Whether or not the amputation should be performed at once, depends upon the general condition of the patient. If the injury is a severe one, and attended with a profound degree of shock, it is better to wait for twenty-four or forty-eight hours. Meanwhile the wound is purified, and the limb wrapped in a sterile dressing. Means are taken to counteract shock and to maintain the patient's strength, and evidence of infection or of hæmorrhage is carefully watched for. When the shock has passed off, the operation is then performed under more favourable auspices. Clinical experience has proved that by this means the mortality of primary amputations may be materially diminished, especially in injuries necessitating removal of an entire limb. Having decided to amputate, it is important to avoid having bruised, torn, or separated tissues in the flaps, as these are liable to slough or to become the seat of infection. In this connection it should be borne in mind that the damage to soft tissues is always wider in extent than appears from external examination. The attempt to save a limb may fail and amputation may be called for later because of spreading infective processes, osteomyelitis, or gangrene; to prevent exhaustion from prolonged suppuration and toxin absorption; or on account of secondary hæmorrhage. #Gun-shot Injuries of Bone.#--Fractures resulting from the impact of bullet or fragments of shell are of necessity compound, and are usually infected from the outset by organisms carried in by the missile or by portions of clothing or other foreign material. Not infrequently the missile lodges in the bone. [Illustration: FIG. 7.--Excessive Callus Formation after infected Compound Fracture of both Bones of Forearm--result of gun-shot wound. Fusion of Bones across Interosseous Space.] The extent of the injury to the bone varies infinitely, from a mere chip or gutter-shaped wound to complete pulverisation of the portion struck. The fracture is of the comminuted and fissured variety, the cracks radiating from the point of impact and extending for a considerable distance, sometimes even implicating the articular surface of the bone some inches away. In comminuted fractures of the shafts of long bones there is often a large wedge-shaped fragment completely isolated from the rest, and in the presence of infection this may form a sequestrum. Healing is often delayed by the separation of sequestra, which takes place slowly, and union is attended with excessive formation of callus. When a considerable section of the shaft has been lost, want of union, fibrous union, or the formation of a false joint may result. The treatment is carried out on the same lines as in other forms of compound fracture, except that mention should be made of the irrigation method of Carrel, found to be the most potent means of overcoming the associated infection. SEPARATION OF EPIPHYSES[1]