"_Chee_," he said drowsily.

He went to sleep, while Calhoun continued the examination of highly
condensed information. Presently he looked up the normal rate of
increase, with other data, among herds of _bovis domesticus_ in a wild
state, on planets where there are no natural enemies.

It wasn't unheard-of for a world to be stocked with useful types of
Terran fauna and flora before it was attempted to be colonized. Terran
life-forms could play the devil with alien ecological systems--very
much to humanity's benefit. Familiar microorganisms and a standard
vegetation added to the practicality of human settlements on otherwise
alien worlds. But sometimes the results were strange.

They weren't often so strange, however, as to cause some hundreds of
men to pack themselves frantically aboard a cargo ship which couldn't
possibly sustain them, so that every man must die while the ship was
in overdrive.

Still, by the time Calhoun turned in on a spare pneumatic mattress, he
had calculated that as few as a dozen head of cattle, turned loose on
a suitable planet, would have increased to herds of thousands or tens
or even hundreds of thousands in much less time than had probably
elapsed.

The Med Ship drove on in seemingly absolute solidity, with no sound
from without, with no sight to be seen outside, with no evidence at
all that it was not buried in the heart of a planet instead of
flashing through emptiness at a speed so great as to have no meaning.