In compound fractures, dislocations, or severe bruises of the soft parts, dark-coloured, prominent points occasionally appear, in consequence of the effusion of bloody serum beneath the cuticle; in these, however, the fluid is speedily absorbed, and the surface resumes its natural aspect, the cuticle exfoliating and being reproduced; and it is of consequence to know their real nature, for, if mistaken for the gangrenous phlyctenæ, the inexperienced practitioner may be alarmed, and, consequently, have recourse to very injudicious practice. When the process of gangrene is checked, the skin immediately beyond the mortified part becomes of a brighter hue, and is affected by a more healthy species of inflammation, which ultimately terminates in ulceration, with purulent discharge, and thereby forms what is called the line of demarcation between the dead and the living parts; the process, commencing in the integuments, gradually extends to the deeply seated parts, so that the mortified portion is ultimately attached to the living merely through the medium of bone or ligament. Arteries appear more than any other texture to resist sloughing; and those leading to a mortified part are found contracted and filled with coagulated blood, so that the spontaneous separation of the sloughs, and even incisions for their removal, made in sound parts, are followed by little or no bleeding. This salutary change in the arteries may be accounted for by supposing, that the inflammatory action which leads to the separation of the dead substance from the living affects the arteries at that point as well as the other structures, causing adhesion of their internal surface, and obliteration of their cavities; and the natural result is, that the calibre of the artery above the obliterated point gradually diminishes in size, and the blood coagulates up to the nearest collateral branch: but in consequence of extension of the inflammatory action, the collateral branches may also be obliterated to a considerable extent upwards, and thus the contraction and coagulation in the larger trunk will also extend in proportion. Besides, before the line of separation has commenced, arteries cannot transmit their contents into the sphacelated part, any more than into an extraneous body; so that the circulation of the blood in them is as effectually obstructed as if a ligature were tightly applied; in this way, also, the contraction and coagulation may be accounted for.