BLOOD STAINS, as determined by modem science, have risen to importance in some criminal trials, where attempts have been made with some success to determine, by microscopic and chemical teas, whether the stains in question were made by the blood of a human being or of some other animal; and even the further question is proposed— was the stain made by the blood of a man, woman, or child? and if by that of a man, can we tell if it was the blood of one or of another man? With proper chemical solv ents it seems easy to determine that a stain is or is not made from blood. If of blood, then the microscope indicates, by the measurements of the corpuscles of which the blood was composed, whether it was human blood., It is asserted as the result of careful examinations that the blood of a man has larger red corpuscles than that of any other animal. The mean diameter of these red corpuscles expressed in ten thousandths of an inch is thus stated: Man, 77; dog, 70; rabbit, 65; rat, 04; pig, 62; mouse, 61; ox, SS; horse, 57; cat, 56; sheep, 44. In fresh blood these measurements may, perhaps, be
depended upon; but when the blood has been dried the corpuscles change their form, and it would probably be impossible to determine whether the stain were human blood or not. As for determining the blood of one person from that of another, there does not seem to be any of doing so; indeed, so far as experiment has gone, it appears that there may be difference in the corpuscles of the same man's blood, taken at different times or from different parts, than between the corpuscles of the blood of different persons. The examination of stains has been a prominent feature in some recent trials for murder, but it does not appear that any considerable dependence has been placed upon the testimony of experts, partly because scientific testimony of such a nature is difficult to comprehend, and partly because experts themselves of equal attainments differ widely in their conclusions.