Murgatroyd yawned.  He settled himself still more comfortably in Calhoun’s lap.

“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.

Next ship-day the girl looked oddly at Calhoun when she appeared in the control room.  Murgatroyd regarded her with great interest.  Calhoun nodded politely and went back to what he’d been doing before she appeared.

“Shall I have breakfast?” she asked uncertainly.

“Murgatroyd and I have,” he told her.  “Why not?”

Silently, she operated the food-readier.  She ate.  Calhoun gave a very good portrayal of a man who will respond politely when spoken to, but who was busy with activities remote from stowaways.

About noon, ship-time, she asked, “When will we get to Orede?”

Calhoun told her absently, as if he were thinking of something else.

“What—­what do you think happened there?  I mean, to make that tragedy in the ship.”

“I don’t know,” said Calhoun.  “But I disagree with the authorities on Weald.  I don’t think it was a planned atrocity of the blueskins.”

“Wh-what are blueskins?” asked the girl.

Calhoun turned around and looked at her directly.

“When lying,” he said mildly, “you tell as much by what you pretend isn’t, as by what you pretend is.  You know what blueskins are!”

“But what do you think they are?” she asked.

“There used to be a human disease called smallpox,” said Calhoun.  “When people recovered from it, they were usually marked.  Their skin had little scar pits here and there.  At one time, back on Earth, it was expected that everybody would catch smallpox sooner or later, and a large percentage would die of it.