ube with distilled water.
I will even divide it in half, and place the other half in this fourth
tube.

"Next I add some of the serum of the uninoculated rabbit to the half in
this tube. You observe, nothing happens. I add a little of the serum of
the inoculated rabbit to the other half in this other tube. Observe how
delicate the test is--"

Kennedy was leaning forward, almost oblivious of the rest of us in the
room, talking almost as if to himself. We, too, had riveted our eyes on
the tubes.

As he added the serum from the inoculated rabbit, a cloudy milky ring
formed almost immediately in the hitherto colourless, very dilute
blood-solution.

"That," concluded Craig, triumphantly holding the tube aloft, "that
conclusively proves that the little round spot on the hardwood floor was
not paint, was not anything in this wide world but blood."

No one in the room said a word, but I knew there must have been someone
there who thought volumes in the few minutes that elapsed.

"Having found one blood-spot, I began to look about for more, but was
able to find only two or three traces where spots seemed to have been.
The fact is that the blood spots had been apparently carefully wiped up.
That is an easy matter. Hot water and salt, or hot water alone, or even
cold water, will make quite short work of fresh blood-spots--at least
to all outward appearances. But nothing but a most thorough cleaning
can conceal them from the Uhlenhuth test, even when they are apparently
wiped out. It is a case of Lady Macbeth over again, crying in the face
of modern science, 'Out, out, damned spot.'

"I was able with sufficient definiteness to trace roughly a course
of blood-spots from the fireplace to a point near the door of the
living-room. But beyond the door, in the hall, nothing."

"Still," interrupted Harrington, "to get back to the facts in the case.
They are perfectly in accord either with my theory of the cigar or the
Record's of spontaneous combustion. How do you account for the facts?"

"I suppose you refer to the charred head, the burned neck, the upper
chest cavity, while the arms and legs were untouched?"

"Yes, and then the body was found in the midst of combustible
furniture that was not touched. It seems to me that even the
spontaneous-combustion theory has considerable support in spite of this
very interesting circumstantial evidence about blood-spots. Next to my
own theory, the combustion theory seems most in harmony