for the man to head back.

"Bracky--it has to be! Chris, that's it. Jake picked out the second
group of men from his friends--and they are all cronies because they
hang around so much in their so-called smoking room. The first time, it
killed the bugs for all of us who smoked--and it didn't work for you
because you never learned the habit."

Lou had the tractor turned and the rheostat all the way to the floor.

She was sitting up now, but she wasn't fully satisfied. "The percentage
of immunes seems about right. But why do some of the smokers get the
disease while some don't?"

"Why not? It depends on whether they pick up the habit before or after
the disease gets started. Tom must have got his while he was in
Northport. They wouldn't let him smoke there--if he had the habit
before, for that matter."

She found no fault with that. He twisted it back and forth in his mind,
trying to find a fault. There seemed to be none. The only trouble was
that they couldn't send a message that bracky was the cure and hope that
Earth would prove it true. No polite note of apology would do after
that. They had to be sure. Too many other ideas had proved wrong
already.

Jake saw them coming and came running toward the laboratory, but Lou
stopped the tractor before it reached the building and let the older man
in.

"Get me a dozen men who have the plague. I want the worst cases you
have, and ones that Harkness tested himself," Doc ordered. "And then
start praying that the cure we've got works fast."

Chris was at the electron mike at once, but one of her hands reached out
for the weed. She began puffing valiantly, making sick faces. Now other
men began coming in, their faces struggling to find hope, but not daring
to believe yet. Jake followed them.

"We'll test at ten-minute intervals. That will be about two hours for
the last from the group," Doc decided. One of the doctors Harkness had
brought to the villages was busy cutting tiny sections from the lumps on
the men's necks, while Chris ran them through the microscope to make
sure the bugs were still alive. The regular optical mike was strong
enough for that.

Doc handed each man a bracky weed, with instructions to keep smoking, no
matter how sick it made him.

There were no results at the end of ten minutes when the first test was
made. The second, at the end of twenty minutes, was still infected with
live bugs. At the half-hour, Chris frowned.

"I can't be sure--take a