icator for the battery. It showed
half-charge. Then he saw that someone had attached another battery
beside it. He puzzled briefly over it, but his immediate concern was for
shelter.

Apparently he was still where he had been knocked out. There was a light
coming from the little station, and he headed toward that, fumbling for
the few quarters that represented his entire fortune.

Maybe it would have been better if the tubemen had killed him. Batteries
were an absolute necessity here, food and shelter would be expensive,
and he had no skills to earn his way. At most, he had only a day or so
left. But meantime, he had to find warmth before the cold killed him.

The tiny restaurant in the station was still open, and the air was warm
inside. He pulled off the aspirator, shutting off the battery.

The counterman didn't even glance up as he entered. Feldman gazed at the
printed menu and flinched.

"Soup," he ordered. It was the cheapest item he could find.

The counterman stared at him, obviously spotting his Earth origin. "You
adjusted to synthetics?"

Feldman nodded. Earth operated on a mixed diet, with synthetics for all
who couldn't afford the natural foods there. But Mars was all synthetic.
Many of the chemicals in food could exist in either of two forms, or
isomers; they were chemically alike, but differently crystallized.
Sometimes either form was digestible, but frequently the body could use
only the isomer to which it was adjusted.

Martian plants produced different isomers from those on Earth. Since the
synthetic foods turned out to be Mars-normal, that was probably the more
natural form. Research designed to let the early colonists live off
native food here had turned up an enzyme that enabled the body to handle
either isomer. In a few weeks of eating Martian or synthetic food, the
body adapted; without more enzyme, it lost its power to handle
Earth-normal food.

The cheapness of synthetics and the discovery that many diseases common
to Earth would not attack Mars-normal bodies led to the wide use of
synthetics on Earth. No pariah could have been expected to afford
Earth-normal.

Feldman finished the soup, and found a cigarette that was smokable. "Any
objections if I sit in the waiting room?"

He'd expected a rejection, but the counterman only shrugged. The waiting
room was almost dark and the air was chilly, but there was normal
pressure. He found a bench and slumped onto it, lighting his cigarette.