nd. The gesture was as old as man, its ritualistic meaning lost in
antiquity.

"No--Marsborn--a neighbor world," Jordan said. "But our customs and
Earth's are the same."

"You're a long way from home," Kennon said.

"No farther than you, Doc." Jordan looked uncomfortable. "But we can
compare origins later. Right now, you'd better come into the office.
I've run across something peculiar."

CHAPTER IX

"There are twelve bays to this station," Jordan said. "Under our present
setup two are used for breeding and the other ten for maturation. We
rotate the youngsters around the bay--a different bay each year until
they're age eleven. Then they're sorted according to type and sent out
for a year of further specialized training after which they go onto the
farms, or to inhouse or export.

"Now here's the peculiar part. There's no trouble in Bays One through
Nine, but Bay Ten has had all our losses except two that have occurred
at the training stations."

"That's good news," Kennon said. "Our parasite can't have had time to
migrate too far. We have him pinpointed unless--say how many training
centers are there?"

"Three," Jordan said.

"Quarantine them," Kennon replied. "Right now. Nothing goes in or out
until we've checked them and completed prophylaxis."

Jordan looked at Blalok inquiringly.

"He's the boss," Blalok said. "Do as you're told. This is his problem."

"Why the quarantine?" Jordan asked.

"I want to get any carriers. We can check them with antigen, and then
give Trematox."

"All that concentration in Bay Ten," Jordan said. "Does it mean
something?"

"Blalok said that there was a Santosian in your division."

"Yeah--Joe Kryla--and come to think of it, he ran Bay Ten!"

"That's a help--now let's see what makes that bay different from the
others."

"Why?"

"I'll tell you--but you may not understand," Kennon said.

"I'll take a chance."

Kennon grinned. "All right, you asked for it. The parasite that's doing
the damage is a flatworm, a trematode called Hepatodirus hominis. As
I've told Blalok, it's a tricky thing. Like all trematodes it has a
three-stage life cycle, but unlike every other fluke, its life cycle is
not fixed to definite intermediate hosts. Depending upon where it is,
the fluke adapts. It still must pass through its life cycle, but its
intermediate host need not be one species of snail, fish, or copepod.
Any cold-blooded host will do. What you have here is a Kardonian vari