“Apart from the watch, however, the appearances suggested that the man had taken his own life. But against this view was the blood on the hall floor. The dead man appeared to have fallen at once from the effects of the shot, and there had been very little bleeding. Then how came the blood in the hall? The inspector decided that it could not have been the blood of the deceased; and when we examined it and saw that there were several little pools and that they seemed to form a track towards the street door, he was convinced that the blood had fallen from some person who had been wounded and was escaping from the house. And, under the circumstances, he was bound to assume that that person was Robert Fletcher; and on that assumption, he despatched the sergeant forthwith to arrest Robert. “On this I held a consultation with Mr. Brodribb, who pointed out that the case turned principally on the blood in the hall. If it was the blood of deceased, and the absence of the watch could be explained, a verdict of suicide could be accepted. But if it was the blood of some other person, that fact would point to murder. The question, he said, would have to be settled, if possible, and his advice to me, if I believed Robert to be innocent--which, from my knowledge of him, I certainly did--was this: Get a couple of small, clean, labelled bottles from a chemist and--with the inspector’s consent--put in one a little of the blood from the hall and in the other some of the blood of the deceased. Seal them both in the inspector’s presence and mine and take them up to Dr. Thorndyke. If it is possible to answer the question, Are they or are they not from the same person? he will answer it. “Well, the inspector made no objection, so I did what he advised. And here are the specimens. I trust they may tell us what we want to know.” Here Mr. Foxley took from his attaché-case a small cardboard box, and opening it, displayed two little wide-mouthed bottles carefully packed in cotton wool. Lifting them out tenderly, he placed them on the table before Thorndyke. They were both neatly corked, sealed--with Brodribb’s seal, as I noticed--and labelled; the one inscribed “Blood of Joseph Riggs,” and the other “Blood of unknown origin,” and both signed “Arthur Foxley” and dated. At the bottom of each was a small mass of gelatinous blood-clot. Thorndyke looked a little dubiously at the two bottles, and addressing the clergyman, said: “I am afraid Mr. Brodribb has rather overestimated our resources. There is no known method by which the blood of one person can be distinguished with certainty from that of another.” “Dear, dear!” exclaimed Mr. Foxley. “How disappointing! Then these specimens are useless, after all?” “I won’t say that; but it is in the highest degree improbable that they will yield any information. You must build no expectations on them.” “But you will examine them and see if anything is to be gleaned,” the parson urged, persuasively.