t the bouillon you served--that last cup especially?" he
asked.

"From the pantry just as usual, sir," the man answered. "It was all served
out from the same cauldron."

"Any chance of any one getting at it?"

"Quite impossible, sir!"

Laura rose to her feet.

"Sorry," she apologized, "I can't eat anything. I'm off on deck."

The Captain rose promptly.

"I'll escort you, if I may," he suggested.

Harris, too, rose from his place, after a final and regretful glance at
the menu, and joined the others. The Captain, however, drew Laura's arm
through his as they reached the stairs, and Harris, with a little shrug of
the shoulders, made his way to Quest's stateroom. The Doctor, the
Professor, Quest and Lenora were all gathered around two little tubes,
which the criminologist was examining with an electric torch.

"No reaction at all," the latter muttered. "This isn't an ordinary poison,
any way."

The Professor, who had been standing on one side, suddenly gave vent to a
soft exclamation.

"Wait!" he whispered. "Wait! I have an idea."

He hurried off to his stateroom. The Doctor was poring over a volume of
tabulated poisons. Quest was still watching his tubes. Lenora sat upon the
couch. Suddenly the Professor reappeared. He was carrying a small notebook
in his hand; his manner betrayed some excitement. He closed the door
carefully behind him.

"I want you all," he begged, "to listen very carefully to me. You will
discover the application of what I am going to read, when I am finished.
Now, if you please."

They looked at him wonderingly. It was evident that the Professor was very
much in earnest. He held the book a little way away from him and read
slowly and distinctly.

"This," he began, "is the diary of a tour made by Craig and myself in
Northern Egypt some fourteen years ago. Here is the first entry of
import:--

"_Monday_. Twenty-nine miles south-east of Port Said. We have
stayed for two days at a little Mongar village. I have to-day
come to the definite conclusion that anthropoid apes were at one
time denizens of this country.

"_Tuesday_. Both Craig and I have been a little uneasy to-day.
These Mongars into whose encampment we have found our way, are
one of the strangest and fiercest of the nomad tribes. They are
descended, without a doubt, from the ancient Mongolians, who
invaded this country some seven hundred years before Christ.
They have interbred with