Gangrene means death of a part, and by common consent is technically applied to the soft tissues, including the fluids. The blood is always involved in this disease, and there can be no death of a part while it is performing its function. With this thought kept before us, that there is no local death where the blood is performing its function, we may inquire into the conditions which result in gangrene.
External violence may crush the tissues, to the extent that circulation is thereby arrested. The channels for the blood-current being destroyed, it is impossible for it to yield its life-giving force, and the part must necessarily die. So long as the arteries and their capillary system are at all intact, life may continue and the injury be repaired. The same may be produced by the extremes of heat and cold, burning and freezing; the tissues being destroyed, the