"She shall die!"
Then his brain sought some way to compass such an end with safety to himself, and before long he had concocted a scheme of devilish ingenuity. His knowledge of chemistry warned him that poisons could be traced in the tissues of the body after death, and that such means would be suicidal.
"But suppose she were to die a natural death? Then, not even suspicion would be aroused."
That was the idea. He must convey to her the germs of some deadly disease from which she would be apt to die. Then the post-mortem would show nothing out of the common. There would be no way to detect how the disease had been contracted. The attending physician would certify that the death was due to a known disease, and an autopsy, if held, would substantiate his statements.
What disease should he choose? Asiatic cholera? He had some pure cultures in a tube in the laboratory. But no! That would not serve his purpose. Cholera is such an uncommon and dangerous malady, that the Board of Health would strictly investigate a sporadic case. It might not be difficult to trace the fact that he had obtained the germs from the European laboratory whence they had been sent to Dr. Medjora for experimental purposes. It would be safer to select some disease of frequent occurrence. He had the germs of diphtheria also, in the form of a pure culture. Should he use them? It would not be sure that the woman would die, but at any rate she might, and surely she would suffer. Yes! He would cause her to contract diphtheria. But how to proceed? Ah! He would use chloroform upon her in her natural sleep, and thus obtain the opportunity for his inoculation.
And so the idea grew, and his plans were arranged and perfected hour after hour, until at last midnight had arrived. Stealthily he left his room and went towards the Doctor's study. Arrived there, he was about to cross and enter the laboratory, when his attention was attracted by a line of light under the door. Some one was evidently in the laboratory. Leon slipped behind a curtain and waited. The minutes passed tediously, but at last the door opened, and there appeared Dr. Medjora, only partly dressed, his feet slippered. In one hand he carried a night lamp, and in the other he held a bottle and a test tube. Of this Leon was certain. Closing the door of the laboratory, the Doctor crossed the study and went out into the hall. Leon stole after him, and saw him start up the stairs. He watched until, as the Doctor ascended, the light gradually disappeared. Then he heard footsteps overhead, and knew that the Doctor had gone to his own room. Madame slept at the other end of the dwelling.
"Some experiment which he is studying out," muttered Leon, and proceeded with his own grim purpose. He went into the laboratory, and lighted a lamp which was on the bench. He searched the closet where the drugs were kept, but the chloroform bottle was missing. He turned to the rack where he had left the tube in which the diphtheria bacillus had been cultivated, but that also could not be found.
In a moment, realizing that the means of committing the contemplated crime had in some mysterious way been taken from him, he awoke from the delirium of his thoughts, which had been brought on by his grief at the death of his dog, and he fervently thanked the fortune which had saved him from committing murder. Like a culprit, he returned stealthily to his room, head down, and there he sat at the window, looking out at the stars, grateful that he could do so, free from that dread secret which might have been his. He was saved!
On the next morning, however, Leon was horrified to hear that Madame had been suddenly taken ill, and that the malady was diphtheria, in its most virulent form. He could not understand it, but he was more than glad that his own conscience was free from stain.
Two days later, Madame Medjora succumbed to the disease, which is often fatal when it attacks one of her age; and so she went to her long account, with her sins upon her head.