k some time to explain to the spokesman why they could not begin
then and there with the mass inoculations against the plague. First,
they needed test cases, in order to make certain that what they thought
would work in theory actually produced the desired results. Controls
were needed, to be certain that the antibody suspension alone was
bringing about the changes seen and not something else. At last, orders
went out from the spokesman. Two hundred uninfected Bruckians were
admitted to a large roped-off area near the ship, and another two
hundred in late stages of the disease were led stumbling into another
closed area. Preliminary skin-tests of the antibody suspension showed no
sign of untoward reaction. Dal began filling syringes while Tiger and
Jack started inoculating the two groups.

"If it works with these cases, it will be simple to immunize the whole
population," Tiger said. "From the amounts we used on the guinea pigs,
it looks as if only tiny amounts are needed. We may even be able to
train the Bruckians to give the injections themselves."

"And if it works we ought to have a brand new medical service contract
ready for signature with Hospital Earth," Jack added eagerly. "It won't
be long before we have those Stars, you wait and see! If we can only get
this done fast enough."

They worked feverishly, particularly with the group of terminal cases.
Many were dying even as the shots were being given, while the first
symptoms of the disease were appearing in some of the unafflicted ones.
Swiftly Tiger and Jack went from patient to patient while Dal kept check
of the names, numbers and locations of those that were inoculated.

And even before they were finished with the inoculations, it was
apparent that they were taking effect. Not one of the infected patients
died after inoculation was completed. The series took three hours, and
by the time the four hundred doses were administered, one thing seemed
certain: that the antibody was checking the deadly march of the disease
in some way.

The Bruckian spokesman was so excited he could hardly contain himself;
he wanted to start bringing in the rest of the population at once.
"We've almost exhausted this first batch of the material," Dal told him.
"We will have to prepare more--but we will waste time trying to move a
whole planet's population here. Get a dozen aircraft ready, and a dozen
healthy, intelligent workers to help us. We can show them how to use the
mater