"I cannot answer that question," he said at last. "I can only offer an opinion. I believe--in fact, I am sure!--the man was poisoned. I am convinced he was poisoned. But I am forced to admit that I do not know what poison was used, and that after a most careful search I have not yet been able to come across any trace or sign of any poison known to me. All the same, I am sure he died from the effects of poison, but what it was, or how administered, frankly, I do not know!" "You made a post-mortem examination?" asked the Coroner. "Yes," replied the specialist, "in company with Dr. Seracold. The deceased was a thoroughly healthy, well-nourished man. There was not a trace of disease in any of the organs--he was evidently a temperate man, and likely to live to over the seventy years' period. And, as I have said, there was not a trace of poison. That is, not a trace of any poison known to me." "I want to ask you a particularly important question," said the Coroner. "Are there poisons, the nature of which you are unacquainted with?" "Yes!" answered the specialist frankly. "There are. But--I should not expect to hear of their use in London." "Is there any European expert who might throw some light on this case?" asked the Coroner. "Yes," said Dr. Sperling-Lawson. "One man--Professor Gagnard, of Paris. As a matter of fact, I have already sent certain portions of certain organs to him--by a special messenger. If he cannot trace this poison, then no European nor American specialist can. I am sure of this--the secret is an Eastern one." "Gentlemen," said the Coroner, "we will adjourn for a week. By that time there may be a report from Paris." The crowd surged out into the damp November morning, eagerly discussing the evidence just given. Purdie, Lauriston, and Guyler, all equally mystified, followed, already beginning to speculate and to theorize. Suddenly Melky Rubinstein hurried up to them, waving a note. "There was a fellow waiting outside with this from Zillah," said Melky. "She'd heard you were all here, and she knew I was. We're to go there at once--she's found some letters to her grandfather from that man Purvis! Come on!--it's another step forward!" CHAPTER TWENTY-TWO MR. KILLICK GOES BACK Ayscough and the man from New Scotland Yard came out of the court at that moment in close and serious conversation: Melky Rubinstein left the other three, and hurried to the two detectives with his news; together, the six men set off for Praed Street. And Purdie, who by this time was developing as much excited interest as his temperament and business habits permitted, buttonholed the Scotland Yard man and walked alongside him. "What's your professional opinion about what we've just heard in there?" he asked. "Between ourselves, of course."