be obtained by someone not a member of the medical profession?"
"There are comparatively few—" The specialist broke off abruptly. "I tell you, there's something wrong with that poisoned-needle theory. I have made about as profound a study of toxicology as anyone in the country, and I do not know of any poison so introduced and leaving no trace which would produce that effect of a slowly progressing septicemia. There are some which would cause instant death and others which would merely paralyze. I naturally do not care to give an opinion before the autopsy, especially in view of the mistake which you have convinced me that my colleagues and I have made; but I don't mind advancing a theory for your consideration.
"What if that needle had not been poisoned in the sense you mean? What if it had merely been dipped in the serum from some other case of blood-poisoning? That is the one serious danger which surgeons have to face, you know, and which has brought about meticulous care in sterilization. The result would have been exactly what was seen in Mrs. Lorne's case at first."
"Yes; but she did not respond to any of the forms of treatment which were tried." Odell saw his carefully built-up theory falling to pieces. "You are positive, Doctor, that there is no poison?"
The specialist waved the question aside impatiently.
"I said 'at first,' Sergeant. Let us suppose, then, that Mrs. Lorne is really suffering from infection: let us suppose also that the would-be murderer or his confederate is right at hand, a trusted member of the household. As I
