t. It would be
vaccine. The other came from the culture oven in the doctor's
laboratory.

The thick-glass phial was simply that. Calhoun removed the cover from
the other. It contained small and horrible squirming organisms,
writhing in what was probably a nutrient fluid to which they could
reduce human refuse. They swarm jerkily in it so that the liquid
seemed to seethe. It smelled. Like skunk.

The grid operator clenched his hands.

"Put it away!" he commanded fiercely. "Out of sight! Away!"

Calhoun nodded. He locked it in a small chest. As he put down the
cover he said in an indescribable tone:

"It doesn't smell as bad to me as it did."

But his hands were steady as he drew a sample of a few drops from the
vaccine bottle. He lowered a wall panel and behind it there was a
minute but astonishingly complete biological laboratory. It was
designed for microanalysis--the quantitative and qualitative analysis
of tiny quantities of matter. He swung out a miniaturized Challis
fractionator. He inserted half a droplet of the supposed vaccine and
plugged in the fractionator's power cable. It began to hum.

The grid operator ground his teeth.

"This is a fractionator," said Calhoun. "It spins a biological sample
through a chromatograph gele."

The small device hummed more shrilly. The sound rose in pitch until it
was a whine, and then a whistle, and then went up above the highest
pitch to which human ears are sensitive. Murgatroyd scratched at his
ears and complained:

"_Chee! Chee! Chee!_"

"It won't be long," Calhoun assured him. He looked once at the grid
operator and then looked away. There was sweat on the man's forehead.
Calhoun said casually: "The substance that makes the vaccine do what
it does do is in the vaccine, obviously. So the fractionator is
separating the different substances that are mixed together." He
added, "It doesn't look much like chromatography, but the principle's
the same. It's an old, old trick!"

It was, of course. That different dissolved substances can be
separated by their different rates of diffusion through wetted powders
and geles had been known since the early twentieth century, but was
largely forgotten because not often needed. But the Med Service did
not abandon processes solely because they were not new.

Calhoun took another droplet of the vaccine and put it between two
plates of glass, to spread out. He separated them and put them in a
vacuum drier.

"I'm not going to