be?
Have you ever seen anything like this in a lung, Murdock?"

The medical officer bent over the microscope for a long time before he
shook his head with a puzzled air.

"I never have," he admitted.

"Then that's probably what we're looking for. Start slicing every lung
in this place and look for those crystals. Save them and put them in
this watch glass. If we can get enough of them, we may be able to
learn something. Carnes, get the rest of those horses in here and open
them up."

Two hours of careful work netted them a tiny pile of the peculiar
crystals. Some had come from the lungs of the dead animals and some
few from the lungs of the dead soldiers. Dr. Bird placed the crystals
in a glass bottle which he covered with layer after layer of black
paper.

"Get me more of those crystals if you can find them, Captain
Murdock," he said, "and in any case, leave the bodies here for
further study. Davis and I will go to the laboratory and try to find
out what they are. Carnes, hasn't Miss Andrews showed up yet?"

"No, Doctor."

"Locate her on the telephone if you can and tell her not to bother
about anything except the autopsy reports and to get them here as
quickly as possible. Let me know when you have that done."

* * * * *

In a dark room of the photographic laboratory, Dr. Bird removed the
black wrappings from the bottle. He dropped a few of the crystals in a
test tube and added distilled water. The water assumed a pink tinge as
the blood with which the crystals were covered dissolved, but the
crystals themselves did not change. They rose and floated on the
surface of the water.

"Insoluble in water, Davis," commented the doctor. "Better wash the
lot and then we'll get after the ultimate analysis. Whether we'll be
able to make a proximate is doubtful in view of the small amount of
sample we have. It's dollars to doughnuts that it's some carbon
compound."

He heated a few of the washed crystals in a watch glass. Suddenly
there was a sharp crack and the material disappeared. Dr. Bird thrust
his nose toward the glass and sniffed carefully.

"The dickens!" he muttered. "Davis, have I got a cold or do you smell
garlic?"

"Faintly, Doctor."

"I have a hunch. Fill a gasometer with purified argon and we'll
introduce a few of these crystals and explode them. If I'm right--"

Half an hour later he straightened up and examined the tube of the gas
analysis apparatus with which h