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.