"Yes," he said, remembering that, after all, there were Board Schools, and even the humblest might sometimes learn, parrot-like, to repeat the "things that are in books." "But we happen to know that the slits were not closed and that neither carbon oxide nor carbon monoxide was the cause of death." "You have taken samples of the blood, of course, to establish that fact beyond question, as one could so readily do?" ventured Cleek suavely. "The test for carbon monoxide is so simple and so very certain that error is impossible. It combines so tensely, if one may put it that way, with the blood, that the colouring of the red corpuscles is utterly overcome and destroyed." "My good sir, those are elementary facts of which I do not stand in need of a reminder." "Quite so, quite so. But in my profession, Doctor, one stands in constant need of 'reminders.' A speck, a spot, a pin-prick--each and all are significant, and----But is this not a slight abrasion on the temple here?" bending over and, with his glass, examining a minute reddish speck upon the dead man's face. "Hum-m-m! I see, I see! Have you investigated this thing, Doctor? It is interesting." "I fail to see the point of interest, then," replied Doctor Hague, bending over and examining the spot. "The skin is scarcely more than abraded--evidently by the finger nail scratching off the head of some infinitesimal pustule." "Possibly," agreed Cleek, "but on the other hand, it may be something of a totally different character--for one thing, the possible point at which contact was established between the man's blood and something of a poisonous character. An injection of cyanide of potassium, for instance, would cause death, and account in a measure for this suggestion of asphyxia conveyed by the expression of the features." "True, my good sir; but have the goodness to ask yourself who could get into the place to administer such hypodermic? And, if self-administered, what can have become of the syringe? If thrown from one of the bowman's slits, it could only have fallen upon the roof of the wing, and I assure you that was searched most thoroughly long before your arrival. I don't think you will go so far as to suggest that it was shot in, attached to some steel missile capable of making a wound; for no such missile is, as you see, embedded in the flesh nor was one lying anywhere about the floor. The cyanide of potassium theory is ingenious, but I'm afraid it won't hold water." "Hold water!" The phrase brought Cleek's thoughts harking back to what he had been told regarding the little puddle of water lying on the floor, and of a sudden his eyes narrowed, and the curious one-sided smile travelled up his cheek. "No, I suppose not," he said, replying to the doctor's remark. "Besides, your test tubes would have settled that when it settled the carbon monoxide question. Had cyanide been present, the specimens of blood would have been clotted and blue."