“Oh,” expostulated Craig, “there must be some mistake.  It’s impossible—­impossible.”

“No,” she asserted.  “Look—­here’s my handkerchief all spotted with blood.”

She opened the bag and displayed the blood-spotted handkerchief.  He took it and examined it carefully.

“Elaine,” he said earnestly, not at all displeased, I could see that something had come up that might blot out the past unfortunate misunderstanding, “there simply must be something wrong here.  Leave this handkerchief with me.  I’ll do my best.”

There was still a little restraint between them.  She was almost ready to beg his pardon, for all the coolness there had been between them, yet still hesitated.

“Thank you,” she said simply as she left the laboratory.

Craig went to work abruptly without a word.  On the laboratory table he placed his splendid microscope and several cases of slides as well as innumerable micro-photographs.  He had been working for some time when he looked up.

“Ever hear of Dr. Edward Reichert of the University of Pennsylvania and his wonderful discoveries of how blood crystals vary in different species?” he asked.

I had not, but did not admit it.

“Well,” he went on, “there is a blood test so delicate that one might almost say that he could identify a criminal by the finger prints, so to speak, of his blood crystals.  The hemoglobin or red coloring matter forms crystals and the variations of these crystals both in form and molecular construction are such that they set apart every species of animal from every other, and even the races of men—­perhaps may even set apart individuals.  Here, Walter, we have sample of human blood crystals.”

I looked through the microscope as he directed.  There I could see the crystals sharply defined.

“And here,” he added, “are the crystals of the blood on Elaine’s handkerchief.”

I looked again as he changed the slides.  There was a marked difference and I looked up at him quickly.

“It is dog’s blood—­not human blood,” he said simply.

I looked again at the two sets of slides.  There could be no doubt that there was a plain difference.

“Wonderful!” I exclaimed.

“Yes—­wonderful,” he agreed, “but what’s the game back of all this—­that’s the main question now.”

Long after Clutching Hand had left, Long Sin was giving instructions to his servant and Adventuress Mary just how he had had to change his plans as a result of the unexpected visit.

“Very well,” nodded Mary as she left him, “I will do as you say—­ trust me.”

It was not much later, then, that Elaine received a second visit from Mary.

“Show her in, Jennings,” she said to the butler nervously.

Indeed, she felt that every eye must be upon her.  Even Jennings would know of her guilt soon.

Anxiously, therefore, Elaine looked at her visitor.