e was working. The level of the gas
showed it to be of the original volume but the liquid under the argon
was stained a light brown.

"It's impossible, Davis," cried the doctor, "but nevertheless, it's
true. Expose some of those crystals to strong sunlight and see what
happens."

The crystals rapidly disappeared as the light from a sun-ray arc fell
on them.

"It's true, Davis," cried the doctor, positive awe in his voice. "Keep
this strictly under your hat for the present. Now that you know what
we're up against, fix up a couple of masks and air-collecting
apparatus. That stuff will show up again in the swamp to-night and I
am going down there to collect some samples. I'll telephone the
hospital now."

* * * * *

As Dr. Bird emerged from the dark room, Carnes hurried up with a
worried expression.

"The devil's to pay, Doctor," was his greeting.

"All right, stall him off for a minute while I telephone the hospital.
I think I can save some of those poor fellows up there."

Carnes paced the floor in anxiety while Dr. Bird got Captain Murdock
on the telephone.

"Bird talking, Murdock," he said crisply. "How much deep therapy X-ray
apparatus have you got up there?... Too bad.... Well, at least you can
give every patient a four-minute dose of maximum intensity and repeat
in an hour or so. Keep them under sun-ray arcs as much as you can. Be
ready for a fresh attack of the same epidemic to-night. As fast as the
patients come in, give them a five-minute dose of X-rays and then
sun-rays. Do you understand?... All right, then."

"Just a moment more, Carnes," he went on as he called the office of
the commanding officer. "Colonel Wesley, this is Dr. Bird. I think
that I have some light on your problem. You must anticipate another
more virulent attack than you had last night, probably as soon as the
sun goes down. Will you arrange to have everyone removed from the
swamp area before that time? Never mind trying to guard the place;
you'll just lose more lives if you do. Warn everyone to keep inside
the buildings with all doors and windows closed tight. Get all the
women and children and everyone else who isn't needed here off the
post before dark. Send them to Aberdeen or Baltimore or anywhere....
No, sir, the sick had better not be moved. I think they will be safer
in the hospital than they would be elsewhere.... Yes, sir, that's all.
Thank you."

* * * * *