Although, generally speaking, the microscope cannot discern any difference between the blood of man and that of other mammalia, yet the merest examination suffices to show the difference between mammalian blood and that of birds, reptiles, or fishes. In the one case the red blood corpuscles are round, and without a nucleus; in the other they are oval and nucleated. On this fact the evidence for a prisoner at Chelmsford charged with murder was completely rebutted. Blood stains had been found on his clothes, which, according to his counsel, had been caused by chicken's blood. But the prosecution brought forward a microscopist, who stated that the blood stains were mammalian, and on this testimony the plea of the prisoner was rejected. In the following year, and at the same assizes, the testimony against a man charged with murder was strengthened by the microscopical discovery of cotton fibres on a certain weapon, which he was said to have used, while the murderers of a man who had been kicked to death were convicted on the evidence of two doctors, who found on the boots of the accused a number of hairs corresponding with the hair on the head of the victim. Evidence of this kind is becoming of extreme importance. Hardly a serious crime is investigated without the application of one or other of these scientific methods of detection, and with each success the career of the criminal becomes increasingly difficult and arduous, and his chances of success more remote. Of remarkable discoveries of crime the microscope, the camera, and the spectroscope furnish the most subtle instances, and it is quite possible that before long other methods of investigation, founded on the most recent scientific achievements, will also be brought into operation. The phonograph and the Röntgen rays are only waiting their turn to serve in the cause of justice. Post-Mortem Trials. BY GEORGE NEILSON. It might be thought that a man's death made an end of him, and that his mere body had no rights or duties except that of getting decently buried. The middle age had other ideas. The dead still had status and duties. Continental laws recognised acts of renunciation in which a widow laid the keys on her husband's corpse, or tapped his grave with the point of a halberd. The body of a murdered person, or, it might be his hand merely, might be carried before the judge to demand vengeance.[18] By English thirteenth century law[19] legal possession of real estate was thought to remain in a man, not until he died, but until his body was borne forth to burial. The dead might be a very potent witness, as shewn by the ordeal of bier-right,[20] a practice founded on the belief that the murderer's touch would cause the victim's wounds to bleed afresh. Thus variously qualified to act as witness or prosecutor as occasion required, it is not surprising to find the dead as defendant also.