_Noma_, known also as _gangrenous stomatitis_, _cancrum oris_, and _gangræna oris_, is a term applied to a form of tissue necrosis affecting the cheeks or parts about the face of young children, occurring frequently as a complication of the exanthemata. A similar condition occasionally involves the external genitals. From the fact that it seldom passes across the middle line, it has been regarded by some as of neurotic origin. Naturally bacteria are always found in the decomposing tissues; but whether there as cause or as result is not yet established. The probability is, however, that we have to deal with a specific form of infection. The loss of substance is usually so great as to determine complete perforation of the cheek, so that the jaw bones may be laid bare. The gums and alveolar processes also frequently share in the process, and the teeth occasionally drop out. Death of tissue is rapid, and septic infection may accompany it to such an extent as to cause the death of the patient in a few days. While most vigorous measures are necessary for combating it, the patients are often so reduced as to preclude the possibility of doing much, and death is the termination of noma. Free incision, even complete excision, is called for, perhaps with combined resort to the actual cautery or such remedies as bromine (strong or diluted). Antistreptococcic serum has also been used with success. Obviously it must be used early if success is expected. Should patients recover, there is extensive deformity as the result of cicatricial contraction. Along the coast of Africa and in the West Indies there occurs among the negroes a peculiar gangrenous affection of the toes known as _ainhum_. This may assume either the moist or the dry type of gangrene, but the result is gradual separation of the part, usually by the dry process, as if it had been strangulated by a ligature. The disease is slow and may extend over ten years. The cause is unknown. Finally, gangrene is the termination of the infectious process in several other zymotic diseases, among the best illustrations being that afforded by _diphtheria_. The formation of diphtheritic ulcers in the mouth and the vulva, about the eyes and elsewhere, as the result of separation of sloughs, is too frequent to pass unnoticed, yet at the same time does not essentially differ from the separation of sloughs due to any other specific cause. All these acute zymotic diseases, therefore, need to be regarded as among the possible causes of gangrene by infection of tissues. The _symmetrical gangrene_, often paroxysmal, affecting the fingers and toes, described by Raynaud and often called by his name, is due to vasomotor spasm, and is accompanied by neuralgia and sensory disturbances, with coldness of the part and discoloration suggestive of impending gangrene. (See above.)