“Well,” replied the doctor, slowly, “when his valet called me in, I must admit that my first impression was that I had to deal with a case of diphtheria.  I was so impressed that I even took a blood smear and examined it.  It showed the presence of a tox albumin.  But it isn’t diphtheria.  The antitoxin has had no effect.  No; it isn’t diphtheria.  But the poison is there.  I might have thought it was cholera, only that seems so impossible here in New York.”  Doctor Murray looked at Kennedy with no effort to conceal his perplexity.  “Over and over I have asked myself what it could be,” he went on.  “It seems to me that I have thought over about everything that is possible.  Always I get back to the fact that there is that tox albumin present.  In some respects, it seems like the bite of a poisonous animal.  There are no marks, of course, and it seems altogether impossible, yet it acts precisely as I have seen snake bites affect people.  I am that desperate that I would try the Noguchi antivenene, but it would have no more effect than the antitoxin.  No; I can only conclude that there is some narcotic irritant which especially affects the lungs and heart.”

“Will you let me have one of the blood smears?” asked Kennedy.

“Certainly,” replied the doctor, reaching over and taking a glass slide from several lying on a table.

For some time after we left the sick-room Craig appeared to be considering what Doctor Murray had said.

Seeking to find Miss Grey in the library, we found ourselves in the handsome, all-wood-paneled dining-room.  It still showed evidences of the late banquet of the night before.

Craig paused a moment in doubt which way to go, then picked up from the table a beautifully decorated menu-card.  As he ran his eye down it mechanically, he paused.

“Champignons,” he remarked, thoughtfully.  “H-m!—­mushrooms.”

Instead of going on toward the library, he turned and passed through a swinging door into the kitchen.  There was no one there, but it was in a much more upset condition than the dining-room.

“Pardon, monsieur,” sounded a voice behind us.

It was the French chef who had entered from the direction of the servants’ quarters, and was now all apologies for the untidy appearance of the realm over which he presided.  The strain of the dinner had been too much for his assistants, he hastened to explain.

“I see that you had mushrooms—­creamed,” remarked Kennedy.

“Oui, monsieur,” he replied; “some that Miss Hargrave herself sent in from her mushroom-cellar out in the country.”

As he said it his eye traveled involuntarily toward a pile of ramekins on a table.  Kennedy noticed it and deliberately walked over to the table.  Before I knew what he was about he had scooped from them each a bit of the contents and placed it in some waxed paper that was lying near by.  The chef watched him curiously.