ng that job as maid to spy on Chris Ryan. Name it and I'll do my
best."

Doc had a vague idea of village politics, but he had more important
things to think of. Most of his foul mood had disappeared with the clue
he'd stumbled on, and his chief worry now was to clinch the facts.

Feldman considered the problem. "I want a report on every case of
jumping headache in every village--who had it, when, and how old they
were. This place first, but every village you can reach. And I'll want
someone to take a letter to Chris Ryan."

Jake frowned at that, but went out to issue instructions. Doc sat down
at a battered old typewriter. Writing Chris might do no good, but some
warning had to be gotten through to Earth, where the vast resources of
Medical Lobby could be thrown into the task of finding the cause and
cure of the disease. The connection with Selznik's migraine had to be
reported. If something could blast the Lobby into action, it wouldn't
matter quite so much what they did to him. He wasn't foolish enough to
expect gratitude from them, but he was getting used to the idea that his
days were numbered. The plague was more important than what happened to
him.

The letter had been dispatched by the time Jake returned. "Here's the
dope for this village. Everybody accounted for except you."

"Never had it, Jake." Feldman went down the list. "Most of it fourteen
years ago. That fits. About the only exceptions are the kids who seem to
get it between the ages of two and three. Eighty-seven out of
ninety-one!"

He stared at the figures sickly. Most of the village not only had the
plague but must be near the end of the incubation period. It looked as
if most of the village would be dead before another year passed.

"Bad?" Jake asked.

"The first symptom of Martian fever."

The old man whistled, the lines around his eyes tightening. "Must be
me," he decided. "I'm the guy who must have brought it here, then. I
used to spend a lot of time with Durwood at his diggings!"

There was a constant commotion all that day and the next as runners went
out to the villages and came back with reports. The variation from
village to village was only slight. Most of Mars seemed to have advanced
cases of Martian fever.

Without animals for investigation and study, real research was
difficult. Doc also needed an electron microscope. He was reasonably
sure that the disease must travel through the nerves, but he had found
no proof beyond the