Medical Jurisprudence, Forensic medicine and Toxicology. Vol. 1 by R. A. Witthaus et al.

blood from a wound inflicted during life coagulates with the exception of that from those suffering from certain pathological or occasional conditions or in certain locations, already mentioned. This coagulation is not immediate, but is complete in about five minutes. The entire amount of blood lost is thus coagulated and the coagula are firm. These coagula (if the wound is not interfered with) occur in the opening of a wound and on its edges, especially at the mouths of the blood-vessels, which are thus plugged. The blood which infiltrates the interspaces of the tissues is coagulated in the form of these interspaces. The same is true of the blood of an ecchymosis whether there be a hematoma or only an infiltration between the tissues, or both. These clots represent more or less the form of the space occupied by the blood. In the case of the scalp a subcutaneous clot may be mistaken for a depressed fracture of the skull from the fact that the edges of the clot become very hard while the centre is still quite soft. A wound in which a large artery has been divided may present very little clotting in the wound if the opening is free and the blood has mostly escaped in a jet. In a wound produced soon after death there may be some clotting, but less in amount, firstly, because there is less hemorrhage, and, secondly, because not all the blood clots. These conditions increase with the length of time after death, so that after a time a wound made on a cadaver would show very little if any clotting owing to very slight hemorrhage, and little or no clotting of the blood extravasated. When the body has lost its animal heat and rigor mortis has begun to set in, then there is no more coagulation of the blood and no more hemorrhage, under normal conditions, for the blood has mostly become clotted in the vessels of the body. Consequently, with the exception of wounds inflicted very soon after death, we can distinguish an ante-mortem from a post-mortem wound by the condition in which the blood is clotted. If there is any hemorrhage, the wound being inflicted before the loss of animal heat and the blood remains entirely fluid on the surface or in an ecchymosis, we know that the wound was produced after death and some hours after death unless any of those conditions exist in which the blood does not normally coagulate. If the hemorrhage is slight or quite moderate in amount and venous in character, if the blood is only clotted in part and the clots are rather soft and do not form a plug at the mouth of each artery, and especially if the staining of the walls of the wound can be washed off, then the wound was probably produced post mortem, but not so long after death as in the first case supposed. If the characters of the hemorrhage and the clotting are still more like those normal to a wound inflicted during life, then, as a rule, it is impossible to say from these two features of the wound, hemorrhage and clotting, whether the wound was inflicted during life or a very short time after death.