form. He was holding in the palm of his hand a little piece of something that shone like silver. It was in the form of a minute hollow cylinder with two grooves on it, a cylinder so tiny that it would scarcely have slipped over the point of a pencil.
"Where did you find it?" I asked eagerly.
He pointed to the wound. "Sticking in the severed end of a piece of vein," he replied, half to himself, "cuffed over the end of the radial artery which had been severed, and done so neatly as to be practically hidden. It was done so cleverly that the inner linings of the vein and artery, the endothelium as it is called, were in complete contact with each other."
As I looked at the little silver thing and at Kennedy's face, which betrayed nothing, I felt that here indeed was a mystery. What new scientific engine of death was that little hollow cylinder?
"Next I should like to visit the laboratory," he remarked simply.
Fortunately, the laboratory had been shut and nothing had been disturbed except by the undertaker and his men who had carried the body away. Strong had left word that he had gone to Boston, where, in a safe deposit box, was a sealed envelope in which Cushing kept a copy of the combination of his safe, which had died with him. There was, therefore, no hope of seeing the assistant until the morning.
Kennedy found plenty to occupy his time in his minute investigation of the laboratory. There, for instance, was the pool of blood leading back by a thin dark stream to the workbench and its terrible figure,
