The specialist seemed to be as completely baffled as myself. He pursued the examination almost in silence, only speaking from time to time to ask me to hand him the different reagents used in testing for poisons. It was quickly evident that none of the common poisons was present. Anything like strychnine or arsenic was out of the question from the first. The rapidity with which death had taken place eliminated the possibility of germs. More subtle agents, such as belladonna and aconite, were tested for in vain. In the midst of my overpowering anxiety I was moved to admiration by the expert’s extraordinary skill. All kinds of tests of which I had never heard were brought to bear; drugs unknown to me even by name were called into requisition; minute discolorations were examined by a powerful microscope; a galvanic battery was applied to one organ, and the X-ray to another. And still there was no positive result. Hours passed away unnoticed in the laborious search. It was nearly dinner-time when Tarleton at length straightened himself up with a look of finality, walked across the room, and began washing his hands. “I have now tried for every agent known to the British Pharmacopœia that might possibly have produced death with such symptoms as those, and not one is present,” he said with extreme gravity. I felt myself shivering. If anyone else had been speaking I should have thought he was attributing the death to a supernatural cause. “There are only two possibilities left, so far as I can see,” he continued. “One is that I am dealing with a murderer whose knowledge of poisons is more extensive than my own.” I shook my head in protest. “In that case,” Tarleton went on deliberately, “he must be a foreigner. And we must be prepared to find that the life of the Crown Prince was aimed at, after all. The Bolsheviks are in close relation with a party among the Chinese. It may well be that the Chinese possess the secret of treating opium in such a way as to make it produce effects unknown to Western science. I shall have to ask Charles to find out what costume the Prince wore last night, and to learn a little more about the Chancellor of the Slavonian Legation.” He broke off for a few moments, and I breathed more freely than I had done for many hours. He finished drying his hands before he spoke again. “There is a second possibility. There is one drug known to me which does in fact produce appearances exactly like those we have seen. But it is a drug not mentioned in the Pharmacopœia, and I had every reason to believe that I was the only person in this part of the world who had any of it in his possession. I keep it in a sealed bottle in my private safe, and I am now going to see if that bottle has been tampered with, and any of the poison is missing.”