The patient is aware of having received a severe blow on the part affected, which does not show much external sign of injury, the skin being often apparently unhurt or only grazed; the power of moving the part is lost, and it is insensible. The bone or bones may or may not be broken, but in either case the sufferer, if the injury be in the leg, is incapable of putting it to the ground. After a short time the limb changes color in the same manner as when severely bruised, and the necessary changes rapidly go on to gangrene. The limb swells, but not to any extent, and more from extravasation between the muscles and the bones than from inflammation, which, although it is attempted to be set up, never attains to any height. The mortification which ensues tends to a state between the humid and the dry, and rather more to the latter than the former. These cases are not of frequent occurrence, and are not commonly observed until after the blackness of the skin, and the want of sensibility and motion attract attention; for the patient is generally stupefied at first by the blow, and the part or parts about the injury feel benumbed. I made these cases an object of particular research after the battle of Waterloo, but could find only one among the British wounded. The man stated that he had received a blow on the back part of the leg, he believed from a cannon-shot, which brought him to the ground, and stunned him considerably. On endeavoring to move, he found himself incapable of stirring, and the sensibility and power of motion in the limb were lost. The leg gradually changed to a black color, in which state he was carried to Brussels. When I saw it, the limb was black, apparently mortified, and cold to the touch; the skin was not abraded; the leg was not so much swollen as in cases of humid gangrene; the mortification had extended nearly as high as the knee; there was no appearance of a line of separation; and the signs of inflammation were so slight that amputation was performed immediately above the knee. On dissecting the limb, I found that a considerable extravasation of bloody fluid had taken place below the calf of the leg, and in the cavity thus formed some ineffectual attempts at suppuration had commenced. The periosteum was separated from the tibia and fibula; the popliteal artery was, on examination, found closed in the lower part of the ham by coagulated lymph, proceeding from a rupture of the internal coat of the vessel. Two inches below this the posterior tibial and fibular arteries were completely torn across, and gave rise, in all probability, to the extravasation. The operation was successful. The proper surgical practice in such cases is to amputate as soon as the extent of the injury can be ascertained, in order that a joint may not be lost, as the knee was in this instance. It is hardly necessary to give a caution not to mistake a simple bruise or ecchymosis for mortification. To prevent such an error leading to