't deserve nerves."

The doctor glanced sharply from his patient to Donaldson himself. He
noted the latter's pupils, his tense lips, his tightened fingers. He
had jumped at the word poison, like a murderer at the word police.

"See here," he demanded, "you have n't any of this stuff in you, have
you?"

"No," answered Donaldson, calmly.

"Anything else the matter with you?"

"Nothing but nervousness, I guess. I 've been under something of a
strain recently."

Donaldson turned away. He was afraid of the keen eyes of this man.
Barstow had not experimented very long with the stuff; perhaps, after
all, it did produce symptoms. But he reassured himself the next
minute, remembering that the drug was unknown. Barstow had not
revealed his discovery to any one. If he showed a dozen symptoms they
would be unrecognizable.

The doctor dropped his questioning and turned to his patient. He
subjected the man to the stomach-pump and hot baths. Donaldson
assisted and watched every detail of the vigorous treatment with
increasing interest. At the end of two hours Arsdale was allowed to
sleep.

Seton put on his coat and wrote out instructions for the further care
of the man. But before leaving he again turned his shrewd eyes upon
Donaldson himself.

"My boy," he said kindly, "you ought to pay some attention to your own
health. I hate to see a man of your age go to pieces."

He squinted curiously at Donaldson's eyes. The latter withdrew a
little.

"What makes you think there is anything wrong with me?" he asked.

"Your eyes for one thing," he answered.

"Nonsense. If I need anything, its only a good sweating, such as you
gave Arsdale."

"There are some poisons not so easily sweated out."

Donaldson hesitated. While watching this man at work upon the boy, he
had felt a temptation which was now burning hot within him. It was
possible that it was not too late even now to clean his own system of
the drug he had swallowed. This man, he knew, would bring to his aid
all the wisdom of medical science. Barstow may have been mistaken,
although he knew the careful chemist well enough to realize this was
well nigh an impossibility. The next second he held out his hand. It
was steady. He smiled as he saw Seton pause a moment to note if it
trembled.

"Thanks for all you 've done, doctor," he said. "Do you think I can
take him home tomorrow?"

"If you follow my instructions. The boy really has a sound physiqu