of, 3;

    —number of vertebræ and ribs in, 3;

    —anomalous forms, 3 (2);

    —development of tusks and bristles in, 3;

    —striped young of, 3;

    —reversion of feral, to wild type, 3 (2), 13 (2);

    —production and changes of breeds of, by intercrossing, 3;

    —effects produced by the first male upon the subsequent progeny of
    the female, 11;

    —pedigrees of, 12;

    —polydactylism in, 12;

    —cross-reversion in, 13;

    —hybrid, wildness of, 13;

    —disappearance of tusks in male under domestication, 14;

    —solid-hoofed, 28;

    —crosses of, 15 (2);

    —mutual fertility of all varieties of, 16;

    —increased fertility by domestication, 16;

    —ill effects of close interbreeding in, 17 (2);

    —influence of selection on, 20;

    —prejudice against certain colours in, 20, 21, 25;

    —unconscious selection of, 20;

    —black Virginian, 21, 25;

    —similarity of the best breeds of, 21;

    —change of form in, 23;

    —effects of disuse of parts in, 24;

    —ears of, 24;

    —correlations in, 25;

    —white buck-wheat injurious to, 25;

    —tail of, grafted upon the back, 27;

    —extinction of the older races of, 28.

PIMENTA, 15.

PIMPERNEL, 19.

PINE-APPLE, sterility and variability of the, 22.

PINK, Chinese, 25.

PINKS, bud-variation in, 11;

    —improvement of, 20.

_Pinus pumilio, mughus,_ and _nana,_ varieties of _P. sylvestris,_ 10.

_Pinus sylvestris,_ 10, 24;

    —hybrids of, with _P. nigricans,_ 17.

PIORRY, on hereditary disease, 12, 14.

_Pistacia lentiscus,_ 23.

_Pistacia vera,_ 11.

PISTILS, rudimentary, in cultivated plants, 24.

PISTOR, sterility of some mongrel pigeons, 6;

    —fertility of pigeons, 16.

_Pisum arvense_ and _sativum,_ 9.

PITYRIASIS versicolor, inheritance of, 14.

PLANCHON, G., on a fossil vine, 10;

    —sterility of _Jussiæa grandiflora_ in France, 18.

PLANE-TREE, variety of the, 10.

PLANTIGRADE carnivora, general sterility of the, in captivity, 18.

PLANTS, progress of cultivation of, 9 (2);

    —cultivated, their geographical derivation, 9;

    —crossing of, 15, 17;

    —comparative fertility of wild and cultivated, 16;

    —self-impotent, 17;

    —dimorphic and trimorphic, 17;

    —sterility of, from changed conditions, 18;

    —from contabescence of anthers, 18 (2);

    —from monstrosities, 9 (2);

    —from doubling of the flowers, 18 (2);

    —from seedless fruit, 18;

    —from excessive development of vegetative organs, 18;

    —influence of selection on, 20;

    —variation by selection, in useful parts of, 20;

    —variability of, 21;

    —variability of, induced by crossing, 22;

    —direct action of change of climate on, 23;

    —change of period of vegetation in, 24;

    —varieties of, suitable to different climates, 24;

    —correlated variability of, 25;

    —antiquity of races of, 28.

PLASTICITY, inheritance of, 21.

PLATEAU, F., on the vision of amphibious animals, 20.

_Platessa flesus,_ , 13.

PLATO, notice of selection in breeding dogs by, 20.

PLICA polonica, 23.

PLINY, on the crossing of shepherd dogs with the wolf, 1;

    —on Pyrrhus’ breed of cattle, 20;

    —on the estimation of pigeons among the Romans, 6;

    —pears described by, 20.

PLUM, 10;

    —stones figured, 10;

    —varieties of the, 10 (2), 20;

    —bud-variation in the, 11;

    —peculiar disease of the, 21;

    —flower-buds of, destroyed by bullfinches, 21;

    —purple-fruited, liable to certain diseases, 25.

PLUMAGE, inherited peculiarities of, in pigeons, 5 (2);

    —sexual peculiarities of, in fowls, 7.

PLURALITY of races, Pouchet’s views on, 1.

_Poa,_ seeds of, used as food, 9;

    —species of, propagated by bulblets, 18.

PODOLIAN cattle, 3.

POINTERS, modification of, 1;

    —crossed with the foxhound, 3.

POIS sans parchemin, 21.

POITEAU, origin of _Cytisus adami,_ 11;

    —origin of cultivated varieties of fruit-trees, 22.

POLISH fowl, 7 (6);

    —skull figured, 7;

    —section of skull figured, 7;

    —development of protuberance of skull, 7;

    —furculum figured, 7.

POLISH, or Himalayan rabbit, 4.

POLLEN, 27 (2);

    —action of, 16;

    —injurious action of, in some orchids, 17 (2);

    —resistance of, to injurious treatment, 18;

    —prepotency of, 19.

POLLOCK, Sir F., transmission of variegated leaves in _Ballota nigra,_
11;

    —on local tendency to variegation, 23.

POLYANTHUS, 12.

POLYDACTYLISM, inheritance of, 12;

    —significance of, 12.

PONIES, most frequent on islands and mountains, 2;

    —Javanese, 2.

POOLE, Col., on striped Indian horses, 2 (2);

    —on the young of _Asinus indicus,_ 13.

POPLAR, Lombardy, 10.

PÖPPIG, on Cuban wild dogs, 1.

POPPY, found in the Swiss lake-dwellings, 9 (2);

    —with the stamens converted into pistils, 10;

    —differences of the, in different parts of India, 18;

    —monstrous, fertility of, 18;

    —black-seeded, antiquity of, 28.

PORCUPINE, breeding of, in captivity, 18.

PORCUPINE family, 12, 14.

_Porphyrio,_ breeding of a species of, in captivity, 18.

PORTAL, on a peculiar hereditary affection of the eye, 12.

PORTO Santo, feral rabbits of, 4.

_Portulaca oleracea,_ 23.

_Potamochoerus penicillatus,_ 18.

POTATO, 9 (2);

    —bud-variation by tubers in the, 11 (2);

    —graft-hybrid of, by union of half-tubers, 11;

    —individual self-impotence in the, 17;

    —sterility of, 18;

    —advantage of change of soil to the, 18.

POTATO, sweet, sterility of the, in China, 18;

    —varieties of the, suited to different climates, 24.

POUCHET, M., his views on plurality of races, 1.

POUTER pigeons, 5;

    —furculum figured, 5;

    —history of, 6.

POWIS, Lord, experiments in crossing humped and English cattle, 3, 13.

POYNTER, Mr., on a graft-hybrid rose, 11.

PRAIRIE wolf, 1.

PRECOCITY of highly-improved breeds, 25.

PREPOTENCY of pollen, 19.

PREPOTENCY of transmission of character, 14, 19;

    —in the Austrian emperors and some Roman families, 14;

    —in cattle, 14 (2);

    —in sheep, 14;

    —in cats, 14;

    —in pigeons, 14;

    —in fowls, 14;

    —in plants, 14;

    —in a variety of the pumpkin, 10;

    —in the jackal over the dog, 14;

    —in the ass over the horse, 14;

    —in the pheasant over the fowl, 14;

    —in the penguin duck over the Egyptian goose, 14;

    —discussion of the phenomena of, 14.

PRESCOTT, Mr., on the earliest known European flower-garden, 20.

PRESSURE, mechanical, a cause of modification, 26 (2).

PREVOST and Dumas, on the employment of several spermatozoids to
fertilise one ovule, 27.

PREYER, Prof., on the effect of circumcision, 12.

PRICE, Mr., variations in the structure of the feet in horses, 2.

PRICHARD, Dr., on polydactylism in the negro, 12;

    —on the Lambert family, 14;

    —on an albino negro, 21;

    —on Plica polonica, 23.

PRIMROSE, 28;

    —double, rendered single by transplantation, 18.

_Primula,_ intercrossing of species of, 10;

    —contabescence in, 18;

    —‘hose in hose,’ 10;

    —with coloured calyces, sterility of, 18.

_Primula sinensis,_ variations, 10;

    —reciprocally dimorphic, 17.

_Primula veris,_ 12, 16.

_Primula vulgaris,_ 12, 16.

PRINCE, Mr., on the intercrossing of strawberries, 27.

PRINGSHEIM, on conjugation, 27.

_Procyon,_ sterility of, in captivity, 18.

PROLIFICNESS, increased by domestication, 19.

PROTOZOA, reproduction of the, 27.

_Prunus armeniaca,_ 10 (2).

_Prunus avium,_ 10.

_Prunus cerasus,_ 10 (2).

_Prunus domestica,_ 10.

_Prunus insititia,_ 10.

_Prunus spinosa,_ 10.

PRUSSIA, wild horses in, 2.

_Psittacus erithacus,_ 18.

_Psittacus macoa,_ 18.

_Psophia,_ general sterility of, in captivity, 18.

PTARMIGAN fowls, 7.

_Pulex penetrans,_ 23.

PUMPKINS, 10.

PUNO ponies of the Cordillera, 2.

PUSEY, Mr., value of crossbred sheep, 17;

    —preference of hares and rabbits for common rye, 21.

PUTSCHE and Vertuch, varieties of the potato, 9.

PUVIS, effects of foreign pollen on apples, 11;

    —supposed non-variability of monotypic genera, 22.

_Pyrrhula vulgaris,_ 21;

    —assumption of the hen-plumage by the male, in confinement, 18.

PYRRHUS, his breed of cattle, 20.

_Pyrus,_ fastigiate Chinese species of, 23.

_Pyrus acerba,_ 10.

_Pyrus aucuparia,_ 21.

_Pyrus communis,_ 10, 11.

_Pyrus malus,_ 10, 11.

_Pyrus paradisiaca,_ 10.

_Pyrus præcox,_ 10.

QUAGGA, previous impregnation by, 11.

QUATREFAGES, A. DE, on the burrowing of a bitch to litter, 1;

    —selection in the silkworm, 8;

    —development of the wings in the silk-moth, 8, 24;

    —on varieties of the mulberry, 10;

    —special raising of eggs of the silk-moth, 20;

    —on disease of the silkworm, 21;

    —on monstrosities in insects, 22, 27;

    —on a change in the breeding season of the Egyptian goose, 24;

    —fertilisation of the _Teredo,_ 27;

    —tendency to similarity in the best races, 21;

    —on his “_tourbillon vital,_” 13;

    —on the independent existence of the sexual elements, 27.

_Quercus cerris,_ 10.

_Quercus robur_ and _pedunculata,_ hybrids of, 17.

QUINCE, pears grafted on the, 22.

RABBITS, domestic, their origin, 4;

    —of Mount Sinai and Algeria, 4;

    —breeds of, 4;

    —Himalayan, Chinese, Polish, or Russian, 4, 15;

    —feral, 4;

    —of Jamaica, 4;

    —of the Falkland Islands, 4;

    —of Porto Santo, 4, 16, 23;

    —osteological characters of, 4;

    —discussion of modifications in, 4, 5;

    —one-eared, transmission of peculiarity of, 12;

    —reversion in feral, 13;

    —in the Himalayan, 13;

    —crossing of white and coloured Angora, 15;

    —comparative fertility of wild and tame, 16;

    —falsified experiments in interbreeding of, 17;

    —high-bred, often bad breeders, 17;

    —selection of, 20;

    —white, liable to destruction, 21;

    —effects of disuse of parts in, 24;

    —skull of, affected by drooping ears, 24;

    —length of intestines in, 24;

    —correlation of ears and skull in, 25 (2);

    —variations in skull of, 26;

    —periosteum of a dog producing bone in, 27.

RACEHORSE, origin of, 2.

RACES, modification and formation of, by crossing, 3;

    —natural and artificial, 21;

    —Pouchet’s views on plurality of, Introduction;

    —of pigeons, 6.

RADCLYFFE, W. F., effect of climate and soil on strawberries, 10;

    —constitutional differences in roses, 10.

RADISHES, 9;

    —crossing of, 15;

    —varieties of, 21.

RADLKOFER, retrogressive metamorphosis in mosses and algæ, 27.

RAFARIN, M., bud-variation and reversion, 11.

RAFFLES, Sir STAMFORD, on the crossing of Javanese cattle with _ Bos
sondaicus,_ 20.

RAM, goat-like, from the Cape of Good Hope, 14.

RAMU, M., on appendages to throat of goat, 3.

RANCHIN, heredity of diseases, 12.

RANGE of gallinaceous birds on the Himalaya, 7.

RANKE, on the effects of use and disuse of organs, 24.

_Ranunculus ficaria,_ 18.

_Ranunculus repens,_ 18.

RAPE, 9.

_Raphanus caudatus,_ 9.

_Raphanus raphanistrum,_ 9.

_Raphanus sativus,_ 26.

RASPBERRY, yellow-fruited, 21.

RATTLESNAKE, experiments with poison of the, 23.

RAVEN, stomach of, affected by vegetable diet, 24.

RAWSON, A., self-impotence in hybrids of _Gladiolus,_ 17 (2).

RÉ, COMTE, on the assumption of a yellow colour by all varieties of
maize, 9.

RÉAUMUR, effect of confinement upon the cock, 13;

    —fertility of fowls in most climates, 18.

REED, Mr., atrophy of the limbs of rabbits, consequent on the
destruction of their nerves, 24.

REGENERATION of amputated parts in man, 12;

    —in the human embryo, 27;

    —in the lower vertebrata, insects, and myriapoda, 27.

RE-GROWTH of amputated joints, 27.

REGNIER, early cultivation of the cabbage by the Celts, 9;

    —selection practised by the Celts, 20.

REINDEER, individuals recognised by the Laplanders, 22.

REISSEK, experiments in crossing _Cytisus purpureus_ and _ laburnum,_
11;

    —modification of a _Thesium_ by _Œcidium,_ 23.

RELATIONS, characters of reproduced in children, 13.

RENGGER, occurrence of jaguars with crooked legs in Paraguay, 1;

    —naked dogs of Paraguay, 1 (2), 15, 16;

    —feral dogs of La Plata, 1;

    —on the aguara, 1;

    —cats of Paraguay, 1, 15, 18;

    —dogs of Paraguay, 15;

    —feral pigs of Buenos Ayres, 3;

    —on the refusal of wild animals to breed in captivity, 18;

    —on _Dicotyles labiatus,_ 18;

    —sterility of plantigrade carnivora in captivity, 18;

    —on _Cavia aperea,_ 18;

    —sterility of _Cebus azarae_ in captivity, 18;

    —abortions produced by wild animals in captivity, 18.

REPRODUCTION, sexual and asexual, contrasted, 27;

    —unity of forms of, 27;

    —antagonism of, to growth, 27.

_Reseda odorata,_ self-sterility of, 17, 21.

RETINITIS, pigmentary, in deaf-mutes, 25.

REUTER, Herr, potato-grafting, 11.

REVERSION, 13 (2), 27 (4);

    —in pigeons, 13;

    —in cattle, 13;

    —in sheep, 13;

    —in fowls, 13;

    —in the heartsease, 13;

    —in vegetables, 13;

    —in feral animals and plants, 13;

    —to characters derived from a previous cross in man, dogs, pigeons,
    pigs, and fowls, 13;

    —in hybrids, 13;

    —by bud-propagation in plants, 13;

    —by age in fowls, cattle, etc., 13 (2);

    —partial, from an injury, 13;

    —caused by crossing, 13;

    —explained by latent characters, 13;

    —producing monstrosities, 13;

    —producing peloric flowers, 13;

    —of feral pigs to the wild type, 3 (2);

    —of supposed feral rabbits to the wild type, 4 (3);

    —of pigeons, in coloration, when crossed, 6;

    —in fowls, 7;

    —in the silkworm, 8;

    —in the pansy, 10;

    —in a pelargonium, 11;

    —in Chrysanthemums, 11;

    —of varieties of the China rose in St. Domingo, 11;

    —by buds in pinks and carnations, 11;

    —of laciniated varieties of trees to the normal form, 11;

    —in variegated leaves of plants, 11;

    —in tulips, 11;

    —of suckers of the seedless barberry to the common form, 11;

    —by buds in hybrids of _ Tropæolum,_ 11;

    —in plants, 11;

    —of crossed peloric snapdragons, 14;

    —analogous variations due to, 26.

RHINOCEROS, breeding in captivity in India, 18.

_Rhododendron,_ hybrid, 22.

_Rhododendron ciliatum,_ 23.

_Rhododendron dalhousiæ,_ effect of pollen of _R. nuttallii_ upon, 11.

_Ribes grossularia,_ 10 (2).

_Ribes rubrum,_ 11.

RIBS, number and characters of, in fowls, 7;

    —characters of, in ducks, 8 (2).

RICE, imperial, of China, 20;

    —Indian varieties of, 22;

    —variety of, not requiring water, 24.

RICHARDSON, H. D., on jaw-appendages in Irish pigs, 3;

    —management of pigs in China, 3;

    —occurrence of striped young in Westphalian pigs, 3;

    —on crossing pigs, 15;

    —on interbreeding pigs, 17;

    —on selection in pigs, 20.

RICHARDSON, Sir John, observations on the resemblance between North
American dogs and wolves, 1 (2);

    —on the burrowing of wolves, 1;

    —on the broad feet of dogs, wolves, and foxes in North America, 1;

    —on North American horses scraping away the snow, 2.

_Ricinus,_ annual in England, 24.

RIEDEL, Dr., on the “Bagadotte” pigeon, 5;

    —on the Jacobin pigeon, 5;

    —fertility of hybrid pigeons, 6;

    —circumcision, 12.

RILEY, on Phylloxera, 10.

RINDERPEST, 27.

RINTOUL, Mr., potato-grafting, 11.

RISSO, on varieties of the orange, 10, 24, 25.

RIVERS, Lord, on the selection of greyhounds, 21.

RIVERS, Mr., persistency of characters in seedling potatoes, 9;

    —on the peach, 10 (2);

    —persistency of races in the peach and nectarine, 10 (2);

    —connection between the peach and the nectarine, 10;

    —persistency of character in seedling apricots, 10;

    —origin of the plum, 10;

    —seedling varieties of the plum, 10;

    —persistency of character in seedling plums, 10;

    —bud-variation in the plum, 11;

    —plum attacked by bullfinches, 21;

    —seedling apples with surface-roots, 10;

    —variety of the apple found in a wood, 22;

    —on roses, 10 (2);

    —bud-variation in roses, 11;

    —production of Provence roses from seeds of the moss-rose, 11;

    —effect produced by grafting on the stock in jessamine, 11;

    —in the ash, 11;

    —on grafted hazels, 11;

    —hybridisation of a weeping thorn, 12;

    —experiments with the seed of the weeping elm and ash, 12;

    —variety of the cherry with curled petals, 21.

RIVIÈRE, reproduction of _Oncidium cavendishianum,_ 17.

ROBERTS, Mr., on inheritance in the horse, 12.

ROBERTSON, Mr., on glandular-leaved peaches, 10.

ROBINET, on the silkworm, 8, 20.

_Robinia,_ 23.

ROBSON, Mr., deficiencies of half-bred horses, 12.

ROBSON, Mr., on the advantage of change of soil to plants, 18 (2);

    —on the growth of the verbena, 23;

    —on broccoli, 24.

ROCK pigeon, measurements of the, 5;

    —figured, 5.

RODENTS, sterility of, in captivity, 18.

_Rodriguezia,_ 17 (2).

RODWELL, J., poisoning of horses by mildewed tares, 25.

ROHILCUND, feral humped cattle in, 3.

ROLLE, F., on the history of the peach, 24.

ROLLER-PIGEONS, Dutch, 5.

ROLLESTON, Prof., inherited effects of injuries, 12;

    —incisor teeth affected in form in cases of pulmonary tubercle, 25.

ROMANES on sternum of the fowl, 7;

    —rudimentary organs, 24.

ROMANS, estimation of pigeons by, 6;

    —breeds of fowls possessed by, 7 (2).

ROOKS, pied, 14.

_Rosa,_ cultivated species of, 10.

_Rosa devoniensis,_ graft-hybrid produced by, on the white Banksian
rose, 11.

_Rosa indica_ and _centifolia,_ fertile hybrids of, 10.

_Rosa spinosissima,_ history of the culture of, 10.

ROSELLINI, on Egyptian dogs, 1.

ROSES, 10 (2);

    —origin of, 10;

    —bud-variation in, 11;

    —Scotch, doubled by selection, 20;

    —continuous variation of, 21;

    —effect of seasonal conditions on, 23;

    —noisette, 20;

    —galls of, 23.

ROSS, Dr., on Pangenesis, 27 (2).

ROUENNAIS, rabbit, 4.

ROUJOU, polydactylism, and arrested development, 12.

ROULIN, on the dogs of Juan Fernandez, 1;

    —on South American cats, 1;

    —striped young pigs, 3;

    —feral pigs in South America, 3, 13;

    —on Columbian cattle, 3, 20, 21;

    —effects of heat on the hides of cattle in South America, 3;

    —fleece of sheep in the hot valleys of the Cordilleras, 3;

    —diminished fertility of these sheep, 18;

    —on black-boned South American fowls, 7;

    —variation of the guinea-fowl in tropical America, 8;

    —frequency of striped legs in mules, 13;

    —geese in Bogota, 18;

    —sterility of fowls introduced into Bolivia, 18.

ROY, M., on a variety of _Magnolia grandiflora,_ 24.

ROYLE, Dr., Indian varieties of the mulberry, 10;

    —on _Agave vivipara,_ 18;

    —variety of rice not requiring irrigation, 24;

    —sheep from the Cape in India, 24.

_Rubus,_ pollen of, 22.

RUDIMENTARY organs, 1, 24.

RUFZ DE LAVISON, extinction of breeds of dogs in France, 28.

RUMINANTS, general fertility of, in captivity, 18.

RUMPLESS fowls, 7.

RUNTS, 5;

    —history of, 6;

    —lower jaws and skull figured, 5.

RUSSELL, Lord A., spiegelcarpe, 21.

RUSSIAN or Himalayan rabbit, 4.

RUTIMEYER, Prof., dogs of the Neolithic period, 1;

    —horses of Swiss lake-dwellings, 2;

    —diversity of early domesticated horses, 2;

    —pigs of the Swiss lake-dwellings, 3 (2);

    —on humped cattle, 3;

    —parentage of European breeds of cattle, 3, 28;

    —on “Niata” cattle, 3;

    —sheep of the Swiss lake-dwellings, 3, 28;

    —goats of the Swiss lake-dwellings, 3;

    —absence of fowls in the Swiss lake-dwellings, 7;

    —on crossing cattle, 15;

    —differences in the bones of wild and domesticated animals, 23;

    —decrease in size of wild European animals, 28.

RYE, wild, De Candolle’s observations on, 9;

    —found in the Swiss lake-dwellings, 9;

    —common, preferred by hares and rabbits, 21;

    —less variable than other cultivated plants, 22.

SABINE, Mr., on the cultivation of _Rosa spinosissima,_ 10;

    —on the cultivation of the dahlia, 10 (2), 22;

    —effect of foreign pollen on the seed-vessel in _Amaryllis
    vittata,_ 11.

ST. ANGE, influence of the pelvis on the shape of the kidneys in birds,
26.

ST. DOMINGO, wild dogs of, 1;

    —bud-variation of dahlias in, 11.

ST. HILAIRE, AUG., milk furnished by cows in South America, 24;

    —husked form of maize, 9.

ST. JOHN, C., feral cats in Scotland, 1;

    —taming of wild ducks, 8.

ST. VALÉRY apple, singular structure of the, 10;

    —artificial fecundation of the, 11.

ST. VITUS’ Dance, period of appearance of, 14.

SACHS, Prof., flow of sap, 24.

SAGERET, origin and varieties of the cherry, 10 (2);

    —origin of varieties of the apple, 10;

    —incapacity of the cucumber for crossing with other species, 10;

    —varieties of the melon, 10;

    —supposed twin-mongrel melon, 11;

    —crossing melons, 16, 17;

    —on gourds, 16;

    —effects of selection in enlarging fruit, 20;

    —on the tendency to depart from type, 21;

    —variation of plants in particular soils, 23.

SALAMANDER, experiments on the, 24, 27 (2);

    —regeneration of lost parts in the, 27.

_Salamandra cristata,_ polydactylism in, 12.

SALISBURY, Mr., on the production of nectarines by peach-trees, 10;

    —on the dahlia, 10 (2).

_Salix,_ intercrossing of species of, 10.

_Salix humilis,_ galls of, 23 (2).

SALLÉ, feral guinea-fowl in St. Domingo, 8.

SALMON, early breeding of male, 27.

SALTER, Mr., on bud-variation in pelargoniums, 11;

    —in the Chrysanthemum, 11;

    —transmission of variegated leaves by seed, 11;

    —bud-variation by suckers in _ Phlox,_ 11;

    —application of selection to bud-varieties of plants, 11;

    —accumulative effect of changed conditions of life, 22;

    —on the variegation of strawberry leaves, 23;

    —on pollen within ovules, 27.

SALTER, S. J., hybrids of _Gallus sonneratii_ and the common fowl, 7;

    —crossing of races or species of rats, 15.

SALVIN, habits of the jackal, 1;

    —mutilation inherited in mot-mot, 12.

SAMESREUTHER, on inheritance in cattle, 12.

SANDFORD. _See_ DAWKINS.

SANSON, M., origin of the horse, 2;

    —lumbar vertebra of pigs, 3.

SAP, ascent of the, 24.

_Saponaria calabrica,_ 12.

SAPORTA, on Pistacia, 11.

SARDINIA, ponies of, 2.

SARS, on the development of the hydroida, 27.

SATIATION of the stigma, 11 (2).

_Saturnia pyri,_ sterility of, in confinement, 18.

SAUL, on the management of prize gooseberries, 10.

SAUVIGNY, varieties of the gold-fish, 8.

SAVAGES, their indiscriminate use of plants as food, 9;

    —fondness of, for taming animals, 18.

SAVI, effect of foreign pollen on maize, 11.

_Saxifraga geum,_ 18.

SAYZID MOHAMMED MUSARI, on carrier-pigeons, 5;

    —on a pigeon which utters the sound “Yahu,” 5.

SCANDEROONS (pigeons), 5 (2).

SCANIA, remains of _Bos frontosus_ found in, 3.

SCAPULA, characters of, in rabbits, 4;

    —in fowls, 7;

    —in pigeons, 5;

    —alteration of, by disuse, in pigeons, 5.

SCARLET fever, 23.

SCHAAFFHAUSEN on the horses represented in Greek statues, 20.

SCHLEIDEN, excess of nourishment a cause of variability, 22.

SCHMERLING, Dr., varieties of the dog found in a cave, 1.

SCHOMBURGK, Sir R., on the dogs of Indians of Guiana, 1 (2), 20;

    —on the musk duck, 6;

    —bud-variation in the banana, 11;

    —reversion of varieties of the China rose in St. Domingo, 11;

    —sterility of tame parrots in Guiana, 18;

    —on _Dendrocygna viduata,_ 18;

    —selection of fowls in Guiana, 20.

SCHREIBERS, on _Proteus,_ 24.

SCHÜTZE on the Torfschwein, 3.

_Sciuropterus volucella,_ 18.

_Sciurus palmarum_ and _cinerea,_ 18.

SCLATER, P. L., on _Asinus tæniopus,_ 2, 13;

    —on _Asinus indicus,_ 13;

    —striped character of young wild pigs, 3;

    —osteology of _Gallinula nesiotis,_ 8;

    —on the black-shouldered peacock, 8;

    —animals breeding in Zoological Gardens, 18;

    —birds breeding in Zoological Gardens, 18;

    —on the breeding of birds in captivity, 18 (2).

SCOTCH fir, local variation of, 10.

SCOTCH kail and cabbage, cross between, 15.

SCOTT, JOHN, irregularities in the sex of the flowers of maize, 9;

    —bud-variation in _Imatophylium miniatum,_ 11;

    —crossing of species of _ Verbascum,_ 16 (2);

    —self-sterility of _Verbascum,_ 17;

    —experiments on crossing _ Primulæ,_ 16;

    —reproduction of orchids, 17;

    —fertility of _Oncidium divaricatum,_ 18;

    —acclimatisation of the sweet pea in India, 24;

    —number of seeds in _Acropera_ and _Gongora,_ 27.

SCROPE, on the Scotch deerhound, 14, 17.

SCUDDER, Dr., on regrowth, 27.

SEBRIGHT, Sir John, effects of close interbreeding in dogs, 20;

    —care taken by, in selection of fowls, 20.

_Secale cereale,_ 22.

SEDGWICK, W., effects of crossing on the female, 11;

    —on the “Porcupine man,” 12;

    —on hereditary diseases, 12;

    —hereditary affections of the eye, 12, 14;

    —inheritance of polydactylism and anomalies of the extremities, 12
    (2);

    —morbid uniformity in the same family, 12;

    —on deaf-mutes, 12;

    —inheritance of injury to the eye, 12;

    —atavism in diseases and anomalies of structure, 13;

    —non-reversion to night-blindness, 13;

    —sexual limitation of the transmission of peculiarities in man, 14
    (2);

    —on the effects of hard-drinking, 23;

    —inherited baldness with deficiency of teeth, 25 (2);

    —occurrence of a molar tooth in place of an incisor, 27;

    —diseases occurring in alternate generations, 27.

SEDILLOT, on the removal of portions of bone, 24.

SEEDS, early selection of, 20;

    —rudimentary, in grapes, 24;

    —relative position of, in the capsule, 26.

SEEDS and buds, close analogies of, 11.

SEEMANN, B., crossing of the wolf and Esquimaux dogs, 1.

SEGREGATION of characters, 11 (2).

SELBY, P. J., on the bud-destroying habits of the bullfinch, 21.

SELECTION, 20;

    —methodical, 6, 20, 21;

    —by the ancients and semi-civilised people, 20;

    —of trifling characters, 20;

    —unconscious, 6 (2);

    —effects of, shown by differences in most valued parts, 20;

    —produced by accumulation of variability, 20;

    —natural, as affecting domestic productions, 19, 21;

    —as the origin of species, genera, and other groups, 28;

    —circumstances favourable to, 21;

    —tendency of, towards extremes, 21;

    —possible limit of, 21;

    —influence of time on, 21 (2);

    —summary of subject, 21 (2);

    —effects of, in modifying breeds of cattle, 3;

    —in preserving the purity of breeds of sheep, 3 (2);

    —in producing varieties of pigeons, 6;

    —in breeding fowls, 7 (2);

    —in the goose, 8;

    —in the canary, 8;

    —in the gold-fish, 8;

    —in the silkworm, 8 (2);

    —contrasted in cabbages and cereals, 9;

    —in white mulberry, 10;

    —on gooseberries, 10;

    —applied to wheat, 9 (2);

    —exemplified in carrots, etc., 9;

    —in potato, 9;

    —in the melon, 10;

    —in flowering plants, 10;

    —in the hyacinth, 10;

    —applied to bud-varieties of plants, 11;

    —illustrations of, 28.

SELECTION, sexual, 14.

SELF-IMPOTENCE in plants, 17;

    —in individual plants, 17;

    —of hybrids, 19.

SELWYN, Mr., on the Dingo, 1.

SELYS-LONGCHAMPS, on hybrid ducks, 6, 13, 18;

    —hybrid of the hook-billed duck and Egyptian goose, 8.

SERINGE, on the St. Valéry apple, 10.

SERPENT melon, 10, 25.

SERRES, OLIVIER DE, wild poultry in Guiana, 7.

SESAMUM, white-seeded, antiquity of the, 28.

_Setaria,_ found in the Swiss lake-dwellings, 9.

SETTEGAST, sheep poisoned by buckwheat, 25.

SETTERS, degeneration of, in India, 1;

    —Youatt’s remarks on, 1.

SEX, secondary characters of, latent, 13 (2);

    —of parents, influence of, on hybrids, 22.

SEXUAL characters, sometimes lost in domestication, 14.

SEXUAL limitation of characters, 14.

SEXUAL peculiarities, induced by domestication in sheep, 3;

    —in fowls, 7;

    —transfer of, 7.

SEXUAL variability in pigeons, 5 (2).

SEXUAL selection, 14.

SHADDOCK, 10.

SHAILER, Mr., on the moss-rose, 11.

SHAN ponies, striped, 2.

SHANGHAI fowls, 7.

SHANGHAI sheep, their fecundity, 3.

SHEEP, disputed origin of, 3;

    —early domestication of, 3;

    —large-tailed, 3 (2), 23;

    —variations in horns, mammæ, and other characters of, 3;

    —sexual characters of, induced by domestication, 3;

    —adaptation of, to climate and pasture, 3 (2);

    —periods of gestation of, 3;

    —effect of heat on the fleece of, 3;

    —effect of selection on, 3;

    —“ancon” or “otter” breeds of, 3;

    —“Mauchamp-merino,” 3 (2);

    —cross of German and merino, 15;

    —black, of the Tarentino, 21;

    —Karakool, 23;

    —Jaffna, with callosities on the knees, 24;

    —Chinese, 24;

    —Danish, of the Bronze period, 28;

    —polydactylism in, 12;

    —occasional production of horns in hornless breeds of, 13;

    —reversion of colour in, 13;

    —influence of male, on offspring, 14;

    —sexual differences in, 14;

    —influence of crossing or segregation on, 15 (2), 16 (2);

    —interbreeding of, 17 (2);

    —effect of nourishment on the fertility of, 16;

    —value of, crossbred, 17;

    —diminished fertility of, under certain conditions, 18;

    —unconscious selection of, 20;

    —natural selection in breeds of, 21 (2);

    —reduction of bones in, 21;

    —individual differences of, 22;

    —local changes in the fleece of, in England, 23;

    —partial degeneration of, in Australia, 23;

    —correlation of horns and fleece in, 25;

    —feeding on flesh, 24;

    —acclimatisation of, 24;

    —mountain, resistance of, to severe weather, 24;

    —white, poisoned by _Hypericum crispum,_ 25.

SHEEP dogs, resembling wolves, 1;

    —mutilated tail inherited, 12.

SHELLS, sinistral and dextral, 13.

SHIRLEY, E. P., on the fallow-deer, 16, 17.

SHIRREFF Mr., new varieties of wheat, 9 (2);

    —on crossing wheat, 16;

    —variability of wheat, 11;

    —continuous variation of wheat, 21.

SHORT, D., hybrids of the domestic cat and _Felis ornata,_ 1.

SIAM, cats of, 1;

    —horses of, 2.

SIBERIA, northern range of wild horses in, 2.

SICHEL, J., on the deafness of white cats with blue eyes, 25.

SIDNEY, S., on the pedigrees of pigs, 12;

    —on cross-reversion in pigs, 13;

    —period of gestation in the pig, 3;

    —production of breeds of pigs by intercrossing, 3, 15;

    —fertility of the pig, 16;

    —effects of interbreeding on pigs, 17;

    —on the colours of pigs, 20, 21.

SIEBOLD, on the sweet potato, 21.

SIEBOLD, CARL VON, on parthenogenesis, 27.

_Silene,_ contabescence in, 18.

SILK FOWLS, 7, 14 (2).

SILK-MOTH, Arrindy, 24 (23);

    —Tarroo, 18.

SILK-MOTHS, 8;

    —domesticated, species of, 8;

    —history of, 8;

    —causes of modification in, 8;

    —differences presented by, 8;

    —crossing of, 15;

    —disease in, 21;

    —effects of disuse of parts in, 24;

    —selection practised with, 20 (2);

    —variation of, 21;

    —parthenogenesis in, 27.

SILKWORMS, variations of, 8;

    —yielding white cocoons, less liable to disease, 25.

SILVER-GREY rabbit, 4 (3).

SIMON, on the raising of eggs of the silk-moth in China, 20.

SIMONDS, J. B., period of maturity in various breeds of cattle, 3;

    —differences in the periods of dentition in sheep, 3;

    —on the teeth in cattle, sheep, etc., 25;

    —on the breeding of superior rams, 20.

SIMPSON, Sir J., regenerative power of the human embryo, 27.

_Siredon,_ breeding in the branchiferous stage, 27.

SISKIN, breeding in captivity, 18.

_Sivatherium,_ resemblance of the, to Niata cattle, 3.

SIZE, difference of, an obstacle to crossing, 16.

SKIN, and its appendages, homologous, 25;

    —hereditary affections of the, 14.

SKIRVING, R. S., on pigeons settling on trees in Egypt, 6.

SKULL, characters of the, in breeds of dogs, 1;

    —in breeds of pigs, 3;

    —in rabbits, 4 (2);

    —in breeds of pigeons, 5 (2);

    —in breeds of fowls, 7;

    —in ducks, 8 (2).

SKULL and horns, correlation of the, 25.

SKYLARK, 18.

SLEEMAN, on the cheetah, 18.

SLOE, 10.

SMALL-POX, 27.

SMITER (pigeon), 5.

SMITH, Sir A., on Caffrarian cattle, 3;

    —on the use of numerous plants as food in South Africa, 9.

SMITH, Colonel HAMILTON, on the odour of the jackal, 1;

    —on the origin of the dog, 1;

    —wild dogs in St. Domingo, 1;

    —on the Thibet mastiff and the alco, 1;

    —development of the fifth toe in the hind feet of mastiffs, 1;

    —differences in the skull of dogs, 1;

    —history of the pointer, 1;

    —on the ears of the dog, 24;

    —on the breeds of horses, 2;

    —origin of the horse, 2;

    —dappling of horses, 2;

    —striped horses in Spain, 2;

    —original colour of the horse, 2;

    —on horses scraping away snow, 2;

    —on _Asinus hemionus,_ 13;

    —feral pigs of Jamaica, 3 (2).

SMITH, Sir J. E., production of nectarines and peaches by the same
tree, 10;

    —on _Viola amoena,_ 10;

    —sterility of _Vinca minor_ in England, 18.

SMITH, J., development of the ovary in _Bonatea speciosa_ by irritation
of the stigma, 11.

SMITH, N. H., influence of the bull “Favourite” on the breed of
Shorthorn cattle, 14.

SMITH, W., on the intercrossing of strawberries, 10.

SNAKE-RAT, 15 (2).

SNAKES, form of the viscera in, 26.

SNAPDRAGON, bud-variation in, 11;

    —non-inheritance of colour in, 12;

    —peloric, crossed with the normal form, 14, 15;

    —asymmetrical variation of the, 25.

SOIL, adaptation of plums to, 10;

    —influence of, on the zones of pelargoniums, 10;

    —on roses, 10;

    —on the variegation of leaves, 11;

    —advantages of change of, 18.

SOIL and climate, effects of, on strawberries, 10.

_Solanum,_ non-intercrossing of species of, 15.

_Solanum tuberosum,_ 9 (2), 11.

SOLID-HOOFED pigs,3.

SOLOMON, his stud of horses, 2.

SOMERVILLE, Lord, on the fleece of Merino sheep, 3;

    —on crossing sheep, 17;

    —on selection of sheep, 20;

    —diminished fertility of Merino sheep brought from Spain, 18.

SOOTY fowls, 7 (2).

_Sorghum,_ 10.

SOTO, FERDINAND DE, on the cultivation of native plants in Florida, 9.

SPAIN, hawthorn monogynous in, 10.

SPALLANZANI, on feral rabbits in Lipari, 4;

    —experiments on salamanders, 24, 27 (2);

    —experiments in feeding a pigeon with meat, 24.

SPANIELS, in India, 1;

    —King Charles’s, 1;

    —degeneration of, caused by interbreeding, 17.

SPANISH fowls, 7 (3);

    —figured, 7;

    —early development of sexual characters in, 7;

    —furculum of, figured, 7.

SPECIES, difficulty of distinguishing from varieties, Introduction;

    —conversion of varieties into, Introduction;

    —origin of, by natural selection, 28;

    —by mutual sterility of varieties, 19.

SPENCER, Lord, on selection in breeding, 20.

SPENCER, HERBERT, on the “survival of the fittest,” Introduction;

    —increase of fertility by domestication, 16;

    —on life, 18, 19;

    —changes produced by external conditions, 23;

    —effects of use on organs, 24;

    —ascent of the sap in trees, 24;

    —correlation exemplified in the Irish elk, 25 (2);

    —on “physiological units,” 27;

    —antagonism of growth and reproduction, 27.

SPERMATOPHORES of the cephalopoda, 27.

SPERMATOZOIDS, 27 (2).

SPHINGIDÆ, sterility of, in captivity, 18.

SPINOLA, on the injurious effect produced by flowering buckwheat on
white pigs, 25.

SPITZ dog, 1.

SPOONER, W. C., cross-breeding of sheep, 3, 15 (2), 17;

    —on the effects of crossing, 15 (2);

    —on crossing cattle, 17;

    —individual sterility, 18.

SPORES, reproduction of abnormal forms by, 11.

SPORTS, 11;

    —in pigeons, 6.

SPOT pigeon, 5, 6.

SPRENGEL, C. K., on dichogamous plants, 15;

    —on the hollyhock, 16;

    —on the functions of flowers, 19.

SPROULE, Mr., transmission of hare-lip, 12.

SPURS, of fowls, 7;

    —development of, in hens, 24.

SQUASHES, 10.

SQUINTING, hereditary, 12.

SQUIRRELS, generally sterile in captivity, 18.

SQUIRRELS, flying, breeding in confinement, 18.

“STAARHALSIGE Taube,” 5.

STAG, one-horned, supposed heredity of character in, 12;

    —degeneracy of, in the Highlands, 20.

STAMENS, occurrence of rudimentary, 24;

    —conversion of, into pistils, 10;

    —into petals, 27.

_Staphylea,_ 18.

STEENSTRUP, Prof., on the dog of the Danish Middens, 1;

    —on the obliquity of flounders, 13.

STEINAN, J., on hereditary diseases, 12, 14.

STEPHENS, J. F., on the habits of the Bombycidæ, 8.

STERILITY, in dogs, consequent on close confinement, 1;

    —comparative, of crosses, 16 (2);

    —from changed conditions of life, 18;

    —occurring in the descendants of wild animals bred in captivity,
    18;

    —individual, 18;

    —resulting from propagation by buds, cuttings, bulbs, etc., 18;

    —in hybrids, 19, 27, 28 (2);

    —in specific hybrids of pigeons, 6;

    —as connected with natural selection, 19.

STERNUM, characters of the, in rabbits, 4;

    —in pigeons, 5 (2);

    —in fowls, 7 (2);

    —effects of disuse on the, 5 (2).

STEWART, H., on hereditary disease, 14.

STIGMA, variation of the, in cultivated Cucurbitaceæ, 10;

    —satiation of the, 11 (2).

STOCKHOLM, fruit-trees of, 24.

STOCKS, bud-variation in, 11;

    —effect of crossing upon the colour of the seed of, 11;

    —true by seed, 12;

    —crosses of, 15;

    —varieties of, produced by selection, 20;

    —reversion by the upper seeds in the pods of, 26.

STOCKTON, HOUGH, direct action of pollen, 11.

STOKES, Prof., calculation of the chance of transmission of abnormal
peculiarities in man, 12.

STOLONS, variations in the production of, by strawberries, 10.

STOMACH, structure of the, affected by food, 24.

STONE in the bladder, hereditary, 12, 14.

STONEHENGE, on maturity of the dog, 1;

    —inherited effects of injury, 12;

    —cross between bulldog and greyhound, 15;

    —close interbreeding of greyhound, 17;

    —fleetness of racehorses, 21.

STORER, J., pedigree of cattle, 17.

STRAWBERRIES, 10;

    —remarkable varieties of, 10 (2);

    —hautbois diœcious, 10;

    —selection in, 20;

    —probable further modification of, 6;

    —variegated, effects of soil on, 23.

STRICKLAND, A., on the domestication of _Anser ferus,_ 8;

    —on the colour of the bill and legs in geese, 8.

_Strictœnas,_ 6.

STRIPES on young of wild swine, 3;

    —of domestic pigs of Turkey, Westphalia, and the Zambesi, 3;

    —of feral swine of Jamaica and New Granada, 3;

    —of fruit and flowers, 11, 13;

    —in horses, 2;

    —in the ass, 2 (2);

    —production of, by crossing species of Equidæ, 13 (2).

_Strix grallaria,_ 24.

_Strix passerina,_ 18.

“STRUPP-TAUBE,” 5.

STRUTHERS, D., osteology of the feet in solid-hoofed pigs, 3;

    —on polydactylism, 12 (2).

STURM, prepotency of transmission of characters in sheep and cattle,
14;

    —absorption of the minority in crossed races, 15;

    —correlation of twisted horns and curled wool in sheep, 25.

SUB-SPECIES, wild, of _Columba livia_ and other pigeons, 6.

SUCCESSION, geological, of organisms, Introduction.

SUCKERS, bud-variation by, 11.

SUGAR-CANE, sterility of, in various countries, 18;

    —sporting of, 11;

    —white, liability of, to disease, 21, 25.

SUICIDE, hereditary tendency to, 12, 14.

SULIVAN, Admiral, on the horses of the Falkland Islands, 2;

    —wild pigs of the Falkland Islands, 3;

    —feral cattle of the Falkland Islands, 3 (2);

    —feral rabbits of the Falkland Islands, 4.

SULTAN fowl, 7 (2).

_Sus indicus,_ 3 (2), 16.

_Sus pliciceps_ (figured), 3.

_Sus scrofa,_ 3 (2), 16.

_Sus scrofa palustris,_ 3.

_Sus sennariensis,_ 3.

_Sus vittatus,_ 3.

SWALLOWS, a breed of pigeons, 2.

SWEET peas, 15;

    —crosses of, 15;

    —varieties of, coming true by seed, 12;

    —acclimatisation of, in India, 8.

SWEET William, bud-variation in, 11.

SWINHOE, R., on Chinese pigeons, 5, 6;

    —on striped Chinese horses, 2;

    —on the japanned peacock, 8.

SWITZERLAND, ancient dogs of, 1;

    —pigs of, in the Neolithic period, 3;

    —goats of, 3.

SYCAMORE, pale-leaved variety of the, 25.

SYKES, Colonel, on a pariah dog with crooked legs, 1;

    —on small Indian asses, 2;

    —on _Gallus sonneratii,_ 7;

    —on the voice of the Indian Kulm cock, 7;

    —fertility of the fowl in most climates, 18.

SYMMETRY, hereditary departures from, 12.

_Symphytum,_ variegated, 11.

SYPHILIS, hereditary, 25.

SYRIA, asses of, 2.

_Syringa persica, chinensis,_ and _vulgaris,_ 18.

TACITUS, on the care taken by the Celts in breeding animals, 20.

_Tagetes signata,_ dwarf variety of, 12.

TAHITI, varieties of cultivated plants in, 22.

TAIL, never curled in wild animals, 24;

    —rudimentary in Chinese sheep, 24.

TAIL-FEATHERS, numbers of, in breeds of pigeons, 5 (2);

    —peculiarities of, in cocks, 7;

    —variability of, in fowls, 7;

    —curled, in _Anas boschas,_ and tame drakes, 8.

TAIT, LAWSON, presence of hairs and teeth in ovarian tumours, 27.

TALENT, hereditary, 12.

TANKERVILLE, Earl of, on Chillingham cattle, 3, 17.

TANNER, Prof., effects of disuse of parts in cattle, 24.

TAPIR, sterility of the, in captivity, 18.

TARGIONI-TOZZETTI, on cultivated plants, 9;

    —on the vine, 10;

    —varieties of the peach, 10;

    —origin and varieties of the plum, 10;

    —origin of the cherry, 10;

    —origin of roses, 10.

TARSUS, variability of the, in fowls, 7;

    —reproduction of the, in a thrush, 27.

TARTARS, their preference for spiral-horned sheep, 20.

TAVERNIER, abundance of pigeons in Persia, 6.

_Taxus baccata,_ 12.

TAYLOR, Mr., potato-grafting, 11.

TEEBAY, Mr., reversion in fowls, 13.

TEETH, number and position of, in dogs, 1;

    —deficiency of, in naked Turkish dogs, 1;

    —period of appearance of, in breeds of dogs, 1;

    —precocity of, in highly-bred animals, 25;

    —correlation of, with hair, 25;

    —double row of, with redundant hair, in Julia Pastrana, 25;

    —affected in form by hereditary syphilis and by pulmonary tubercle,
    25;

    —developed on the palate, 27.

TEGETMEIER, Mr., on a cat with monstrous teeth, 1;

    —on a swift-like pigeon, 5;

    —on sexual colours, 5;

    —naked young of some pigeons, 5;

    —fertility of hybrid pigeons, 6;

    —on white pigeons, 21;

    —reversion in crossed breeds of fowls, 7;

    —chicks of the white silk fowl, 7;

    —development of the cranial protuberance in Polish fowls, 7;

    —on the skull in the Polish fowl, 7 (2);

    —on the intelligence of Polish fowls, 7;

    —correlation of the cranial protuberance and crest in Polish fowls,
    7;

    —development of the web in the feet of Polish fowls, 7;

    —early development of several peculiarities in Spanish cocks, 7;

    —on the comb in Spanish fowls, 7;

    —on the Spanish fowl, 24;

    —varieties of game-fowls, 7;

    —pedigrees of game-fowls, 12;

    —assumption of female plumage by a game-cock, 7;

    —natural selection in the game-cock, 21;

    —pugnacity of game-hens, 7;

    —length of the middle toe in Cochin fowls, 7;

    —origin of the Sebright bantam, 13;

    —differences in the size of fowls, 7;

    —effect of crossing in fowls, 7;

    —effects of interbreeding in fowls, 17 (2);

    —incubation by mongrels of non-sitting races of fowls, 13;

    —inverse correlation of crest and comb in fowls, 7;

    —occurrence of pencilled feathers in fowls, 13;

    —on a variety of the goose from Sebastopol, 8;

    —on the fertility of the peahen, 16;

    —on the intercrossing of bees, 17.

TEMMINCK, origin of domestic cats, 1;

    —origin of domestic pigeons, 6;

    —on _Columba guinea,_ 6;

    —on _Columba leucocephala,_ 6;

    —asserted reluctance of some breeds of pigeons to cross, 6;

    —sterility of hybrid turtle-doves, 6;

    —variations of _Gallus bankiva,_ 7;

    —on a buff-coloured breed of turkeys, 8;

    —number of eggs laid by the peahen, 16;

    —breeding of guans in captivity, 18;

    —behaviour of grouse in captivity, 18;

    —sterility of the partridge in captivity, 18.

TENDRILS in Cucurbitaceæ, 10, 24.

TENNENT, Sir J. E., on the goose, 8;

    —on the growth of the apple in Ceylon, 23;

    —on the Jaffna sheep, 24.

_Teredo,_ fertilisation in, 27.

TERRIERS, wry-legged, 21;

    —white, subject to distemper, 25.

TESCHEMACHER, on a husked form of maize, 9.

TESSIER, on the period of gestation of the dog, 1;

    —of the pig, 3;

    —in cattle, 3;

    —experiments on change of soil, 18.

_Tetrao,_ breeding of species of, in captivity, 18.

_Tetrapteryx paradisea,_ 18.

_Teucrium campanulatum,_ pelorism in, 26.

TEXAS, feral cattle in, 3.

THEOGNIS, his notice of the domestic fowl, 7.

THEOPHRASTUS, his notice of the peach, 24.

_Thesium,_ 23.

THOMPSON, Mr., on the peach and nectarine, 10;

    —on the varieties of the apricot, 10;

    —classification of varieties of cherries, 10;

    —on the “Sister ribston-pippin,” 10;

    —on the varieties of the gooseberry, 10 (2).

THOMPSON, WILLIAM, on the pigeons of Islay, 6;

    —feral pigeons in Scotland, 6;

    —colour of the bill and legs in geese, 8;

    —breeding of _Tetrao scotius_ in captivity, 18;

    —destruction of black fowls by the osprey, 21.

THORN, grafting of early and late, 10;

    —Glastonbury, 10.

THORNS, reconversion of, into branches, in pear trees, 24.

THRUSH, asserted reproduction of the tarsus in a, 27.

_Thuja pendula_ or _filiformis,_ a variety of _T. orientalis,_ 10.

THURET, on the division of the zoospores of an alga, 27.

THWAITES, G. H., on the cats of Ceylon, 1;

    —on a twin seed of _Fuchsia coccinea_ and _fulgens,_ 11.

TIBURTIUS, experiments in rearing wild ducks, 8.

TIGER, rarely fertile in captivity, 18.

_Tigridia conchiflora,_ bud-variation in, 11.

TIME, importance of, in the production of races, 21.

TINZMANN, self-impotence in the potato, 17.

TISSUES, affinity of, for special organic substances, 27.

TITMICE, destructive to thin-shelled walnuts, 10;

    —attacking nuts, 10;

    —attacking peas, 21.

TOBACCO, crossing of varieties of, 16;

    —cultivation of, in Sweden, 24.

TOBOLSK, red-coloured cats of, 1.

TOES, relative length of, in fowls, 7;

    —development of fifth, in dogs, 24.

TOLLET, Mr., his selection of cattle, 20.

TOMATO, 15.

TOMES, inheritance of dental malformations, 12.

TOMTITS. _See_ TITMICE.

TONGUE, relation of, to the beak in pigeons, 3.

TOOTH, occurrence of a molar, in place of an incisor, 27.

“TORFSCHWEIN,” 3.

TRAIL, R., on the union of half-tubers of different kinds of potatoes,
11.

TREES, varieties of, suddenly produced, 10;

    —weeping or pendulous, 10;

    —fastigiate or pyramidal, 10;

    —with variegated or changed foliage, 10;

    —early or late in leaf, 10;

    —forest, non-application of selection to, 21.

“TREMBLEUR” (pigeons), 5.

TREMBLEY, on reproduction in Hydra, 27.

“TREVOLTINI” silkworms, 8 (2).

_Trichosanthes anguina,_ 10.

TRICKS, inheritance of, 12 (2).

_Trifolium minus_ and _repens,_ 18.

TRIMORPHIC plants, conditions of reproduction in, 19.

TRISTRAM, H. B., selection of the dromedary, 20.

_Triticum dicoccum,_ 9.

_Triticum monococcum,_ 9.

_Triticum spelta,_ 9.

_Triticum turgidum,_ 9.

_Triticum vulgare,_ wild in Asia, 9.

TRITON, breeding in the branchiferous stage, 27.

“TROMMEL-TAUBE,” 5.

“TRONFO” pigeon, 5.

_Tropæolum,_ 13.

_Tropæolum minus_ and _majus,_ reversion in hybrids of, 22.

TROUBETZKOY, Prince, experiments with pear-trees at Moscow, 24.

TROUSSEAU, Prof., pathological resemblance of twins, 22.

TRUMPETER pigeon, 5;

    —known in 1735, 6.

TSCHARNER, H. A. DE, graft-hybrid produced by inosculation in the vine,
11.

TSCHUDI, on the naked Peruvian dog, 1;

    —extinct varieties of maize from Peruvian tombs, 9, 11.

TUBERS, bud-variation by, 11.

TUCKERMAN, Mr., sterility of _Carex rigida,_ 18.

TUFTED ducks, 8.

TULIPS, variability of, 10;

    —bud-variation in, 11 (2);

    —influence of soil in “breaking,” 11.

TUMBLER pigeon, 5;

    —short-faced, figured, 5;

    —skull figured, 5;

    —lower jaw figured, 5;

    —scapula and furculum figured, 5;

    —early known in India, 6;

    —history of, 6;

    —sub-breeds of, 6;

    —young, unable to break the egg-shell, 21;

    —probable further modification of, 21.

“TÜMMLER” (pigeons), 5.

TUMOURS, ovarian, occurrence of hairs and teeth in, 27;

    —polypoid, origin of, 27.

TURBIT (pigeon), 5, 6.

TURKEY, domestic, origin of, 8;

    —crossing of, with North American wild turkey, 8 (2);

    —breeds of, 8;

    —crested white cock, 8;

    —wild, characters of, 8 (2);

    —degeneration of, in India, 8, 23;

    —failure of eggs of, in Delhi, 18;

    —feral, on the Parana, 6;

    —change produced in, by domestication, 22.

TURKEY, striped young pigs in, 3.

“TURKISCHE TAUBE,” 5.

TURNER (pigeon), 5.

TURNER, C., on the hollyhock, 3.

TURNER, W., on cells, 27.

TURNIPS, origin of, 9;

    —reversion in, 13;

    —run wild, 13;

    —crosses of, 15 (2);

    —Swedish, preferred by hares, 21;

    —acclimatisation of, in India, 24.

TURNSPIT, on an Egyptian monument, 1;

    —crosses of the, 15.

TURTLE-DOVE, white and coloured, crossing of, 15.

_Turtur auritus,_ hybrids of, with _T. cambayensis_ and _T.
suratensis,_ 6.

_Turtur risorius,_ crossing of, with the common pigeon, 6;

    —hybrids of with _T. vulgaris,_ 6.

_Turtur suratensis,_ sterile hybrids of, with _T. vulgaris,_ 6;

    —hybrids of, with _T. auritus,_ 6.

_Turtur vulgaris,_ crossing of, with the common pigeon, 6;

    —hybrid of, with _T. risorius,_ 6;

    —sterile hybrids of, with _T. suratensis_ and _Ectopistes
    migratorius,_ 6.

TUSKS of wild and domesticated pigs, 3 (2).

_Tussilago farfara,_ variegated, 11.

TWIN-SEED of _Fuchsia coccinea_ and _fulgens,_ 11.

TYERMAN, B., on the pigs of the Pacific Islands, 3, 15;

    —on the dogs of the Pacific Islands, 15.

TYLOR, Mr., on the prohibition of consanguineous marriages, 17.

UDDERS, development of the, 24.

_Ulex,_ double-flowered, 18.

_Ulmus campestris_ and _effusa,_ hybrids of, 17.

UNIFORMITY of character, maintained by crossing, 15.

UNITS of the body, functional independence of the, 27.

UNITY or plurality of origin of organisms, Introduction.

UREA, secretion of, 27.

USE and disuse of parts, effects of, 24 (2), 26 (2), 28 (2);

    —in rabbits, 4;

    —in ducks, 8.

UTILITY, considerations of, leading to uniformity, 21.

VALENTIN, experimental production of double monsters by, 27.

_Vallota,_ 17.

VAN BECK, BARBARA, a hairy-faced woman, 12.

VAN MONS, on wild fruit-trees, 9, 22;

    —production of varieties of the vine, 10;

    —correlated variability in fruit-trees, 25;

    —production of almond-like fruit by peach-seedlings, 10.

_Vanessa,_ species of, not copulating in captivity, 18.

VARIABILITY, Introduction, 27 (2), 28;

    —causes of, 22;

    —correlated, 25, 26 (2), 28 (2);

    —law of, equable, 26 (2);

    —necessity of, for selection, 19;

    —of selected characters, 21;

    —of multiple homologous parts, 26.

VARIATION, laws of, 24;

    —continuity of, 21;

    —possible limitation of, 21, 28 (2);

    —in domestic cats, 1;

    —origin of breeds of cattle by, 3;

    —in osteological characters of rabbits, 4;

    —of important organs, 10;

    —analogous or parallel, 9;

    —in horses, 2;

    —in the horse and ass, 2;

    —in fowls, 7;

    —in geese, 8;

    —exemplified in the production of fleshy stems in cabbages, etc.,
    9;

    —in the peach, nectarine, and apricot, 10 (2);

    —individual, in wheat, 9.

VARIEGATION of foliage, 11, 18.

VARIETIES and species, resemblance of, Introduction, 28;

    —conversion of, into species, Introduction;

    —abnormal, 28;

    —domestic, gradually produced, 28.

VARRO, on domestic ducks, 8;

    —on feral fowls, 13;

    —crossing of the wild and domestic ass, 20.

VASEY, Mr., on the number of sacral vertebræ in ordinary and humped
cattle, 3;

    —on Hungarian cattle, 3.

VAUCHER, sterility of _Ranunculus ficaria_ and _Acorus calamus,_ 18.

VEGETABLES, cultivated, reversion in, 13;

    —European, culture of, in India, 18 (2).

VEITH, Mr., on breeds of horses, 2.

_Verbascum,_ intercrossing of species of, 10, 15, 16;

    —reversion in hybrids of, 11;

    —self-sterility of, 17;

    —contabescent, wild plants of, 18;

    —villosity in, 23.

_Verbascum austriacum,_ 17.

_Verbascum blattaria,_ 16 (2).

_Verbascum lychnitis,_ 16 (2), 17.

_Verbascum nigrum,_ 17.

_Verbascum phœniceum,_ 16, 17;

    —variable duration of, 24.

_Verbascum thapsus,_ 16, 17.

VERBENAS, origin of, 10;

    —white, liability of, to mildew, 21 (2);

    —scorching of dark, 21 (2);

    —effect of changed conditions of life on, 23.

VERLOT, on the dark-leaved barberry, 10;

    —inheritance of peculiarities of foliage in trees, 10;

    —production of _Rosa cannabifolia_ by bud-variation from _R. alba,_
    11;

    —bud-variation in _Aralia trifoliata,_ 11;

    —variegation of leaves, 11;

    —colours of tulips, 11;

    —uncertainty of inheritance, 12;

    —persistency of white flowers, 12;

    —peloric flowers of _Linaria,_ 13;

    —tendency of striped flowers to uniformity of colour, 14;

    —non-intercrossing of certain allied plants, 15;

    —sterility of _Primulæ_ with coloured calyces, 18;

    —on fertile proliferous flowers, 18;

    —on the Irish yew, 21;

    —differences in the _Camellia,_ 22;

    —effect of soil on the variegated strawberry, 23;

    —correlated variability in plants, 25.

_Verruca,_ 13, 27.

VERTEBRAE, characters of, in rabbits, 4;

    —in ducks, 8 (2);

    —number and variations of, in pigeons, 5 (2);

    —number and characters of, in fowls, 7;

    —variability of number of, in the pig, 3.

VERTUCH. _See_ PUTSCHE.

“VERUGAS,” 23.

VESPUCIUS, early cultivation in Brazil, 9.

VIBERT’S experiments on the cultivation of the vine from seed, 10.

_Viburnum opulus,_ 19, 24.

_Vicia sativa,_ leaflet converted into a tendril in, 27.

VICUNAS, selection of, 20.

VILLOSITY of plants, influenced by dryness, 23.

VILMORIN, cultivation of the wild carrot, 9, 23;

    —colours of tulips, 11;

    —uncertainty of inheritance in balsams and roses, 12;

    —experiments with dwarf varieties of _Saponaria calabrica_ and
    _Tagetes signata,_ 12;

    —reversion of flowers by stripes and blotches, 13;

    —on variability, 22.

_Vinca minor,_ sterility in, 18.

VINE, 10;

    —parsley-leaved, reversion of, 11;

    —graft-hybrid produced by inosculation in the, 11;

    —disease of, influenced by colour of grapes, 21 (2);

    —influence of climate, etc., on varieties of the, 23;

    —diminished extent of cultivation of the, 24;

    —acclimatisation of the, in the West Indies, 24.

_Viola,_ species of, 10.

_Viola lutea,_ different coloured flowers in, 11.

_Viola tricolor,_ reversion in, 13 (2).

VIRCHOW, Prof., on the growth of bones, 24, 27;

    —on cellular prolification, 16;

    —independence of the elements of the body, 27;

    —on the cell-theory, 27;

    —presence of hairs and teeth in ovarian tumours, 27;

    —of hairs in the brain, 27;

    —special affinities of the tissues, 27;

    —origin of polypoid excrescences and tumours, 27.

VIRGIL, on the selection of seed corn, 9, 20;

    —of cattle and sheep, 20.

VIRGINIAN Islands, ponies of, 2.

VISION, hereditary peculiarities of, 12 (2);

    —in amphibious animals, 20;

    —varieties of, 24;

    —affections of organs of, correlated with other peculiarities, 25.

_Vitis vinifera,_ 10, 11.

_Viverra,_ sterility of species of, in captivity, 18.

VOGEL, varieties of the date palm, 22.

VOGT, on the indications of stripes on black kittens, 13.

VOICE, differences of, in fowls, 7;

    —peculiarities of, in ducks, 8;

    —inheritance of peculiarities of, 12.

VOLZ, on the history of the dog, 1;

    —ancient history of the fowl, 7;

    —domestic ducks unknown to Aristotle, 8;

    —Indian cattle sent to Macedonia by Alexander, 20;

    —mention of mules in the Bible, 20;

    —history of the increase of breeds, 21.

VON BERG, on _Verbascum phœniceum,_ 24.

VOORHELM, G., his knowledge of hyacinths, 10, 22.

VROLIK, Prof., on polydactylism, 12;

    —influence of the shape of the mother’s pelvis on her child’s head,
    26.

WADE, drooping eyelids transmitted, 12.

WADERS, behaviour of, in confinement, 18.

WAGNER, MORITZ, oriental dogs, 21.

WAHLENBORG, on the propagation of Alpine plants by buds, runners,
bulbs, etc., 18.

“WAHLVERWANDTSCHAFT” of Gärtner, 19.

WALES, white cattle of, in the tenth century, 3.

WALKER, A., on intermarriage, 11;

    —on the inheritance of polydactylism, 12.

WALKER, D., advantage of change of soil to wheat, 18.

WALKER, R., reversion in cattle, 13.

WALLACE, A. R., on the multiple origin of the dog, 1;

    —on a striped Javanese horse, 2;

    —on the conditions of life of feral animals, 13;

    —artificial alteration of the plumage of birds, 23;

    —on polymorphic butterflies, 27;

    —on reversion, 28;

    —on the limits of change, 28.

WALLACE, Dr., on the sterility of Sphingidae hatched in autumn, 18.

WALLACHIAN sheep, sexual peculiarities in the horns of, 3.

WALLFLOWER, bud-variation in, 11.

WALLICH, Dr., on _Thuja pendula_ or _filiformis,_ 10.

WALNUTS, 10 (2);

    —thin-shelled, attacked by tomtits, 10;

    —grafting of, 22.

WALSH, B. D., on attacks of insects, 10;

    —on galls, 23 (2);

    —his “Law of equable variability,” 26 (2).

WALTHER, F. L., on the history of the dog, 1;

    —on the intercrossing of the zebu and ordinary cattle, 3.

WARING, Mr., on individual sterility, 18.

WATERER, Mr., spontaneous production of _Cytisus alpino-laburnum,_ 11.

WATERHOUSE, G. R., on the winter-colouring of _Lepus variabilis,_ 4.

WATERTON, C., production of tailless foals, 2;

    —on taming wild ducks, 8;

    —on the wildness of half-bred wild ducks, 13;

    —assumption of male characters by a hen, 13.

WATSON, H. C., on British wild fruit-trees, 9;

    —on the non-variation of weeds, 9;

    —origin of the plum, 10;

    —variation in _Pyrus malus,_ 10;

    —on _Viola amœna_ and _ tricolor,_ 10;

    —on reversion in Scotch kail, 13;

    —fertility of _Draba sylvestris_ when cultivated, 18;

    —on generally distributed British plants, 23.

WATTLES, rudimentary, in some fowls, 24.

WATTS, Miss, on Sultan fowls, 7.

WEBB, JONAS, interbreeding of sheep, 17.

WEBER, effect of the shape of the mother’s pelvis on her child’s head,
26.

WEDDERBURN, Mr., correlation of teeth and hair, 25.

WEEDS, supposed necessity for their modification, coincidently with
cultivated plants, 9.

WEEPING varieties of trees, 10.

WEEPING habit of trees, capricious inheritance of, 12 (2).

WEEVIL, injury done to stone-fruit by, in North America, 21.

WEIJENBERGH, on parthenogenesis, 27.

WEIR, H., large litter of pigs, 16.

WEIR, JENNER, on the japanned peacock, 8;

    —mare and quagga, 11;

    —wildness of mule siskins, 13.

WEISMANN, Prof., reversion from unnatural conditions, 13;

    —isolation, 23;

    —dimorphic butterflies, 23;

    —causes of variability, 23.

WELSH cattle, descended from _Bos longifrons,_ 3.

WEST Indies, feral pigs of, 3;

    —effect of climate of, upon sheep, 3.

WESTERN, Lord, change effected by, in pigs, 3 (2);

    —in the sheep, 20.

WESTPHALIA, striped young pigs in, 3.

WESTWOOD, J. O., on peloric flowers of _Calceolaria,_ 26.

WETHERELL, Mr., on inheritance of mutilations, 12.

WHATELY, Archbishop, on grafting early and late thorns, 10.

WHEAT, specific unity or diversity of, 9 (4);

    —Hasora, 9;

    —presence or absence of barbs in, 9;

    —Godron on variations in, 9;

    —varieties of, 9 (2);

    —effects of soil and climate on, 9;

    —deterioration of, 9;

    —crossing of varieties of, 9, 15, 16, 17;

    —in the Swiss lake-dwellings, 9;

    —selection applied to, 9, 20;

    —increased fertility of hybrids of, with _Ægilops,_ 16;

    —advantage of change of soil to, 18;

    —differences of, in various parts of India, 18;

    —continuous variation in, 20;

    —red, hardiness of, 21, 25;

    —Fenton, 21;

    —natural selection in, 21;

    —varieties of, found wild, 22;

    —effects of change of climate on, 24;

    —ancient variety of, 28.

WHITBY, Mrs., on the markings of silkworms, 8;

    —on the silk-moth, 8.

WHITE, Mr., reproduction of supernumerary digits after amputation, 12;

    —time occupied in the blending of crossed races, 15.

WHITE, GILBERT, vegetable diet of dogs, 24.

WHITE and white-spotted animals, liability of, to disease, 25 (2).

WHITE flowers, most truly reproduced by seed, 12.

WICHURA, MAX, on hybrid willows, 13;

    —analogy between the pollen of old-cultivated plants and of
    hybrids, 22.

WICKING, Mr., inheritance of the primary characters of _Columba livia_
in cross-bred pigeons, 6;

    —production of a white head in almond tumblers, 20.

WICKSTED, Mr., on cases of individual sterility, 18.

WIEGMANN, spontaneous crossing of blue and white peas, 11;

    —crossing of varieties of cabbage, 17;

    —on contabescence, 18.

WIGHT, Dr., sexual sterility of plants propagated by buds, etc., 18.

WILCKENS, Dr., effect of previous impregnation, 11;

    —alpine breeds, 24;

    —drooping ears, 24;

    —correlation of hair and horns, 25.

WILDE, Sir W. R., occurrence of Bos frontosus and longifrons in Irish
crannoges, 3;

    —attention paid to breeds of animals by the ancient Irish, 20.

WILDER, Dr. B., on the brain of dogs, 1;

    —supernumerary digits, 12.

WILDMAN, on the dahlia, 20, 23.

WILDNESS of the progeny of crossed tame animals, 13 (2).

WILKES, Capt., on the taming of pigeons among the Polynesians, 18.

WILKINSON, J., on crossed cattle, 16.

WILLIAMS, Mr., change of plumage in a Hamburgh hen, 7.

WILLIAMS, Mr., intercrossing of strawberries, 10.

WILLIAMSON, Capt., degeneration of dogs in India, 1;

    —on small Indian asses, 2.

WILLIAMSON, Rev. W., doubling of _Anemone coronaria_ by selection, 20.

WILLOWS, weeping, 10;

    —reversion of spiral-leaved weeping, 11;

    —hybrids of, 22;

    —galls of, 23 (2).

WILLUGHBY, F., notice of spot pigeons, 5;

    —on a fantail pigeon, 6;

    —on tumbler pigeons, 6;

    —on the turbit, 6;

    —on the barb and carrier pigeons, 6;

    —on the hook-billed duck, 8.

WILMOT, Mr., on a crested white Turkey-cock, 8;

    —reversion of sheep in colour, 13.

WILSON, B. O., fertility of hybrids of humped and ordinary cattle in
Tasmania, 3.

WILSON, Dr., prepotency of the Manx over the common cat, 14.

WILSON, JAMES, origin of dogs, 1.

WILSON, Mr., on prepotency of transmission in sheep, 14;

    —on the breeding of bulls, 20.

WINGS, proportionate length of, in different breeds of pigeons, 5 (2);

    —of fowls, effects of disuse on, 7;

    —characters and variations of, in ducks, 8;

    —diminution of, in birds of small islands, 8 (2).

WING-FEATHERS, number of, in pigeons, 5;

    —variability of, in fowls, 7.

WOLF, recent existence of, in Ireland, 1;

    —barking of young, 1;

    —hybrids of, with the dog, 1.

WOLF-DOG, black, of Florida, 1.

WOLVES, North American, their resemblance to dogs of the same region, 1
(2);

    —burrowing of, 1.

WOODBURY, Mr., crossing of the Ligurian and common hive bees, 8, 17;

    —variability of bees, 8.

WOODWARD, S. P., on Arctic Mollusca, 22.

WOOD, WILLOUGHBY, reversion from a cross, 13;

    —on Mr. Bates’ cattle, 17.

WOOLER, W. A., on the young of the Himalayan rabbit, 4;

    —persistency of the coloured calyx in a crossed polyanthus, 10.

WOUNDS, healing of, 24.

WRIGHT, J., production of crippled calves by short-horned cattle, 17;

    —on selection in cattle, 20;

    —effect of close interbreeding on pigs, 17;

    —deterioration of game-cocks by close interbreeding, 17.

WRIGHT, STRETHILL, on the development of the hydroida, 27.

WYMAN, Dr., on Niata cattle, and on a similar malformation in the
codfish, 3;

    —on Virginian pigs, 21;

    —browsing under water, 24.

XENOPHON, on the colours of hunting dogs, 20.

XIMENES, Cardinal, regulations for the selection of rams, 20.

“YAHU,” the name of the pigeon in Persia, 5.

YAKS, domestication of, 20;

    —selection of white-tailed, 20.

YAM, development of axillary bulbs in the, 18.

YARRELL, Mr., deficiency of teeth in hairless dogs, 1, 25;

    —on ducks, 8, 22;

    —characters of domestic goose, resembling those of _Anser
    albifrons,_ 8;

    —whiteness of ganders, 8;

    —variations in gold-fish, 8 (2);

    —assumption of male plumage by the hen-pheasant, 13;

    —effect of castration upon the cock, 13 (2);

    —breeding of the skylark in captivity, 18;

    —plumage of the male linnet in confinement, 18;

    —on the dingo, 22.

YELLOW fever, in Mexico, 23.

YEW, fastigiate, 21.

YEW, Irish, hardy in New York, 24.

YEW, weeping, 10;

    —propagation of, by seed, 12.

YOLK, variations of, in the eggs of ducks, 8.

YOUATT, Mr., history of the dog, 1;

    —variations of the pulse in breeds of dogs, 1;

    —liability to disease in dogs, 1, 21;

    —inheritance of goitre in dogs, 12;

    —on the greyhound, 1 (2);

    —on King Charles’ spaniels, 1;

    —on the setter, 1;

    —on breeds of horses, 2;

    —variation in the number of ribs in the horse, 2;

    —inheritance of diseases in the horse, 12 (2);

    —introduction of Eastern blood into English horses, 20 (2);

    —on white Welsh cattle, 3, 20;

    —improvement of British breeds of cattle, 3;

    —rudiments of horns in young hornless cattle, 13, 24;

    —on crossed cattle, 16, 17;

    —on Bakewell’s long-horned cattle, 17;

    —selection of qualities in cattle, 20;

    —degeneration of cattle by neglect, 21;

    —on the skull in hornless cattle, 25;

    —disease of white parts of cattle, 25;

    —displacement of long-horned by short-horned cattle, 28;

    —on Angola sheep, 3;

    —on the fleece of sheep, 3;

    —correlation of horns and fleece in sheep, 3;

    —adaptation of breeds of sheep to climate and pasture, 3;

    —horns of Wallachian sheep, 3;

    —exotic sheep in the Zoological Gardens, 3, 24;

    —occurrence of horns in hornless breeds of sheep, 13;

    —on the colour of sheep, 13;

    —on interbreeding sheep, 17;

    —on Merino rams in Germany, 20;

    —effect of unconscious selection on sheep, 20;

    —reversion of Leicester sheep on the Lammermuir Hills, 21;

    —on many-horned sheep, 25;

    —reduction of bone in sheep, 21;

    —persistency of character in breeds of animals in mountainous
    countries, 14;

    —on interbreeding, 17;

    —on the power of selection, 20 (2);

    —slowness of production of breeds, 21;

    —passages in the Bible relating to the breeding of animals, 20.

YOUNG, J., on the Belgian rabbit, 4.

YULE, Capt., on a Burmese hairy family, 14, 25.

ZAMBESI, striped young pigs on the, 3.

ZAMBOS, character of the, 13.

ZARCO, J. G., introduction of rabbits into Porto Santo by, 4.

_Zea altissima,_ 9;

    —_mays,_ 9.

ZEBU, 3;

    —domestication of the, 3;

    —fertile crossing of, with European cattle, 3, 16.

ZEBRA, hybrids of, with the ass and mare, 13.

_Zephyranthes candida,_ 18.

_Zinnia,_ cultivation of, 22.

ZOLLINGER on Malayan penguin ducks, 8.

ZOOSPORE, division of, in Algæ, 23.

“ZOPF-TAUBE,” 5.