Craig smiled at my surprise. "I'm making a little study of intestinal poisons," he commented, "poisons produced by microbes which we keep under more or less control in healthy life. In death they are the little fellows that extend all over the body and putrefy it. We nourish within ourselves microbes which secrete very virulent poisons, and when those poisons are too much for us—well, we grow old. At least that is the theory of Metchnikoff, who says that old age is an infectious chronic, disease. Somehow," he added thoughtfully, "that beautiful white kitchen in the Pitts home had really become a factory for intestinal poisons."
There was an air of suppressed excitement in his manner which told me that Kennedy was on the trail of something unusual.
"Mouth murder," he cried at length, "that was what was being done in that wonderful kitchen. Do you know, the scientific slaying of human beings has far exceeded organised efforts at detection? Of course you expect me to say that; you think I look at such things through coloured glasses. But it is a fact, nevertheless.
"It is a very simple matter for the police to apprehend the common murderer whose weapon is a knife or a gun, but it is a different thing when they investigate the death of a person who has been the victim of the modern murderer who slays, let us say. with some kind of deadly bacilli. Authorities say, and I agree with them, that hundreds of murders are committed in this country every year and are not detected because the detectives are not scientists,
