=Treatment.=--_Threatening gangrene_ should be attacked and the cause removed. Threatening bed-sores may be avoided by equalizing surface pressure, which can be done with the water-bed; by protecting the skin or by stimulating and toughening it with alcoholic and astringent lotions; by frequent changes of position; by attention to the heart, which should be stimulated to a point that may make it capable of forcing or distributing blood equally over the entire body. So, too, with limbs which are enveloped in dressings or splints; it is well to leave exposed the tips of the toes or fingers in order that discoloration of the same may be recognized and the threatening disasters averted. Local gangrene as the result of pressure by tumors, aneurysms, etc., cannot always be averted. For gangrene there is but one relief, the _removal of the dead and dying tissue_. The method and location of the operation must be determined by the general character of the cause. For a case of acute traumatic gangrene amputation at the nearest point of election above the injury will often suffice. In case of gangrene from frostbite the tissues in the neighborhood of the line of demarcation are so affected or their vitality so compromised that to separate the tissues along the lines at which nature is endeavoring to remove them is not enough, and to go an inch or so above this line is to operate in tissues which bleed readily and heal badly. Consequently it is often advisable to select a point at some distance above. It is especially in diabetic and senile gangrene that surgeons have laid down the rule that if _amputation_ is done at all it must be _high_. For gangrene of the toe, as the result of disease of the vessels, it is best to amputate above the ankle; whereas if any greater portion of the foot is threatened, amputation should take place above the knee. The tibial arteries have been found so brittle as to snap under a ligature, and the femorals so disorganized as to require handling and ligating with the greatest caution. These high amputations are therefore necessitated by the condition of the vessel walls. While amputation for traumatic and acute cases is, in the majority of instances, if not too long delayed, successful in saving life, in the senile and particularly in the diabetic forms it is, in the majority of cases, a disappointment. PART II. SURGICAL DISEASES. CHAPTER VI. AUTO-INFECTION, ESPECIALLY IN SURGICAL PATIENTS.