The landing of the Qul-En ship, a tiny craft no more than fifteen feet in diameter, went completely unnoticed, as its operator intended. It was armed, of course, but its purpose was not destruction. If this ship, whose entire crew consisted of one individual, were successful in its mission then a great ship would come, wiping out the entire population of cities before anyone suspected the danger.

A great ship would come, wiping out the entire population of cities before anyone suspected danger....

But this lone Qul-En was seeking a complex hormone substance which Qul-En medical science said theoretically must exist, but the molecule of which even the Qul-En could not synthesize directly. Yet it had to be found, in great quantity; once discovered, the problem of obtaining it would be taken up, with the resources of the whole race behind it. But first it had to be found.

The tiny ship assigned to explore the Solar System for the hormone wished to pass unnoticed. Its mission of discovery should be accomplished in secrecy if possible. For one thing, the desired hormone would be destroyed by contact with the typical Qul-En ray-gun beam, so that normal methods of securing zoological specimens could not be used.

The ship winked into being in empty space, not far from Neptune. It drove for that chilly planet, hovered about it, and decided not to land. It sped inward toward the sun and touched briefly on Io, but found no life there. It dropped into the atmosphere of Mars, and did not rise again for a full week, but the vegetation on Mars is thin and the animals mere degenerate survivors of once specialized forms. The ship came to Earth, hovered lightly at the atmosphere's very edge for a long time, and doubtless chose its point of descent for reasons that seemed good to its occupant. Then it landed.

It actually touched Earth at night. There was no rocket-drive to call attention and by dawn it was well-concealed. Only one living creature had seen it land—a mountain-lion. Even so, by midday the skeleton of the lion was picked clean by buzzards, with ants tidying up after them. And the Qul-En in the ship was enormously pleased. The carcass, before being abandoned to the buzzards, had been studied with an incredible competence. The lion's nervous system—particularly the mass of tissue in the skull—unquestionably contained either the desired hormone itself, or something so close to it that it could be modified and the hormone produced. It remained only to discover how large a supply of the precious material could be found on earth. It was not feasible to destroy a group of animals—say, of the local civilized race—and examine their bodies, because the hormone would be broken down by the weapon which allowed of a search for it. So an estimate of available sources would have to be made by sampling. The Qul-En in the ship prepared to take samples.

The ship had landed in tumbled country some forty miles south of Ensenada Springs, national forest territory, on which grazing-rights were allotted to sheep-ranchers after illimitable red tape. Within ten miles of the hidden ship there were rabbits, birds, deer, coyotes, a lobo wolf or two, assorted chipmunks, field-mice, perhaps as many as three or four mountain-lions, one flock of two thousand sheep, one man, and one dog.

The man was Antonio Menendez. He was ancient, unwashed, and ignorant, and the official shepherd of the sheep. The dog was Salazar, of dubious ancestry but sound worth, who actually took care of the sheep and knew it; he was scarred from battles done in their defense. He was unweariedly solicitous of the wooly half-wits in his charge. There were whole hours when he could not find time to scratch himself, because of his duties. He was reasonably fond of Antonio, but knew that the man did not really understand sheep.

Besides these creatures, among whom the Qul-En expected to find its samples, there were insects. These, however, the tiny alien being disregarded. It would not be practical to get any great quantity of the substance it sought from such small organisms.

By nightfall of the day after its landing, the door of the ship opened and the explorer came out in a vehicle designed expressly for sampling on this planet. The vehicle came out, stood on its hind legs, closed the door, and piled brush back to hide it. Then it moved away with the easy, feline gait of a mountain-lion. At a distance of two feet it was a mountain-lion. It was a magnificent job of adapting Qul-En engineering to the production of a device which would carry a small-bodied explorer about a strange world without causing remark. The explorer nested in a small cabin occupying the space—in the facsimile lion—that had been occupied by the real lion's lungs. The fur of the duplicate was convincing; its eyes were excellent, housing scanning-cells which could make use of anything from ultraviolet far down into the infra-red. Its claws were retractable and of plastic much stronger and keener than the original lion's claws. It had other equipment, including a weapon against which nothing on this planet could stand, and for zoological sampling it had one remarkable advantage. It had no animal smell; it was all metal and plastics.

On the first night of its roaming, nothing in particular happened. The explorer became completely familiar with the way the controls of the machine worked. As a machine, of course, it was vastly more powerful than an animal. It could make leaps no mere creature of flesh and blood could duplicate; its balancing devices were admirable; it was, naturally, immune to fatigue. The Qul-En inside it was pleased with the job.

That night Antonio and Salazar bedded down their sheep in a natural amphitheatre and Antonio slept heavily, snoring. He was a highly superstitious ancient, so he wore various charms of a quasi-religious nature. Salazar merely turned around three times and went to sleep. But while the man slept soundly, Salazar woke often. Once he waked sharply at a startled squawking among the lambs. He got up and trotted over to make sure that everything was all right, sniffed the air suspiciously. Then he went back, scratched where a flea had bitten him, bit—nibbling—at a place his paws could not reach, and went back to sleep. At midnight he made a clear circle around his flock and went back to slumber with satisfaction. Toward dawn he raised his head suspiciously at the sound of a coyote's howl, but the howl was far away. Salazar dozed until daybreak, when he rose, shook himself, stretched himself elaborately, scratched thoroughly, and was ready for a new day. The man waked, wheezing, and cooked breakfast; it appeared that the normal order of things would go undisturbed.

For a time it did; there was certainly no disturbance at the ship. The small silvery vessel was safely hidden. There was a tiny, flickering light inside—the size of a pin-point—which wavered and changed color constantly where a sort of tape unrolled before it. It was a recording device, making note of everything the roaming pseudo-mountain-lion's eyes saw and everything its micro-phonic ears listened to. There was a bank of air-purifying chemical which proceeded to regenerate itself by means of air entering through a small ventilating slot. It got rid of carbon dioxide and stored up oxygen in its place, in readiness for further voyaging.

Of course, ants explored the whole outside of the space-vessel, and some went inside through the ventilator-opening. They began to cart off some interesting if novel foodstuff they found within. Some very tiny beetles came exploring, and one variety found the air-purifying chemical refreshing. Numbers of that sort of beetle moved in and began to raise large families. A minuscule moth, too, dropped eggs lavishly in the nest-like space in which the Qul-En explorer normally reposed during space-flight. But nothing really happened.

Not until late morning. It was two hours after breakfast-time when Salazar found traces of the mountain-lion which was not a mountain-lion. He found a rabbit that had been killed. Having been killed, it had very carefully been opened up, its various internal organs spread out for examination, and its nervous system traced in detail. Its brain-tissue, particularly, had been most painstakingly dissected, so the amount of a certain complex hormone to be found in it could be calculated with precision. The Qul-En in the lion shape had been vastly pleased to find the sought-for hormone in another animal besides a mountain-lion.

The dissection job was a perfect anatomical demonstration; no instructor in anatomy could have done better, and few neuro-surgeons could have done as well with the brain. It was, in fact, a perfect laboratory job done on a flat rock in the middle of a sheep-range, and duly reproduced on tape by a flickering, color-changing light. The reproduction, however, was not as good as it should have been, because the tape was then covered by small ants who had found its coating palatable and were trying to clean it off.

Salazar saw the rabbit. There were blow-flies buzzing about it, and a buzzard was reluctantly flying away because of his approach. Salazar barked at the buzzard. Antonio heard the barking; he came.

Antonio was ancient, superstitious, and unwashed. He came wheezing, accompanied by flies who had not finished breakfasting on the bits of his morning meal he had dropped on his vest. Salazar wagged his tail and barked at the buzzard. The rabbit had been neatly dissected, but not eaten. The cuts which opened it up were those of a knife or scalpel. It was not—it was definitely not!—the work of an animal. But there were mountain-lion tracks, and nothing else. More, every one of the tracks was that of a hind foot! A true mountain-lion eats what he catches; he does not stand on his hind paws and dissect it with scientific precision. Nothing earthly had done this!

Antonio's eyes bulged out. He thought instantly of magic, Black Magic. He could not imagine dissection in the spirit of scientific inquiry; to him, anything that killed and then acted in this fashion could only come from the devil.

He gasped and fled, squawking. When he had run a good hundred yards, Salazar caught up to him, very much astonished. He overtook his master and went on ahead to see what had scared the man so. He made casts to right and left, then went in a conscientious circle all around the flock under his care. Presently he came back to Antonio, his tongue lolling out, to assure him that everything was all right. But Antonio was packing, with shaking hands and a sweat-streaked brow.

In no case is the neighborhood of a mountain-lion desirable for a man with a flock of sheep. But this was no ordinary mountain-lion. Why, Salazar—honest, stout-hearted Salazar—did not scent a mountain-lion in those tracks. He would have mentioned it vociferously if he had, so this was beyond nature. The lion was un fantasmo or worse; Antonio's thoughts ran to were-tigers, ghost-lions, and sheer Indian devils. He packed, while Salazar scratched fleas and wondered what was the matter.

They got the flock on the move. The sheep made idiotic efforts to disperse and feed placidly where they were. Salazar rounded them up and drove them on. It was hard work, but even Antonio helped in frantic energy—which was unusual.

2

Near noon, four miles from their former grazing-ground, there were mountain-peaks all around them. Some were snow-capped, and there were vistas of illimitable distance everywhere. It was very beautiful indeed, but Antonio did not notice; Salazar came upon buzzards again. He chased them with loud barkings from the meal they reluctantly shared with blow-flies and ants. This time it wasn't a rabbit; it was a coyote. It had been killed and most painstakingly taken apart to provide at a glance all significant information about the genus canis, species latrans, in the person of an adult male coyote. It was a most enlightening exhibit; it proved conclusively that there was a third type of animal, structurally different from both mountain-lions and rabbits, which had the same general type of nervous system, with a mass of nerve-tissue in one large mass in a skull, which nerve-tissue contained the same high percentage of the desired hormone as the previous specimens. Had it been recorded by a tiny colored flame in the hidden ship—the flame was now being much admired by small red bugs and tiny spiders—it would have been proof that the Qul-En would find ample supplies on Earth of the complex hormone on which the welfare of their race now depended. Some members of the Qul-En race, indeed, would have looked no farther. But sampling which involved only three separate species and gave no proof of their frequency was not quite enough; the being in the synthetic mountain-lion was off in search of further evidence.

Antonio was hardly equipped to guess at anything of this sort. Salazar led him to the coyote carcass; it had been neatly halved down the breast-bone. One-half the carcass had been left intact; the other half was completely anatomized, and the brain had been beautifully dissected and spread out for measurement. Antonio realized that intelligence had been at work. But—again—he saw only the pad-tracks of a mountain lion, and he was literally paralyzed by horror.

Antonio was scared enough to be galvanized into unbelievable energy. He would have fled gibbering to Ensenada Springs, some forty miles as the crow flies, but to flee would be doom itself. The devils who did this sort of work liked—he knew—to spring upon a man alone. But they can be fooled.

The Qul-En in the artificial mountain-lion was elated. To the last quivering appendage on the least small tentacle of its body, the pilot of the facsimile animal was satisfied. It had found good evidence that the desired nervous system and concentration of the desired hormone in a single mass of nerve-tissue was normal on this planet! The vast majority of animals should have it. Even the local civilized race might have skulls with brains in them, and, from the cities observed from the stratosphere, that race might be the most numerous fair-sized animal on the planet!

It was to be hoped for, because large quantities of the sought-for hormone were needed; taking specimens from cities would be most convenient. Long-continued existence under the artificial conditions of civilization—a hundred thousand years of it, no less—had brought about exhaustion of the Qul-En's ability to create all their needed hormones in their own bodies. Tragedy awaited the race unless the most critically needed substance was found. But now it had been!

Antonio saw it an hour later, and wanted to shriek; it looked exactly like a mountain-lion, but he knew it was not flesh and blood because it moved in impossible bounds. No natural creature could leap sixty feet; the mountain-lion shape did. But it was convincingly like its prototype to the eye. It stopped, and regarded the flock of sheep, made soaring progression to the front of the flock, and came back again. Salazar ignored it. Neither he nor the sheep scented carnivorous animal life. Antonio hysterically concluded that it was invisible to them; he began an elaborate, lunatic pattern of behavior to convince it that magic was at work against it, too.

He began to babble to his sheep with infinite politeness, spoke to blank-eyed creatures as Senor Gomez and Senora Onate. He chatted feverishly with a wicked-eyed ram, whom he called Senor Guttierez. A clumsy, wabbling lamb almost upset him, and he scolded the infant sheep as Pepito. He lifted his hat with great gallantry to a swollen ewe, hailing her as Senora Garcia, and observed in a quavering voice that the flies were very bad today. He moved about in his flock, turning the direction of its march and acting as if surrounded by a crowd of human beings. This should at least confuse the devil whom he saw. And while he chatted with seeming joviality, the sweat poured down his face in streams.

Salazar took no part in this deception. The sheep were fairly docile, once started; he was able to pause occasionally to scratch, and once even to do a luxurious, thorough job on that place in his back between his hind legs which is so difficult to reach. There was only one time when he had any difficulty. That was when there was a sort of eddying of the sheep, ahead. There were signs of panic. Salazar went trotting to the spot. He found sheep milling stupidly, and rams pawing the ground defying they had no idea what. Salazar found a deer-carcass on the ground and the smell of fresh blood in the air and the sheep upset because of it. He drove them on past, barking where barking would serve and nipping flanks where necessary—afterward disgustedly tonguing bits of wool out of his mouth.

The sheep went on. But Antonio, when he came to the deer-carcass, went icy-cold in the most exquisite of terror; the deer had been killed by a mountain-lion—there were tracks about. Then it, too, had been cut into as if by a dissector's scalpel, but the job was incomplete. Actually, the pseudo-mountain-lion had been interrupted by the approach of the flock. There were hardly blow-flies on the spot as yet. Antonio came to it as he chatted insanely with a sheep with sore eyes and a halo of midges about its head, whom he addressed as Senorita Carmen. But when he saw the deer his throat clicked shut. He was speechless.

To pass a creature laid out for magical ceremony was doom indubitable, but Antonio acted from pure desperation. He recited charms which were stark paganism and would involve a heavy penance when next he went to confession. He performed other actions, equally deplorable; when he went on, the deer was quite spoiled, for neat demonstration of the skeletal, circulatory, muscular and especially the nervous system and brain-structure of genus cervus, species dama, specimen an adult doe. Antonio had piled over the deer all the brush within reach, had poured over it the kerosene he had for his night-lantern, and had set fire to the heap with incantations that made it a wholly impious sacrifice to quite nonexistent heathen demons.

Salazar, trotting back to the front of the flock after checking on Antonio and the rear-guard, wrinkled his nose and sneezed as he went past the blaze again. Antonio tottered on after him.

But Antonio's impiety had done no good. The tawny shape bounded back into sight among the boulders on the hillside. It leaped with infinite grace for impossible distances. Naturally! No animal can be as powerful as a machine, and the counterfeit mountain-lion was a machine vastly better than men could make.

The Qul-En now zestfully regarded the flock of sheep. It looked upon Salazar and Antonio with no less interest. The Qul-En explorer was an anatomist and organic chemist rather than a zoologist proper, but it guessed that the dog was probably a scavenger and that the man had some symbiotic relationship to the flock.

Salazar, the dog, was done a grave injustice in that estimate. Even Antonio was given less than he deserved. Now he was gray with horror. The blood in his veins turned to ice as he saw the false mountain-lion bounding back upon the hillside. No normal wild creature would display itself so openly. Antonio considered himself both doomed and damned; stark despair filled him. But with shaking hands and no hope at all, he carved a deep cross on the point of a bullet for his ancient rifle. Licking his lips, he made similar incisions on other bullets in reserve.

The Qul-En vehicle halted. The flock had been counted; now to select specimens and get to work. There were six new animal types to be dissected for the nervous organ yielding the looked-for hormone. Four kinds of sheep—male and female, and adult and immature of each kind—the biped, and the dog. Then a swift survey to estimate the probable total number of such animals available, and—.

Antonio saw that the devil mountain-lion was still. He got down on one knee, fervently crossed himself and fed a cross-marked bullet into the chamber of his rifle. He lined up the sights on the unearthly creature. The lion-facsimile watched him interestedly; the sight of a rifle meant nothing to the Qul-En, naturally. But the kneeling posture of the man was strange. It was part, perhaps, of the pattern of conduct which had led him to start that oxidation process about the deer-specimen.

Antonio fired. His hands trembled and the rifle shook; nothing happened. He fired again and again, gasping in his fear. And he missed every time.

The cross-marked bullets crashed into red earth and splashed from naked rock all about the Qul-En vehicle. When sparks spat from a flint pebble, the pilot of the mountain-lion realized that there was actual danger here. It could have slaughtered man and dog and sheep by the quiver of a tentacle, but that would have ruined them as specimens. To avoid spoiling specimens it intended to take later, the Qul-En put the mountain-lion shape into a single, magnificent leap. It soared more than a hundred feet up-hill and over the crest at its top; then it was gone.

Salazar ran barking after the thing at which Antonio had fired, sniffed at the place from which it had taken off. There was no animal smell there at all. He sneezed, and then trotted down again. Antonio lay flat on the ground, his eyes hidden, babbling. He had seen irrefutable proof that the shape of the mountain-lion was actually a fiend from hell.

3

Behind the hill-crest, the Qul-En moved away. It had not given up its plan of selecting specimens from the flock, of course, nor of anatomizing the man and dog. It was genuinely interested too, in the biped's novel method of defense. It dictated its own version of the problems raised, on a tight beam to the wavering, color-changing flame. Why did not the biped prey on the sheep if it could kill them? What was the symbiotic relationship of the dog to the man and the sheep? The three varieties of animal associated freely. The Qul-En dictated absorbed speculations, then it hunted for other specimens. It found a lobo wolf, and killed it, verified that this creature also could be a source of hormones. It slaughtered a chipmunk and made a cursory examination. Its ray-beam had pretty well destroyed the creature's brain-tissue, but by analogy of structure this should be a source also.

In conclusion, the Qul-En made a note via the wavering pin-point of flame that the existence of a hormone-bearing nervous system, centralized in a single mass of hormone-bearing nerve-tissue inside a bony structure, seemed universal among the animals of this planet. Therefore it would merely examine the four other types of large animal it had discovered, and take off to present its findings to the Center of its race. With a modification of the ray-beam to kill specimens without destroying the desired hormone, the Qul-En could unquestionably secure as much as the race could possibly need. Concentrations of the local civilized race in cities should make large-scale collection of the hormone practical unless that civilized race was an exception to the general nervous structure of all animals so far observed.

This was dictated to the pin-point flame, and the flame faithfully wavered and changed color to make the record. But the tape did not record it; a rather large beetle had jammed the tape-reel. It was squashed in the process, but it effectively messed up the recording apparatus. Even before the tape stopped moving, though, the record had become defective; tiny spiders had spun webs, earwigs got themselves caught. The flame, actually, throbbed and pulsed restlessly in a cobwebby coating of gossamer and tiny insects. Silverfish were established in the plastic lining of the Qul-En ship; beetles multiplied enormously in the air-refresher chemical; moth-larvae already gorged themselves on the nest-material of the intrepid explorer outside. Ants were busy on the food-stores. Mites crawled into the ship to prey on their larger fellows, and a praying-mantis or so had entered to eat their smaller ones. There was an infinite number of infinitesimal flying things dancing in the dark; larger spiders busily spun webs to snare them, and flies of various sorts were attracted by odors coming out of the ventilator-opening, and centipedes rippled sinuously inside....

Night fell upon the world. The pseudo-mountain-lion roamed the wild, keeping in touch with the tide of baa-ing sheep now headed for the lowlands. It captured a field-mouse and verified the amazing variety of planetary forms containing brain-tissue rich in hormones. But the sheep-flock could not be driven at night. When stars came out, to move them farther became impossible. The Qul-En returned to select its specimens in the dark, with due care not to allow the man to use his strange means of defense. It found the flock bedded down.

Salazar and Antonio rested; they had driven the sheep as far as it was possible to drive them, that day. Though he was sick with fear and weak with horror, Antonio had struggled on until Salazar could do no more. But he did not leave the flock; the sheep were in some fashion a defense—if only a diversion—against the creature which so plainly was not flesh and blood.

He made a fire, too, because he could not think of staying in the dark. Moths came and fluttered about the flames, but he did not notice. He tried to summon courage. After all, the unearthly thing had fled from bullets marked with a cross, even though they missed; with light to shoot by, he might make a bullseye. So Antonio sat shivering by his fire, cutting deeper crosses into the points of his bullets, his throat dry and his heart pounding while he listened to the small noises of the sheep and the faint thin sounds of the wilderness.

Salazar dozed by the fire. He had had a very hard day, but even so he slept lightly. When something howled, very far away, instantly the dog's head went up and he listened. But it was nowhere near; he scratched himself and relaxed. Once something hissed and he opened his eyes.

Then he heard a curious, strangled "Baa-a-a". Instantly he was racing for the spot. Antonio stood up, his rifle clutched fast. Salazar vanished. Then the man heard an outburst of infuriated barking; Salazar was fighting something, and he was not afraid of it, he was enraged. Antonio moved toward the spot, his rifle ready.

The barking raced for the slopes beyond the flock. It grew more enraged and more indignant still. Then it stopped. There was silence. Antonio called, trembling. Salazar came padding up to him, whining and snarling angrily. He could not tell Antonio that he had come upon something in the shape of a mountain-lion, but which was not—it didn't smell right—carrying a mangled sheep away from its fellows. He couldn't explain that he'd given chase, but the shape made such monstrous leaps that he was left behind and pursuit was hopeless. Salazar made unhappy, disgusted, disgraced noises to himself. He bristled; he whined bitterly. He kept his ears pricked up and he tried twice to dart off on a cast around the whole flock, but Antonio called him back. Antonio felt safer with the dog beside him.

Off in the night, the Qul-En operating the mountain-lion shape caused the vehicle to put down the sheep and start back toward the flock. It would want at least four specimens besides the biped and the dog, but the dog was already on the alert. The Qul-En had not been able to kill the dog, because the mouth of the lion was closed on the sheep. It would probably be wisest to secure the dog and biped first—the biped with due caution—and then complete the choice of sheep for dissection.

The mountain-lion shape came noiselessly back toward the flock. The being inside it felt a little thrill of pleasure. Scientific exploration was satisfying, but rarely exciting; one naturally protected oneself adequately when gathering specimens. But it was exciting to have come upon a type of animal which would dare to offer battle. The Qul-En in the mountain-lion shape reflected that this was a new source of pleasure—to do battle with the fauna of strange planets in the forms native to those planets.

The padding vehicle went quietly in among the wooly sheep. It saw the tiny blossom of flame that was Antonio's campfire. Another high-temperature oxidation process.... It would be interesting to see if the biped was burning another carcass of its own killing....

The shape was two hundred yards from the fire when Salazar scented it. It was upwind from the dog; its own smell was purely that of metals and plastics, but the fur, now, was bedabbled with the blood of the sheep which had been its first specimen of the night. Salazar growled. His hackles rose, every instinct for the defense of his flock. He had smelled that blood when the thing which wasn't a mountain-lion left him behind with impossible leapings.

He went stiff-legged toward the shape. Antonio followed in a sort of despairing calm born of utter hopelessness.

A sheep uttered a strangled noise. The Qul-En had come upon a second specimen which was exactly what it wished. It left the dead sheep behind for the moment, while it went to look at the fire. It peered into the flames, trying to see if Antonio—the biped—had another carcass in the flames as seemed to be a habit. It looked....

Salazar leaped for its blood-smeared throat in utter silence and absolute ferocity. He would not have dreamed of attacking a real mountain-lion with such utter lack of caution, but this was not a mountain-lion. His weight and the suddenness of his attack caught the operator by surprise, the shape toppled over. Then there was an uproar of scared bleatings from sheep nearby, and bloodthirsty snarlings from Salazar. He had the salty taste of sheep-blood in his mouth and a yielding plastic throat between his teeth.

The synthetic lion struggled absurdly. Its weapon, of course, was a ray-gun which was at once aimed and fired when the jaws opened wide. The being inside tried to clear and use that weapon. It would not bear upon Salazar; the Qul-En would have to make its device lie down, double up its mechanical body, and claw Salazar loose from its mechanical throat with the mechanical claws on its mechanical hind-legs. At first the Qul-En inside concentrated on getting its steed back on its feet.

That took time, because whenever Salazar's legs touched ground he used the purchase to shake the throat savagely. In fact, Antonio was within twenty yards when the being from the ship got its vehicle upright. It held the mechanical head high, then, to keep Salazar dangling while it considered how to dislodge him.

And it saw Antonio. For an instant, perhaps, the Qul-En was alarmed. But Antonio did not kneel; he made no motion which the pilot—seeing through infra-red-sensitive photo-cells in the lion's eyeballs—could interpret as offensive. So the machine moved boldly toward him. The dog dangling from its throat could be disregarded for the moment. The killing-ray was absolutely effective, but it did spread, and it did destroy the finer anatomical features of tissues it hit. Especially, it destroyed nerve-tissue outright. So the closer a specimen was when killed, the smaller the damaged area.

The being inside the mountain-lion was pleasantly excited and very much elated. The biped stood stock-still, frozen by the spectacle of a mountain-lion moving toward it with a snarling dog hanging disregarded at its throat. The biped would be a most interesting subject for dissection, and its means of offense would be most fascinating to analyze....

Antonio's fingers, contracting as the shape from the ship moved toward him, did an involuntary thing. Quite without intention, they pulled the trigger of the rifle. The deeply cross-cut bullet seared Salazar's flank, removing a quarter-inch patch of skin. It went on into the shape of plastic and metal, hit a foreleg. Although that leg was largely plastic, what metal it contained being mostly magnesium for lightness there were steel wires imbedded for magnetic purposes. The bullet smashed through plastic and magnesium, struck a spark upon the steel.

There was a flaring, sun-bright flash of flame, a dense cloud of smoke. The mountain-lion shape leaped furiously and the jerk dislodged the slightly singed Salazar and sent him rolling. The mountain-lion vehicle landed and rolled over and over, one leg useless and spouting monstrous, white, actinic fire. The being inside knew an instant's panic; then it felt yielding sheep-bodies below it, thrashed about violently and crazily, and at last the Qul-En jammed the flame-spurting limb deep into soft earth. The fire went out; but that leg of its vehicle was almost useless.

For an instant deadly rage filled the tiny occupant of the cabin where a mountain-lion's lungs should have been. Almost, it turned and opened the mouth of its steed and poured out the killing-beam. Almost. The flock would have died instantly, and the man and the dog, and all things in the wild for miles. But that would not have been scientific; after all, this mission should be secret. And the biped....

4

The Qul-En ceased the thrashings of its vehicle. It thought coldly. Salazar raced up to it, barking with a shrillness that told of terror valorously combatted; he danced about, barking.

The Qul-En found a solution. Its vehicle rose on its hind legs and raced up the hillside. It was an emergency method of locomotion for which this particular vehicle was not designed, and it required almost inspired handling of the controls to achieve it. But the Qul-En inside was wholly competent; it guided the vehicle safely over the hilltop while Salazar made only feigned dashes after it. Safely away, the Qul-En stopped and deliberately experimented until the process of running on three legs developed. Then the mountain-lion, which was not a mountain-lion, went bounding through the night toward its hidden ship.

Within an hour, it clawed away the brush from the exit-port, crawled inside, and closed the port after it. As a matter of pure precaution, it touched the "take-off" control before it even came out of its vehicle.

The ventilation-opening closed—very nearly. The ship rose quietly and swiftly toward the skies. Its arrival had not been noted; its departure was quite unsuspected.

It wasn't until the Qul-En touched the switch for the ship's system of internal illumination to go on that anything appeared to be wrong. There was a momentary arc, and darkness. There was no interior illumination; ants had stripped insulation from essential wires. The lights were shorted. The Qul-En was bewildered; it climbed back into the mountain-lion shape to use the infrared-sensitive scanning-cells.

The interior of the ship was a crawling mass of insect life. There were ants and earwigs, silverfish and mites, spiders and centipedes, mantises and beetles. There were moths, larvae, grubs, midges, gnats and flies. The recording-instrument was shrouded in cobweb and hooded in dust which was fragments of the bodies of the spiders' tiny victims. The air-refresher chemicals were riddled with the tunnels of beetles. Crickets devoured plastic parts of the ship and chirped loudly. And the controls—ah! the controls! Insulation stripped off here; brackets riddled or weakened or turned to powder there. The ship could rise, and it did. But there were no controls at all.

The Qul-En went into a rage deadly enough to destroy the insects of itself. The whole future of its race depended on the discovery of an adequate source of a certain hormone. That source had been found. Only the return of this one small ship—fifteen feet in diameter—was needed to secure the future of a hundred-thousand-year-old civilization. And it was impeded by the insect-life of the planet left behind! Insect-life so low in nervous organization that the Qul-En had ignored it!

The ship was twenty thousand miles out from earth when the occupant of the mountain-lion used its ray-beam gun to destroy all the miniature enemies of its race. The killing beam swept about the ship. Mites, spiders, beetles, larvae, silverfish and flies—everything died. Then the Qul-En crawled out and began to make repairs, furiously. The technical skill needed was not lacking; in hours, this same being had made a perfect counterfeit of a mountain-lion to serve it as a vehicle. Tracing and replacing gnawed-away insulation would be merely a tedious task. The ship would return to its home planet; the future of the Qul-En race would be secure. Great ships, many times the size of this, would flash through emptiness and come to this planet with instruments specially designed for collecting specimens of the local fauna. The cities of the civilized race would be the simplest and most ample sources of the so-desperately-needed hormone, no doubt. The inhabitants of even one city would furnish a stop-gap supply. In time—why—it would become systematic. The hormone would be gathered from this continent at this time, and from that continent at that, allowing the animals and the civilized race to breed for a few years in between collections. Yes....

The Qul-En worked feverishly. Presently it felt a vague discomfort; it worked on. The discomfort increased; it could discover no reason for it. It worked on, feverishly....

Back on Earth, morning came. The sun rose slowly and the dew lay heavy on the mountain grasses. Far-away peaks were just beginning to be visible through clouds that had lain on them overnight. Antonio still trembled, but Salazar slept. When the sun was fully risen he arose and shook himself; he stretched elaborately, scratched thoroughly, shook himself again and was ready for a new day. When Antonio tremblingly insisted that they drive the flock on toward the lowlands, Salazar assisted. He trotted after the flock and kept them moving; that was his business.

Out in space, the silvery ship suddenly winked out of existence. Enough of its circuits had been repaired to put it in overdrive. The Qul-En was desperate, by that time. It felt itself growing weaker, and it was utterly necessary to reach its own race and report the salvation it had found for them. The record of the flickering flame was ruined. The Qul-En felt that itself was dying. But if it could get near enough to any of the planetary systems inhabited by its race, it could signal them and all would be well.

Moving ever more feebly, the Qul-En managed to get lights on within the ship again. Then it found what it considered the cause of its increasing weakness and spasmodic, gasping breaths. In using the killing-ray it had swept all the interior of the ship. But not the mountain-lion shape. Naturally! And the mountain-lion shape had killed specimens and carried them about. While its foreleg flamed, it had even rolled on startled, stupid sheep. It had acquired fleas—perhaps some from Salazar—and ticks. The fleas and ticks had not been killed; they now happily inhabited the Qul-En.

The Qul-En tried desperately to remain alive until a message could be given to its people, but it was not possible. There was a slight matter the returning explorer was too much wrought up to perceive, and the instruments that would have reported it were out of action because of destroyed insulation. When the ventilation-slit was closed as the ship took off, it did not close completely; a large beetle was in the way. There was a most tiny but continuous leakage of air past the crushed chitinous armor. The Qul-En in the ship died of oxygen-starvation without realizing what had happened, just as human pilots sometimes black out from the same cause before they know what is the matter. So the little silvery ship never came out of overdrive. It went on forever, or until its source of power failed.

The fleas and ticks, too, died in time; they died very happily, very full of Qul-En body-fluid. And they never had a chance to report to their fellows that the Qul-En were very superior hosts.

The only entity who could report told his story and was laughed at. Only his cronies, ignorant and superstitious men like himself, could believe in the existence of a thing not of earth, in the shape of a mountain-lion that leaped hundreds of feet at a time, which dissected wild creatures and made magic over them, but fled from bullets marked with a cross and bled flame and smoke when such a bullet wounded it.

Such a thing, of course, was absurd!

THE END