"Then," said I, "if he is innocent, there must be some means of proving his innocence."

"Yes. I suppose so," she rejoined in a dejected whisper. "At any rate we shall soon know now."

At this moment the usher's voice was heard calling out the name of the first witness for the defence.

"Edmund Horford Rowe!"

A keen-looking, grey-haired man, with a shaven face and close-cut side-whiskers, stepped into the box and was sworn in due form.

"You are a doctor of medicine, I believe," said Anstey, addressing the witness, "and lecturer on Medical Jurisprudence at the South London Hospital?"

"I am."

"Have you had occasion to study the properties of blood?"

"Yes. The properties of blood are of great importance from a medico-legal point of view."

"Can you tell us what happens when a drop of blood-say from a cut finger-falls upon a surface such as the bottom of an iron safe?"

"A drop of blood from a living body falling upon any non-absorbent surface will, in the course of a few minutes, solidify into a jelly which will, at first, have the same bulk and colour as the liquid blood."

"Will it undergo any further change?"

"Yes. In a few minutes more the jelly will begin to shrink and become more solid so that the blood will become separated into two parts, the solid and the liquid. The solid part will consist of a firm, tough jelly of a deep red colour, and the liquid part will consist of a pale yellow, clear, watery liquid."

"At the end, say, of two hours, what will be the condition of the drop of blood?"

"It will consist of a drop of clear, nearly colourless liquid, in the middle of which will be a small, tough, red clot."

"Supposing such a drop to be taken up on a piece of white paper, what would be its appearance?"

"The paper would be wetted by the colourless liquid, and the solid clot would probably adhere to the paper in a ma.s.s."

"Would the blood on the paper appear as a clear, red liquid?"

"Certainly not. The liquid would appear like water, and the clot would appear as a solid ma.s.s sticking to the paper."

"Does blood always behave in the way you have described?"

"Always, unless some artificial means are taken to prevent it from clotting."

"By what means can blood be prevented from clotting or solidifying?"

"There are two princ.i.p.al methods. One is to stir or whip the fresh blood rapidly with a bundle of fine twigs. When this is done, the fibrin-the part of the blood that causes solidification-adheres to the twigs, and the blood that remains, though it is unchanged in appearance, will remain liquid for an indefinite time. The other method is to dissolve a certain proportion of some alkaline salt in the fresh blood, after which it no longer has any tendency to solidify."

"You have heard the evidence of Inspector Sanderson and Sergeant Bates?"

"Yes."

"Inspector Sanderson has told us that he examined the safe at 10.31 a.m. and found two good-sized drops of blood on the bottom. Sergeant Bates has told us that he examined the safe two hours later, and that he took up one of the drops of blood on a piece of white paper. The blood was then quite liquid, and, on the paper, it looked like a clear, red liquid of the colour of blood. What should you consider the condition and nature of that blood to have been?"

"If it was really blood at all, I should say that it was either defibrinated blood-that is, blood from which the fibrin has been extracted by whipping-or that it had been treated with an alkaline salt."

"You are of opinion that the blood found in the safe could not have been ordinary blood shed from a cut or wound?"

"I am sure it could not have been."

"Now, Dr. Rowe, I am going to ask you a few questions on another subject. Have you given any attention to finger-prints made by b.l.o.o.d.y fingers?"

"Yes. I have recently made some experiments on the subject."

"Will you give us the results of those experiments?"

"My object was to ascertain whether fingers wet with fresh blood would yield distinct and characteristic prints. I made a great number of trials, and as a result found that it is extremely difficult to obtain a clear print when the finger is wetted with fresh blood. The usual result is a mere red blot showing no ridge pattern at all, owing to the blood filling the furrows between the ridges. But if the blood is allowed to dry almost completely on the finger, a very clear print is obtained."

"Is it possible to recognise a print that has been made by a nearly dry finger?"

"Yes; quite easily. The half-dried blood is nearly solid and adheres to the paper in a different way from the liquid, and it shows minute details, such as the mouths of the sweat glands, which are always obliterated by the liquid."

"Look carefully at this paper, which was found in the safe, and tell me what you see."

The witness took the paper and examined it attentively, first with the naked eye and then with a pocket-lens.

"I see," said he, "two blood-marks and a print, apparently of a thumb. Of the two marks, one is a blot, smeared slightly by a finger or thumb; the other is a smear only. Both were evidently produced with quite liquid blood. The thumb-print was also made with liquid blood."

"You are quite sure that the thumb-print was made with liquid blood?"

"Quite sure."

"Is there anything unusual about the thumb-print?"

"Yes. It is extraordinarily clear and distinct. I have made a great number of trials and have endeavoured to obtain the clearest prints possible with fresh blood; but none of my prints are nearly as distinct as this one."

Here the witness produced a number of sheets of paper, each of which was covered with the prints of b.l.o.o.d.y fingers, and compared them with the memorandum slip.

The papers were handed to the judge for his inspection, and Anstey sat down, when Sir Hector Trumpler rose, with a somewhat puzzled expression on his face, to cross-examine.

"You say that the blood found in the safe was defibrinated or artificially treated. What inference do you draw from that fact?"

"I infer that it was not dropped from a bleeding wound."

"Can you form any idea how such blood should have got into the safe?"

"None whatever."

"You say that the thumb-print is a remarkably distinct one. What conclusion do you draw from that?"

"I do not draw any conclusion. I cannot account for its distinctness at all."