+Treatment.+ The local treatment calls for special mention. If the ulcer is of limited extent, the most satisfactory method is complete removal by means of the knife, scissors, or sharp spoon, of the ulcerated surface and of all of the infected area around it, so as to leave a healthy surface from which granulations may spring. If the raw surface left is likely to result in cicatricial contraction, skin grafting should be employed. The general treatment should consist of tonics, plenty of fresh air, and a good nutritious diet. Bowels must be regulated. +Perforating Ulcer of the Foot+ occurs in connection with lowered resisting powers of the tissues, due usually to some lesion of the nerves or vessels. The ulcer is circular in shape, painless, with callous borders, and eats progressively into the deeper tissues and bones, and has little or no tendency to heal. +Etiology.+ Although formerly looked upon as a specific disease, perforating ulcer is now known to depend upon many local and general conditions of which it is occasionally a more or less accidental manifestation. The various theories as to its immediate causation may be divided into: (1) mechanical, (2) vascular, (3) nervous, (4) mixed. +The Mechanical Theory+ regards injury as the sole cause, due in most instances to the pressure or rubbing of a shoe. If this explanation were adequate, however, such ulcers would be extremely common, while in reality they are rare. +The Vascular+ theory assumes that arteriosclerosis is always present, and causes ischemic necrosis through arterial and capillary thrombosis. +The Nerve+ theory, which is the one most commonly accepted, is that perforating ulcer is always of trophic origin and depends upon a chronic peripheral neuritis. In support of this assertion, attention is called to certain interstitial and parenchymatous alterations frequently demonstrable in the nerves of the affected part. It must not be forgotten, however, that these nerve changes may be due to secondary disturbances in nutrition, depending upon arteriosclerosis as in senile, diabetic, and other forms of gangrene. +According to the Mixed Theory+ either vessels or nerves, or both may be at fault. It admits that traumatism is an important factor, although seldom if ever an exclusive cause. Perforating ulcer is observed in connection with various diseases and conditions, the most prominent of which are locomotor ataxia, fractures of the spine, injuries of the cord, diabetes, spina bifida, syringomyelitis and injury and division of the peripheral nerves. Perforating ulcer from lesions of the central nervous system is comparatively rare and it is doubtful if it is ever due to embolism or to ligation of the arteries. The three most prominent causes, therefore are, (1) affections of the spinal cord (2) injuries of the peripheral nerves and (3) diabetes.