"B E good enough to remove your coat," said the old man with a politeness hardly consistent with his fearful purpose.

"Sir," said Oliver, hoping that he might be accessible to reason, "you have no right to experiment upon me without my permission."

"I should prefer your permission," said the old doctor.

"I can\'t give it," said Oliver hastily.

"My young friend," said the old man, with an air of superior wisdom, "you do not appreciate the important part you are invited to take in the progress of scientific discovery. You will lose your life, to be sure, but what is a single life to the discovery of a great truth! Your name will live for ages in connection with the great principle which I shall have the honor of discovering."

"I would rather live myself," said Oliver bluntly. "Science may be all very well, but I prefer that somebody else should have the privilege of dying to promote it."

"They all say so," said the old man musingly. "No one has the noble courage to sacrifice himself for the truth."

"I shouldn\'t think they would," retorted Oliver. "Why don\'t you experiment on yourself?"

"I would willingly, but there are two impediments. I cannot at once be operator and subject. Besides, I am too old. My natural force is abated, while you are young, strong, and vigorous. Oh, yes," and he looked gloatingly at our hero, "you will be a capital subject."

"Look here," said Oliver desperately, "I tell you I won\'t be a subject."

"Then I must proceed without your permission," said the old doctor calmly. "I have already waited too long. I cannot let this opportunity slip."

"If you kill me you will be hanged!" exclaimed Oliver, the perspiration starting from every pore.

"I will submit cheerfully to an ignominious death, if time is only given me to complete and announce my discovery," said the old man composedly.

Evidently he was in earnest. Poor Oliver did not know what to do. He determined, however, to keep the old man in conversation as long as possible, hoping that help might yet arrive, and the struggle—for he meant to fight for his life—be avoided.

"Did you have this in view when you invited me to dine with you?" he asked.

"Surely I did."

"Why did you select me rather than someone else?"

"Because you are so young and vigorous. You are in the full flush of health."

Now this is a very pleasant assurance in ordinary cases, but under the circumstances Oliver did not enjoy the compliment. A thought struck him.

"You are mistaken," he said. "I am not as well as I look. I have—heart disease."

"I can hardly believe it," said the old man. "Heart disease does not go with such a physique."

"I\'ve got it," said Oliver. "If you want a perfectly healthy subject, you must apply to someone else."

"I will test it," said the old man, approaching. "If you really are subject to disease of the heart, you will not answer my purpose."

"Put down that knife, then," said Oliver.

The doctor put it down. Oliver shuddered while the relentless devotee of science placed his hand over his heart, and waited anxiously his decision.

It came.

"You are mistaken, my young friend," he said. "The movement of your heart is slightly accelerated, but it is in a perfectly healthy state."

"I don\'t believe you can tell," said Oliver desperately, "just by holding your hand over it a minute."

"Science is unerring, my young friend," said the old man calmly. "But we waste time. Take off your coat and prepare yourself for the operation."

The crisis had come, the old man approached with his dangerous weapon. At this supreme moment Oliver espied a bell-knob. He sprang to it, and rang a peal that echoed through the house, and was distinctly heard even in the chamber where they were standing.

"What did you do that for?" demanded the old man angrily.

"I am not going to stay here to be murdered!" exclaimed Oliver. "I give you warning that I will resist you with all my s............