It was all very weird and fascinating. But what he could have been doing with a dead body, I could not imagine. Was there some subtle, unknown poison which had hitherto baffled science, but which now he was about to reveal to us?

He seemed to be in no hurry to overcome the psychological effect his words had on his auditors, for as he picked up and glanced at a number of sheets of figures, he went on: "In the case of live persons, there is a food aperture here, a little window with air locks arranged for the passage of food and drink. That large window through which you looked admits light. There is also a telephone. Everything is arranged so that all that enters, no matter how minute, is weighed and measured. The same is true of all that leaves. Nothing is too small to take into account."

He shook the sheaf of papers before us. "Here I have some records which have been made by myself, and, in my absence, by one of my students. In them the most surprising thing that I have discovered is that in the body of Leon metabolism seems still to be going on."

I listened to him in utter amazement, wondering toward what his argument was tending.

"I got my first clew from an injection of fluoriscine," he resumed. "You know there are many people who have a horror of being buried alive. It is a favorite theme of the creepy-creep writers. As you know, the heart may stop beating, but that does not necessarily mean that the person is dead. There are on record innumerable cases where the use of stimulants has started again the beating of a heart that has stopped.

"Still, burial alive is hardly likely among civilized people, for the simple reason that the practice of embalming makes death practically certain. At once, when I heard that there had been objections to the embalming of this body, I began to wonder why they had been made.

"Then it occurred to me that one certain proof of death was the absolute cessation of circulation. You may not know, but scientists have devised this fluoriscine test to take advantage of that. I injected about ten grains. If there is any circulation, there should be an emerald green discoloration of the cornea of the eye. If not, the eye should remain perfectly white.

"I tried the test. The green eye-ball gave me a hint. Then I decided to make sure with a respiration calorimeter that would measure whatever heat, what breath, no matter how minute they were."

Collette gave a start as she began to realize vaguely what Craig was driving at.

"It was not the voodoo sign, Mademoiselle," he said, turning to her. "It was a sign, however, of something that suggested at once to me the connection of voodoo practices."