, it was too late to do anything
about that. Mice-like animals were inside and had to be controlled
where they were.

The biologist straightened up. "Catch me a few of them alive and I'll
see what I can do."

* * * * *

In the morning, a dozen live specimens were delivered to the lab. They
actually did resemble mice.

Their reactions were puzzling. No two of them were affected by the
same poison. A compound that stiffened one in a matter of minutes left
the others hale and hearty, and the poison he had developed to control
the omnivores was completely ineffective.

The depredations in the warehouse went on. Black mice, white ones,
gray and brown, short-tailed and long-eared, or the reverse, they
continued to eat the concentrates and spoil what they didn't eat.

Marin conferred with the executive, outlined the problem as he saw it
and his ideas on what could be done to combat the nuisance.

"But we can't build another warehouse," argued Hafner. "Not until the
atomic generator is set up, at any rate. And then we'll have other
uses for the power." The executive rested his head in his hands. "I
like the other solution better. Build one and see how it works."

"I was thinking of three," said the biologist.

"One," Hafner insisted. "We can't spare the equipment until we know
how it works."

At that he was probably right. They had equipment, as much as three
ships could bring. But the more they brought, the more was expected of
the colony. The net effect was that equipment was always in short
supply.

Marin took the authorization to the engineer. On the way, he privately
revised his specifications upward. If he couldn't get as many as he
wanted, he might as well get a better one.

In two days, the machine was ready.

It was delivered in a small crate to the warehouse. The crate was
opened and the machine leaped out and stood there, poised.

"A cat!" exclaimed the quartermaster, pleased. He stretched out his
hand toward the black fuzzy robot.

"If you've touched anything a mouse may have, get your hand away,"
warned the biologist. "It reacts to smell as well as sight and sound."

Hastily, the quartermaster withdrew his hand. The robot disappeared
silently into the maze of stored material.

In one week, though there were still some mice in the warehouse, they
were no longer a danger.

* * * * *

The executive called Marin into his office, a sm