"No doubt. But to me, of course, it is a most interesting piece of research," and the professor went on: "I have never met this substance before, though I had heard whispers of it. Professor Orosi, who lived in Cologne a few years ago and is now dead, produced this poison quite accidentally, and among his intimate friends disclosed its existence, though he had no idea how to test for it with certainty. For five years all toxicologists made constant tests until apparently quite by accident Professor Sonnenschein, of Hanover, discovered the reagent which would reveal the actual glucosid, and determine its identity. It gives a yellowish-white precipitate," he added, holding up for my inspection a small test-tube containing a liquid of the colour he had indicated. "Marvellous!" I exclaimed. "I had no idea that medical science could carry inquiries so far. I know that in criminal cases in London our pathologists, with their mirror-tests for arsenic, fix the guilt upon poisoners in a manner most amazing. But I have never heard of this secret and most subtle poison which was placed beside my bed, the intention being for me to tread upon the impregnated pin." "And if you had done so you would have been taken with a sudden fatal seizure, the cause of which would never have been detected." "You mean I should have died of poison?" "You certainly would. No medical aid would have been of any avail, for orosin is the most deadly substance which has ever been discovered. It is indeed good for humanity that it is known to only a few toxicologists, but that in itself reveals the fact, monsieur, that an exceedingly clever and secret attack has been made upon your life. A single puncture of the skin with one or other of those pins which were placed so conveniently at your bedside when you sprang out to meet the intruder, and you would by this time have been buried as one whose death had been due to natural causes!" I held my breath. This declaration by one of the greatest professors of toxicology in Europe staggered me. A dastardly attempt had been made upon me by one of the most notorious of modern criminals! Why? No attempt at assassination is made without some motive, and the game must ever be "worth the candle." The whole of the dramatic incidents of the night flashed across my memory; how I had faced the fellow in my room, challenged him at the point of my pistol, and compelled him to give me meekly proofs of his respectability. Truly it was all humorous--but only from Despujol's point of view. I recollected those innocent-looking pins which apparently had been left so carelessly in my room. Each held for me a sudden and suspicious death. "The slightest puncture of the skin would inevitably prove fatal," the Professor continued. "Feeling yourself pricked you would naturally remove the pin and very quickly afterwards death would supervene. So prior to it you yourself would no doubt have removed all trace of the crime!"