us. Since your duties will
primarily involve Thurston's Disease, you'd better know something about
it." He settled himself more comfortably across the lab bench and went
on talking in a dry schoolmasterish voice. "Alan Thurston was an
immunologist at Midwestern University Medical School. Like most men in
the teaching trade, he also had a research project. If it worked out,
he'd be one of the great names in medicine; like Jenner, Pasteur, and
Salk. The result was that he pushed it and wasn't too careful. He wanted
to be famous."

"He's well known now," Mary said, "at least within the profession."

"Quite," Kramer said dryly. "He was working with gamma radiations on
microorganisms, trying to produce a mutated strain of _Micrococcus
pyogenes_ that would have enhanced antigenic properties."

"Wait a minute, doctor. It's been four years since I was active in
nursing. Translation, please."

Kramer chuckled. "He was trying to make a vaccine out of a common
infectious organism. You may know it better as _Staphylococcus_. As you
know, it's a pus former that's made hospital life more dangerous than it
should be because it develops resistance to antibiotics. What Thurston
wanted to do was to produce a strain that would stimulate resistance in
the patient without causing disease--something that would help patients
protect themselves rather than rely upon doubtfully effective
antibiotics."

"That wasn't a bad idea."

"There was nothing wrong with it. The only trouble was that he wound up
with something else entirely. He was like the man who wanted to make a
plastic suitable for children's toys and ended up with a new explosive.
You see, what Thurston didn't realize was that his cultures were
contaminated. He'd secured them from the University Clinic and had, so
he thought, isolated them. But somehow he'd brought a virus
along--probably one of the orphan group or possibly a phage."

"Orphan?"

"Yes--one that was not a normal inhabitant of human tissues. At any rate
there was a virus--and he mutated it rather than the bacteria. Actually,
it was simple enough, relatively speaking, since a virus is infinitely
simpler in structure than a bacterium, and hence much easier to modify
with ionizing radiation. So he didn't produce an antigen--he produced a
disease instead. Naturally, he contracted it, and during the period
between his infection and death he managed to infect the entire
hospital. Before anyone realized what they were