"The body must be buried before long," I remarked. "How will you obtain a medical certificate and get it buried by an undertaker?" "Mr. Holford," he said, turning to me with an expression of slight annoyance upon his face, "I beg of you not to anticipate difficulty. It is the worst attitude a man can take up--especially in trying to solve a problem such as this. The future kindly leave entirely with me." At that moment I was fingering a small test-tube containing some thick grey-coloured liquid, and as I turned I accidentally dropped it upon the tiles with which the Professor had had the place paved. In an instant there was a bright flash, almost like a magnesium light, so brilliant that for a second we were both blinded. "I wonder what that was?" he remarked, startled by the result. "One must be careful in handling what the dead man has left behind." "Evidently," I said; "we cannot tell what these various experimental apparatus and tubes contain. Therefore we should handle them delicately." And I bent to the table to examine another tube containing some bright red crystals held over an extinguished spirit-lamp by a brass holder, an action which my companion, I noticed, watched with a curious expression. Was it suspicion of myself? "Well, my dear friend," he exclaimed suddenly as he stood beside the table, "the problem is, as you see, rendered the more difficult of solution by the inexplicable fate which has overtaken the Professor's daughter. Here is a man against whom, as far as we know, nobody in the world had a grudge, who receives a telegram which he is careful to destroy, makes a preconcerted signal at his drawing-room window, and goes upon a journey to Edinburgh. We know that he went, for the conductor recollects asking if he would take an early cup of tea. Again, he received his daughter's telegram and replied to it. Yet at the same time he was in Edinburgh he was in this very room behind two locked doors of which he alone had the key, the victim of a brutally murderous attack! These doors were locked, and to enter here both he and the assassin must have passed through the boudoir within a yard or so of his daughter." "Is there no other means of access except through the boudoir?" I asked. "Have the windows been examined?" "Yes; all the windows were screwed down on the inside. To-morrow, in the light, you shall satisfy yourself. I must come here to search for any finger-prints," was his hasty reply. "When I caused these doors to be opened, I was careful not to allow the locksmith to see that any tragedy had occurred. The man was paid, and went away in ignorance. Yet when Miss Ethelwynn realised the truth she was as one demented. At first she refused to leave the place, but I persuaded her, and she went with her maid to her aunt's. I impressed upon her the value of silence, and she gave me her word that she would say nothing of what had occurred." "What about her maid Morgan?"