Transcriber’s Note

In the following transcription, italic text is denoted by _underscores_
while bold text is denoted by =equal signs=. Small capitals in the
original text have been transcribed as ALL CAPITALS.

For technical reasons it has been necessary to split some long
paragraphs into two in order to allow the correct positioning of
illustrations in the HTML version of the transcription.

See end of this document for details of corrections and other changes.

             ————————————— Start of Book —————————————


                           THE MINOR HORRORS
                                OF WAR


[Illustration: Photograph of enlarged model of the house-fly (_Musca
domestica_) in the American Museum of Natural History, New York. (From
Gordon Hewitt.) P. 57.
                                                      [_Frontispiece_
]




                           THE MINOR HORRORS
                                OF WAR


                                  BY


                         A. E. SHIPLEY, Sc.D.

                      HON.SC.D. PRINCETON, F.R.S.

     MASTER OF CHRIST’S COLLEGE, CAMBRIDGE, AND READER IN ZOOLOGY
                           IN THE UNIVERSITY


                              ILLUSTRATED


                                LONDON
                 SMITH, ELDER & CO., 15 WATERLOO PLACE
                                 1915


                         [All rights reserved]




                     HENRICO ARTHURO ADEANE MALLET
                                  ET
                    HENRICO ANTONIO PATRICIO DISNEY


                        ALTERI MARI AERE ALTERI
                          UTRIQUE FIDELISSIME
                            PATRIAM TUTANTI




                                PREFACE


The contents of this little book hardly justify its title. There
are whole ranges of ‘Minor Horrors of War’ left untouched in the
following chapters. The minor poets, the pamphlets of the professors,
the people who write to the papers about ‘Kultur’ and think that this
is the German for Matthew Arnold’s over-worked word ‘Culture,’ the
half-hysterical ladies who offer white feathers to youths whose hearts
are breaking because medical officer after medical officer has refused
them the desire of their young lives to serve their country. Surely, as
Carlyle taught us, ‘_There is no animal so strange as man!_’

These ‘Minor Horrors of War,’ and many besides, have for the moment
been neglected in favour of certain others which attack the bodies, the
food, or the accoutrements of the men who are giving all that they have
to give, even unto their lives, for their homes and for their country.

I deal with certain little Invertebrata: animals which work in
darkness and in stealth, little animals which in times of Peace we
politely ignore, yet little animals which in times of War may make or
unmake an army corps. As that wise old Greek, Aristotle, wrote—and he
knew quite a lot about them—‘_One should not be childishly contemptuous
of the study of the most insignificant animal. For there is something
marvellous in all natural objects._’

We are shy of mentioning these organisms in times of Peace; but all of
them are within the cognisance of every medical officer of health and
of every police-court missionary. These gentlemen do not talk about
them in general society: the subject is as a rule ‘taboo.’ Yet if we
face these troubles with courage and frankness, they can be overcome.
As ‘Emigration Jane’ says: ‘_Well, there’s nothink lower than Nature,
an’ She Goes as ’Igh as ’Eaven._’

I confess that these articles have been written in a certain spirit
of gaiety. This is the reflex of the spirit of those who have gone
to the Front and of my fellow countrymen in general. For more years
than I care to remember, the spirit of Great Britain and of Ireland
had been sombre, self-distrusting—we were till half a year ago far
too ‘_conscious of each other’s infirmities_’; but with the outbreak
of the War everything changed. Our nearest relatives, our dearest
friends, are dead, or dying, or wounded, or prisoners; but we at home
at once caught the spirit of those who have died or have suffered
for us abroad, and we have kept and still keep a high heart. As Mrs.
Aberdeen, the immortal ‘bedmaker’ at King’s College, Cambridge, said:
_But surely, Miss, the world being what it is, the longer one is able
to laugh in it, the better._’ Mrs. Aberdeen spoke in times of Peace;
but I feel that that indomitable old lady would have said the same in
times of War.

These chapters first appeared in the columns of the _British Medical
Journal_. I very gratefully thank the editor and the proprietors of
that Journal for their permission to reprint them.

                                                    A. E. SHIPLEY.

  CHRIST’S COLLEGE LODGE,
        CAMBRIDGE.

            _February 14, 1915._




                               CONTENTS


    CHAPTER                                                     PAGE
       I. THE LOUSE (_Pediculus_)                                  1

      II. THE BED-BUG (_Cimex lectularius_)                       23

     III. THE FLEA (_Pulex irritans_)                             35

      IV. THE FLOUR-MOTH (_Ephestia kühniella_)                   46

       V. FLIES: THE HOUSE-FLY (_Musca domestica_)                57

      VI. FLIES: THE BLUE-BOTTLE (_Calliphora erythrocephala_)
            AND OTHERS                                            74

     VII. MITES: THE HARVEST-MITE (_Trombidium_)                  87

    VIII. MITES: ENDO-PARASITIC MITES (_Demodex_, _Sarcoptes_)    97

      IX. TICKS: _ARGASIDAE_, _IXODIDAE_                         112

       X. LEECHES: THE MEDICINAL LEECH (_Hirudo medicinalis_)    123

      XI. LEECHES: THE MEDICINAL LEECH (_continued_)             136

     XII. LEECHES: _Limnatis nilotica_, _Haemadipsa zeylanica_   149

          INDEX                                                  163




                             ILLUSTRATIONS


   FIG.                                                         PAGE
        Photograph of enlarged model of the house-fly (_Musca
            domestica_)                               _Frontispiece_

     1. _Pediculus vestimenti_                                     2

     2. _Pediculus vestimenti_ (dorsal and ventral views)          6

     3. _Cimex lectularius_ (male)                                24

     4. Egg of _Cimex lectularius_                                28

     5. Newly hatched young of _Cimex lectularius_                29

     6. _Pulex irritans_ (female)                                 36

     7. Larva of _Pulex irritans_                                 39

     8. Pupa of flea                                              41

     9. _Ceratophyllus gallinulae_ (male and female)              44

    10. _Ephestia kühniella._ Moth-infested biscuit               47

    11. _Ephestia kühniella_                                      49

    12. _Ephestia kühniella_ (larva and pupa)                     50

    13. _Corcyra cephalonica._ Moth-infested biscuit              51

    14. Eggs of _Musca domestica_                                 59

    15. Eggs of _M. domestica_                                    60

    16. Abdomen of female house-fly, showing the extended
            ovipositor                                            61

    17. Mature larva of _M. domestica_                            62

    18. ‘Nymph’ of _M. domestica_ dissected out of pupal-case
            about thirty hours after pupation                     63

    19. Pupal-case or puparium of _M. domestica_ from which
            the imago has emerged                                 64

    20. _M. domestica_ in the act of regurgitating food           65

    21. Foot of a fly, showing hairs bearing bacteria             69

    22. Chart illustrating the relation of the numerical
            abundance of house-flies to summer diarrhoea in
            the city of Manchester in 1904                        71

    23. Latrine-fly (_Fannia scalaris_)                           75

    24. Larva of _F. canicularis_                                 76

    25. Blow-fly or blue-bottle (_Calliphora erythrocephala_)     77

    26. Green-bottle (_Lucilia caesar_)                           79

    27. Flesh-fly (_Sarcophaga carnaria_)                         80

    28. Side view of blow-fly (_Calliphora erythrocephala_)       81

    29. _Trombidium holosericeum_ (female)                        89

    30. _Leptus autumnalis_ = larva of _Trombidium holosericeum_  90

    31. _Leptus autumnalis_, with the so-called proboscis         92

    32. _Leptus autumnalis_                                       93

    33. _Pediculoides ventricosus_ (male and female)              96

    34. _Demodex_ in hair-follicle of dog. _Demodex
            folliculorum_                                         98

    35. _Sarcoptes scabiei_ (female)                             100

    36. _Sarcoptes scabiei_ (male)                               101

    37. One of the legs of _Sarcoptes scabiei_ showing the
            stalked sucker and the curious ‘cross-gartering.’    102

    38. A diagrammatic view of the tunnel made by the female
            of _Sarcoptes scabiei_, with the eggs she has laid
            behind her as she burrows deeper and deeper          104

    39. A female _Sarcoptes scabiei_, with four eggs in
            different stages of development                      105

    40. _Nephrophages sanguinarius_ (male and female)            110

    41. Evolution of _Argas persicus_                            113

    42. _Ixodes ricinus_ (mouth-parts of the female)             114

    43. _Argas reflexus_ (female)                                115

    44. _Ornithodorus moubata_ (an unfed female)                 116

    45. _Ornithodorus moubata_ (female)                          117

    46. _Ixodes ricinus_ (male and female)                       118

    47. _Ixodiphagus caucurtei_ laying eggs in the nymph of
            _Ixodes ricinus_                                     120

    48. _Hirudo medicinalis_                                     124

    49. View of the internal organs of _Hirudo medicinalis_      126

    50. Head of a leech (_Hirudo medicinalis_)                   130

    51. _Hirudo medicinalis_                                     133

    52. Cocoon of the medicinal leech                            142

    53. A _Nephelis_ forming its cocoon and withdrawing
            from it                                              143

    54. Cocoons of _Nephelis_                                    144

    55. A leech-farm in the south of France                      145

    56. _Glossosiphonia heteroclita_, with eggs and emerging
            embryos                                              146

    57. _Helobdella stagnalis_, with adhering young              147

    58. _Limnatis nilotica_                                      150

    59. Anterior sucker of _Hirudo medicinalis_                  152

    60. The Japanese variety of _Haemadipsa zeylanica_           156

    61. _Haemadipsa zeylanica_ (from above)                      157

    62. _Haemadipsa zeylanica_ (head)                            158

    63. _Haemadipsa zeylanica_ (land-leeches), on the earth      159


                                  THE
                         MINOR HORRORS OF WAR




                               CHAPTER I

                        THE LOUSE (_Pediculus_)

    Care’ll kill a cat, up-tailles all and a louse for the hangman!
                            (B. JONSON, _Every Man in his Humour_.)


LICE form a small group of insects known as the _Anoplura_, interesting
to the entomologist because they are now entirely wingless, though it
is believed that their ancestry were winged. They are all parasites
on vertebrates. In quite recent books the _Anoplura_ are described
as ‘lice or disgusting insects, about which little is known’; but
lately, owing to researches carried on at Cambridge, we have found out
something about their habits. As lice play a large part in the minor
discomforts of an army, it is worth while considering for a moment what
we know about them.

[Illustration: FIG. 1.—_Pediculus vestimenti_ (Nitzsch). A, Magnified
20 times; B, natural size.]

Recently, the group has been split up into a large number of genera,
but of these only two have any relation to the human body. I do
not propose, in the present chapter, to consider one of these
two genera—_Phthirius_—which frequents the hairs about the pubic
region of man and is conveyed from one human being to another by
personal contact. We will confine our attention to the second genus,
_Pediculus_, which contains two species parasitic upon man—(_Pediculus
capitis_) the hair-louse and (_Pediculus vestimenti_) the body-louse.
Both of these are extremely difficult to rear in captivity, though in
their natural state they abound and multiply to an amazing degree.

Wherever human beings are gathered together in large numbers, with
infrequent opportunities of changing their clothes, _P. vestimenti_
is sure to spread. It does not arise, as the uninformed think, from
dirt, though it flourishes best in dirty surroundings. No specimen of
_P. vestimenti_ exists which is not the direct product of an egg laid
by a mother-louse and fertilised by a father-louse. In considerable
collections of men drawn from the poorer classes, some unhappy being or
other—often through no fault of his own—will turn up in the community
with lice on him, and these swiftly spread to others in a manner that
will be indicated later in this chapter.

Like almost all animals lower than the mammals, the male of the
body-louse is smaller and feebler than the female. The former attains
a length of about 3 mm., and is about 1 mm. broad. The female is about
3·3 mm. long and about 1·4 mm. broad. It is rather bigger than the
hair-louse, and its antennae are slightly longer. It so far flatters
its host as to imitate the colour of the skin upon which it lives; and
Andrew Murray gives a series of gradations between the black louse
of the West African and Australian native, the dark and smoky louse
of the Hindu, the orange of the Africander and of the Hottentot, the
yellowish-brown of the Japanese and Chinese, the dark-brown of the
North and South American Indians, and the paler-brown of the Esquimo,
which approaches the light dirty-grey colour of the European parasites.

                   As plump an’ grey as onie grozet,

as Burns has it.

The latter were the forms dealt with in the recent observations
undertaken by Mr. C. Warburton in the Quick Laboratory at Cambridge,
at the request of the Local Government Board, the authorities of
which were anxious to find out whether the flock used in making cheap
bedding was instrumental in distributing vermin. Mr. Warburton at once
appreciated the fact that he must know the life-history of the insect
before he could successfully attack the problem put before him. At
an early stage of his investigations, he found that _P. vestimenti_
survives longer under adverse conditions than _P. capitis_, the
head-louse.

The habitat of the body-louse is that side of the under-clothing which
is in contact with the body. The louse, which sucks the blood of its
host at least twice a day, is when feeding always anchored to the
inside of the under-clothing of its host by the claws of one or more
of its six legs. Free lice are rarely found on the skin in western
Europeans; but doctors who have recently returned from Serbia report
dark-brown patches, as big as half-crowns, on the skins of the wounded
natives, which on touching begin to move—a clotted scab of lice! But
the under-side of a stripped shirt is often alive with them.

After a great many experiments, Mr. Warburton succeeded in rearing
these delicate insects, but only under certain circumscribed
conditions: one of which was their anchorage in some sort of flannel
or cloth, and the second was proximity to the human skin. He anchored
his specimens on small pieces of cloth which he interned in small
test-tubes plugged with cotton-wool, which did not let the lice out,
but did let air and the emanations of the human body in. For fear of
breakage the glass tube was enclosed in an outer metal tube, and the
whole was kept both night and day near the body. Two meals a day were
necessary to keep the lice alive. When feeding, the pieces of cloth,
which the lice would never let go of, were placed on the back of the
hand, hence the danger of escape was practically _nil_, and once given
access to the skin the lice fed immediately and greedily.

His success in keeping lice alive was but the final result of many
experiments, the majority of which had failed. Lice are very difficult
to rear. When you want them to live they die; and when you want them to
die they live, and multiply exceedingly.

[Illustration: FIG. 2.—_Pediculus vestimenti._ Dorsal and ventral
views.]

A single female but recently matured was placed in a test-tube, and a
male admitted to her on the second day. The two paired on the sixth day
and afterwards at frequent intervals. Very soon after pairing an egg
was laid, and during the remaining twenty-five days of her life the
female laid an average of five eggs every twenty-four hours. The male
died on the seventeenth day, and a second male was then introduced,
who again paired with the female. The latter, however, died on the
thirtieth day, but the second male survived.

The difficulty of keeping the male and female alive was simple compared
with the difficulty of rearing the eggs. Very few hatched out. The
strands of cloth upon which they were laid had been carefully removed
and placed in separate tubes, at the same time being subjected to
different temperatures. It was not, however, until the eggs were left
alone undisturbed in the position where they had been laid and placed
under the same conditions that the mother lived in that eight, and only
eight, of the twenty-four eggs laid on the cloth hatched out after
an incubation period of eight days. The remaining sixteen eggs were
apparently dead. But the tube in which they were was then subjected
to normal temperature of the room at night (on occasions this fell
below freezing-point), and after an incubation period of upwards of a
month six more hatched out. Hence it is obvious that, as in the case
of many other insects, temperature plays a large part in the rate
of development, and it becomes clear that the eggs or nits of _P.
vestimenti_ are capable of hatching out up to a period of at least from
thirty-five to forty days after they are laid.

Difficult as it was to keep the adults alive, and more difficult as it
was to hatch out the eggs, it was most difficult to rear the larvae.
Their small size made them difficult to observe, and, like most young
animals, they are intolerant of control, apt to wander and explore, and
less given to clinging to the cloth than their more sedentary parents.
Naturally, they want to scatter, spread themselves, and pair.

Like young chickens, the larvae feed immediately on emerging from the
egg. They apparently moult three times, at intervals of about four
days, and on the eleventh day attain their mature form, though they do
not pair until four or five days later.

Mr. Warburton summarises the life-cycle of the insects, as indicated by
his experiments, as follows:—

  Incubation period: eight days to five weeks. From larva to imago:
  eleven days. Non-functional mature condition: four days. Adult life:
  male, three weeks; female, four weeks.

But we must not forget that these figures are based upon laboratory
experiments, and that under the normal conditions the rate may be
accelerated. From Mr. Warburton’s experience it is perfectly obvious
that, unless regularly fed, body-lice very quickly die. Of all the
verminous clothing sent to the Quick Laboratory, very little contained
_live_ vermin. The newly hatched larvae perish in a day and a half
unless they can obtain food.

With regard to the head-louse:—

                Ye ugly, creepin’, blastit wonner,
                Detested, shunn’d by saunt an’ sinner,

it is smaller than the body-louse, and is of a cindery grey colour.
The female measures 1·8 mm. in length and 0·7 in breadth. Like the
body-louse, it varies its colour somewhat with the colour of the hair
on the different branches of the human race. It lives amongst the hair
of the head of people who neglect their heads; it is also, but more
rarely, found amongst the eyelashes and in the beard. The egg, which
has a certain beauty of symmetry, is cemented to the hair, and at
the end of six days the larvae emerge, which, after a certain number
of moults, become mature on the eighteenth day. The methods adopted
by many natives of plastering their hair with coloured clay, or of
anointing it with ointments, probably guards against the presence of
these parasites. The Spartan youths, who used to oil their long locks
before going into battle, may have feared this parasite. Some German
soldiers, before going to war, shave their heads: thus they afford no
nidus for _P. capitis_. The wigs worn in the late seventeenth and at
the beginning of the eighteenth centuries undoubtedly owed something
to the difficulty of keeping this particular kind of vermin down. The
later powdering of the hair may have been due to the same cause.

This book, however, attempts to deal more with the troubles of
the camp, and _P. capitis_ is in war time less important than _P.
vestimenti_. The former certainly causes a certain skin trouble,
but the latter not only affords constant irritation, but, like most
biting insects, from time to time conveys most serious diseases. _P.
vestimenti_ is said to be the carrier of typhus. This was, I believe,
first demonstrated in Algeria, but was amply confirmed last year in
Ireland, when a serious outbreak of this fever took place, though
little was heard of it in England. Possibly, _P. capitis_ also conveys
typhus, but undoubtedly both convey certain forms of relapsing or
recurrent fever. The irritation due to the body-louse weakens the host
and prevents sleep, besides which there is a certain psychic disgust
which causes many officers to fear lice more than they fear bullets.
Lice are the constant accompaniment of all armies; and in the South
African War as soon as a regiment halted they stripped to the skin,
turned their clothes inside out, and picked the _Anoplura_ off. As a
private said to me: ‘We strips and we picks ’em off and places ’em in
the sun, and it kind o’ breaks the little beggars’ ’earts!’

In conjunction with the Quick Professor of Biology at Cambridge, I have
drawn up the following rules. None of them will be possible at all
times, but some of them may be possible at some time in the campaign.
At any rate, by acting on these rules, a relative of mine who took part
in the South African War was able to escape the presence of lice on his
body, and the General commanding his brigade told me on his return that
he was the only officer—and in fact the only man—in the brigade who had
so escaped.


                   HOW THE SOLDIER MAY GUARD HIMSELF
                     AGAINST INFESTATION WITH LICE

In times of war, when men are aggregated in large numbers and personal
cleanliness—but especially an adequate change of clothing—cannot be
secured, infestation with lice commonly takes place. The prevalence of
lice in troops in the South African War was a source of serious trouble
in that their attacks caused much irritation to the skin and disturbed
men’s sleep.

Lice occur chiefly on the body (_Pediculus vestimenti_) and head (_P.
capitis_). They are small greyish-white insects. The female lays about
sixty eggs during two weeks; the eggs hatch after nine to ten days.
The lice are small at first; they undergo several moults and grow in
size, sucking blood every few hours, and attain sexual maturity in
about two weeks. The eggs will not develop unless maintained at a
temperature of 22° C. or over—such as prevails in clothing worn on the
human body or in the hair of the head. This is why, _when clothing is
worn continuously_, men are more prone to become infested with lice
derived from habitually unclean persons, their clothing, bedding,
&c. _P. capitis_ lives between the hair in the head, and the eggs,
called ‘nits,’ are attached to the hairs. _P. vestimenti_ lives in the
clothing, to which it usually remains attached when feeding on man; it
lays its eggs in the clothing, and usually retreats into the seams and
permanent folds therein. This is of importance in considering the means
of destroying lice.

To avoid these pests the following rules should be observed:—

1. Search your person as often as possible for signs of the presence of
lice—that is, their bites. As soon as these are found, lose no time in
taking the measures noted under paragraph 5.

2. Try not to sleep where others, especially the unclean, have slept
before. Consider this in choosing a camping-ground.

3. Change your clothing as often as practicable. After clothes have
been discarded for a week the lice are usually dead of starvation.
Change clothes at night if possible, and place your clothing away from
that of others. Jolting of carts in transport aids in spreading the
lice, which also become disseminated by crawling about from one kit to
another. Infested clothing and blankets, until dealt with, should be
kept apart as far as possible.

4. Verminous clothes for which there is no further use should be burnt,
buried, or sunk in water.

5. If lice are found on the person, they may be _readily destroyed by
the application of either petrol, paraffin oil, turpentine, xylol, or
benzine_. Apply these to the head in the case of _P. capitis_. Remember
that these fluids are all =highly inflammable=. When possible, soap
and wash the head twenty-four hours after the last application of
petrol, &c. The application may be repeated on two or more days if the
infestation is heavy. Fine combs are useful in detecting and removing
vermin from the head. Tobacco extract has been advocated failing other
available remedies. In the case of _P. vestimenti_, the lice can be
killed as follows: Under-clothes may be scalded—say, once in ten days.
Turn coats, waistcoats, trousers, &c., _inside out_; examine beneath
the folds at the seams and expose these places to as much heat as can
be borne before a fire, against a boiler, or allow a jet of steam from
a kettle or boiler to travel along the seams. The clothing will soon
dry. If available, a hot flat-iron, or any piece of heated metal, may
be used to kill vermin in clothing. Petrol or paraffin will also kill
nits and lice in clothing. If no other means are available, turn the
clothing inside out, beat it vigorously, remove and kill the vermin by
hand—this will, at any rate, mitigate the evil.

6. As far as possible avoid scratching the irritated part.

7. Privates would benefit by instruction in these matters.

8. Apart from the physical discomfort and loss of sleep caused by the
attacks of lice, it should be noted that they have been shown to be
the carriers of typhus and relapsing fever from infected to healthy
persons. Typhus, especially, has played havoc in the past, and has been
a dread accompaniment of war.

Dr. R. F. Drummond has drawn my attention to a common folklore belief
emplanted in the minds of our poorer people. Incredible as it seems,
these uneducated and ignorant folk believe that lice on the person
is a sign of productivity, and that should they be removed their
hosts will become barren or sterile. They transfer, by a process of
sympathetic magic, the productivity of the lice to the lousy. As
Dr. Drummond writes, these ignorant mothers and aunts believe that
the nits and the lice arise spontaneously, and are ‘an outward and
visible sign of an inward and invisible fertility.’ Those who try to
cleanse the heads and the bodies of our primary schoolchildren are
‘up against’ the superstitions of the little ones’ guardians, and the
guardians unfortunately often prove the stronger. Similar views are
held widely by the various peoples of India and the East—people we call
heathen—and, apart from the connexion thought to be established between
fertility and lice, the presence of the latter is considered both at
home and abroad to be a sign of robust health.

The rather obscure connexion of the louse and the pike (_Esox lucius_)
is probably due to the fact that the Latin name for the pike is
_Lucius_. The poor pun in ‘The Merry Wives of Windsor’ on the Lucy
family is due to a similar resemblance in sound.

The Editor of the _Morning Post_ has given me leave to quote the
following paragraphs from an article by his able Correspondent at
Petrograd.

  All armies, after a few weeks’ campaigning, whatever other hardships
  may come their way, are sure of one—namely, certain parasites. Even
  officers under most favourable conditions are unable to keep clear
  of this scourge. Silk under-clothing is some palliative, but no
  real preventative. Various measures have been proposed to relieve
  the intense annoyance caused by millions of parasites of at least
  two species. Flowers of sulphur, worn in bags round the neck, were
  supposed to be a preventative, but proved fallacious.[1] What seems
  likely to prove perfect prophylactery is recommended by M. Agronom,
  who writes from Bokhara, where he has noted the habits of the Sarts
  and their preventative measures.

  The Sarts never wash, and hardly ever in lifetime change their
  clothes; therefore their condition would be impossible without some
  preventative measures. They take a small quantity of mercury, which
  they bray into an amalgam with a plant used in the East for dyeing
  the hair and nails—probably henna. This paste is evenly laid on
  strands of flax or other fibres. One string thus prepared is worn
  round the neck and the other round the waist next the skin, the heat
  of the body producing exhalations which kill parasites. The string
  lasts quite a long time.

  M. Agronom has made experiments with the ordinary mercurial ointment
  prepared with any kind of fat, and finds the effect precisely the
  same. He asserts that such a minute quantity of mercury as is
  required to produce the desired result is perfectly harmless to the
  system. A half-crown’s worth of mercury brayed in a mortar with lard
  or other fat will suffice to treat enough threads for several hundred
  soldiers. The threads should be of ten or a dozen strands or some
  very loosely twisted material like worsted, and should be wrapped in
  parchment paper before boxing for dispatch to the soldiers. This is
  effective and lasting for body parasites. Others are easily dealt
  with by rubbing in petroleum, which must be done twice at a week’s
  interval.

  It should also be noted that no ordinary washing methods will clear
  the parasites from body-linen even when dipped in boiling water; but
  if a couple of spoonfuls of petroleum are added to every gallon of
  water, perfect success is assured even without boiling.

I confess I think he is a little bit too dogmatic about the habits of
the Sarts. I am told the better-class Sarts do occasionally bathe, or
why are there public baths at Khiva? After all, in our oldest and most
cultured University, only a year ago, the venerable Head of a House
exclaimed with some acerbity, when a junior Fellow suggested putting up
hot-water baths for the undergraduates: ‘Baths! why the young men are
only up eight weeks!’

And, again, though the clothes of the Sarts are doubtless flowing,
unless they are elastic, they must get bigger as babyhood passes to
boyhood and boyhood passes to manhood.

Preparations of mercury are also used in India: not only against human
lice, but against the Mallophaga or biting-lice which infest the Indian
birds used in falconry. It is difficult for a zoologist to believe the
last paragraph of the _Morning Post_ correspondent. The temperature
of boiling water coagulates animal protoplasm as it does that of the
white-of-egg; and what would the lice do then, poor things?

Early in the year, Mr. C. P. Lounsbury, the well-known Government
Entomologist in South Africa, wrote that they were supplying the troops
there with sulphur-bags which were supposed to keep the lice away. The
sulphur is put in small bags of thin calico, and several of these are
secured on the under-clothing, next to the skin. The bags are about
two inches square, and I am told that it is customary to have one worn
on the trunk of the body and one against each of the nether limbs.
Whether this is effective will probably be known soon; but that flowers
of sulphur do play an effective part in keeping down these troubles is
shown by a letter of Dr. Harding H. Tomkins:—

  Over thirty years ago, when house-surgeon at the Children’s
  Infirmary, Liverpool, I used this with absolute success in all cases
  of plaster-of-Paris jackets who formerly had been much distressed by
  vermin getting under the jacket. The sulphur was rubbed well into the
  under-clothes.

But still more interesting evidence is given by Dr. N. Bishop Harman:—

  When I was serving in the South African War, and attached to No. 2
  General Hospital at Pretoria, I was detailed to take medical charge
  of the camp of released prisoners that was established a few miles
  out of the town on the Delagoa Bay railway line. I moved into the
  camp the night they came in. Next day an inspection was held. I
  do not think I ever saw such a sorry sight. The men were in the
  most nondescript garments, and they were flabby from the effects
  of the food the Boers had given them—mealy pap, for the most part.
  They had had no washing facilities, and they were dirty in the
  extreme. Amongst them were a number of men of the D.C.O. Yeomanry,
  many of them Cambridge men, and when these came to me for special
  examination, unwarily I invited them into my tent to strip, and
  their clothes were laid on the only available support—my bed. The
  next day or two was spent in cleaning up the men and refitting them.
  By the end of the week I noticed in the evening an unpleasant itch
  about the lower part of the trunk: a sub-acute sort of itch, it did
  not seem like a flea, and I could find nothing. But after a most
  diligent search with all the candles I could borrow, I found, to
  my horror, a louse. It was a genuine body-louse. Then I remembered
  my folly in inviting strangers into my tent. Water was scarce, the
  morning tub was only the splash from a can. Laundry was impossible.
  But after some trouble I managed to get a can of hot water and get
  some sort of a hot wash. My man did the best he could with my shirt
  and pants. What to do with the bedding—dark brown blankets—I did
  not know, except to expose them to the hot sunshine. I rode into the
  town, but insect-powder could not be got. It came into my mind that
  I had read or heard that people who took sulphur-tablets smelled of
  H2S, so on the chance that an outside application might be of
  some service I got a supply of flowers of sulphur. This I liberally
  sprinkled all over my clothes, bedding, and rubbed into the seams of
  my tunic and riding-breeches. The itching was stopped in a day, and
  it never came again. But I soon noticed another circumstance: all the
  bright brass buttons of my tunic, although freshly polished by my man
  every morning, were tarnished before evening, even in the clean, dry
  atmosphere of the dry veld. Also my silver watch-case went black.
  There was no doubt that the sulphur was acted upon by the secretions
  of the skin and H2S was produced, and this I had no doubt killed
  off any lice that could not be got at by washing. Subsequently, I
  always used it when I was in likely places. And some places were very
  likely! In Cape Town, I had to inspect all the soldiers’ lodgings
  in view of the spread of the plague. And, again, I had charge of a
  Boer prison-ship, and never once did I catch so much as a hopper. The
  prison-ship was literally alive with cockroaches of all sizes; our
  cabins swarmed with them, but they avoided my clothes and kit like
  a plague, and there was never a nibble-mark to be found. I gave the
  hint to many men and they confirmed my experience. I have since met
  other men who hit on the same device with equal success. In this war
  I have told the tip to many friends, and some relatives, who have
  gone out, and so far they have been free from the plague. You will
  note that I used all the other measures I could, but my bedding and
  uniform were not washed, and the lice must have come through the
  bedding; there was no other possible means I could trace. Yet the
  flowers of sulphur killed off all that might be therein.

A very effective method for exterminating vermin in infected troops was
carried out by Dr. S. Monckton Copeman, F.R.S., at Crowborough. To put
the matter briefly, I append a copy of his able and concise memorandum
which was distributed to all the medical officers of the Division; but
further details may be obtained by referring to the _British Medical
Journal_, or the _Lancet_ of February 6, 1915.

  To the Medical Officer....

      Treatment for Destruction of Vermin.

  Arrangements should be made for the bathing of affected
  individuals and other inmates of infected tents.

  After drying themselves, men to lather their bodies with
  cresol-soap solution (water 10 galls., Jeyes’ fluid 1½ oz., soft
  soap 1½ lb.), especially over hairy parts, and to allow the
  lather to dry on.

  Shirts to be washed in cresol-soap solution made with boiling
  water.

  Tunics and trousers to be turned inside out, and rubbed with same
  lather, especially along the seams. Lather to be allowed to dry
  on the garment.

  The materials can be obtained from the A.S.C. on indent
  authorised by A.D.M.S. in the form attached.

  Infected blankets were at first treated by soaking them
  in cresol-soap solution, after which they were sent to a
  neighbouring laundry to be washed—a small contract rate having
  previously arranged. In the first week in November, however, a
  portable Thresh’s steam disinfecting apparatus was supplied to
  the Division, through the Second Army, since when no difficulty
  has been experienced in the disinfection both of clothing and
  blankets.

  As a matter of fact the simple and inexpensive method which has
  been employed by us over a period of several months has proved so
  successful that no necessity has arisen for a trial of any other
  means of treatment.

Professor Lefroy, of the Royal College of Science and Technology,
recommends two effective remedies, known respectively as ‘Vermijelli’
and ‘Vermin Westropol.’[2] Lieut.-Colonel E. J. Cross has successfully
treated the clothes and bedding of his men with a powder consisting of
three parts of black hellebore root and one of borax, and many similar
powders are produced by the manufacturers of insecticides.

Let us end up this chapter cheerfully!

The importance of lice is equalled by their unpopularity. A lady,
driven to extremes by—well let us call it—the want of gallantry of
Dr. Johnson, called him ‘a louse.’ The great lexicographer retorted,
‘People always talk of things that run in their heads!’




                              CHAPTER II

                   THE BED-BUG (_Cimex lectularius_)

          In ‘x’ finita tria sunt animalia dira;
          Sunt pulices fortes, cimices, culicumque cohortes;
          Sed pulices saltu fugiunt, culicesque volatu,
          Et cimices pravi nequeunt foetore necari.
                                                     (ANON.)


AMONG the numerous disagreeable features of the bed-bug is the fact
that it has at least two scientific names—_Cimex_ (under which name it
was known to the classical writers) and _Acanthia_. The latter name is
favoured by French and some German authorities, but _Cimex_ was the
name adopted by Linnaeus, and is mostly used by British writers, and
will be used throughout this article. One cannot do better than take
the advice of that wise old entomologist, Dr. David Sharp, and allow
the name ‘_Acanthia_ to fall into disuse.’

The species which is the best known in England is _C. lectularius_; but
there is a second species which is much commoner in warm climates, _C.
rotundatus_. As regards carrying disease, this latter species is even
more dangerous than its more temperate relative. Other species, which
rarely if ever attack man, are found in pigeon-houses and dove-cotes,
martins’ nests, poultry-houses, and the homes of bats.

[Illustration: FIG. 3.—_Cimex lectularius_, male. × 15. (From Brumpt.)]

The common bed-bug seems to have arrived in England about the same time
as the cockroach—that is, over four hundred years ago, early in King
Henry VIII’s reign. Apparently, it came from the East, and was for many
years confined to seaports and harbours. It seems to have been first
mentioned by playwriters towards the beginning of the seventeenth
century. The sixteenth-century dramatists could never have resisted
mentioning the bug had it been in their time a common household pest.
It would have appealed to their sense of humour.

How the insect got the name of ‘bug’ is unknown. It has been suggested
that the Old English word ‘bug,’ meaning a ghost or phantom which
walked by night, has been transferred to _Cimex_. This may be so, but
the ‘Oxford English Dictionary’ tells us that proof is lacking.

The insect is some 5 mm. in length and about 3 mm. in breadth, and is
of a reddish- or brownish-rusty colour, fading into black. Its body is
extraordinarily flattened, so that it can readily pass into chinks or
between splits in furniture and boarding, and this it does whenever
daylight appears, for the bug loves darkness rather than light. The
head is large, and ends in a long, piercing, four-jointed proboscis,
which forms a tube with four piercing stylets in it. As a rule the
proboscis is folded back into a groove, which reaches to the first pair
of legs on the under surface of the thorax. This folding back of the
proboscis gives the insect a demure and even a devout expression: it
appears to be engaged in prayer, but a bug never prays. The head bears
two black eyes and two four-jointed antennae. Each of the six legs
is provided with two claws, and all the body is covered with fairly
numerous hairs. The abdomen shows seven visible segments and a terminal
piece.

The bug has no fixed period of the year for breeding; as long as
the temperature is favourable and the food abundant, generation
will succeed generation without pause. Should, however, the weather
turn cold the insects become numbed and their vitality and power of
reproduction are interrupted until a sufficient degree of warmth
returns.

Like the cockroach, the bed-bug is a frequenter of human habitations,
but only of such as have reached a certain stage of comfort. It is said
to be comparatively rare in the homes of savages, but it is only too
common in the poorer quarters of our great cities. Its presence does
not necessarily indicate neglect or want of cleanliness. It is apt to
get into trunks and luggage, and in this way may be conveyed even into
the best-kept homes. It is also very migratory and will pass readily
from one house to another, and when an infested dwelling is vacated
these insects usually leave it for better company and better quarters.
Their food-supply being withdrawn, they make their way along gutters,
water-pipes, &c., into adjoining and inhabited houses. _Cimex_ is
particularly common in ships—especially emigrant ships—and, although
unknown to the aboriginal Indians of North America, it probably entered
that continent with the ‘best families’ in the _Mayflower_.

Perhaps the most disagreeable feature of the bed-bug is that it
produces an oily fluid which has a quite intolerable odour; the
glands secreting this fluid are situated in various parts of the
body. The presence of such glands in free-living Hemipterous insects
is undoubtedly a protection—birds will not touch them. One, however,
fails to see the use of this property in the bed-bug. At any rate, it
does not deter cockroaches and ants, as well as other insects, from
devouring the _Cimex_. There is a small black ant in Portugal which
is said to clear a house of these pests in a few days, but one cannot
always command the services of this small black ant.

Another remarkable feature is that the insect has no wings, although in
all probability its ancestors possessed these useful appendages. As the
American poet says:—

                 The Lightning-bug has wings of gold,
                   The June-bug wings of flame,
                 The Bed-bug has no wings at all,
                   But it _gets_ there all the same!

The power of ‘getting there’ is truly remarkable. Man, their chief
victim, has always warred against bugs, yet, like the poor, bugs ‘are
always with us.’ I heard it stated, when I was living in southern
Italy, that if you submerged the legs of your bed in metal saucers full
of water and placed the bed in the centre of the room, the bugs will
crawl up the wall, walk along the ceiling and drop on to the bed and on
to you. Anyhow, whether this be so or not, there is no doubt that these
insects have a certain success in the struggle for life, and only the
most systematic and rigorous measures are capable of ridding a dwelling
of their presence.

[Illustration: FIG. 4.—Egg of _Cimex lectularius_. Enlarged. (After
Marlatt.)]

The eggs of the bed-bug are pearly white, oval objects, perhaps 1 mm.
in length. At one end there is a small cap surrounded by a projecting
rim, and it is by pushing off this cap, and through the orifice thus
opened, that the young bug makes its way into the outer world after an
incubation period of a week or ten days. There is no metamorphosis—no
caterpillar and no chrysalis stages. The young hatch out, in structure
miniatures of their parents, but in colour they are yellowish-white and
nearly transparent. The young feed readily, and feeding takes place
between each moult, and the moults are five in number, before the adult
imago emerges. This it does about the eleventh or twelfth week after
hatching. These time-limits depend, however, upon the temperature after
hatching, and the rate of growth depends not only upon the temperature
but also upon the amount of food.

When bred artificially and under good conditions, the rate of progress
can be ‘speeded up’ so that the eggs hatch out in eight days, and every
following moult takes place at intervals of eight days, so that the
period from egg to adult can be run through in as short a time as seven
weeks.

[Illustration: FIG. 5.—Newly hatched young of _Cimex lectularius_.
1, Ventral view; 2, dorsal view. Enlarged. (After Marlatt.)]

Unless fed after each moult, the following moult is indefinitely
postponed. Hence it follows that in the preliminary stages bugs must
bite their hosts five times before the adult form emerges, and the
adult must, further, have a meal before it lays its eggs. The eggs are
deposited in batches of from five to fifty in cracks and crevices, into
which the insects have retired for concealment.

Bugs can, however, live a very long time without a meal. Cases
are recorded in which they have been kept alive for more than a
year incarcerated in a pill-box. When the pill-box was ultimately
opened, the bugs appeared to be as thin as oiled paper and almost so
transparent that you could read _The Times_[3] through them; but even
under these conditions they had managed to produce offspring. De Geer
kept several alive in a sealed bottle for more than a year. This power
of existing without food may explain the fact that vacated houses
occasionally swarm with bugs even when there have been no human beings
in the neighbourhood for many months.

The effect of their bite varies in different people. As a rule, the
actual bite lasts for two or three minutes before the insect is gorged,
and at first it is painless. But very soon the bitten area begins to
swell and to become red, and at times a regular eruption ensues. The
irritation may be allayed by washing with menthol or ammonia. Some
people seem immune to the irritation; and I know friends who, in the
West Indian Islands, have slept through the attacks of thousands of
bugs, and only awoke to their presence when in the morning they found
their night-clothing and their sheets red with blood, expressed from
the bodies of their tormentors as the victims turned from side to side.

As a rule, the uncovered parts of the body—the face, the neck, and the
hands—are said to be more bitten than the parts which are covered by
the bedclothes. This is not, however, my experience.

The bug has been accused of conveying many diseases—typhus,
tuberculosis, plague, and a form of recurrent fever produced by a
spirochaete (_Spirochaeta obermeieri_); but a critical examination
throws some doubt upon the justice of the accusation, and Professor C.
J. Martin writes as follows:—

  There is really no evidence to incriminate the bed-bug in the case of
  either typhus or relapsing fever. It is possible to transmit plague
  experimentally by means of bugs, but there is no epidemiological
  reason for supposing this takes place to any extent in nature.

  There are two differences in the habits of bugs and those of fleas
  and lice which may possess epidemiological significance. The first
  concerns the customary intervals between their meals. Bugs show no
  disposition to feed for a day or two after a full meal, whereas fleas
  and lice will suck blood several times during the twenty-four hours.
  The second is in respect to the time the insects retain a meal and
  the extent to which it is digested before being excreted. Fleas and
  lice, if constantly fed, freely empty their alimentary canals, and
  the nature of their faeces indicates that the blood has undergone but
  little digestion.

  Both these insects evacuate such undigested or half-digested blood
  _per rectum_ during the act of feeding, and the remnants of the
  previous meal are thus deposited in the immediate vicinity of a fresh
  puncture. It is not unlikely that, should the alimentary canal of the
  insect be infected with plague bacilli, spirochaete, or the organism
  responsible for typhus fever, these may be inoculated by rubbing or
  scratching. Bugs have not this habit; and in all the cases I have
  examined their dejections were fully digested, almost free from
  protein, and consisted mostly of alkaline haematin.

Whether bugs be guilty of these crimes or not, they are the cause of
an intense inconvenience and disgust, and should, if possible, be
dealt with drastically. At the present time[4] there are rumours that
some of our largest camps are infested with these insects, and there
seems no doubt that some of the prisoners and refugees to this country
have brought their fauna with them, and this fauna is very capable of
spreading in concentration camps. The erection of wooden huts—no doubt
a pressing necessity—will afford convenient quarters for these pests.

Among the measures which have been most successful in the past has been
fumigating houses with hydrocyanic-acid gas; but this is a process
involving considerable danger, and should only be carried out by
competent people under the most rigorous conditions. In all fumigating
experiments every crack and cranny of a house should be shut, windows
closed, keyholes blocked, and so on. A second method of fumigation
is that of burning sulphur. Four ounces of brimstone are set alight
in a saucer, this in its turn is placed in a larger vessel, which
protects the floor of the room from a possible overflow of the burning
material. After all apertures have been successfully plugged, four or
five hours of the sulphurous fumes are said to be sufficient to kill
the bugs, but to ensure complete success a longer time is needed. This
is not only a much less expensive but a much less dangerous operation
than using hydrocyanic-acid gas. Two pounds of sulphur will suffice
for each thousand cubic feet of space, but it is well to leave the
building closed for some twenty-four hours after the fumigation.
Another more localised method of destroying these pests is the liberal
application of benzine, kerosene, or any other petroleum oil. These
must be introduced into all crevices or cracks by small brushes or
feathers, or injected with syringes. In the same way oil of turpentine
or corrosive-sublimate has proved effective. Boiling water is also
very fatal when it can be used; and recently in the poorer quarters
of London the ‘flares’ which painters use in burning off paint have
proved of great use in ridding matchboarding, or wainscoting, from the
harbouring bugs. Passed quickly along, the flame of the ‘flare’ does
not burn the wood, but it produces a temperature which is fatal to the
bug and to its young and to its eggs. And thus:—

‘This painted child of dirt, that stinks and stings’[5] is destroyed.




                              CHAPTER III

                      THE FLEA (_Pulex irritans_)

             Marke but this flea, and marke in this,
             How little that which thou denyst me is;
             It sucked me first, and now sucks thee,
             And in this flea our two bloods mingled bee.

                                                    (DR. DONNE.)


THE fact, now fully established, that the bubonic plague is conveyed to
man from infected rats, or from infected men to healthy men, by fleas
has taken that wingless insect out of the category of those animals
which it is indelicate to discuss.

No doubt, as Mr. Dombey says, ‘_Nature is on the whole a very
respectable institution_’; but there are times when she presents
herself in a form not to be talked about, and until a few years ago the
flea was such a form. Hence, few but specialists have any clear idea
either of the structure or of the life-history or of the habits—save
one—of the flea.

[Illustration: FIG. 6.—_Pulex irritans_, female. The legs of the left
side only are shown. Enlarged. (After a drawing by A. Dampf.)]

Fleas are temporarily parasitic on many mammals and birds, but some
mammals and some birds are much freer from fleas than others. As the
flea is only on its host for part of the time, it has to put in the
rest of its existence in some other place, and this, in the case of
the human flea, is usually the floor, and in the case of bird-fleas
the nest; from these habitats they can easily regain their hosts
when the latter retire to rest. But large numbers of Ungulates—deer,
cattle, antelopes, goats, wild boars—sleep in different places each
recurrent night, and to this is probably due the fact that, with the
exception of two rare species—one taken in Northern China and the other
in Transcaucasia—the Ungulates have furnished descriptive science
with no fleas at all. Both of these Ungulate fleas are allied to the
burrowing-fleas or ‘chigoes.’

I know none of my readers will believe me when I say that the same
is true of monkeys; but I do this on the undoubted authority of Mr.
Harold Russell, who has recently published a charming little monograph
on these lively little creatures. Monkeys in nature are cleanly in
their habits; and although in confinement occasionally a human flea
attacks them, and although occasionally a chigo bores into the toes of
a gorilla or chimpanzee, ‘speaking generally, it may be said that no
fleas have been found truly parasitic on monkeys.’ Whatever the monkeys
are looking for, it is not fleas. What they seek and find is in effect
little scabs of scurf which are made palatable to their taste by a
certain sour sweat.

As a rule, each host has its own species of flea; but though for the
most part _Pulex irritans_ is confined to man it is occasionally
found on cats and dogs, whilst conversely the cat- and dog-fleas
(_Ctenocephalus felis_ and _Ct. canis_) from time to time attack man.

The bite of the flea is accompanied by the injection of the secretions
of the so-called salivary glands of the insect, and this secretion
retards the coagulation of the victim’s blood, stimulates the
blood-flow, and sets up the irritation we have all felt.

It is only a few years ago that the spread of bubonic plague was
associated first with rats, and then with rat-fleas; and at once it
became of enormous importance to know which of the numerous species
of rat-flea would attack human beings. The Hon. Charles Rothschild,
who has accumulated a most splendid collection of preserved fleas
in the museum at Tring, had some years ago differentiated from an
undifferentiated assemblage of fleas a species first collected in
Egypt, but now known to be the commonest rat-flea in all tropical
and sub-tropical countries. This species _Xenopsylla cheopis_—and to
a lesser extent _Ceratophyllus fasciatus_—unfortunately infests and
bites man. If they should have fed upon a plague-infected rat and
subsequently bite man, their bites communicate bubonic plague to human
beings. Plague—the Old English ‘Black Death’—is a real peril in our
armies now operating in Asia and in certain parts of Africa.

Just as some fleas attack one species of mammal or bird and avoid
closely allied species, so the human flea has its favourites and
its aversions. There is a Turkish proverb which says ‘an Englishman
will burn a bed to catch a flea,’ and those who suffer severely from
fleabites would certainly do so. The courage of the Turk in facing
the flea, and even worse dangers, may be, as the schoolboy wrote,
‘explained by the fact that a man with more than one wife is more
willing to face death than if he had only one.’ But there are persons
even a flea will not bite. Mr. Russell has reminded us in his Preface
of the distinguished French lady who remarked, ‘Quant à moi ce n’est
pas la morsure, c’est la promenade!’

[Illustration: FIG. 7.—Larva of _Pulex irritans_. _C.f._ frontal horn;
_d_, antenna. Enlarged. (After Brumpt.)]

There are one or two structural features in a flea which are peculiar:
the most remarkable being that, unlike most other insects, it is much
taller than it is broad. As a rule, insects—such as a cockroach, the
bed-bug, or a stag-beetle—are like skates, broader than they are thick,
but the flea has a laterally compressed shape, like a mackerel or a
herring. Then, again, the three segments or rings which come after the
head are not fused into a solid cuirass or thorax as they are in the
fly or the bee, but they are movable one on the other. Finally, it
is usual in insects for the first joint of the leg to be pressed up
against and fused with those segments of the body that bear them; but
in the flea not only is this joint quite free, but the body-segment
gives off a projection which stretches out to bear the leg. Thus the
legs seem, unless carefully studied, to have an extra joint and to
be—as indeed it is—of unusual length. They certainly possess unusual
powers of jumping—as Gascoigne, a sixteenth-century poet (1540–78)
writes, ‘The hungry fleas which frisk so fresh.’

The male, as is so often the case amongst the Invertebrata, is much
smaller than the female. The latter lays at a time from one to
five minute, sticky, white eggs, one-fortieth of an inch long by
one-sixtieth broad. They are not laid on the host, but in crevices
between boards, on the floor, between cracks in the wainscoting, or
at the bottom of a dog-kennel or in birds’ nests. Mr. Butler recalls
the case of a gentleman who collected on four successive mornings
sixty-two, seventy-eight, sixty-seven, and seventy-seven cat-fleas’
eggs from the cloth his cat had slept upon. Altogether 284 eggs in four
nights! The date of hatching varies very much with the temperature.
_Pulex irritans_ takes half as long again—six weeks instead of four—to
become an adult imago in winter than it does in summer. But in India
the dog-flea will complete its cycle in a fortnight.


[Illustration: FIG. 8.—Pupa of flea. (After Westwood.)]

When it does emerge from the egg the larva is seen to be a whitish
segmented little grub without any limbs, but with plenty of bristles
which help it to move about; this it does very actively. There are two
small antennae and a pair of powerful jaws, for the larva does not take
liquid food, but eats any scraps of solid organic matter which it comes
across: dead flies and gnats are readily devoured. The larva casts its
skin several times, though exactly how often it moults seems still
uncertain.

After about twelve days of larval existence it spins itself a little
cocoon in some sheltered crevice, and turns into a whitish inert
chrysalis or pupa. During its pupal existence it takes, of course, no
food, but it grows gradually darker, and after undergoing a tremendous
internal change, breaking down its old tissues and building up new
ones, the chrysalis-case cracks and the adult flea jumps out into the
world.

There are many superstitions about fleas. March 1st is in some way
connected with them, and in the south of England the house-doors are
in some villages closed on that day under the belief that this will
render the building immune for the following twelve months. The most
successful insecticide is said to be prepared from _Pyrethrum_, which
is grown in the Near East in large quantities for this purpose. But the
Austrians, the Serbians, and the Montenegrins are fighting over the
chief world-supply of this plant—possibly without knowing what they
are doing—and ‘_Insektenpulver_’ is bound to go up in price. Wormwood
(_Artemisia_) is also recommended.

  While wormwood hath seed, get a handfull or twaine,
  To save against March, to make flea to refraine;
  When chambere is swept and wormwood is strowne,
  No flea for his life dare abide to be known.
                                        (=TUSSER.=)

The author of ‘A Thousand Notable Things’ suggests the following plan,
but, so far, I have not met anyone who has tried it: ‘If you mark where
your right foot doth stand at the first time that you do hear the
cuckow, and then grave or take up the earth under the same; wheresoever
the same is sprinkled about, there will no fleas breed. I know it hath
proved true.’

Plastering a floor with cow-dung is a common practice in South Africa,
and seems to be an efficacious means of keeping down fleas. Dr. R.
J. Drummond tells me that all natives of India and Ceylon spread an
emulsion of cow-dung in hot-water over the floors and the walls of
their dwellings to keep out fleas. This has been done from immemorial
times, and is effective. The efficacy of the emulsion in keeping fleas
away has been doubted, and so I am glad to quote a few lines from a
kind letter sent me by Dr. P. A. Nightingale of Victoria, Southern
Rhodesia, which put the matter in a happy light:—

  I think the correct facts are these: the floors of certain houses,
  huts, &c., throughout the South African veld are made of ant-heap
  earth, moistened and beaten hard and flat with sticks. This floor
  is then smeared at regular intervals—say, every ten days—with fresh
  cow-dung, when the room becomes fresh and sweet (!) and free from
  insects.

  However, before the smearing can be done it is necessary to turn all
  the furniture out of the room and to sweep it thoroughly; after the
  smearing, the doors and windows are left open for drying purposes.

  Hence, I think that the absence of fleas in such quarters is really
  due to general cleanliness, sunlight, and fresh air, and not to any
  special virtue in the cow-dung.

  I am, however, sure that the smearing of the floor at frequent
  intervals _does_ keep many pests down by filling up, and temporarily
  sealing, the numerous cracks in the floor where fleas, &c., reside
  and breed in vast numbers.

  Huts—especially unused ones—not smeared for many weeks contain
  (approximately) several thousands of fleas, white ants, centipedes,
  and scorpions to the square inch, when the only treatment is to
  cleanse the walls and floor with cyanide solution, or burn the whole
  place down.

[Illustration: FIG. 9.—_Ceratophyllus gallinulae._ Male (above) and
female (below). Drawn to scale and both highly magnified. These
specimens, taken from a grouse, are of the same genus as one of the
plague-conveying fleas.]

  From long experience, I am very nearly insect proof; but cannot stand
  the myriads of fleas I occasionally have to sleep with in a hut of
  the above description—especially just before the rains set in, when
  additional veld pests come into the huts for shelter.

We must, in the long run, treat fleas seriously. Although the _Pulex
irritans_ is a very common insect, the greatest living authority
on fleas tells me it has never been accurately drawn. We have
Blake’s ‘ghost of a flea’; but what did Blake know of entomology? In
distinguishing one flea from another—fleas which may attack man and
fleas which have hitherto declined to do so—every hair, every bristle,
counts. Hence, I illustrate this article with accurate outlines of
certain fleas found on the grouse, and for whose accuracy I can vouch
(Fig. 9).

As I have said above, a certain rat-flea (_Xenopsylla cheopis_) and
another (_Ceratophyllus fasciatus_) undoubtedly convey the bacillus of
plague from rats and other Murinae to man and vice versa. The _Bacillus
pestis_ is unlikely to establish itself in the present war in Europe,
but _Quién sabe?_ The Black Death of 1349–51 was conveyed by fleas, and
so was Pepys’s Plague of 1665. Plague—flea-borne, we must remember—is
still endemic in places as near Europe as Tripoli, and in numerous
centres in Asia. Not a disease altogether to be neglected, since the
spread of war to the Near East, but still not very threatening in
Europe in the twentieth century.




                              CHAPTER IV

          THE FLOUR-MOTH (_Ephestia kühniella_) IN SOLDIERS’
                               BISCUITS

             Where moth ... doth corrupt. (MATT. vi. 19.)


IT is not only those insects that destroy the continuity of our
soldiers’ integument which play a part in war. It has been well said
that an army marches on its stomach; and the admirable commissariat
arrangements which have been so distinctive a feature of the British
Expeditionary Force during the present war are the result of much
patient care and attention during times of peace. I am in no position
to discriminate, but I do believe that the admirable service of the
A.S.C. and the R.A.M.C. is at least equal to the splendid record of
those in the fighting-line.

Every one knows that recruits are frequently rejected for some defect
in their teeth. A soldier, indeed, requires strong teeth, for his
farinaceous food in the field is largely supplied to him in the form of
biscuits—not that ‘moist and jovial sort of viand,’ as Charles Dickens
described the Captain biscuit, but ‘hard-tack’ which challenges the
stoutest molars.

During the summer of 1913 the authorities of the British Museum at
South Kensington arranged a very interesting but somewhat gruesome
exhibit in their Central Hall. The exhibit consisted mainly of Army
biscuits eaten through and through by the larva of a small moth and
covered by horrible webs or unwholesome-looking skeins of silky threads.

[Illustration: FIG. 10.—_Ephestia kühniella._ Moth-infested biscuit.]

Together with these derelict biscuits were certain long metallic
coils and other apparatus used in investigating certain phases of
the life-history of the moth and the manufacture of the biscuit. The
exhibit illustrates an article which had recently appeared on the
Baking of Army Biscuits, by Mr. Durrant and Lieut.-Colonel Beveridge,
on the ‘biscuit-moth’ (_Ephestia kühniella_), a member of the family
Pyralidae. The article recorded their efforts to arrive at a means of
checking this very serious pest to service stores.[6]

The biscuit-moth (_E. kühniella_) was described two years before
its larva had been noted damaging flour at Halle. There has always
been a certain amount of international courtesy in attributing
the _provenance_ of insect pests to other countries; and when _E.
kühniella_ began, about ten years later, to attract attention in
England it was believed to have been introduced from the United States,
via the Mediterranean ports, in American meal. The American origin was,
however, denied by Professor Riley, who, in a letter to Miss Ormerod,
states, ‘I think I can safely say that this species does not occur in
the United States.’ At the moment of writing these words Professor
Riley was in the act of packing-up to leave Washington for Paris.
Possibly he was excited, certainly he was inaccurate, for the species
was then known to be prevalent in Alabama, North Carolina, and other
States. In fact, to-day it is recorded throughout Central America and
the Southern States, and in most of the temperate regions of the New
World.

[Illustration: FIG. 11.—_Ephestia kühniella._ × 2.]

The moth itself is a rather insignificant, small insect, of a
slatey-grey colour. Its eggs, rather irregular ovoids, are laid upon
the biscuit into which the issuing larvae bore. These latter are soft
and like most creatures which live in the dark, whitish, though with a
tinge of pink; the head, however, is brown and hardened. The larva is
constantly spinning silken webs or tissues, which in the most untidy
way envelop the biscuit. It finally entombs itself in a whitish silken
cocoon, and herein it ultimately turns into a chrysalis or pupa.

Another Pyralid moth—_Corcyra cephalonica_—makes similar unpleasant
webs all over biscuits, rice, or almost any farinaceous food; but,
since its larvae are unable to live unless there be a certain degree
of moisture in its food, it is less injurious to baked food than the
_Ephestia_, for whose larvae nothing can be too dry. _Corcyra_ seems
originally to be a pest of rice, and to have been introduced into
Europe with Rangoon rice; but it readily alters its diet in new
surroundings, and will live on almost any starchy stuff, if not too
desiccated.

The problem that Lieut.-Colonel Beveridge and Mr. Durrant, of the
British Museum, set out to solve was at what stage in the manufacture
of the Army biscuits does our soldiers’ food become infested, and
whether any steps could be taken to avoid or minimise such infestation.

[Illustration: FIG. 12.—_Ephestia kühniella._ A, Larva; B, pupa.
Greatly magnified.]

First, as to infestation. The biscuit must become infested either (1)
at home before packing, (2) during transit, or (3) in the country where
they are stored. The biscuits are packed in tins, hermetically sealed,
and enclosed in wooden cases to prevent injury; it was therefore
obvious that if insects could be found within intact tins it would
be demonstrated at once that infestment must have taken place in the
factories, and not subsequently.

[Illustration: FIG. 13.—_Corcyra cephalonica._ Moth-infested biscuit.]

With a view to determine the origin of infestation sample tins were
withdrawn from stocks at various stations abroad, and inspected by
experts at Woolwich; and tins which, after careful examination, had
been pronounced intact, were found to contain _Ephestia kühniella_ and
_Corcyra cephalonica_ in various stages of development, thus proving
conclusively that infestation had taken place in the factories before
the tins were soldered, and indicating that preventive or remedial
measures must be undertaken within the biscuit-making factories
themselves.

It is obvious either that the heat to which the biscuit is subjected
in the process of baking is insufficient to destroy any of the insect
eggs present in the moist dough or that the moths and beetles deposit
their eggs in or on the biscuits after baking, and during the process
of cooling and of packing into the tins. Cooling before packing is
necessary in order to allow the moisture in the centre of the biscuit
to become evenly distributed throughout the ‘tissue’ of the biscuit.
And it is during the time occupied in cooling and packing that the
biscuit is exposed to the greatest risk of infestation; any risk
occasioned by subsequent injury must be exceptional, and is probably
negligible.

By a series of most ingenious experiments, the two investigators were
able to determine the temperature in the centre of the biscuits during
the various stages of its baking and cooling. Army biscuits are made
from dough which contains about 25 per cent. of water. When stamped
out they are placed in rows on the revolving floor of an oven, and
are submitted to a high temperature for twenty minutes whilst they
travel over a space of 40 feet. The dough at first contains, as we have
said above, 25 per cent. of water, but during baking this is reduced
to about 10 per cent., and the moisture now collects in the centre of
the mass of the biscuit in consequence of the external hardening or
‘caramelisation,’ as it is called. The holes which are pricked in so
many biscuits of course help to equalise the spread of the moisture
throughout the biscuit.

Too little attention has been paid to the internal temperature of
edibles which are being cooked. Very few people, for instance, have any
conception of what is going on in the centre of a joint of meat whilst
it is being roasted or boiled. After two hours’ boiling the temperature
in the centre of a large ham has only risen to 35° C.; after six hours’
boiling to 65° C., and it is only after ten hours’ continuous boiling
that 85° C. is reached. I have, I am sorry to say, no conception as to
how long a ham ought to be boiled, but it is obvious that to be really
effective against such parasites as _Trichinella_—the _causa causans_
of trichinosis—the cooking of pork and ham should be more prolonged and
thorough than seems to be customary. But that is another story.

However, to return to our biscuits. The Colonel and Mr. Durrant
devised an ingenious instrument which determined the rising temperature
at the centre of our Army biscuits whilst baking. When the tip of
their recording apparatus lay within the moist area of the biscuit,
the temperature registered was only a little over 100° C.; but when
the tip of the instrument rested on the hard ‘caramelised’ portion
much higher temperatures were observed—even as high as 125° C. Colonel
Beveridge and Mr. Durrant were thus able to establish the fact that
the temperatures of the biscuit were, during baking, such as to rule
out the idea that the eggs of the biscuit-moth—which do not survive a
temperature of 69° C. for twelve minutes—were deposited in the biscuit
before cooking.

After the baking is completed the biscuits are cooled, and it is
at this period that they are most exposed to risk of infestation
by _Ephestia kühniella_. This insect is a well-known nuisance in
Flour-mills. So persistent and numerous are these moths at times that
they clog the rollers with their cocoons, and sometimes completely
stop them. The webbing of the elevators in the mills gets covered with
them and with their silky skeins, and then the elevators stop working.
They mat together the flour and meal with their silken excreta, and so
uniform is the temperature of the Mill, and so favourable to the life
of the insect, that they complete their life-cycle in this country in
two months, and in the warmer parts of America even more rapidly. In
well-heated mills the proceeding is continuous, so that six generations
at least may be produced each year.

The most efficient method of getting rid of this pest of the Army
biscuit is a complete and thorough fumigation of the infested premises
with carbon bisulphide. But, as this substance is not only poisonous
but inflammable, it is well to get a chemist to undertake the
proceeding, and also to notify the Insurance Company. Fumigation by
sulphur ruins the flour. Another remedial measure is that of turning
the steam from the boilers on to all the infected machinery and walls.

That this destruction of the Army biscuit is a matter of considerable
importance is shown by the fact that biscuit-rations exported to the
colonies in hermetically sealed tins have become quite unfit for
consumption, and this destruction has been noted in places as far
distant from each other as Gibraltar, the Sudan, Mauritius, Ceylon,
South Africa, and Malta. That it is also an old trouble is shown by the
following quotation from the diary which Sergeant Daniel Nicol, of the
92nd (the Gordon Highlanders), kept during the expedition to Egypt in
1801:—

  Some vessels were dispatched to Macri Bay for bullocks, and others
  to Smyrna and Aleppo for bread which was furnished us by the Turks—a
  kind of hard dry husk. We were glad to get this, as we were then put
  on full rations, and our biscuits were bad and full of worms; many of
  our men could only eat them in the dark.[7]

With regard to the actual baking of the biscuit, Colonel Beveridge and
Mr. Durrant suggest that the temperature conditions during the process
of cooling should be made as unfavourable as possible for the moths by
introducing screened cool air, which can be forced in at one end of the
cooling-chamber and sucked out at the other. Could such a scheme be
adopted it would be difficult, if not impossible, for the moths to lay
their eggs, and the biscuit would thus be more rapidly cooled. In any
case it should not be difficult to ensure that the cooling takes place
in some chambers which are practically free from these destructive
moths.




                               CHAPTER V

                                 FLIES

                                PART I

                   THE HOUSE-FLY (_Musca domestica_)

    Musca est meus pater, nil potest clam illum haberi;
    Nec sacrum nec tam profanum quidquam est, quin Ibi ilico adsit.
                                             (PLAUTUS, _Mercator_.)


  ‘THE common house-fly [says Ruskin] is the most perfectly free and
  republican of creatures. There is no courtesy in him; he does not
  care whether it is a king or clown whom he teases, and in every step
  of his swift mechanical march and in every pause of his resolute
  observation there is one and the same perfect expression of perfect
  egotism, perfect independence and self-confidence and conviction
  of the world having been made for flies. Your fly free in the air,
  free in the chamber, a black incarnation of caprice, wandering,
  investigating, fleeting, flitting, feasting at his will with rich
  variety of feast from the heaped sweets in the grocer’s window to
  those of the butcher’s back yard, and from the galled place on your
  horse’s neck to the brown spot on the road from which, as the hoof
  disturbs him, he rises with angry republican buzz; what freedom is
  like his?’

The house-fly is all that Ruskin describes it to be, but it is more. It
is the most cosmopolitan of insects. Wherever man is there is the fly.
It is found—

                    From Greenland’s icy mountains
                    To India’s coral strand.

But it is naturally more frequent in warm climates than in cold, as
the rate of its development depends very largely upon an average high
temperature.

Unlike the lice and the bed-bug, the fly like the flea, passes through
a complete metamorphosis—egg, larva, pupa, and imago. It will breed
in almost any rotten matter, whether vegetable or animal, and it
breeds most successfully, as Gordon Hewitt has pointed out, when
certain processes of organic fermentation are taking place in its
breeding-place. Probably the fermentation has a favourable effect upon
the food of the larvae. Undoubtedly the place most readily selected by
the female for laying her eggs is stable-manure. A few years ago there
was a remarkable reduction in the number of house-flies in London, and
Lord Montagu of Beaulieu attributed this reduction to the refreshing
and insecticidal petrol vapour with which the streets of that town
were then bathed.

[Illustration: FIG. 14.—Mass of eggs of _M. domestica_. (From Gordon
Hewitt.)]

I do not know what experiments Lord Montagu had made on the subject
of the insecticidal value of petrol vapour, but the ordinary man in
the street attributed—and I think more correctly—the diminution of
the plague of flies to the absence of the nidus in which the female
fly lays her eggs. Stable-yards had been turned into garages. But
flies will, indeed, breed in almost any kind of dejecta—including the
human—and in rotten straw, rotten wool, cotton garments, decaying
vegetables and fruits, bad meat, rotten grain, and even in spittoons,
but they prefer horse-manure.

[Illustration: FIG. 15.—Eggs of _M. domestica_, × 40. (From Gordon
Hewitt).]

In our country house-flies usually begin to breed in June and July,
continuing well on into October if the weather be but warm. Their
greatest activity is, however, in the hotter month of August and the
beginning of September. But in warm stables, restaurants, and kitchens
flies are able to reproduce the whole year round. A single fly will
deposit at one time 100 to 150 eggs, and in the course of her summer
life may produce five, or even six, batches of ova of this size. The
eggs are pearly white, elongated structures, with two converging lines,
along which the egg-case will ultimately split to give exit to the
larva. The eggs are laid, by means of a long ovipositor, a little way
beneath the surface of the dung-heap in a position where they will not
readily be dried up. In favourable conditions the eggs hatch in from
eight to twenty-four hours.

The first larva is legless, tapering towards the head, which bears
a pair of breathing-holes, or spiracles; the body is much stouter
towards the hinder end. On the whole it is a white, unpleasant-looking
maggot, called by freshwater-fishermen a ‘gentle.’ By contracting and
expanding its body it pushes its way through the moist, semi-liquid
surroundings. The skin is usually moulted some twenty-four hours after
birth, but all these time-limits depend much upon the temperature and
favourable conditions. With normally high temperatures—say, with 30° C.
to 35° C.—the larva will become fully grown in five or six days. The
third and final larval stage, after the second moult or ecdysis, lasts
three days, and when fully grown the maggot is now about half an inch
in length. Externally, twelve segments are visible, but the internal
anatomy shows that thirteen are really present, though one is almost
‘masked.’

[Illustration: FIG. 16.—Abdomen of female house-fly, showing the
extended ovipositor. (From Gordon Hewitt.)]

It is only during these larval stages that the insect grows, and it
is never more bulky than in the third larval stage. Now it leaves the
moist situation, in which it has flourished, and, crawling through the
manure, seeks some dry or sheltered corner. For a time it rests, and
then after an hour or two’s quiescence it retracts its anterior end
and assumes a barrel-shaped outline, its creamy white colour slowly
changing to a mahogany brown. The larval skin forms the pupa-case,
and within this pupa-case the body of the larva undergoes a wonderful
change, far greater than even human beings undergo at the time of
puberty. Many of its organs are disintegrated and re-formed, and in the
course of three or four days the white, legless, repellent maggot, who
‘loves darkness rather than light,’ is changed into a lively, flying
insect, seeking ‘a place in the sun’ and the companionship of man. As
the Frenchman said of the pig which goes into one end of the machine in
the Chicago meat-factory as live pig and comes out at the other end in
the form of sausages, ‘Il est diablement changé en route.’

[Illustration: FIG. 17.—Mature larva of _M. domestica_. _a.sp_,
Anterior spiracular process; _an.l_, anal lobe; _sp_, spiniferous pad.
I-XIII, Body segments. (From Gordon Hewitt.)]

In a very short time after leaving the pupa-case the adult fly has
stretched her wings, the chitin of her body has hardened, and she flies
away ‘on her several occasions.’

[Illustration: FIG. 18.—‘Nymph’ of _M. domestica_ dissected out of
pupal-case about thirty hours after pupation. _an_, Swellings of
nymphal sheath marking bases of antennae; _cx_, coxa of leg; _lb_,
labial portion of proboscis sheath; _lbr_, labral portion of same;
_n.sp_, spiracular process of nymph; _w_, wing in nymphal alar sheath.
(From Gordon Hewitt.)]

[Illustration: FIG. 19.—Pupal-case or puparium of _M. domestica_ from
which the imago has emerged, thus lifting off the anterior end or ‘cap’
of the pupa; ventro-lateral aspect. _a.sp_, Remains of the anterior
spiracular process of larva; _l.tr_, remains of the larval lateral
tracheal trunk; _n.sp_, temporary spiracular process of nymph; _p.sp_,
remains of the posterior spiracles of larva. (From Gordon Hewitt.)]

Flies become sexually mature in a week or ten days after emerging from
the chrysalis-case, and are capable of depositing their eggs four days
after mating, so that if the conditions be indeed favourable the whole
development from the egg to the perfect fly may be accomplished in nine
or ten days, and the second generations are able to lay their eggs ten
days later. The appalling fecundity of such an insect explains the fact
that in the hotter parts of the world nearly every edible thing seems
to be covered with them.

The proboscis of a fly can only suck up liquid food; and when we see
it feeding on solid substances, such as sugar, it has really dissolved
the sugar by depositing some saliva on it, and is sucking up the sugary
solution so produced. It not infrequently regurgitates its food in a
spherical drop, which it generally re-absorbs.

As we have seen, flies are very susceptible to temperature, and with
the approach of cold weather they seem to die. We used to think that
some, in a state suspended animation, ‘carried on’ through the winter
months. This is, however, ‘non-proven.’ Many of them undoubtedly die
in the autumn, as bees die, of old age. They are literally worn out.
But a great number fall victims to a parasitic fungus called _Empusa_.
Flies killed by this fungus are frequently to be seen in autumn,
hanging dead on windows, &c., surrounded by a little whitish powdery
ring of spores formed by the fungus.

Flies, like many other insects, are extremely difficult to keep alive
in captivity, and few have succeeded in rearing them for more than a
month or two. At one time, as we have said, it was thought that those
flies which survive the winter were fertilised females of the younger
broods, and that during the winter they subsisted on their ‘fat bodies.’

[Illustration: FIG. 20.—_M. domestica_ in the act of regurgitating
food. × 4½. (From Gordon Hewitt.)]

Doubt has recently been thrown on this theory, and in a recent
report[8] of the Local Government Board Dr. Newsholme sets forth the
results of the researches of Dr. Monckton Copeman and Mr. E. E. Austen
in the following words:—

  Until recently there was general agreement that a certain number of
  flies managed to survive the winter and spring by hibernating in
  dark nooks and crannies in dwelling-houses, or, as contended by Dr.
  Laver,[9] in various sheltered situations outside dwellings—such as
  the under-surface of the thatch of farmyard stacks. The researches of
  Mr. Jepson and others have shown that, during the period extending
  from late autumn to early summer, flies may be found occasionally
  in all active conditions in warmed houses, and especially in such
  places as kitchens and bake-houses, where the temperature is kept
  relatively high; and further, that under these conditions, and in
  presence of sufficient food material they may even continue to breed.
  Doubt has, however, been expressed as to whether a sufficient number
  of flies remain in active condition in these localities to perpetuate
  the species and to start the rapidly multiplying generations of the
  following summer. As to whether flies can persist through the winter
  in other than adult form practically nothing is known.

  In view of the importance of obtaining further information on these
  points, some inquiries were undertaken into the hibernation of flies,
  the results of which were set out in a communication by Dr. Copeman
  published in the sixth report of this series. Arrangements were made
  with a working naturalist for the collection of any flies that could
  be found in situations like those which Dr. Laver and other observers
  had found to be favourite winter quarters of hibernating flies. In
  view of the need, pointed out by Howard, for expert identification of
  the species of all flies captured in a dormant condition during the
  winter months, the co-operation of Mr. Austen of the British Museum
  (Natural History) was obtained, and to him all the flies collected
  were submitted for examination. The one specially interesting and
  unexpected point emerging from this inquiry was that not a single
  specimen of the house-fly (_Musca domestica_) was met with among the
  considerable number of hibernating flies caught in situations which
  have hitherto been regarded as the special habit of this fly. Under
  these circumstances it was felt that further detailed investigation
  of the matter was needed; and, accordingly, inquiry on a more
  extended scale, and covering—as it proved—an extensive area, was
  initiated and carried through during the past winter.

                   *       *       *       *       *

  Once more, the results obtained afford no support to the belief that
  house-flies hibernate, in this country, in the adult state; and the
  problem as to the manner in which the interval between one fly-season
  and the next is bridged over still remains unsolved.

Gordon Hewitt, Copeman, Howlett, Merriman,[10] and others, have made
experiments as to how far a fly can travel. Marked flies have been
taken within forty-eight hours at distances ranging from 300 yards to a
mile. Apparently the direction of the wind plays a considerable part
in the distance they travel.

The importance of the house-fly as a carrier of disease, especially
bacterial disease, has recently been recognised especially in times of
war. Moses was as great as a Principal Medical Officer as he was as a
Director of Supplies; and this is shown in Deuteronomy, chapter xxiii,
where he deals with the need of strict hygiene in the camp.

In the middle of the last century already attention was being drawn
to the fact that the house-fly and the blow-fly transmitted various
diseases. But it was during the Spanish-American War and the South
African War which followed shortly afterwards that the part played by
these pests in conveying enteric became definitely established. Flies
coming straight from the latrines, with their legs and their wings and
their proboscides soiled with typhoid bacilli, would enter the camp and
the tents of the soldiers and settle on their food-supplies—crawling
over their jam, floating in their milk. Thirty per cent. of the deaths
in our South African War were due to typhoid fever. The bacillus, as is
well known, is capable of existing for a long time and of persisting
alive in the alimentary canal of the insect. Dr. Graham-Smith has shown
that the bacilli may remain active for six days after feeding, and
that the feet of flies which have the bacillus on them are capable of
infecting surfaces upon which they walk for at least two days after
first coming in contact with the germs that cause ‘enteric.’

[Illustration: FIG. 21.—A, Foot of a fly, showing hairs bearing
bacteria; B, a single hair more highly magnified; C and C´, bacteria.
Diagrammatic.]

Faichne reared maggots in dejecta infected with typhoid bacilli, and
he was able to show that the flies into which these maggots turned
contained virulent typhoid germs in their intestines. There is
absolutely no doubt that typhoid is largely conveyed by the agency of
these insects; and as flies are perfectly controllable, if ‘the people
will but have it so,’ it is one of the disgraces of our civilisation
that this disease should be so prevalent.

The protective inoculation against enteric is now almost perfect, and
its value is shown by quotations from a leaflet issued by the Research
Defence Society:—

  Sir William Leishman, in a letter published during the present war,
  August 22, 1914, says: ‘The benefits of inoculation are so well
  recognised in the regular forces that we find little difficulty,
  in foreign stations, in securing volunteers for inoculation: for
  instance, about 93 per cent. of the British garrison of India have
  been protected by inoculation; and typhoid fever, which used to cost
  us from 300 to 600 deaths annually, was last year responsible for
  less than 20 deaths. Inoculation was made compulsory in the American
  army in 1911, and has practically abolished the disease; in 1913
  there were only 3 cases, and no deaths in the entire army of over
  90,000 men.’

  In Avignon, in the south of France, during the summer of 1912,
  typhoid fever broke out in the barracks. Of 2053 men, 1366 were
  protected and 687 were not. The non-protected had 155 cases of
  typhoid, of whom 21 died; the protected had not one case. In the
  winter of 1913 the French Senate resolved that the protective
  treatment should be made compulsory throughout the French army; and,
  in special circumstances, among the reservists.

[Illustration: FIG. 22.—Chart illustrating the relation of the
numerical abundance of house-flies to summer diarrhoea in the city of
Manchester in 1904. Prepared from statistics and chart given by Niven.
(From Gordon Hewitt.)]

Infantile diarrhoea, which so afflicts the crowded, poorer quarters
of our cities in the summer, is another disease intimately associated
with _Musca domestica_. But that is hardly a disease likely to trouble
the soldiers. The tubercle bacillus is another germ conveyed by
flies. House-flies are particularly fond of feeding on saliva; and
Hayward, Lord, and Graham-Smith have obtained virulent bacilli from the
intestines and dejecta of flies which had been fed on tubes containing
tuberculous sputum. These experiments have been amply confirmed by
other workers. Anyone who has ever been in Egypt will remember the
terrible sight of the flies attacking little children suffering from
ophthalmia and it is believed that the wide prevalence of this most
pitiful trouble is attributable to the abundance of flies—the flies of
Egypt, a plague even in the times of the Pharaohs. Things do not alter
much in Egypt, and the Biblical plagues are wont to recur.

Another disease—anthrax, or wool-sorter’s disease—may be conveyed by
the same carriers from infected cattle to man, and there is a good deal
of epidemiological and bacteriological evidence available to show that
flies play an important part in the spread of cholera, which is now
threatening the soldiers in the eastern seat of the war, and possibly
in disseminating the organisms which cause yaws and tropical sore.

It will be noticed that the fly is not a necessary second host for any
of these germs. They are conveyed, as if by an inoculating needle, by
contact with the proboscis or the legs or some other tainted organ
of the fly. The bacilli, however, pass through the alimentary canal
apparently unchanged and unharmed, and are deposited either with the
regurgitated food from the fly’s stomach (Fig. 20), or with the dejecta
of the insect. There is no subcutaneous inoculation—such as takes
place in the case of the mosquito when it conveys malaria, or in the
case of the tsetse-fly when it conveys sleeping sickness—where the
disease-causing organism is injected into the human body. The action of
the fly is mechanical, but none the less efficient. The poisoning of
the soldiers’ food-supply is its chief rôle in war.




                              CHAPTER VI

                                 FLIES

                                PART II

            THE BLUE-BOTTLE (_Calliphora erythrocephala_),
                              AND OTHERS

         Who fills our butchers’ shops with large blue flies?
                                         (_Rejected Addresses._)


BUT there are other flies: first amongst which may be mentioned _Fannia
canicularis_ and _F. scalaris_. These belong to the family known as
Anthomyidae, and are distinguished from the house-fly by being smaller
in size, and by many other small details in the imago stage hardly to
be appreciated except by trained dipterologists. For a short time at
the beginning of the summer, during part of May and June, specimens
of _F. canicularis_ are more abundant than _M. domestica_, and, when
seen on the window-panes of our living-rooms, are apt to be thought, by
the uninformed, to be young specimens of the latter. But, as has been
said, flies, when they are once flies, do not grow; all the growing
they do is done in the larval stage.

[Illustration: FIG. 23.—Latrine-fly, _Fannia scalaris_, male (× 3).
Antenna. Head of female, dorsal view. Natural size, resting position.
(From Graham-Smith.)]

As the days lengthen the common house-fly becomes vastly more common
than _F. canicularis_, the ‘lesser house-fly,’ and the latter now tend
to aggregate in those rooms of our houses not devoted to cooking,
and may frequently be noticed flying in a jerky and disconcerting
manner around the chandeliers or bedposts in unfrequented living- or
bed-rooms. The relative proportion of these two genera in full summer
varies in different localities. Roughly speaking, out of 100 flies
collected in a house there is something between 90 and 99 per cent. of
_M. domestica_, but the numbers not only vary with locality, but with
temperature.

On the other hand, there is a curious disproportion between the number
of sexes found ‘at home’ in the lesser house-fly. For every 100 _F.
canicularis_ taken indoors seventy to seventy-five are males, the
numbers being evened by an equal preponderance of females who have
remained out of doors.

[Illustration: FIG. 24.—Larva of _F. canicularis_. (From Gordon
Hewitt’s Report to Local Government Board, 1912.) Magnified.]

The larva of _Fannia_ is a flattened-looking grub with distinct
segments, decorated by numerous feathery processes. It lives amongst
decaying vegetation and fruit, and also amongst fermenting animal
matter and dejecta. Sometimes it is found in rotting grass. As we shall
see later, it frequently passes into the human alimentary canal. _F.
scalaris_, usually known as the ‘latrine-fly,’ is even commoner than
its congener, and the external structural differences are minute. As
its name indicates, it is found as a rule breeding in human dejecta,
and is, therefore, as a typhoid carrier, much more dangerous than
_F. canicularis_. Its larva is also more commonly found in the human
intestine.

Then there are two species of large flies known as blue-bottles or
blow-flies—_Calliphora erythrocephala_ and _C. vomitoria_. The former
of these is the more common. The sides of its face are golden yellow,
set with black hair; whereas in _C. vomitoria_ the sides of the face
are black, but the hair is golden. Both are handsome, sturdy-looking
diptera, with bluish-black thoraces, and abdomens of a dark metallic
gun-metal sort of colour.

Blow-flies deposit their eggs on fresh or decaying flesh, and this is
one of the great sources of trouble to the officers of the Army Service
Corps. But they are not content with killed flesh. They will lay their
eggs on any living flesh which is exposed, or in sores or tumours, and
here their larvae will thrive. Dr. Graham-Smith tells us he once found
the exposed muscles of the broken leg of a living rabbit seething with
a mass of small blow-fly larvae, which were nourishing themselves upon
the living tissues.

[Illustration: FIG. 25.—Blow-fly or blue-bottle, _Calliphora
erythrocephala_, female (× 3). Antenna. Male head, dorsal view. Side
view of head. Natural size, resting position. (From Graham-Smith.)]

The eggs of the blow-fly hatch out in from ten to twenty hours in
normal British temperatures; the larval life, in its three stages,
lasts from seven to eight and a half days; the pupa state lasts a
fortnight, so that the total development extends a day or two over
three weeks. The maggots are unusually voracious; and Linnaeus used to
say that the progeny of three blow-flies will dispose of a dead horse
as quickly as three lions.

_C. erythrocephala_ is essentially an outdoor fly and enters houses
only in search of a nidus on which to deposit its eggs. _C. vomitoria_
resembles its congener in size and habits, but it is not so abundant.
Occasionally its eggs have been known to be deposited in the nostrils
of animals and men.

But there are:—

              All species of resplendent flies,
              Some with green bodies and green eyes,
              Pricking like pins’ heads from their holes
              Like tiny incandescent coals.
                                                 (ANON.)

[Illustration: FIG. 26.—Green-bottle, _Lucilia caesar_, male (× 3).
Antenna. Female head, dorsal view. Natural size, resting position.
(From Graham-Smith.)]

One of these, _Lucilia caesar_, is a marked nuisance to those
responsible for victualling a camp. This green-bottle fly, like the
_Calliphora_ and the house-fly, belongs to the family Muscidae, and its
larvae are said to be indistinguishable from those of blue-bottles.
Some species of _Lucilia_ deposit their eggs in great quantities
amongst the wool of sheep when the sheep are ill-kept, and they do much
damage. But as far as war is concerned the harm that _Lucilia_ does
is laying its eggs upon dead animals. It does this on all sorts of
meat-stores; but in times of peace it especially infests stale fish,
which the issuing larva very soon eat clean to the bone. When feeding
upon a dead fish lying upon a beach they burrow down in the sand below
their food. They descend some two to six inches, and for the most part
remain deep in the sand during the daytime, coming up to feed at
night. They also have a habit of migrating from one fish to another.
This fly has also been known to lay its eggs in the neglected wounds of
human beings.

[Illustration: FIG. 27.—Flesh-fly (_Sarcophaga carnaria_), female
(× 3). Antenna. Natural size, resting position. (From Graham-Smith.)]

_Sarcophaga carnaria_ is another species which occasionally infests
human sores, and which enters houses in search of filth or carrion on
which to lay its eggs; it is viviparous and produces not eggs but live
larvae. One female can give birth to 20,000 young; and Redi states
that the larvae of these flesh-flies will in twenty-four hours devour
so much food and grow so quickly that they increase their weight
two-hundredfold.

Finally, there is a group of flies whose larvae penetrate under the
skin of human beings and give rise to definite subcutaneous troubles.
But, fortunately, these are, with few exceptions, confined to the
warmer regions of the earth, and there is very little risk of their
causing real trouble in Northern or Central Europe.

[Illustration: FIG. 28.—Side view of blow-fly (_Calliphora
erythrocephala_) (× 5). A, Cheek (jowl); B, squama; C, halter.
(From Graham-Smith.)]

The troubles or diseases caused by the presence of fly larvae in the
body are grouped in medical language under the term ‘myiasis,’ which
Graham-Smith defines as follows:—

‘The term myiasis signifies the presence of dipterous larvae in the
living body (whether of man or animals), as well as the disorders
(whether accompanied or not by the destruction of tissue) caused
thereby. Though not strictly coming within this definition, the
sucking of blood by larvae through punctures of the skin, which they
themselves produce, may be included for the sake of convenience in
classification.

Myiasis in man may be produced by dipterous larvae:—

  (_a_) Sucking blood through punctures in the skin (_Auchmeromyia
  luteola_).

  (_b_) Deposited in natural cavities of the body (_Chrysomyia_,
  _Lucilia_, _Sarcophaga_, _Calliphora_, _Oestrus_).

  (_c_) Deposited in neglected wounds (_Chrysomyia_, _Lucilia_,
  _Sarcophaga_, _Calliphora_).

  (_d_) Living in subcutaneous tissue (_Cordylobia_, _Dermatobia_,
  _Bengalia_ (?), _Hypoderma_).

  (_e_) Passing through the alimentary canal (_Fannia_, _Musca_,
  _Eristalis_, _Syrphus_, _Gastrophilus_).

In the above list, only the more common genera producing myiasis are
mentioned. In England, Type (_e_) is fairly common, and Types (_b_) and
(_c_) are occasionally observed.’

We may now consider in detail, but very shortly, the categories set
forth by Dr. Graham-Smith:—

  (_a_) The very peculiar blood-sucking maggot known as the
  Congo-floor-maggot—the larva of _Auchmeromyia luteola_—fortunately
  does not spread beyond tropical and sub-tropical Africa. It chiefly
  affects the natives who sleep on mats.

  (_b_) The flies which deposit their ova and larvae in the cavities of
  the body are again mostly foreign. The worst of all is the screw-worm
  (_Chrysomyia macellaria_) of the Southern States, Central and South
  America. Although it extends to Canada it is not troublesome north of
  Texas.

  Occasionally, blow-flies in Great Britain deposit their ova in
  the human nose or ear. They very rapidly hatch and cause great
  inflammation and necrosis until they can be discharged or removed.
  They have even been found in the anterior chamber of the eye; and I
  have some microscopic sections showing the presence of these larvae
  in that chamber, whither they had probably proceeded from the nasal
  sinuses. But on the whole, cases of this sort are comparatively rare,
  and cause but little trouble.

  (_c_) The real difficulty, and one which late last summer proved a
  serious trouble to our army in the field, are the cases in which
  maggots were found in neglected wounds. Here, however, we may take
  some comfort in the fact that the trouble is fortunately much greater
  in the tropical and sub-tropical regions than in more temperate
  climates, and diminishes as the cold weather draws on. Still, during
  the hot weeks of last August there were cases of wounded soldiers
  left lying on the fields for two or three days who were found to be
  suffering in this way. One almost hesitates to offer suggestions to
  our heroes in such cruel conditions; but whenever and wherever it can
  be done wounds should as far as possible be kept covered.

  Not only are neglected wounds affected, but tumours and ulcers are
  often attacked. But, as I have said, the danger is much greater in
  warmer climates. We know that Herod Agrippa ‘was eaten of worms, and
  gave up the ghost’: a fact which recalls the translation given by an
  undergraduate in difficulties with the Acts of the Apostles in the
  ‘Little-Go’ who rendered ‘καì γενóμενος σκωληκóβρωτος ἐξέψυξεν’ ‘He
  became a Skolekobrote, and died in the enjoyment of that office.’

  (_d_) Flies burrowing in the subcutaneous tissues are again very much
  commoner in tropical climates than in Northern Europe, and the cases
  quoted in our country are comparatively rare.

  (_e_) The presence of larvae in the alimentary canal of man is by
  no means uncommon. Both the larvae of _Musca_ and _Fannia_ are not
  infrequently found; and over a thousand of the latter have been
  passed by a highly infected individual at one time. They probably
  make their way into the body with over-ripe fruit. In some cases
  they give rise to no symptoms, but in others violent pains are felt
  and a certain dizziness, and the digestive functions are interfered
  with. The presence of these larvae in the urinary passages is even
  more difficult to explain, but they undoubtedly are at times found in
  these channels.

A few years ago an elaborate investigation was carried on by Mr. W.
Nicol, for the Local Government Board, on the part played by flies
in the dispersal of the eggs of parasitic worms. He showed quite
definitely that the ova of certain human parasites are taken into the
fly and pass through its body undigested. Should these be deposited
on the food of man, there is great risk of his becoming infected. As
I have said before, flies take only liquid food, and it is only when
the ova of the parasites are very small that they can pass into their
alimentary canals. Some eggs are too large for the fly to swallow. Eggs
of parasitic worms have also been shown to be carried on the legs and
proboscides of flies, and these are deposited on the spot where the
fly next cleans itself. Probably, however, in the end little harm is
really done by flies in disseminating parasitic worms, but it is a
possibility which must not be altogether disregarded.

The remedial measures for the control of flies are fully dealt with in
Graham-Smith’s admirable book, ‘Flies in Relation to Disease,’ from
which I have ventured to borrow many figures; and again by Dr. Gordon
Hewitt, in his work on ‘House-flies,’ which has had such a wonderful
success in stimulating our North-American cousins to decrease the
numbers of one of the gravest enemies to mankind.

It has been shown over and over again that we can control the mosquito:
the building of the Panama Canal alone proves this. We could equally
control the ‘Infinite Torment of Flies.’ The Canadians and Americans
are doing their best; but are we? The knowledgeable world has at least
discovered the reason why Beelzebub was called the ‘Lord of flies.’




                              CHAPTER VII

                                 MITES

                                PART I

                    THE HARVEST-MITE (_Trombidium_)

                   Natura in minimis maxime miranda.
                                                     (LINNAEUS.)


WE do not know what life is, but we can at any rate record its
manifestations; and we know that it is always associated with an
extremely complex substance called by Purkinje ‘protoplasm.’ This
substance Huxley described as ‘the physical basis of life.’ Protoplasm,
though we know of what elements it is composed, defies accurate
analysis, and, indeed, is never the same for two minutes together. It
is constantly changing, it is in a state of flux and is, in effect,
a stream into which matter is continuously entering and continuously
leaving.

Protoplasm may be living, or it may be dead; and when dead it soon
undergoes dissolution; but there is no life without protoplasm.
Somewhere or other Dr. David Sharp has stated that of the total amount
of protoplasm ‘in being’ in the world, the active volume of the
life-material of our globe, at least one-half is wrapped up in the body
of insects. But insects only form one sub-group out of the several
which make up the great group _Arthropoda_, or those animals which are
distinguished from others by possessing externally jointed legs—that
is, jointed appendages. This group includes also the Crustacea, the
multi-segmented Centipedes, and the Arachnids or spider-like animals.

Insects, like aeroplanes, dominate the air; Crustacea, like submarines,
inhabit the water; the poet has passionately asked:—

  Ah! who has seen the mailèd lobster rise,
  Clap her broad wings and soaring claim the skies?

But the answer, in the language of those curious mammals the
politicians, is ‘in the negative.’ Crustaceans are essentially aquatic.
On the other hand, centipedes and spiders are earth-loving animals but
some have unhappily developed parasitic or pseudo-parasitic habits.

The last-named sub-group, the Arachnids, comprise many subdivisions.
There are the spiders, the harvest-men, the scorpions, the king-crabs,
and so on. But one of the most numerous of the subdivisions of the
group are the mites and ticks (_Acarina_). I have for years been trying
to find some organ or structure shared by insects and mites and ticks,
and not found in any other group of arthropods. If I could do this I
would invent a long polysyllabic word—with lots of Greek in it—which
would really be a short way of designating those arthropods which
convey disease to man.

[Illustration: FIG. 29—_Trombidium holosericeum._ Female,
dorsal view. × 20. (After Railliet.)]

The acarines are for the most part small, and they differ from spiders
in having no waist. In fact, the three divisions into which the body
of an arthropod is normally divided—head, thorax, and abdomen—are
indistinguishable in mites, the body forming an unconstricted whole. As
a rule, these little creatures breathe, as do insects, by tracheae, or,
if these be absent, by the general surface of the body. They live for
the most part on vegetable and animal juices, and their mouth-parts
are, as a rule, piercing and suctorial; but in some species the
appendages of the mouth are capable of biting as well as piercing. The
adults have typically eight legs. The larval stages are very numerous,
and at times six distinct moults of the skin are recognisable. With few
exceptions the larva emerges from the egg as a six-legged creature. In
fact mites undergo a metamorphosis which varies in complexity and in
completeness in different groups, and it is often one of the larval
stages which causes the greatest trouble to man.

[Illustration: FIG. 30.—_Leptus autumnalis_ = larva of
_Trombidium holosericeum_. Ventral view. × 100.
(After Railliet.)]

One of these six-legged larvae has been long known as the harvest-mite,
under the name of _Leptus autumnalis_. But this is not a real species,
and there is still considerable confusion as to what the exact status
of _Leptus autumnalis_, the harvest-mite, is. Probably the larvae of
several species are involved, but it seems pretty certain that in many
cases the larvae will grow up into specimens of the genus _Trombidium
holosericeum_, though a certain and at present unknown percentage of
the larvae will grow up into _Trombidium something-or-other-else_.

They are minute bright-scarlet little creatures—the Cardinals of the
Mite world—of a beautiful satiny red, decorated here and there with
blackish spots. The body of the adult is somewhat square, tapering
slightly to the hinder end. Both legs and body are covered with red
hairs. The eyes are borne on little stalks—like lighthouses. The legs
have six joints and end in two little claws. The male is usually
smaller and more feeble than the female, the latter reaching a length
of 3 mm. to 4 mm. The adults are commonly met with in the spring or
commencing summer. Apparently, they nourish themselves on vegetable
sap. The larval form of this species[11] is undoubtedly one of the
forms confused under the now discarded name of _Leptus autumnalis_.
When starving, the body is orbicular in outline, but it becomes oblong
when it is fed, and in this case it may attain a length of ½ mm. Its
colour is of a deep orange.

[Illustration: FIG. 31.—_Leptus autumnalis_, with the so-called
proboscis. Magnified. (After Gudden.)]

This harvest mite, or, as it is called in France _le rouget_, is
most troublesome at the end of summer or at the beginning of autumn,
when it is found in enormous numbers in grass and amongst many other
plants—gooseberries, raspberries, currants, haricot-beans, sorrel,
and elderberries. From these plants it passes on to any warm-blooded
animals: particularly it attacks small mammals. Hares, rabbits, and
moles are often covered with them, but they leave their victim,
should it be shot, as soon as the body chills. They are particularly
common in Great Britain and in the centre and west of France, and
in certain parts of Germany. These irritating little semi-parasites
may be dislodged by the application of petrol or benzine—both very
inflammable—and the itching they cause allayed by the application of
acid or alcoholic lotions.

[Illustration: FIG. 32.—_Leptus autumnalis_ (× 100). The so-called
proboscis is formed around the hypo-pharynx sunk into the skin. (After
Trouessart).]

Men working in the fields are frequently attacked. During September
1914, the soldiers of the Sixth Division, stationed in and about
Cambridge, and living in tents, suffered severely from their ‘bites.’
They mostly attacked the ankles, the wrists, and the neck, but they
rapidly extend over the body. If they be checked by the presence of any
stricture, such as a garter or wrist-band, they accumulate behind it,
and the irritation is accentuated. The presence of their hypo-pharynx
in the skin causes the surrounding tissues to harden and form a
cylindrical tube—the so-called proboscis.

The amount of trouble they cause varies very greatly in different
people. Children and women with soft skins suffer, as a rule,
most; but, as happens in the case of other biting insects, certain
individuals seem to be almost immune, whilst others suffer very
considerably. The trouble is caused by the mite implanting its
mouth-parts in the skin—preferably in the hair-follicles or the
sweat-glands. When it is once fixed it rarely moves. The body remains,
of course, on the surface of the skin as a little reddish-orange
point, scarcely perceptible unless many of them are congregated in the
same position. The effect of their presence is to produce a swelling
in the skin, which may be as large as a split pea, accompanied by an
intense itching and a smarting which banishes sleep. This leads to the
patient scratching, and this scratching is the departure-point of many
troubles. Scoriated papules appear and eczematous patches, and when
the mites are very numerous an erythema, named by Rubies _Erythema
autumnale_, supervenes. The skin near the point of puncture swells,
becomes red, sometimes almost purple, and irregular patches, which when
confluent, appear a centimetre in diameter.

These skin troubles, which may end in a kind of generalised eruption,
are accompanied by a rise of temperature and a certain—sometimes a
high—degree of fever. Besides men, dogs and cats suffer from these
pests; and in these domestic pets the parasites give rise to a miliary
eruption. Domestic cattle—sheep and horses—are also attacked. And,
according to some authorities, poultry are not only attacked but killed
by these parasites. The larvae apparently only lives a few days in the
skin of the victim.

As far as is known at present the larvae of _Trombidium_ convey no
protozoal disease; but there is a terrifying little creature, known
as the Kedana mite, which in some districts of Japan causes a serious
illness, with a mortality of some 70 per cent. Apparently, it does not
act as an inoculating agent itself, but the papule, surrounded by the
red area which forms as a result of its bite, changes to a pustule, and
this lesion becomes the point of entrance of bacteria which produce the
so-called ‘river’ or ‘flood’ fever. If these mites be carefully removed
the patient suffers no harm.

Another species of mite, _Pediculoides ventricosus_, lives in stalks
of cereals, and is very apt to attack labourers who are dealing with
grain. Their bites cause severe irritation, local swellings, reddening
of the epidermis, and fever. In this particular species the female
before she is fertilised has an elongated form 0·2 mm. in length and
0·07 mm. in breadth; but when fertilised the ovaries increase to such
an extent that the posterior end of the body becomes spherical. In
this respect it resembles that remarkable flea, the chigo or jigger.
The larvae are exceptional in being born with four legs instead of the
usual three, and they pair almost immediately after emerging from the
egg-shell.

[Illustration: FIG. 33.—_Pediculoides ventricosus._ Male, ventral view
(× 250). Female, before fertilisation (× 225). A, after fertilisation;
the abdomen has begun to swell (× 250). B, with abdomen fully swollen
(× 40). (After Laboulbène and Mégnin.)]




                             CHAPTER VIII

                                 MITES

                                PART II

             ENDO-PARASITIC MITES (_Demodex_, _Sarcoptes_)

             Say what the use, were finer optics giv’n,
             T’ inspect a mite, not comprehend the heav’n.
                                         (POPE, _Essay on Man_.)

                                DEMODEX

WE have seen that harvest mites are wont to insert their heads—or
rather their mouth-parts—into the skin of human beings, but other
mites show less restraint, and insert their whole bodies. One of
these, the well-known _Demodex folliculorum_, is, according to Guiart
and Grimbert, ‘Le plus commun des parasites de l’homme et nous en
sommes presque tous porteurs.’ Without taking quite so gloomy a view,
_Demodex_ is undoubtedly widely distributed in the skin of mankind
and of other mammals.

[Illustration: FIG. 34.—(_a_) _Demodex_ in hair-follicle of dog;
magnified. (After Neumaun.) (_b_) _Demodex folliculorum_; highly
magnified. (After Railliet.)]

There are differences of opinion as to whether this form should be
split up into numerous species, or subspecies, according to the genus
of the mammals upon which it lives. We, at any rate, will confine
our attention to the human kind and so avoid losing ourselves in the
tortuous maze of synonymy and the arid discussion of a meticulous
classification so dear to the analytical German mind. To us a _Demodex_
shall be a _Demodex_, and we will leave it at that.

Unlike the majority of mites, _Demodex_ is a good deal longer than it
is broad. But even for a mite it is very small, and shows signs of
bodily degradation associated with its parasitic habit of life. Its
shape is adapted to its habitat, which is the sebaceous glands of the
skin. The long abdomen appears to be segmented, but the annulations are
not true segments. The legs are reduced to conical stumps. The male
is 300 µ[12] long and 40 µ broad across the cephalothorax. The female
is, as usual, larger, measuring 380 µ in length by 45 µ in breadth. The
minute larvae have, as is so often the case with mites, but three pairs
of legs, and are 60 µ to 100 µ in length.

This parasite, which lives on all parts of the skin of the human body,
is perhaps most commonly seen on the nose and in the passages leading
into the ear. It can be expressed by firmly pressing over the black
spot which indicates its presence in the skin of the nose or elsewhere
any small cylindrical tube, such as a watch-key. When expressed it is
not always easy to see, as coming away with it is a mass of sebaceous
matter which can best be dissolved off with oil on the microscopic
slide. Whether this particular parasite causes much disease is not
known. But in some cases it is certainly associated with acne and other
skin disorders; and as it is also found in hair-follicles, it may
possibly destroy the hair. It is apparently spread by personal contact.


                             THE ITCH-MITE

A much more serious trouble is due to _Sarcoptes scabiei_—often called
the Acarus—which gives rise to the disease known in England as the
‘itch’ and in France as the ‘_gale_.’

[Illustration: FIG. 35.—_Sarcoptes scabiei._ Female. × 180.
Ventral view. (From Bourguignon.)]

_Sarcoptes scabiei_ in both sexes is but little longer than broad.
The female is, as usual, larger than the male. These mites are shaped
very much like microscopic tortoises, of a pearly grey colour, passing
at parts into a rusty brown. Of the four pairs of legs two run
forward close to the head, and two point backwards. The integument is
semi-transparent and strengthened by parallel folds, and bears many
little bilaterally symmetrical protuberances and scales. There are also
certain hairs which have some systematic value.

[Illustration: FIG. 36.—_Sarcoptes scabiei_. Male. × 300. Ventral view.
The sucker on the fourth leg on the right is accidentally folded over
the third leg. (From Bourguignon.)]

The male is usually recognised by the fact that its third pair of legs
terminates in a long hair, whilst the other legs end in pedunculated
suckers.

[Illustration: FIG. 37.—One of the legs of _Sarcoptes scabiei_
(× about 450), showing the stalked sucker and the curious
‘cross-gartering.’ (After Bourguignon.)]

The male measures 200 µ to 235 µ in length, by 145 µ to 190 µ in
breadth. By preference, he lives under the scales which the presence of
the parasite produce on the human host. The female is markedly larger
than the male, measuring 330 µ to 450 µ in length by 250 µ to 350 µ
in breadth. Her two anterior legs end in stalked suckers, whilst the
two posterior end in hairs. The legs, like Malvolio’s, are curiously
‘cross-gartered’ with chitinous bars and rings.

At first she promenades about with the male on the surface of the human
skin, but when they have paired the female begins to tunnel in the
epidermis. The poor male, having been used, dies. As the mother-mite
tunnels she begins to lay eggs, leaving them one by one behind her as
she burrows deeper and deeper into the epidermis. Hence those that are
nearer the entrance of the tunnel are always more advanced in age and
development than those farther in. She always works head forward, and
as her tunnel is but slightly bigger than the breadth of her body, she
cannot turn round, and she is prevented from retreating by the backward
hairs or spines of her body. Hence she burrows always forward, until
she has dug her own grave at the far end of her excavation.

She is said to live two or three months and to lay one or two eggs a
day. Thus one female is, in time, enough to infect seriously a single
host. The egg is, relatively to the size of the mother, enormous: its
length being 150 µ and its width 100 µ. The egg is hatched out after
three to six days, and the young larva is hexapodous—that is, as is so
usual in Acarines, six-legged. It escapes from the burrow on to the
skin and soon tunnels into the epidermis of its host, where it moults
and transforms, about the ninth day, into a four-legged nymph. At the
end of another six days the mites moult again, and at this period one
can distinguish nymphs of two sizes: the larger female, and the smaller
male.

[Illustration: FIG. 38.—A diagrammatic view of the tunnel made by the
female of _Sarcoptes scabiei_, with the eggs she has laid behind her as
she burrows deeper and deeper. The black dots represent the excrement.
(After Guiart and Grimbert.)]

Within a month after hatching the _Sarcoptes_ has become adult, and the
sexes are occupied in seeking each other on the surface of the skin,
and it is in this stage that they are easily passed by personal contact
from one human being to another.

[Illustration: FIG. 39.—A female _Sarcoptes scabiei_, with four eggs
in different stages of development; × about 180. (After Bourguignon.)]

Many animals suffer from _Sarcoptes_; and the fact that this genus can
be transferred to man from the horse, the ox, the sheep, the goat, the
dog, the cat, the camel, the lion, &c., is a slight argument in favour
of their being one species. There is another undoubtedly distinct
species which causes serious epidemics, especially in Norway; but that
is hardly likely to enter into the scope of this book.

_Sarcoptes scabiei_, the itch-mite, is, however, a cause of serious
trouble in an army ‘in being.’ The tunnel or gallery in which the
female mite burrows is the only lesion produced directly by the
parasite. To the naked eye it presents a little whitish or greyish
line, varying in length from some millimetres to one or even three
centimetres, the longer ones occurring most frequently on the hands
or wrists. It is of course open at one end, and ends in a cul-de-sac,
which is slightly swollen, and here it is the female has taken up her
abode. She is visible as a small white, brilliant spot. Besides the
wrist, and the inner faces of the fingers—the interdigital areas—the
palms of the hands are most commonly affected.

If there is any doubt as to the cause of the existence of these
tunnels, a diagnosis can easily be verified by extracting the mite.
With the point of a needle, held almost parallel to the skin, the
tunnel can be slit open, and when the point has reached the inner
end the mite is very apt to seize it with its suckers, and can be so
withdrawn, and, if not, it can easily be picked out. It can then be
examined in a drop of diluted glycerine under a microscope.

I am no doctor, hence I venture to refer my readers to the article on
Scabies in the ‘Encyclopaedia Medica,’ by Dr. G. Pernet, and to quote
the following paragraphs from Dr. H. Radcliffe Crocker’s ‘Diseases of
the Skin,’ third edition, vol. ii.:—

  _Symptoms of Pathology._—The clinical picture of scabies is made
  up of two elements: the burrows, or cuniculi, and the attendant
  inflammation excited directly by the _Acarus scabiei_[13]; and,
  indirectly, the lesions produced by scratching, and the modifying
  influences of pressure, friction, &c. The result is a great
  multiformity of lesions, which, combined with their distribution,
  is in itself suggestive of the nature of the disease, and enables a
  practised eye to detect a well-marked case at a glance.

  When the skin is first penetrated by the acarus, inflammation is
  often set up, and a papule, vesicle, or pustule is the consequence.
  These papules or small vesicles, individually indistinguishable
  from eczema vesicles, are the most common form of eruption; but the
  inflammatory symptoms are absent in many burrows. The tract extends
  and forms a sinuous, irregular, or rarely straight line, which in
  very clean people is white, but, as a rule, is brownish or blackish
  from dirt being entangled in the slightly roughened epidermis; the
  length of these burrows is generally from an eighth to half an inch,
  but occasionally much longer—Hebra having noticed one four inches
  long. When a pustule is formed, part of the burrow lies in the roof,
  but the acarus is always well beyond the pustule or vesicle; or,
  if there is none, lies at the far end, and with a lens may often be
  discerned as a white speck in the epidermis. The degree and number of
  inflammatory lesions vary much; there may be no inflammation at all
  about many burrows, or the whole hand—especially in children—may be
  covered by pustules, vesicles, or papules; and, indeed, a pustular
  eruption on the hands is always strongly suggestive of scabies; there
  is, however, no grouping or arrangement of any of the eruptions, as
  in eczema, the lesions being scattered about irregularly. It must be
  remembered that burrows are not always present, from various causes.
  If the disease is recent it may not have got beyond the papular or
  vesicular stage; while in washerwomen, bricklayers, or others whose
  hands are constantly soaked in water or alkaline fluids, or who
  have to scrub their hands violently, the burrows become destroyed.
  The eruptions due to scratching have already been described in the
  descriptions of the ‘scratched skin,’ and comprise excoriations,
  erythema in parallel lines, eczema, impetiginous or so-called
  ecthymatous eruptions and wheals, and the inflammatory scab-topped
  papules often left after the subsidence of the wheals—especially in
  children. In carmen, cobblers, tailors, and others who sit on hard
  boards for hours together, pustular and scabbed eruptions, situated
  over the ischial tuberosities, are so abundant and constant as to be
  practically diagnostic of scabies in such people. Similar eruptions
  may be seen where there is friction from trusses, belts, &c.

  _Treatment._—I use in private practice, after the preliminary soaking
  and scrubbing, naphthol 15 parts, cret. prep. 10 parts, sap. mollis
  50 parts, adipis 100 parts, as recommended by Kaposi, well rubbed in.
  For infants it can be used half-strength, and I omit the soft-soap. I
  can speak of it in the highest praise. It is effectual, has no smell,
  and is not liable to irritate the skin, as sulphur does. It is,
  however, too expensive for public practice. Nephritis has occurred
  from its over-use, but I have never seen any bad symptoms. Another
  remedy less likely to irritate the skin than sulphur is balsam of
  Peru, of which the vapour alone is said to be fatal to the acari. The
  balsam is rubbed in for twenty minutes every night; a night-shirt
  impregnated with the drug is worn, and in the morning an ordinary
  soap-and-water bath is taken.

Colonel Allcock says that the best treatment for the itch ‘consists
in the free use of soap and hot water and the liberal application
of sulphur ointment, continued for several days. Some prefer baths
of potassa sulphurata (1 ounce of the salt to 4 gallons of water).
Clothing and bedding should be fumigated with sulphur or baked.’


                         ENDO-PARASITIC MITES

Certain little mites whose appearance is as repellent as their name—for
they are known as _Nephrophages sanguinarius_—were recorded by two
Japanese observers twenty years ago as coming away in the urine of a
Japanese patient who was suffering from various bladder troubles. As
the mites were in all cases dead, the Japanese doctors thought that
they must have been endo-parasites of the kidney. They were found day
after day for a week or more, and they were found also in the water
with which the bladder had been washed out, but always dead. It is, of
course, possible that the Japanese doctors were right in their surmise,
but the best that can be said for the case is that it is ‘not proven.’

[Illustration: FIG. 40.—_Nephrophages sanguinarius_ (enlarged). Male,
ventral surface. Female, dorsal aspect. (After Miyake and Seriba.)]

These awful-looking little mites are said to have two large eyes, and
legs of five segments and of equal length. Their colour is greenish
to brownish yellow. Undoubtedly there are many mites which live as
endo-parasites; certain members of the group Analgesinae, such as
_Laminosioptes gallinarum_, live in the intramuscular and subcutaneous
tissue of fowls, and _Cytoleichus sarcoptioides_ in their air-sacs. I
have myself found one of these species in the pigeon, so that it is
by no means beyond the bounds of human possibility that _Nephrophages
sanguinarius_ really lived in the tissues of the Japanese. Very strange
things live in the tissues of some Japanese.




                              CHAPTER IX

                                 TICKS

       A waterleche or a tyke hath neuer ynow, tyl it brestyth.
                                           (_Jacob’s Well_, 1440.)


TICKS are mites ‘writ large,’ and until about the beginning of this
century they were regarded with what one might call mild disgust and
regret. Now, however, that they have been proved to play a part—and a
very important part—in the dissemination of disease, we have come to
regard them, as Calverley said we should regard the Decalogue, ‘with
feelings of reverence mingled with awe.’

The body of a tick is covered with a tough, smooth or crinkled skin,
capable almost of any amount of extension. Until they have fed they are
flattened in shape, but after a meal of blood they very soon lose the
outlines of a Don Quixote and attain those of a Sancho Panza. In the
adult, the legs are eight in number and have six joints ending in two
claws and sometimes in suckers. Some have eyes and some have no eyes.

[Illustration: FIG. 41.—Evolution of _Argas persicus_. 1, the egg; 2,
the six-legged larva; 3, the same gorged; 4, an unfed nymph; 5, nymph
gorged. (After Brumpt.)]

The most formidable part of their armour is, however, the mouth-parts,
consisting of the tactile pedipalps, and the piercing-probe which they
stick into our bodies. This probe consists of a dorsal membranous
sheath and a ventral hypostome armed with recurved teeth, forming
together a tube within which play two cutting and tearing chelicerae.
When these have cut a way into the flesh they are withdrawn, and
the tube is inserted into the wound and blood is pumped up it by
the sucking-pharynx. It is the teeth on the hypostome, and not the
chelicerae, which anchor the ticks to their prey.

Ticks, as they affect the soldier, may be divided into two families.
The first of these, the _Argasidae_, are usually associated with human
dwellings, fowl-houses, dove-cotes, and so on, and are more commonly
parasitic on fowls than on cattle or human beings. The members of this
group hide away in crevices and corners during the day, and come out at
night to feed, for ‘their deeds are evil.’

[Illustration: FIG. 42.—_Ixodes ricinus._ Mouth-parts of the female:
A, seen from the dorsal, B, from the ventral surface. The median,
dotted, portion of the left-hand figure is the sheath; the toothed
portion the hypostome. The lateral process is the pedipalp shown only
on one side. × 35. (After Nuttall and Warburton.)]

_Argas persicus_, known to travellers as the ‘teigne de miana,’ is of
an oval form, of brownish-red colour. The male measures 4 mm. to 5 mm.
in length by 3 mm. in breadth; the female 7 mm. to 10 mm. in length
by 5 mm. to 6 mm. in breadth. This creature frequents the northern
parts of Persia, and occurs in many other warm countries. In South
Africa it is known as the ‘tampan’ and ‘wandlius,’ where it is mainly a
fowl-parasite. In Persia it is very much dreaded, though probably the
effects of its bite are due to the unsuitable treatment the punctured
skin receives and the consequent invasion of the tissues by septic
bacteria. In South Africa it is frequently fatal to fowls, especially
to chickens; but the death is there believed to be due to the loss of
blood. It is definitely proved to convey Spirochaetosis.

We have not yet explained that ticks pass through several stages
as they advance from the egg to the adult. The larval stage of _A.
persicus_ will remain on its host for five days. It then leaves, and
moults in retirement. After the moulting it visits its host by night
and remains on it for about an hour. This second stage, known as the
‘nymph’ stage, moults twice, and the female in each stage becomes much
distended with blood—‘gorged,’ as the saying is. With each moult it
becomes larger, but otherwise does not alter much in appearance. The
adult female also, like the nymph, visits the host from time to time,
and between these visits deposits eggs in great quantities in sheltered
crevices—some 50 to 100 being deposited at once.

[Illustration: FIG. 43.—_Argas reflexus_, female. On the left the
dorsal view of a specimen laying eggs; on the right a ventral view
of the same. (After Brumpt.)]

_Argas reflexus_, the ‘marginated tick,’ is yellow and white—the Papal
colours. It is common near dove-cotes and pigeon-houses, and often
attacks people sleeping in their neighbourhood. Its bite causes much
irritation, and sometimes leads to vesicles and ulcers. At one time it
was very common in Canterbury Cathedral, and so worried the worshippers
that it took all the eloquence of the ‘Very Reverend the Dean’ to
overcome its repellent powers.

[Illustration: FIG. 44.—_Ornithodorus moubata_, an unfed female. To the
left a ventral, to the right a dorsal view, showing the crinkled skin.
(After Brumpt.)]

_Ornithodorus moubata_, sometimes known as the ‘tampan,’ occurs pretty
often in South Africa, and was a cause of considerable trouble to our
troops during the South African War. It lives normally in the shade of
vegetation, but frequently invades the native huts. It is catholic in
its taste and attacks most mammals, and it has a decided preference
for men. In Uganda the natives frequently die from its bites—dying of
so-called ‘tick-fever.’

[Illustration: FIG. 45.—_Ornithodorus moubata._ Female, gorged,
seen in profile. (After Brumpt.)]

I myself once assisted in identifying two ticks, in the nymph stage,
taken in Cambridge from the ear of an American visitor to this country,
who had been camping out in Arizona shortly before his arrival. This
tick turned out to be a species of _Ornithodorus megnini_, which, as
a rule, attacks the horse, the ass, and the ox about the ears. But
it frequently attacks man, and is well known in the United States,
infesting the ears of children. An allied species, _O. turicata_,
proves fatal to fowls in the Southern States and in Mexico, and is
very harmful to human beings. The chief harm that these ticks do is to
transmit protozoal diseases to man and other animals.

A very few ticks are said to be parthenogenetic, but by far the greater
part lay fertilised eggs, and lay them in considerable numbers; and the
eggs are agglutinated together in solid little masses, by the sticky
secretion of a cephalic gland, which opens below the rostrum. The eggs
are small and elliptical, and are laid to the number of many thousands.
The young tick, which is usually born with but three pairs of legs,
hatches out in a few days if the weather be warm, or a few weeks
should it prove cold. A certain amount of moisture must be present, or
the eggs are apt to dry up. These masses of eggs are laid on the ground
under herbs or grass, or on leaves.

[Illustration: FIG. 46.—_Ixodes ricinus._ The male is
inserting its rostrum in the female genital duct before
depositing its spermatophore. × 6. (From Brumpt.)]

The issuing six-legged larvae, like the young of other animals, are
very agile, climbing on to leaves and herbage. They passionately
wait with their front legs eagerly stretching out for the passage
of the host upon which they desire to settle. Of course, but one in
ten thousand succeeds, and it is terrible to think of the amount of
unsatisfied desire which must be going on in the tick world! The rest
perish miserably. Those that do succeed attach themselves to the skin
of the host, and thrust their rostrum and sucking-tube into the hole
already prepared by the cutting chelicerae. They suck the blood, and
when gorged fall to the earth, or in some cases remain on the host in a
state of inertia or apparent syncope.

Soon, however, the gorged larva moults, and gives rise to the first
nymph—an eight-legged creature. This affixes itself anew upon a
host—either upon the same or another one—again gorges itself, and in
all points resembles the adult, except from the fact that the sexual
orifice has not yet appeared. After some days the first nymph moults,
and then again remains either on the host or it falls to the ground.
In some cases there are two successive nymph forms; but as a rule the
first nymph gives rise by a second moult to the adult form, which
again for the third time regains a host. The adults are now ripe for
pairing, and the male having enlarged the orifice of the oviduct by
inserting its rostrum, deposits therein a spermatophore or capsule full
of spermatozoa. The female is often successively fertilised by several
males.

In many cases the male dies after fertilisation. The female swells
enormously when gorged, sometimes becoming as large as a filbert, or
even a small walnut. These ticks are seldom parasites of one particular
host, but attack many mammals indifferently. They have many natural
enemies: amongst the most important of which are certain hemipterous
insects whose female attacks the nymph of the _Ixodes_, and lays within
the body of the tick a number of eggs which develop inside the nymph
until they reach the adult stage, when they make their escape through
an orifice, generally at the hind end, leaving behind them the dead
body of their host. Three species of such Hemipterous insects are
known to be parasitic on ticks: of these _Ixodiphagus caucurtei_ is
ubiquitous. It attacks all kinds of ticks, but especially _Dermacentor
venustus_.

[Illustration: FIG. 47.—_Ixodiphagus caucurtei_ laying eggs
in the nymph of _Ixodes ricinus_. × 20. (After Brumpt.)]

_Ixodes ricinus_, of a brownish colour in the male, is very common
in England and, indeed, almost everywhere. The female is yellow and
flattened, somewhat resembling a grain of rice. It is the well-known
dog-tick, but it attacks oxen, goats, deer, horses, and man. It also
attacks the grouse, and is particularly common in some parts of Great
Britain. It is impossible to rid certain areas of these troublesome
guests. In some cases they produce tumours and introduce bacteria, and
in cattle it introduces an organism known as _Babesia bovis_, which is
the cause of haematuria in oxen. _Dermacentor venustus_ transmits Rocky
Mountain fever, which is common in certain parts of the States. The
fever is accompanied with pains in the joints and in the muscles and
an eruption on the surface of the skin, appearing first on the wrists
and forehead, and invading in time all parts of the body, followed by
a scaling of the skin during a period of convalescence. In Montana the
mortality caused by this disease is very high, varying in different
years from 33 to 75 per cent. In Idaho the mortality is far less, only
about 4 per cent.

_Ornithodorus moubata_ inoculates man with a spirochaete (_Spirochaeta
duttoni_), which is the agent of the African tick-fever or relapsing
fever. One of the curiosities about the organisms transmitted by
ticks is that they live through the whole cycle of the tick’s life.
If they are taken in by the larva they are only transmissible by the
following larval stage. If they are taken in by the nymph they are
only transmissible when again the nymph stage is met with, and the
same is true of the adult. Think what such a protozoon must have seen!
The fertilisation of the egg by the spermatozoon, the fusion of their
nuclei, the extrusion of the polar-bodies, the breaking up of the egg
into segments, the gradual building up of the tissues of the larva, the
sudden inrush of the host’s blood when the larva is safely fixed, the
moulting, the changes in the nymph, the development of the generative
organs, the formation of the eggs! What a text-book of embryology and
anatomy it could write if only it had descriptive powers! If I may
paraphrase Kipling:—

                        Think where ’e’s been,
                        Think what ’e’s seen,
                        Think of his future,
                        AND GAWD SAVE THE QUEEN!




                               CHAPTER X

                                LEECHES

                                PART I

              THE MEDICINAL LEECH (_Hirudo medicinalis_)

    Hardly anything real in the shop but the leeches and _they’re_
           second-hand. (BOB SAWYER, _The Pickwick Papers_.)


AS Mr. W. A. Harding has pointed out, eleven species of fresh-water
leeches occur in these islands. But one of these, the _Hirudo
medicinalis_, seems to be vanishing, and yet it is just the one we
should cherish and preserve.

[Illustration: FIG. 48.—_Hirudo medicinalis_; about life size.
1, Mouth; 2, posterior sucker; 3, sensory papillae on the anterior
annulus of each segment. The remaining four annuli which make up
each true segment are indicated by the markings on the dorsal
surface.]

There are people who do not like leeches. This is shown by the
agitation amongst the travellers in an omnibus, as depicted in _Punch_
by Leech, years and years ago, when an old gentleman had upset a bottle
of them in their midst. But the medicinal leech, which is our theme, is
really the friend of man and of the soldier, and is a beneficial and
not a harmful animal. There are, of course, other leeches in our rivers
and in our seas, but of the latter our knowledge is scanty and it is
difficult to increase it at present—at any rate, in the Channel or in
the North Sea. In any case the marine leeches in our island-waters have
no human interest except the influence they exercise on our fish-food
supply, and this is practically negligible.

Zoologically speaking, leeches are undoubtedly degenerate earth worms
(_Oligochaeta_); and some very interesting ‘Zwischenformen’—like Mr.
Vincent Crummles, I am ‘not a Prussian’; but in spite of the war, we
may as well employ a useful term captured from the enemy—have been
found in Russia and Siberia: forms which combine many of the characters
of the _Oligochaeta_ and the _Hirudinea_. Possibly the degeneracy which
leeches are said to exhibit is associated with a semi-parasitic habit
of life. But a semi-parasitic habit does not apply to all leeches—in
fact, it applies but to few genera; there are many others, equally
degenerate—if degenerate they be—who have no trace of semi-parasitism.

A curious thing about leeches is that all the varying genera have the
same number of somites or segments; and though some of these segments
or somites are masked and fused, when analysed by the number of
segments in the embryo, by the number of the nerve ganglia, and so on,
leeches seem always to have thirty-four such segments. These do not
correspond with the rings or annulations so visible on the outside;
but a certain number of these annulations, varying in each species,
‘go’ to each somite, and so constant are these numbers that it would
not be very difficult to represent any given species of leech by a
mathematical formula.

The known species readily fall into two sub-orders: (1) The
_Rhynchobdellae_, which are marine and fresh-water leeches with
colourless blood, with no jaws, and with an extensile proboscis; and
(2) the _Arhynchobdellae_, which are all fresh-water or terrestrial,
with red blood, and generally with jaws. There is no extensile
proboscis, and the anterior sucker has a ventral aspect, and is in no
way distinct from the body. There are always in this group seventeen
pairs of nephridia or kidneys. We shall have mostly to do with the
latter sub-order.

[Illustration: FIG. 49.—View of the internal organs of _Hirudo
medicinalis_. On the left side the alimentary canal is shown, but the
right half of this organ has been removed to show the excretory and
reproductive organs. 1, Head, with eye-spots; 2, muscular pharynx;
3, first diverticulum of the crop; 4, eleventh diverticulum of the
crop; 5, stomach; 6, rectum; 7, anus; 8, cerebral ganglia; 9, ventral
nerve-cord; 10, nephridium; 11, lateral blood-vessel; 12, testis;
13, vas deferens; 14, prostate; 15, penis; 16, ovary; 17, uterus,
a dilatation formed by the conjoined oviducts.]

_Hirudo medicinalis_, the medicinal leech, is found in stagnant waters
throughout Europe and the western parts of Asia. It is rather commoner
in the southern parts of Europe than in the north. It used to be common
enough in England, where at one time, it was bred; but already a
hundred years ago its numbers were diminishing.

In a treatise on the Medicinal Leech, published by J. R. Johnson in the
year 1816, he records: ‘Formerly the species was very abundant in our
island; but from their present scarcity, owing to their being more in
request among medical men, and to the rapid improvements which have of
late years taken place in agriculture—particularly in the draining and
cultivation of waste lands—we are obliged to receive a supply from the
Continent, chiefly from Bordeaux and Lisbon.’ In his time he considered
that for every native leech employed at least a hundred foreigners were
used.

The same scarcity was very apparent to the poet Wordsworth,
whose insatiate curiosity is recorded in the following lines in
1802—Wordsworth was always asking rather fatuous questions:—

  My question eagerly did I renew,
  ‘How is it that you live, and what is it you do?’
  He with a smile did then his words repeat:
  And said that, gathering leeches, far and wide
  He travelled; stirring thus about his feet
  The waters of the pools where they abide.
  ‘Once I could meet with them on every side;
  But they have dwindled long by slow decay;
  Yet still I persevere, and find them where I may.’

In Europe, where the leech was once very abundant, it is now chiefly
confined to the south and east, and in Germany it is still found in
the island of Borkum and in Thuringia—but just now we need not trouble
ourselves very much about their distribution in Germany.

In 1842, leeches were occasionally found in the neighbourhood of
Norwich, and there are villagers still living in Heacham in Norfolk who
remember the artificial leech-ponds. In the middle of the last century
the medicinal leeches ‘of late years ... have become scarce.’ At about
the same time, it is also recorded that they were becoming scarce,
though still to be found, in Ireland. Apparently this species is now
almost extinct in England, although I know of a naturalist who can
still find them in the New Forest, but he will not tell where. If they
were getting scarce in the beginning of the nineteenth century they are
far scarcer now[14]—_for there is no leech in London_—at least, there
are only a dozen or two, and they, like those of the firm ‘Sawyer late
Nockemorf,’ are second-hand and I have heard that there is a similar
shortage in North America. And yet leeches are wanted by doctors!

Harding tells us that:—

  _Hirudo medicinalis_ is not the only leech which has been used in
  phlebotomy. _Hirudo troctina_ (Johnson, 1816), occurring in North
  Africa and in Southern Europe, where it is perhaps an introduced
  species, was largely imported at one time for medical uses....

  Several other species have been used for blood-letting in different
  countries. _Limnatis (Poecilobdella) granulosa_ in India, _Liostoma
  officinalis_ in Mexico, _Hirudo nipponia_ in Japan (Whitman), and
  _Macrobdella decora_ in the United States (Verrill), are or have been
  used in phlebotomy.

‘Our chief hope seems to lie in India.’ These words I wrote in October
1914, and my hopes were justified. Owing to the energy of Dr. Annandale
of the Indian Museum, and the anxious care of the authorities of the
P. & O. Company, I was able to land, early in the present year, a
consignment of many hundred _Limnatis granulosa_—in sound health, good
spirits, and obviously anxious to do their duty.

Leeches are still used much more than the public are aware. One
pharmaceutical chemist in the West End of London tells me he sells
between one and two thousand a year; and as they are bought wholesale
at about one penny each and sold retail at about sixpence, there is
some small profit.

[Illustration: FIG. 50.—Head of a leech, _Hirudo medicinalis_,
opened ventrally to show the three teeth and the pharynx _p_,
with its muscles; _s_, a nephridium.]

Leeches were well known to the ancients, and it would be easy to quote
case after case from the classical medical authorities of their use
in fevers and headaches and for many ill-defined swellings. They were
frequently used for blood-letting where a cupping-glass was out of the
question. With his curious uncritical instinct, Pliny records that the
ashes of a leech sprinkled over a hirsute area or formed into a paste
with vinegar and applied to the part will remove hair from any region
of the body. Leeches were also used by the Greek and Roman physicians
in angina—especially when accompanied by dyspnoea.

Probably the traffic in leeches reached its height in the first half
of the nineteenth century. Harding reminds us that in the year 1832
Ébrard records that 57,500,000 of these annelids were imported into
France, and by this time the artificial cultivation of leeches had
become a very profitable industry. Although in a small way leeches may
have been cultivated in special ponds in Great Britain, the English
never undertook the industry on a large scale. In Ireland the natives
used to gather the leeches in Lough Mask, and other inland lakes, by
sitting on the edge of the pool dangling their legs in the water until
the leeches had fastened on them. But the native supply was totally
inadequate, and the great majority of leeches used in this country were
then imported. In 1842 Brightwell mentions a dealer in Norwich who
always kept a stock of 5000 of these annelids in two large tanks. The
traffic, as we have seen, was very considerable.

The French leech-merchants recognised five classes, as follows:—

  1. Les filets ou petites Sangsues, qui ont de un à cinq ans;

  2. Les petites moyennes, qui ont de cinq à huit ans;

  3. Les grosses moyennes, qui ont de huit à douze ans;

  4. Les mères Sangsues ou les grosses, qui sont tout à fait adultes;

  5. Les Sangsues vaches, dont la taille est énorme.

They also recognised many colour-varieties, of which we need only
mention the speckled, or German leech—‘Sangsues grise medicinalis,’
with a greenish-yellow ventral surface spotted with black, and the
green Hungarian leech with olive-green spotted ventral surface. Both
are merely colour-varieties of _Hirudo medicinalis_—a species which
shows great variation in colour, and often forms colour-races when bred
artificially.

The varying sizes of the five categories mentioned above may be seen
by the fact that one thousand of ‘les filets’ weigh from 325 to 500
grammes, one thousand of ‘les petites moyennes’ weigh 500 to 700
grammes, one thousand of the ‘grosses moyennes’ weigh 700 to 1300
grammes, and one thousand of the ‘grosses’ 1300 to 2500 or even to 3000
grammes. Whereas one thousand of ‘les vaches’ weigh up to 10 kilograms,
and sometimes even more. To increase their weight the dishonest dealer
sometimes gives them a heavy meal just before selling them.

[Illustration: FIG. 51.—_Hirudo medicinalis._ _o_, Anterior sucker
covering triradiate mouth; _e_ points to an annulus midway between the
male and female openings, _s_ to a nephridium, _u_ to the bladder of
the latter; _a_, anus. Four testes and four lateral diverticula of the
crop are also shown.]

They were transported from place to place in casks half filled with
clay and water, or in stone vases full of water. Sometimes they
travelled in sacks of strong linen, or even of leather, and these had
to be watered from time to time. Another mode of conveying them was to
place them in baskets full of moss or grass soaked in water, but care
had to be taken lest they should escape. These baskets, again, could
not be packed one upon another, or the leeches were crushed. In the old
days each sack often weighed 20 to 25 kilograms; and travelling thus,
suspended in a kind of hammock, _dans une voiture ou fourgon_, from
Palota near Pesth, they reached Paris in from twelve to fifteen days.

They generally travelled via Vienna to Strassburg, where twelve great
reservoirs, appropriately placed near the hospital, received them, and
here they rested for awhile. Others collected in Syria and Egypt came
by ship to Trieste, whence they are sent to Bologna, to Milan, and to
Turin, or by water to Marseilles. Marseilles also received directly
by sea the leeches from the Levant and Africa, and expedited them to
Montpellier, Toulouse, and many another town in the south.

The best time of year for their journey was found to be the spring and
autumn. They were more difficult to manage in the summer, and they were
all the better for having a rest every now and then, as they used to
do at Strassburg. There were times when consignments of from 60,000 to
80,000 a day used to leave Strassburg for Paris. In 1806 a thousand
leeches in France fetched 12 to 15 francs; but in 1821 the price had
risen to 150 to 200 and even 283 francs. In the latter year they were
retailed at 20 to 50 for 4 to 10 sous.

As in England, however, for the most part the artificial cultivation of
leeches is diminishing in France, though half a century ago leech-farms
were common in Finistère and in the marshes in the neighbourhood of
Nantes. There were some years when, if the season was favourable,
the peasants carried to market 60,000 a day. Spain and Portugal also
furnished leeches for a long time; but by the middle of last century
the Peninsula had become almost depleted. But some leeches were still
at that period being received from Tuscany and Piedmont. Perhaps the
richest fields which still exist are the marshy regions in Hungary.

It will be observed that, probably without their knowing anything at
all about it, General Joffre, General von Kluck, Field-Marshal French,
the Grand Duke Nicholas, General von Hindenburg are fighting on some of
the best leech-areas in Europe—a point to which we shall return when
dealing with the leeches of the Orient.

One wonders what the leeches think of it all!




                              CHAPTER XI

                                LEECHES

                                PART II

        THE MEDICINAL LEECH (_Hirudo medicinalis_)—_continued_

            Non missura cutem, nisi plena cruoris, hirudo.
                                                     (HORACE.)


THERE is no doubt that the medicinal leech is one of the most
beautiful of animals. Many of its cousins are uniform and dull in
colour—‘self-coloured,’ as the drapers would call them; but the
coloration of the medicinal leech could not be improved upon. It is a
delicious harmony of reddish-browns and greens and blacks and yellows,
a beautiful soft symphony of velvety orange and green and black, the
markings being repeated on each segment, but not to the extent of a
tedious repetition. So beautiful are they that the fastidious ladies
who adorned the _salons_ at the height of the leech mania, during the
beginning of the eighteenth century, used to deck their dresses with
embroidered leeches, and by repeating the design one after the other
constructed a chain of leeches which, as a ribbon, was inserted around
the confines of their vesture.

Harding tells us that the dorsal surface of _H. medicinalis_ is
‘usually of a green, richly variegated colour, with orange and black
spots, exhibiting an extremely variable pattern, based generally upon
three pairs of reddish-brown or yellowish, more of less, longitudinal
stripes, often interrupted by black or sessile spots occurring on the
rim of each somite. The ventral surface is more or less green, more or
less spotted with black, with a pair of black marginal stripes.’

The shape of the medicinal leech, and indeed of other leeches, is
difficult to put into figures, as their bodies are as extensile as
the conscience of a politician and as flexible as that of a candidate
for parliamentary honours. The length of _H. medicinalis_ in extreme
extension is said to range from some 100 mm. to 125 mm.; in extreme
constriction from 30 mm. to 35 mm. The width in the former state would
be 8 mm. to 10 mm., and in the latter 15 mm. to 18 mm.

The movements of the medicinal leech are as graceful as its colour
is tasteful. When in the water they move like looper-caterpillars
(Geometrids), stretching out their anterior sucker, attaching it to
some object, and then releasing the posterior sucker they draw the body
up towards the mouth. Or, casting loose from all attachment, the leech
elongates and at the same time flattens its body until it assumes the
shape of a band or short piece of red tape, and by a series of the most
seductive undulations swims through the water. Kept in an aquarium
they are rather apt at times to leave the water and take up a position
on the sides of their home an inch or two above the aqueous surface.
When outside the water they keep their bodies moist by the excretion
of their nephridia or kidneys. This fluid plays the same part on the
skin of a leech as the coelomic fluid of an earthworm, which escapes
by the earthworm’s dorsal pores. There is very little doubt that both
these fluids contain some bactericidal toxin which prevents epizootic
protozoa and bacteria from settling on their skins. Such external
parasites settle on many fresh-water crustacea—such as _Cyclops_, which
is a floating aquarium of Ciliata. In fact, leeches, like earthworms,
have a self-respecting, well-groomed external appearance. Like our dear
soldiers, they are, so to speak, always clean shaven.

There has been a very widely spread tradition that in their comings
and goings in and out of the water, leeches act as weather prophets.
The poet Cowper, who throughout his chequered career ever showed but
an imperfect sympathy with science, tells us that ‘leeches in point of
the earliest intelligences are worth all the barometers in the world’;
and Dr. J. Foster mentions that leeches, ‘confined in a glass of water,
by their motions foretell rain and wind, before which they seem much
agitated, particularly before thunder and lightning.’ Modern opinion,
however, prefers the barometer.

The great Chancellor, Lord Erskine, kept a couple of tame leeches and
Sir Samuel Romilly records the fact in one of his decorous letters:—

  He told us how that he had got two favourite leeches. He had been
  blooded by them last autumn when he had been taken dangerously ill
  at Portsmouth; they had saved his life, and he had brought them with
  him to town, had ever since kept them in a glass, had himself every
  day given them fresh water, and had formed a friendship with them.
  He said he was sure they both knew him, and were grateful to him.
  He had given them different names, Home and Cline (the names of two
  celebrated surgeons), their dispositions being quite different. After
  a good deal of conversation about them, he went himself, brought them
  out of his library, and placed them in their glass upon the table.
  It is impossible, however, without the vivacity, the tones, the
  details, and the gestures of Lord Erskine, to give an adequate idea
  of this singular scene. He would produce his leeches at consultation
  under the name of ‘bottle conjurers,’ and argue the result of the
  cause according to the manner in which they swam or crawled.[15]

The medicinal leech lives on the blood of vertebrates and
invertebrates. Mr. H. O. Latter records that ‘cattle, birds, frogs and
tadpoles, snails, insects, small soft-bodied crustacea, and worms are
all attacked by various species’ of leech; but the true food of _Hirudo
medicinalis_ is the blood of vertebrates. The three teeth, which cause
the well-known triradiate mark on the skin, are serrated and sharp. The
strong sucking-pharynx has its wall attached by numerous muscles to the
underside of the skin of the leech. By the contraction of these muscles
its lumen is enlarged, and by thus creating a vacuum the blood of the
host flows in.

In the walls of the pharynx and the neighbouring parts are numerous
large unicellular glands which secrete an anti-coaguline fluid which
prevents the blood of the host clotting, so that even when the leech
moves its mouth to another point the triradiate puncture continues to
ooze. The same anti-coaguline secretion no doubt prevents the blood
coagulating in the enormous crop of the leech in which this meal of
blood is stored. Opportunities for a meal presumably occur but seldom
in nature, and the leech is the ‘boa-constrictor’ of the invertebrate
world. Its interior economy is laid out on the basis of a large and
capacious storage and of a very restricted and very slow digestion.
The blood sucked into the sucking-pharynx passes on to the thin-walled
crop, which occupies almost all of the space in the animal. This crop
is sacculated, having eleven large lateral diverticula on each side.
In a fed leech the whole of this crop is swollen with blood, which,
as we have said above, does not coagulate. The actual area where the
digestion takes place is ludicrously small, as shown at 5, Fig. 49,
p. 126. The rectum, which runs from the real seat of assimilation to
the opening of the posterior sucker, transmits the undigested food—but
there is not much of it.

An active medicinal leech will draw from one to two drams of blood, and
as much more will flow from the wound when the leech moves, because the
coagulation of the blood has been put out of action. No scab or clot
is formed. If necessary, the flow of blood can be stimulated by hot
fomentations. Sometimes the bleeding is so great that artificial means
have to be taken to check it. When leeches are applied to the human
integument they are generally first dried in a cloth, and if they will
not bite the part required, the part should be moistened with sweetened
milk or a drop of blood. To remove leeches when replete, salt, sugar,
or snuff sprinkled over the back is used. They may then be made to
disgorge by placing them in a salt solution of 16 parts salt and 100 of
water at 100° F. A full meal is said to last leeches nine months.

[Illustration: FIG. 52.—Cocoon of the medicinal leech, and longitudinal
and transverse views of the same cut open.]

Leeches are hermaphrodite; and in some genera the acting male inserts
spermatophores, or little cases containing spermatozoa, anywhere in
the skin of the leech that is being fertilised, and the spermatozoa
then make their way through the tissues of the body of the potential
female till they arrive at the ovary and there fuse with the ova. In
the medicinal leech the mating is said to be encouraged by adding fresh
water to the vessels in which the leeches are living.

The eggs are laid in capsules or cocoons attached to some water-plant
or buried in the mud, about twenty-four hours after the leeches have
mated. The cocoon is formed, as it is in an earthworm, by certain
glands in the skin which form a secretion that hardens and takes the
form of a broad ring, as it were, round the body of the leech.

[Illustration: FIG. 53.—A _Nephelis_ forming its cocoon and withdrawing
from it.]

Through this broad ring the body of the leech is withdrawn and the
fertilised eggs are deposited in it. The two ends close up, but not
entirely, for the young leeches eventually make their way into the
outer water through one of the remaining pores. Within the cocoon are
six to twenty ova, and these gradually mature and the young hatch
out. When they leave the cocoon they are minute, and of the thickness
of pack-thread. More than one cocoon is deposited by each leech, but
unless the cocoons are anchored to some submerged object they often
rise to the surface of the water and float half submerged, and are then
apt to be destroyed by water-rats, voles, and other enemies of leeches.
At times the leeches themselves destroy their cocoons.

[Illustration: FIG. 54.—Cocoons of _Nephelis_, showing the growth of
the eggs and the issuing larvae, which in the lower figure are leaving
the cocoons.]

The exact time of the emergence from the cocoon does not seem to be
very definitely known, but leeches are long-lived annelids. It is not
till their third year that they are of any use for medicinal purposes,
and they are said not to pair until they are six or seven years
old. They certainly live twelve or fifteen years. But, if we adopt
an optimistic view—and in this little book we do—the fact that they
grow up so slowly and live so long shows that it will be difficult to
replace the shortage of leeches in Great Britain and Ireland during the
present war. This could hardly be done by home culture, for even if the
war lasts three or four years we have lost the cocoons of the summer of
1914, even if we ever had them.

Leeches have many enemies:—water-rats, voles, the larvae of
the _Dytiscus_ beetle, the larvae of _Hydrophylus_, the _Nepa_
or water-scorpion, the larvae of the dragonfly, and the adult
_Dytiscus_—all feed upon them. Many birds also eat leeches; and it is
recorded that at one artificial leech-farm, where there were 20,000
leeches, they were all eaten up in twenty-four hours by an invasion of
ducks. Frogs and newts also devour them, and they are not above eating
their own brothers. _Aulostoma_ will devour its own species as readily
as it will an earthworm.

Those artificially reared, as is usually the case with animals reared
in captivity—probably against their will—are peculiarly liable to
disease of various sorts. They not only become diseased themselves, but
they act as carriers of disease and play the same part to fish which
biting insects play to man and other terrestrial animals. They convey
to fishes protozoal diseases similar to those that insects convey to
man and other warm-blooded vertebrates.

[Illustration: FIG. 55.—A leech-farm in the south of France.]

Leech-farming used to be a profitable undertaking, but now it has
fallen into desuetude in these islands. Leeches are, however, still
cultivated in some parts of the world; and in America, Latter describes
a farm, situated at Newton in Long Island, where there is, or was, a
leech-farm some thirteen acres in extent. The farm consists of oblong
ponds of about one and a half acres, each three feet deep. The bottom
of each pond is covered with clay, and the banks are made of peat. The
French writers recommend, as a rule, the use of clay for the banks. The
‘eggs’ (cocoons) are deposited in the peat from June onwards, till the
weather gets chilly. The adult leeches are fed every six months with
fresh blood placed in stout linen bags suspended in the water. A more
cruel method of feeding these domesticated leeches is that of driving
horses, asses, or cattle into the ponds—and this was the custom in
France.

[Illustration: FIG. 56.—_Glossosiphonia heteroclita_, with eggs
and emerging embryos. Ventral view. × 4. (From Harding.)]

[Illustration: FIG. 57.—_Helobdella stagnalis_, with adhering young.
Ventral view, magnified. (From Harding.)]

Some leeches show a considerable amount of maternal affection.
_Glossosiphonia heteroclita_, for instance, carries its eggs about with
it, and _Helobdella stagnalis_ has its little young larvae attached by
their tiny suckers to the mother’s body, which they are loath to leave.

_Aulostoma gulo_, the horse-leech, is notoriously a very ferocious
feeder. Exactly why this species is called a _horse_-leech is a
matter of speculation; but ‘horse’ used as an adjective seems to
imply something large and something rather coarse—for instance,
horse-chestnuts, horse-play, horse-sense, and horse-laugh.

The rapacity of the daughters of the ‘horse-leach’ is dwelt on in the
Bible.[16] I am not an authority on exegesis, but I have never felt
quite sure whether these two ladies were not the offspring of the
local veterinary surgeon. But _Aulostoma_ does occur in Palestine, and
its voracity may very well have been known to the Hebrews. I entirely
reject the idea that the word indicates some ghost or phantom: that
explanation is due to the craven policy of taking refuge in the unknown.

I conclude this chapter with a couple of sentences taken from Dr.
Phillips’s ‘Materia Medica’ on the present use of leeches:—

  The special value of leeching is shown in the early stage of local
  congestion and inflammations: such as arise from injuries, and in
  orchitis, laryngitis, haemorrhoids, and inflammations of the ear and
  eye, cerebral congestions, and congestive fixed headache.

  Leeches are also of service, in a manner less easy to understand,
  in inflammations of deep-seated parts without direct vascular
  connexion with the surface—for example, in hepatitis, pleuritis, and
  pericarditis, as well as in pneumonia, peritonitis, and, according to
  some observers, in meningitis. In all these disorders, however, they
  are very much less used than formerly—in the larger hospitals, for
  instance, when at one time they cost many hundred pounds annually, a
  few dozens in the year would represent the total employed.[17]




                              CHAPTER XII

                                LEECHES

                               PART III

                            EXOTIC LEECHES

           (_Limnatis nilotica_ and _Haemadipsa zeylanica_).

            Rulers that neither see nor feel nor know,
            But leech-like to their fainting country cling,
            Till they drop, blind in blood, without a blow.
                                   (SHELLEY, _England in 1819_.)


THE extension of war into the Near and Far East has brought into
action two genera of leeches which were and still are the cause of
extreme inconvenience and even of real danger to troops operating in
these areas. The enemies of our Allies will still insist on fighting
on richly stocked leech-grounds. For in the new war area, in southern
Europe, Asia Minor, Syria, Palestine, Egypt, and parts of India and the
real East, two genera of leeches—which are indeed not the friend but
the enemy of man, especially of the soldier—abound.

The first of these two is _Limnatis nilotica_ (Sav.), and it is from
Savigny that I have stolen the picture of this species.

[Illustration: FIG. 58.—I. _Limnatis nilotica_, side view. II. Oral
sucker, showing the characteristic median dorsal slit and the three
teeth; III. ventral view. (From Savigny.)]

It is a leech of considerable size, attaining a length of 8 cm. to
10 cm., and its outline rather slopes inward at the anterior end.
The dorsal surface is brownish-green with six longitudinal stripes,
and the ventral surface is dark. It is a fresh-water leech, and it
occurs from the Atlantic Islands, the Azores, and the Canaries—its
western limit—all along the northern edge of Africa until it reaches
Egypt, Palestine, Syria, Armenia, and Turkestan, where it achieves
its uttermost eastern boundary. This leech lives in stagnant water;
especially does it congregate in drinking-wells—the wells so often
mentioned in the New Testament. In the Talmud (Abōdāh Zārāh, 17_b_)
an especial warning is given against drinking water from the rivers
or wells or pools for fear of swallowing leeches. Doubtless the New
Testament Jew knew in his day almost as much as we know now about these
leeches. They were the cause of endless trouble to Napoleon’s soldiers
in his Egyptian campaign, and are still a real pest in the Near East.

I cannot recall that Napoleon talked much about spreading ‘Kultur,’[18]
but he certainly did it. He took with his army into Egypt a score
of the ablest men of science he could gather together in France. He
established in Cairo an ‘Institut’ modelled on that of Paris; and
his scientific ‘corps’ produced a series of monographs on Egyptian
antiquities and on the natural history of Egypt that has not yet been
equalled by any other invading force. Napoleon freed the serfs in
Germany, he codified the laws of France, and these laws were adopted
by large parts of Europe; he extended the use of the decimal system.
Napoleon had a constructive policy, and was never a consistent apostle
of wanton destruction. If he destroyed it was to build up again, and in
many instances he ‘builded better than he knew.’ He seldom so mistook
his enemies as to destroy, to terrify; the ‘frightfulness,’ though
bad enough in his times, had limits. Napoleon had at least in him the
elements of a sane and common-sense psychology. He knew that what
was ‘frightful’ to the French was not necessarily ‘frightful’ to the
Russian.

[Illustration: FIG. 59.—Anterior sucker of _Hirudo medicinalis_. This
is to compare with the anterior sucker of _Limnatis nilotica_, which
has a characteristic dorsal median slit. See preceding figure. (From
Savigny.)]

Amongst the wonderful series of books and monographs on Egypt which
described the varying activities of the savants he took in his train,
and who, at the confines of the eighteenth and nineteenth centuries
invaded the country of the Pharaohs, none is more remarkable than
Savigny’s monograph on the ‘Natural History’ of that country. And in
this folio the leech (_Limnatis nilotica_) was for the first time fully
described and depicted.

This particular leech is swallowed by man, by domestic cattle, and
doubtlessly by wild animals, with their drinking-water. Amongst the
medical writers of the Eastern world in classical times who mention
leeches there was always, as there was amongst the authors of the
Talmud, a great and haunting fear of leeches being swallowed, and these
writers mostly wrote from the area where _Limnatis nilotica_ still
abounds.

According to Masterman, who has had, as a medical officer in Palestine,
a first-hand opportunity of studying this leech, the pest attaches
itself to the mouth or throat or larynx during the process of
swallowing, and he is convinced that if it be once really swallowed and
reaches the stomach it is killed and digested.

_Limnatis nilotica_, unlike _Hirudo medicinalis_ the medicinal leech,
is unable to bite through the outer integument of man and is only able
to feed when it has access to the softer mucous membrane of the mouth
or of the pharynx or of the larynx, and of the other thinner and more
vascular internal mucous linings.

In Palestine these pests are particularly common in the region of
Galilee and in the district of Lebanon. They are, in these and other
districts, so plentiful in the autumn that almost every mule and
almost every horse the tourist comes across is bleeding from its mouth
or from its nose, for this species of leech is by no means only a
human parasite. The natives, who know quite a lot about these pests,
generally strain them out of their drinking-water by running the water
through a piece of muslin or some such sieve when they fill their
pitchers at the common well. In certain districts these leeches in the
local pools or reservoirs are kept in check by a fish—a species of carp
(_Capöeta fratercula_).

In the cases which recently came under Mr. Masterman’s observation,
the leeches were attached to the epiglottis, the nasal cavities,
and perhaps most commonly of all to the larynx of their host. When
they have been attached to the anterior part of the mouth, or any
other easily accessible position, their host or their host’s friends
naturally remove them, and such cases do not come to the hospital for
treatment.

The effect of the presence of this leech (_L. nilotica_) on the human
being is to produce constant small haemorrhages from the mouth or nose.
This haemorrhage, when the leech is ensconced far within the buccal,
the nasal, or the pharyngeal passages of the host, may be prolonged,
serious, and even fatal. Masterman records two cases under his own
observation which ended in death: one of a man and the other of a young
girl, both of whom died of anaemia produced by these leeches.

The average patients certainly suffer. They show marked distress,
usually accompanied by a complete or partial loss of voice; but all the
symptoms disappear, and at once, on the removal of the semi-parasite.
Sometimes the leeches are attached so closely to the vocal cords that
their bodies flop in and out of the vocal aperture with each act of
expiration and inspiration. The hosts of leeches so situated usually
suffer from dyspnoea, and at times were hardly able to breathe.

The native treatment is to remove the leech, when accessible, by
transfixing it with a sharp thorn; or they dislodge it by touching it
with the so-called ‘nicotine’ which accumulates in tobacco-pipes. But
nicotine is destroyed at the temperature of a lighted pipe, so whatever
the really efficient juice is, it is not nicotine. Still, as long as
the fluid proves efficient, the native is hardly likely to worry about
its chemical composition.

Masterman says that the two means he has found most effective were:
(1) Seizing the leech, when accessible, with suitable forceps; or (2)
paralysing the leech with cocaine. In the former case the surgeon
is materially assisted by spraying the leech with cocaine, which
partially paralyses it and puts it out of action. In the latter case,
if the spraying of cocaine is not sufficient, Masterman recommends the
application of a small piece of cotton-wool dipped in 30 per cent.
cocaine solution, which must be brought into actual contact with the
leech’s body. The effect of the cocaine in contact with the skin of the
leech is to paralyse it and to cause it at once to relax its hold. In
such a case the leech is occasionally swallowed, but it is more often
coughed up and out. Headaches and a tendency to vomit are symptoms
associated with the presence of this creature in the human body; the
removal of the leech or leeches coincides with the cessation of these
symptoms.

[Illustration: FIG. 60.—The Japanese variety of _Haemadipsa zeylanica_.
× 1. (From Whitman.)]

In the East, where many of our Territorial regiments are now stationed,
we come across another species of leech even more injurious to mankind
than _Limnatis nilotica_. This Asiatic leech is known as _Haemadipsa
zeylanica_, and is one of a considerable number of leeches which have
left the water, their natural habitat, and have taken to live on land.

From India and Ceylon, throughout Burma, Cochin China, Formosa to
Japan, the Philippines, and the Sunda Island, this terrible, and at
certain elevations ubiquitous, pest is spread. It lives upon damp and
moist earth. The family to which it belongs is essentially a family
which dwells in the uplands and shuns the hot, low-lying plains.
Its members do not occur on the hot, dry, sandy flats. Tennant has
described the intolerable nuisance they are in Ceylon. In fact of the
many visible plagues of tropical Asia and its eastern islands they are
perhaps the worst. Yet few have recorded their dread doings, and those
few have escaped credence.

[Illustration: FIG. 61.—_Haemadipsa zeylanica_, seen from above. × 2.
(From Blanchard.)]

Each specimen of _Haemadipsa zeylanica_ is of a clear brown colour
with a yellow stripe on each side and with a greenish dorsal stripe.
There are five pairs of eyes, of which the first four occupy contiguous
rings; but between the fifth and seventh ring there are two eyeless
rings interposed. As in the medicinal leech there are three teeth, each
serrated like a saw.

In dry weather they miraculously disappear, and nobody seems to know
quite what becomes of them; but with returning showers they are found
again on the soil and on the lower vegetation in enormous profusion.
Each leech is about one inch in length and is about as thick as a
knitting-needle. But they contract until they attain the diameter of a
quill pen, or extend their bodies until they have doubled their normal
length. They are the most insinuating of creatures, and can force their
way through the interstices of the tightest laced boot, or between
the folds of the most closely wound puttee. Making their tortuous way
towards the human skin, they wriggle about under the under-clothing
until they attain almost any position on the body they wish to take
up. Their bite is absolutely painless, and it is usual for the human
sufferer to become aware that he has been bitten by these silent and
tireless leeches when he notices sundry streams of blood running down
his body when he at last has the opportunity of undressing.

[Illustration: FIG. 62.—_Haemadipsa zeylanica._ Head, showing the eyes
and the serrations of the jaw. Highly magnified. (From Tennant.)]

Sometimes, as Tennant’s figure shows, these land-leeches (_H.
zeylanica_) rest upon the ground. At other times they ascend the
leaves of herbs and grasses, and especially the twigs of the forest
undergrowth. Perched upon the ends of growing shoots, leaves, and
twigs, stretching their quivering bodies into the void, they eagerly
watch and wait the approach of some travelling mammal. They easily
‘scent’ their prey, and on its approach advance upon it with surprising
rapidity in semicircular loops. A whole and vast colony of land-leeches
is set in motion without a moment’s delay, and thus it comes about
that the last of a travelling or prospecting party in a land-leech
area invariably fares the worst, as these land-leeches mobilise and
congregate with extraordinary rapidity when once they are warned of
the approach of a possible host, but not always in time to engage in
numbers the advanced guard.

[Illustration: FIG. 63.—_Haemadipsa zeylanica_ (land-leeches), on the
earth. (From Tennant.)]

Horses are driven wild by them, and have poor means of reprisal. They
stamp their hooves violently on the ground in the hope of ridding their
fetlocks of these tangled masses of bloody tassels. The bare legs of
the natives, who carry palanquins, are particularly subject to the
bites of these bloodthirsty brutes, as the palanquin-bearer has no free
hand to pick them off. Tennant writes that he has actually seen the
blood welling over the boots of a European from the innumerable bites
of these land-leeches; and it is on record that during the march of
the troops in Ceylon, when the Kandyans were in rebellion, many of the
Madras sepoys, and their coolies, perished from their innumerable and
united attacks. It is also certain that men falling asleep over-night
in a Cingalese forest have, so to speak, ‘woke up dead’ next morning.
These sleepers have succumbed during the night to the repeated attacks
of these intolerable and insatiable pests.

Dr. Charles Hose, for many years Resident at Sarawak, has told me that
on approaching the edges of woods in Borneo you can hear every leaf
rustling, and this is due to the fact that the eager leech, perched on
its posterior sucker on the edge of each leaf in the undergrowth, is
swaying its body up and down, yearning with an ‘unutterable yearning,’
to get at the integument of man or some other mammal.

Landor, who wrote, I think, the best book about our adventure into
Thibet some ten years ago, entitled ‘Lhassa’ (London, 1905), says of
Sikkim:—

  The game here is very scanty: the reason is not uninteresting. For
  dormant or active, visible or invisible, the curse of Sikkim waits
  for its warm-blooded visitor. The leeches of these lovely valleys
  have been described again and again by travellers. Unfortunately
  the description, however true in every particular, has, as a rule,
  but wrecked the reputation of the chronicler. Englishmen cannot
  understand these pests of the mountain-side, which appear in March,
  and exist, like black threads fringing every leaf, till September
  kills them in myriad millions.

  To remove them a bowl of warm milk at the cow’s nose, a little
  slip-knot, and a quick hand are all that is required. Fourteen or
  fifteen successively have been thus taken from the nostrils of one
  unfortunate heifer.

When fully fed, a process which takes some time with _Haemadipsa
zeylanica_, the individual leeches drop off; and they can be made
to loosen their hold by the application of a solution of salt or of
weak acid. Attempts to pull them off should be avoided, as parts of
the biting apparatus are then often left in the wound, and these may
cause inflammation and suppuration. Dr. R. J. Drummond, who has had
experience of these land-leeches in Ceylon, has told me that the bite
is often septic and that it often leads to a serious abscess which is
long in healing. He recommends pushing a match, which has been dipped
into carbolic acid, well home into the sinus made by the leech’s head.

When winter approaches the leeches die down with extraordinary
rapidity, and the species ‘carry on’ over the cold-weather period in
the form of eggs laid in cocoons on the ground, under leaves, or other
débris. Hence no land-leech ever sees its offspring, and no land-leech
has ever known a mother’s care.




                               FOOTNOTES


[1] p. 18.

[2] _B.M.J._ No. 2824, Feb. 13, 1915.

[3] Only the larger print, such as the leading articles and letters
from Admirals.

[4] September 1914.

[5] Pope’s _Epistle to Dr. Arbuthnot_.

[6] _Journ. Roy. Army Med. Corps_, vol. xx. No. 6, 1913. The
figures in this chapter are taken from this article.

[7] _With Napoleon at Waterloo._ By Edward Bruce Low; edited by
Mackenzie MacBride; p. 21. London: Francis Griffiths, 32 Maiden Lane,
Strand, W.C. 1911.

[8] New Series, No. 102.

[9] _Reports on Public Health and Medical Subjects_ (New Series),
No. 85, pp. 15 and 16.

[10] One of the first to fall a victim in defending the South African
Federation against De Wet’s rebellion.

[11] _T. holosericeum_.

[12] A µ = 1000th of a millimetre.

[13] _Sarcoptes scabiei._

[14] November 1914.

[15] Campbell’s _Lives of the Chancellors_, vol. vi.

[16] Proverbs xxx. 15.

[17] _Materia Medica and Therapeutics._ By Charles D. F. Phillips,
p. 1015.

[18] I wonder if it is _any_ use pointing out that the German
word _Kultur_ is not the equivalent—as our daily Press takes it
to be—of the English word ‘Culture,’ brought into fashion forty years
ago by Matthew Arnold and sadly overworked. Put shortly _Kultur_
= ‘civilisation.’ The German word which we associate with ‘Culture’ is
_Bildung_.




                                 INDEX


    _Acanthia_, 23
    _Acarina_, 89
    Acarus (_Sarcoptes scabiei_), 99
    Acne, 99
    African tick-fever, 116, 121
    Agronom, M., 16, 17
    Allcock, Colonel, 109
    Analgesinae, 111
    Annandale, Dr., 129
    _Anoplura_, 1, 11
    Antelopes, 36
    Antennae, of lice, 3;
      of bed-bug, 25
    Anthomyidae, 74
    Anthrax, 72
    Ants, 27
    Arachnids, 88
    _Argas persicus_, characteristics of, 114;
      breeding habits, 115
    Argasidae, 113
    _Arhynchobdellae_, 125. See _Rhynchobdellae_
    _Arthropoda_, 88
    _Auchmeromyia luteola_, 82, 83
    _Aulostoma_, 144;
      _A. gulo_, 147
    Austen, Mr. E. E., 65

    _Babesia bovis_, 120
    _Bacillus pestis_, 45
    Bed-bug (_Cimex lectularius_), 23;
      antennae of, 25;
      characteristics, 25–26
    Benzine, 13, 33
    Beveridge, Lieut.-Colonel, 48, 50
    Biscuits, infestation of Army, 50
    Biscuit-moth, 48
    Black Death, 38, 45
    Blake, 45
    Blow-flies, 83
    Blue-bottle (_Calliphora erythrocephala_), 74, 76
    Boars, 36
    Body-louse, 3, 10, 20
    Boer prison-ship, 20
    Brightwell, 131
    British Expeditionary Force, 46
    _British Medical Journal_, 21
    British Museum, 50
    Bubonic plague, 35, 38
    Bug. _See_ Bed-bug
    Burns, 4
    Butler, Mr., 40

    _Calliphora erythrocephala_ (blue-bottle), 76;
      _C. vomitoria_, 76
    Carp, 153
    Centipedes, 88
    _Ceratophyllus fasciatus_, 45
    Chigo (burrowing-flea), 37
    _Chrysomyia macellaria_, 83
    Ciliata, 138
    _Cimex_, 23, 25, 26, 27;
      _C. lectularius_ (bed-bug), 23;
      _C. rotundatus_, 23
    Cockroach, 21, 24, 26, 27, 39
    Cocoons, 161
    Congo-floor-maggot, 82
    Copeman, Dr. S. Monckton, 21, 65
    _Corcyra_, 49;
      _C. cephalonica_, 49
    Cow-dung, 42
    Cresol-soap solution, 21, 22
    Crustacea, 88
    _Ctenocephalus canis_, 37;
      _Ct. felis_, 37
    _Cyclops_, 138
    _Cytoleichus sarcoptioides_, 111

    Deer, 36
    De Geer, 30
    _Demodex_, 97 ff
    _Demodex folliculorum_, 97
    _Dermacentor vernustus_, 120
    Diarrhoea, 70
    Dizziness, 85
    Dog-flea, 40
    Dog-tick, 120
    Drummond, Dr. R. J., 15, 42
    Durrant, Mr., 48, 50
    _Dytiscus_, 144

    Ébrard, 131
    _Empusa_, 65
    Enteric, 69
    Entomologist, 18
    _Ephestia kühniella_, 48
    Erskine, Lord, 139
    Erythema, 94
    _Erythema autumnale_, 94
    _Esox lucius_, 15

    Faichne, 69
    _Fannia_, 76, 84;
      _F. canicularis_, 74, 75;
      _F. scalaris_, 74, 76
    Flea (_Pulex irritans_), 35;
      extermination of, 42
    Flies (_Musca domestica_), 57;
      breeding habits, 59;
      powers of travel, 67
    Flour-moth, the (_Ephestia kühniella_), in soldiers’
      biscuits, 46
    Flowers of sulphur, 16
    Folklore, 15
    French, Field-Marshal, 135
    Frogs, 144
    Fumigation, method of, 33

    Gascoigne, 40
    Goats, 36
    Graham-Smith, Dr., 68, 81
    Grimbert, 97
    Guiart, 97

    _Haemadipsa zeylanica_, 156, 157
    Harding, Mr. W. A., 123, 129, 137
    Hair-follicles, 94
    Hair-louse, 3
    Harman, Dr. N. Bishop, 19
    Harvest-mite (_Trombidium_), 87, 91, 92, 97
    Head-louse, 4, 9
    Hemipterous insects, 27
    Henna, 16
    Herod Agrippa, 84
    Hewitt, Dr. C. Gordon, 58
    _Hirudinea_, 124
    _Hirudo medicinalis_, 123, 127, 129, 136, 140, 153
    _Horse_-leech, 147
    Hose, Dr. Charles, 160
    Huxley, 87
    Hydrocyanic-acid gas, 33
    _Hydrophylus_, 144

    Itch-mite, 99
    _Ixodes_, 119;
      _I. ricinus_, 120
    _Ixodiphagus caucurtei_, 120

    Jeyes’ fluid, 22
    Jigger (chigo), 95
    Joffre, General, 135

    Khiva, 17
    Kerosene, 33

    _Laminosioptes gallinarum_, 111
    _Lancet_, 21
    Landor, 160
    Larva, 8;
      of flea, 41
    Latter, Mr. H. O., 140
    Leech, 123;
      the medicinal (_Hirudo medicinalis_), 123;
      breeding habits, 142, 143;
      coloration of, 137;
      enemies of, 144;
      exotic (_Limnatis nilotica_ and _Haemadipsa zeylanica_), 149;
      farming of, 145;
      fear of swallowing, 152;
      modes of conveying, 133;
      movements of, 137;
      suffering caused by, 154;
        Asiatic, 156;
        characteristics of, 157, 161;
        disappearance of, 157;
        method of attack, 158;
        size of, 157
      to remove, 142;
      traffic in, 131;
      uses of, 130
    Leech-ponds, 128
    Lefroy, Professor, 22
    Leishman, Sir William, 70
    _Leptus autumnalis_, 91
    Lice (_Pediculus_), 1;
      rules for avoidance of, 12
    _Limnatis granulosa_, 129;
      _L. nilotica_, 149, 152, 153, 154, 156
    Linnaeus, 87
    Lounsbury, Mr. C. P., 18
    _Lucius_, 15

    Maggot, 82
    Mallophaga, 18
    Martin, Professor C. J., 31
    Masterman, Dr., 154, 155
    Mercury, 17
    Mites, 87;
      bites of, symptoms and treatment, 107–9;
      breeding habits of, 103;
      characteristics, 103, 104;
      _Demodex, Sarcoptes_, 97;
      epidemics caused by, 105;
      endo-parasitic, 109;
      nourishment of, 91
    Montagu, Lord, 59
    Murinae, 45
    Murray, Andrew, 3
    _Musca_, 84;
      _M. domestica_ (house-fly), 57, 70, 74, 75
    Myiasis, 81

    Napoleon, 151
    Necrosis, 83
    _Nepa_, 144
    _Nephrophages sanguinarius_, 109, 111
    Newsholme, Dr., 65
    Nicholas, Grand Duke, 135
    Nicol, Sergeant Daniel, 55
    Nicol, W., 85
    Nicotine, 155
    Nightingale, Dr. P. A., 43
    Nits, 12
    Nymph, 117

    _Oligochaeta_, 124
    Ophthalmia, 72
    Ormerod, Miss, 48
    _Ornithodorus megnini_, 117;
      _O. moubata_ (‘tampan’), 116, 121;
      _O. turicata_, 117

    Panama Canal, 86
    Paraffin, 13, 14
    _Pediculoides ventricosus_, 95
    _Pediculus_ (lice), 2;
      _P. capitis_, 2, 4, 10, 12, 13;
      _P. vestimenti_, 2, 4, 8, 10, 12, 14
    Pernet, Dr. G., 107
    Petrol, 13, 14
    Petroleum, 17
    Pharynx, 140;
      sucking, 141
    Phillips, Dr., 147
    _Phthirius_, 2
    Pike, 15
    Plague, 31;
      Pepys’s, 45
    Proboscis, 25
    Protoplasm, 87
    Protozoal diseases transmitted by ticks, 117
    _Pulex irritans_ (flea), 37, 40, 45
    Purkinje, 87

    Quick Laboratory, 9;
       Quick Professor of Biology, 11

    Radcliffe, Dr. H., 107
    Rat-fleas, 38
    Redi, 80
    Relapsing fever, 14
    _Rhynchobdellae_, 125. See _Arhynchobdellae_
    Rice, 49
    Riley, Professor, 48
    Rocky Mountain Fever, 120
    Romilly, Sir Samuel, 139
    Rothschild, Hon. Charles, 38
    Rubies, 94
    Ruskin, 57
    Russell, Mr., 39

    _Sarcophaga carnaria_, 80
    _Sarcoptes_, 104
    _Sarcoptes scabiei_, 106
    Sarts, 16, 17
    Savigny, 149, 152
    Scabies, 107
    Sharp, Dr. David, 88
    South African War, 11, 19
    Spirochaete, 31;
      _S. obermeieri_, 31
    Spirochaetosis, conveyed by _A. persicus_, 114
    Stable-yards, 59
    Stag-beetle, 39
    Sulphur, 33;
      bags, 18;
      flowers of, 18
    Sweat-glands, 94

    Talmud, 150
    ‘Tampan,’ 114, 116
    Tennant, Mr., 159
    Ticks, characteristics of, 112, 113, 117;
      breeding habits, 119;
      habits, 114, 115
    Tomkins, Dr. H. H., 18
    _Trichinella_, 53
    _Trombidium_ (harvest-mite), 95;
      _T. holosericeum_, 91
    Tuberculosis, 31
    Tunnels, burrowed by mite, 106
    Turpentine, 13;
      oil of, 34
    Typhoid, 69;
      bacilli, 68
    Typhus, 10, 14, 31

    ‘Vermijelli,’ 22
    Von Hindenburg, General, 135
    Von Kluck, General, 135
    Voles, 143

    Warburton, Mr. C., 4, 5, 8, 9
    Water-rats, 143
    Wordsworth, 127

    _Xenopsylla cheopis_, 45
    _Xylol_, 13

    Yeomanry, D.C.O., 19


                              PRINTED BY
                 SPOTTISWOODE AND CO. LTD., COLCHESTER
                            LONDON AND ETON

                          ——————————————————




                With Portraits. Demy 8vo. 10s. 6d. net.

                                  “J”
                              A Memoir of
                           John Willis Clark

        Registrary of the University of Cambridge, and sometime
                      Fellow of Trinity College.

                           By A. E. SHIPLEY,

                      Master of Christ’s College.

  _In the Cambridge Review, the Provost of King’s says_:—“A book of
  permanent value to Cambridge men and of vivid immediate interest
  to the generations who knew ‘J.’ Dr. Shipley has told his story
  with a combination of true appreciation and perceptive humour.”

  _Times_:—“The affectionate and sympathetic portrait of ‘J’ in
  his private life as he was known and loved by hundreds. He was
  above all remarkable for his power of winning and retaining the
  affection of generation after generation of young men.”

  _Evening Standard_:—“It ought to be generally read, being one
  of the most cheerful biographies we have ever come on. A vivid
  picture of a remarkable character.”

                                ——————

                 A GIFT FOR NATURALISTS AND SPORTSMEN.

     Royal 8vo. 12s. 6d. net. In 1 Volume. With Coloured and other
                Illustrations. NEW AND CHEAPER EDITION.

                      The Grouse in Health and in
                               Disease.

[Illustration of a grouse]

           Edited by A. S. LESLIE and A. E. SHIPLEY, F.R.S.

               (Master of Christ’s College, Cambridge).

                  With an Introduction by LORD LOVAT.

  _Times_:—“The editors have fully fulfilled their expressed
  intention of making the book a practical guide to sportsmen and
  naturalists.”

  _Scotsman_:—“A book which, for many years to come, is likely to
  remain the standard authority on the grouse.”

                                ——————

          London: SMITH, ELDER & CO., 15 Waterloo Place, S.W.

                          ——————————————————




                  _Smith, Elder & Co.’s Publications_

                                ——————

The Minor Horrors of War. By Dr. A. E. SHIPLEY, F.R.S., Master of
Christ’s College, Cambridge. Crown 8vo. With 64 Illustrations. 1s. 6d.
net in Paper Cover, or 2s. net in Cloth.

                                ——————

The Early Diagnosis of Heart Failure and other Essays on the Heart and
Circulation. By T. STACEY WILSON, M.D.Edin., F.R.C.P.Lond., Senior
Physician to the General Hospital, Birmingham; Lecturer on Medicine
in the Dental School of the University of Birmingham. With over
130 original Diagrams showing the results of auscultation, and of
percussion of the heart and liver, in cases of cardiac inefficiency,
and 30 Figures showing cardiac tracings. Demy 8vo., 12s. 6d. net.

  _Medical World._—“The importance of this volume cannot be
  over-estimated. We doubt if anything so valuable has ever been
  written on the subject of cardiac disease.”

                                ——————

An Index of Symptoms with Diagnostic Methods. By RALPH WINNINGTON
LEFTWICH, M.D., late Assistant Physician to the East London Children’s
Hospital; Author of “Tabular Diagnosis,” “A Pocket-Book of Treatment,”
“Syphonage in the Large Intestine,” &c. Fifth and enlarged edition.
Crown 8vo., 10s. 6d. net.

  _Medical Review._—“Wholly admirable and unique.”

  _Lancet._—“A most useful compilation.”

  _British Medical Journal._—“We can strongly recommend the book.”

  _Medical Press._—“It fills a genuine gap in medical literature.”

                                ——————

        With Illustrations and Diagrams. Demy 8vo, 3s. 6d. net.

How to Diagnose Small Pox. A Guide for General Practitioners, Post
Graduate Students, and Others. By W. McC. WANKLYN, B.A.Cantab.,
M.R.C.S., L.R.C.P., D.P.H. Assistant Medical Officer of the London
County Council, and formerly Medical Superintendent of the River
Ambulance Service (Small Pox) of the Metropolitan Asylums Board.

  _Universal Medical Record._—“Dr. Wanklyn is well able to lay down
  golden rules for the guidance of the general medical practitioner
  and the post-graduate student. Dr. Wanklyn, by his original and
  chatty style, brings out every point of importance with great
  clearness.”

                                ——————

A Junior Course of Practical Zoology. By the late A. MILNES MARSHALL,
M.D., D.Sc., M.A., F.R.S., and the late C. HERBERT HURST, Ph.D. Revised
by F. W. GAMBLE, D.Sc., Lecturer in Zoology in the University of
Birmingham. Seventh Edition. With Illustrations. Crown 8vo., 10s. 6d.

                                ——————

Animal Life. By F. W. GAMBLE, D.Sc., F.R.S., Lecturer in Zoology
in the University of Birmingham. With numerous Half-tone and Line
Illustrations. Crown 8vo., 6s. net.

                                ——————

          London: SMITH, ELDER & CO., 15 Waterloo Place, S.W.

                          ——————————————————




          Works by Sir FREDERICK TREVES, Bart., G.C.V.O., &c.
                  Serjeant Surgeon to H.M. The King.

                                ——————

  With a Coloured Frontispiece, 40 pages of Half-Tone Illustrations,
                              and a Map.

                        The Cradle of the Deep:
               AN ACCOUNT OF A VISIT TO THE WEST INDIES.

  TIMES.—“A very attractive book ... fresh, instructive, humorous,
  and inspiring.”

  STANDARD.—“The best book that has been written about the West
  Indies since Kingsley and Froude laid down their brilliant pens.”

  DAILY TELEGRAPH.—“Rich in touches of genuine wit and humour, and
  richest of all in those flashes of humanity and personal sympathy
  which are the very life-blood of literature ... the traveller’s
  note-book _in excelsis_.”

  DAILY NEWS.—“A very attractive book, so attractive that it will
  probably be the most popular West Indian guide book for many
  years to come.”

                                ——————

   With 72 Illustrations from Photographs by the Author, and a Map.

                         Uganda for a Holiday.

  TIMES.—“ ... Sir Frederick possesses a talent for observation,
  and, what is more, the gift of describing what he observes in
  terse and vivid sentences.”

  MORNING POST.—“The distinguished surgeon writes for the benefit
  not of big game hunters, but of tourists like himself, who
  desire, for a change, to get beyond the beaten track.”

  STANDARD.—“ ... Another agreeable record of unconventional
  travel.... The book is written with imagination and humour.”

  DAILY MIRROR.—“From start to finish the book brims over with good
  things.”

                                ——————

     With Illustrations from Photographs by the Author, and a Map.

                      The Land that is Desolate:
                  AN ACCOUNT OF A TOUR IN PALESTINE.

  DAILY NEWS.—“It sets down in entertaining and well-turned
  sentences those things which are likely to interest the eye and
  the mind of a cultured and humane holiday maker.”

  GLASGOW HERALD.—“Admirable illustrations reach the very highest
  standard of amateur work. The author’s pen is as remorselessly
  faithful as his camera. The caustic humour which enlivens the
  book helps to make it most interesting.”

  GLOBE.—“Much of the charm that characterises Sir Frederick
  Treves’ book lies in that ironic humour which every now and then
  breaks forth in his descriptions of cities and men.”

                                ——————

          London: SMITH, ELDER & CO., 15 Waterloo Place, S.W.

                          ——————————————————




                         _Recent Publications_

                                ——————

                     Small demy 8vo. 7s. 6d. net.

=Canadian Nights.= Being Sketches and Reminiscences of Life and Sport
in the Rockies, and the Canadian Woods.

       By the Right Honble. The Earl of Dunraven, K.P., C.M.G.,
              Under-Secretary to the Colonies, 1885–1887.
                   Author of ‘The Great Divide,’ &c.

  _Sunday Times._—‘Short stories, bright, racy and fascinating. The
  author’s style is excellently adapted to reproduce the atmosphere
  of the mountains and the woods and will attract many readers.’

                                ——————

                With 26 Illustrations and a Sketch Map.
                    Small royal 8vo. 10s. 6d. net.

=Hunting and Hunted in the Belgian Congo.= By R. Davey Cooper.

                     Edited by R. Keith Johnston.

  _Court Journal._—‘A wonderful series of adventures. As thrilling
  a travel book as has been published for many a long day.’

                                ——————

                     Small demy 8vo. 7s. 6d. net.

   With Portraits, one being that of Lord Kitchener, G.C.M.G., K.P.,
              from the Painting by the Hon. John Collier.

=Egypt in Transition.= By Sidney Low.

    Author of ‘A Vision of India.’ &c. With an Introduction by the
           Right Hon. The Earl of Cromer, O.M., P.C., G.C.B.

  _Times._—‘The best picture of the more accessible parts of the
  Sudan which has yet been published. Mr. Low is a deft craftsman;
  he can make you a picture of the desert, of feathery palm-trees,
  of the shining waters of the Nile, in a few telling phrases.’

  _Country Life._—‘The book has a story to tell of infinitely
  greater interest than that in any novel.’

                                ——————

        With Illustrations and a Map. Large post 8vo. 5s. net.

Travel and Politics in Armenia.

           By Noel Buxton, M.P., and the Rev. Harold Buxton.

      With an Introduction by the Right Hon. Viscount Bryce, and
            a Contribution on Armenian History and Culture
                            by Aram Raffi.

  _Scotsman._—‘An excellent purpose will be achieved by the present
  book if it serves to focus attention on Armenian affairs. A
  pleasant blend of travel talks and political discussions.’

                                ——————

          London: Smith, Elder & Co., 15 Waterloo Place, S.W.

                          ——————————————————




                         _Recent Publications_

                                ——————

                          Crown 8vo. 1s. net.

=Principles of Property.= By J. Boyd Kinnear,

            Author of ‘Principles of Civil Government,’ &c.

  _Scotsman._—‘An able, interesting and well-reasoned statement of
  some cardinal principles of modern sociology.’

  _Belfast Northern Whig._—‘The publication is in every way useful
  and timely, and it is written with a fulness of knowledge and a
  clearness and restraint of expression that add immensely to its
  value.’

                                ——————

              Large medium 8vo. With Portraits. 6s. net.

=Memories of John Westlake.= Contributed by some of the many friends of
the distinguished international lawyer.

  _Times._—‘A scholar, thinker, and a man of science. His influence
  was deep and lasting. A few men are the teachers of their age,
  and among them was John Westlake.’

                                ——————

       Small demy 8vo. With 16 page Illustrations. 7s. 6d. net.

St. Margaret’s, Westminster.

                       By H. F. Westlake, M.A.,
            Custodian and Minor Canon of Westminster Abbey.

  _Pall Mall Gazette._—‘We are indebted to Canon Westlake for one
  of the most interesting monographs that the still unexhausted
  field of London history has produced. Deeply interesting and
  abundantly informing.’

                                ——————

                       Large post 8vo. 6s. net.

Shakespeare Personally.

       By the late Professor Masson. Edited by Rosaline Masson.

  _Scotsman._—‘Lectures edited and arranged by his daughter with a
  skill that makes them read like a new treatise. Their appearance
  is an event not without its own importance in the history of
  contemporary Shakespearean criticism.’

                                ——————

                      2 vols. Demy 8vo. 15s. net.

=American and English Studies.= By the late Whitelaw Reid. With an
Introduction by Royal Cortissoz.

  _Times._—‘Few men’s speeches show on every page so lofty a
  standard of civic ethics, so much courage, and so wide and
  intimate an acquaintance with the literature and history of other
  countries besides those of their own.’

                                ——————

                        Demy 8vo. 10s. 6d. net.

=Malcolm MacColl.=

Memoirs and Correspondence. With a Portrait.

              By the Right Honble. George W. E. Russell,
              Author of ‘Collections and Recollections.’

  _Daily Chronicle._—‘A correspondence of inordinate importance. An
  excellent memorial to Canon MacColl, the most effective of modern
  pamphleteers. A book of abiding interest.’

                                ——————

          London: Smith, Elder & Co., 15 Waterloo Place, S.W.

                          ——————————————————




                         SMITH, ELDER & CO.’S
                       NEW SHILLING NET SERIES.

                                ——————

   1. Deeds that Won the Empire.               Dr. W. H. Fitchett.
   2. The Cruise of the “Cachalot.”               Frank T. Bullen.
   3. Fights for the Flag.                     Dr. W. H. Fitchett.
   4. The Log of a Sea Waif.                      Frank T. Bullen.
   5. The Gamekeeper at Home.                   Richard Jefferies.
   6. A Londoner’s Log Book.            Rt. Hon. G. W. E. Russell.
   7. The Sowers.                                  H. S. Merriman.
   8. Jess.                                      H. Rider Haggard.
   9. Vice Versâ.                                       F. Anstey.
  10. Woodland, Moor, and Stream.                      J. A. Owen.
  11. The Tale of the Great Mutiny.            Dr. W. H. Fitchett.
  12. Sixty Years in the Wilderness.            Sir Henry W. Lucy.
  13. A Vision of India.                               Sidney Low.
  14. The Defence of Plevna.              Capt. F. W. von Herbert.
  15. The Memoirs of Sherlock Holmes.              A. Conan Doyle.
  16. Nelson and His Captains.                 Dr. W. H. Fitchett.
  17. With Edged Tools.                      Henry Seton Merriman.
  18. The Adventures of Sherlock Holmes.           A. Conan Doyle.
  19. The Exploits of Brigadier Gerard.            A. Conan Doyle.
  20. Wellington’s Men.                        Dr. W. H. Fitchett.
  21. The Red Hand of Ulster.                George A. Birmingham.
  22. The Honourable Molly.                       Katharine Tynan.
  23. A Life’s Morning.                            George Gissing.
  24. Court Royal.                                S. Baring-Gould.

                                ——————

          London: SMITH, ELDER & CO., 15 Waterloo Place, S.W.

         —————————————————— End of Book ——————————————————




                   Transcriber’s Note (continued)

Minor typographical errors have been corrected in this transcription.

Other errors and unusual or variable spelling and hyphenation have been
left unchanged except as noted below.

  Page xvi — “Sargophaga” changed to “Sarcophaga” (Sarcophaga carnaria)

  Page 27 — “features” changed to “feature” (Perhaps the most
            disagreeable feature)

  Page 38 — “bubonic-plague” changed to “bubonic plague” (bubonic plague
            was associated first with rats)

  Page 38 — “subtropical” changed to “sub-tropical” (in all tropical and
            sub-tropical countries)

  Page 49 — “inself” changed to “itself” (The moth itself is a rather
            insignificant)

  Page 65 — “Austin” changed to “Austen” (Dr. Monckton Copeman and
            Mr. E. E. Austen)

  Page 75 — “housefly” changed to “house-fly” (F. canicularis, the
            ‘lesser house-fly,’)

  Page 93 — “proboscis” changed to “hypo-pharynx” (presence of their
            hypo-pharynx in the skin)

  Page 123 — “gentlemen” changed to “gentleman” (when an old gentleman
             had upset)

  Page 126 — “has removed been” changed to “has been removed” (the right
             half of this organ has been removed to show)

  Page 135 — “von Hinderberg” changed to “von Hindenburg” (General von
             Hindenburg)

  Page 150 — “freshwater” changed to “fresh-water” (It is a fresh-water
             leech)

  Page 152 — “preceeding” changed to “preceding” (See preceding figure.)

  Page 158 — “underclothing” changed to “under-clothing” (they wriggle
             about under the under-clothing)

  Page 163 — “Austin” changed to “Austen” (Austen, Mr. E. E.)

  Page 163 — “lectularis” changed to “lectularius” (Bed-bug
             (Cimex lectularius))

  Page 164 — “Ctenophalus” changed to “Ctenocephalus” (Ctenocephalus
             canis)

  Page 164 — “Ebrard” changed to “Ébrard” (Ébrard, 131)

  Page 164 — “Hirudi” changed to “Hirudo” (Hirudo medicinalis)

  Page 164 — “Lemna” changed to “Henna” (Henna, 16)

  Page 164 — “Limnalis” changed to “Limnatis” (Limnatis nilotica)

  Page 164 — “vernustus” changed to “venustus” (Dermacentor venustus)

  Page 166 — “Trombidum” changed to “Trombidium” (Trombidium
             (harvest-mite))

  Page 166 — “Von Hinderberg” changed to “Von Hindenburg” (Von
             Hindenburg, General)

Footnotes have been re-indexed using numbers and placed before the Index.