, judging by the length of time it had taken to
hit Durwood. It must spread from person to person during an early
contagious stage, leaving widening circles behind Durwood and those
first infected. When matured, any other sickness would set it off, with
few symptoms of its own. But without help, it still killed its victims,
apparently driving them madly toward frenzied physical effort.

He studied the culture on a slide again. He'd tried Koch's method to get
a pure strain, splattering the bugs onto a native starchy root and
plucking off individual colonies. About twenty specimens had been
treated with every chemical he could find. So far he'd found a few
things that seemed to stop their growth, but nothing that killed them,
except stuff far too harsh to use in living tissue.

He had nearly forty cases of deaths that showed symptoms now, and he
went back over them, looking for anything in common that went back ten
to twenty years before death. There were no rashes nor blisters. A few
had had apparent colds, but such were too common to mean anything.

Only one thing appeared, about fourteen years before their deaths. The
people interviewed about the victims might be vague about most things,
but they remembered the time when "Jim had the jumping headache."

"Jake," Doc called, "what's jumping headache? Most people seem to have
it some time or other, but I haven't run across a case of it."

"Sure you have, Doc. Mamie Brander's little girl a few weeks ago. Feels
like your pulse is going to rip your skull off, right here. Can't eat
because chewing drives you crazy. Back of your head, neck and shoulders
swell up for about a week. Then it goes away."

Then it goes away--for fourteen years, until it comes back to kill!

Doc stared at his charts in sudden horror. It was a new disease--thought
to be some virus, but not considered dangerous. Selznik's migraine,
according to medical usage; you treated it with hot pads and anodyne,
and it went away easily enough.

He'd seen hundreds of such cases on Earth. There must be millions who
had been hit by it. The patent-medicine branch of the Lobby had even
brought out something called Nograine to use for self-treatment.

"Something important?" Jake wanted to know.

Feldman nodded. "How much weight do you swing in other villages, Jake?"

"People sort of do me favors when I ask," Jake admitted. "Like swiping
those medical journals from Northport for you, or like Molly Badger
getti