rasensory perception, and, instead of executing me at
once, they tried to persuade me to continue this work for the government
along specific lines and under supervision. I refused, because I knew
that anything I helped them develop would not be used for the benefit of
the Martian colonists, but for greater profits for the spacelines.

"At last I was able to escape into these underground caverns where they
grow food plants hydroponically and sell them to supplement the produce
of the dome farms and the gardens in the dome cities. These caverns are
extensive and, with the friendship and help of the Jellies, I've evaded
discovery for twenty-five years."

"Just who and what are the Jellies?" asked Dark. "I haven't been able to
get a very satisfactory answer to that question from Happy."

"They're human experimental animals," answered Old Beard. "The
terrestrial food plants grown hydroponically and sold in the dome cities
actually are a supplemental sideline to the real purpose of this place.
Marscorp is conducting its own experiments here, with a crew of expert
geneticists.

"What Marscorp is trying to do is to breed native Martian plants, that
will grow in the open lowlands without expensive oxygenation and
irrigation, that are not poisonous to humans and can be used for food.
At the same time, they're approaching the problem from the other side,
and the Jellies are men and women whose glandular structure has been
altered in an effort to make their physiology more receptive to native
Martian vegetation. If they succeed, of course, Marscorp has just as
complete a monopoly over such a food supply as it does over imports from
Earth, but at considerably less expense."

"And the Toughs?"

"They're human experimental animals, too, based on a different type of
glandular alteration. They're neither as docile nor as intelligent as
the Jellies, so they can't be used for slave labour as the Jellies can.
About the only way they're ever used is as occasional goon squads to
terrorize the Jellies and keep them in line."

"You've been here twenty-five years and have never been able to escape?"
asked Dark incredulously.

"This place isn't guarded," replied Old Beard, with a wry smile. "They
don't have to guard it. All they have to guard are the supply room where
the marsuits are kept and the motor pool of groundcars. This place is in
the middle of the Desert of Candor, and no one can live in the Martian
desert without oxygen."