ed, and fired. It was high; he missed the
animal in the field. A neat strip of smoking brown appeared in the
green vegetation.

He aimed more carefully and fired again. The charge screamed out of
the muzzle. It struck the animal on the forepaw. The beast leaped high
in the air and fell down, dead and broiled.

They stood over the animal Hafner had killed. Except for the lack of
markings, it was a good imitation of a tiger. The exec prodded it with
his toe.

"We chase the rats out of the warehouse and they go to the fields," he
muttered. "We hunt them down in the fields with dogs and they breed
tigers."

"Easier than rats," said Marin. "We can shoot tigers." He bent down
over the slain dog near which they had surprised the big cat.

The other dog came whining from the far corner of the field to which
he had fled in terror. He was a courageous dog, but he could not face
the great carnivore. He whimpered and licked the face of his mate.

The biologist picked up the mangled dog and headed toward the
laboratory.

"You can't save her," said Hafner morosely. "She's dead."

"But the pups aren't. We'll need them. The rats won't disappear merely
because tigers have showed up."

The head drooped limply over his arm and blood seeped into his
clothing as Hafner followed him up the hill.

"We've been here three months," the exec said suddenly. "The dogs have
been in the fields only two. And yet the tiger was mature. How do you
account for something like that?"

Marin bent under the weight of the dog. Hafner never would understand
his bewilderment. As a biologist, all his categories were upset. What
did evolution explain? It was a history of organic life on a
particular world. Beyond that world, it might not apply.

Even about himself there were many things Man didn't know, dark
patches in his knowledge which theory simply had to pass over. About
other creatures, his ignorance was sometimes limitless.

Birth was simple; it occurred on countless planets. Meek grazing
creatures, fierce carnivores--the most unlikely animals gave birth to
their young. It happened all the time. And the young grew up, became
mature and mated.

He remembered that evening in the laboratory. It was accidental--what
if he had been elsewhere and not witnessed it? They would not know
what little they did.

He explained it carefully to Hafner. "If the survival factor is high
and there's a great disparity in size, the young need not ever be
you