#Malignant Oedema.#—­This form of acute gangrene has been defined as “a spreading inflammatory oedema attended with emphysema, and ultimately followed by gangrene of the skin and adjacent parts.”  The predominant organism is the bacillus of malignant oedema or vibrion septique of Pasteur, which is found in garden soil, dung, and various putrefying substances.  It is anaerobic, and occurs as long, thick rods with somewhat rounded ends and several laterally placed flagella.  Spores, which have a high power of resistance, form in the centre of the rods, and bulge out the sides so as to give the organisms a spindle-shaped outline.  Other pathogenic organisms are also present and aid the specific bacillus in its action.

At the bedside it is difficult, if not impossible, to distinguish it from acute infective gangrene.  Both follow on the same kinds of injury and run an exceedingly rapid course.  In malignant oedema, however, the incidence of the disease is mainly on the superficial parts, which become oedematous and emphysematous, and acquire a marbled appearance with the veins clearly outlined.  Early disappearance of sensation is a particularly grave symptom.  Bullae form on the skin, and the tissues have “a peculiar heavy but not putrid odour.”  The constitutional effects are extremely severe, and death may ensue within a few hours.

#Acute Emphysematous# or #Gas Gangrene# was prevalent in certain areas at various periods during the European War.  It follows infection of lacerated wounds with the bacillus aerogenes capsulatus, usually in combination with other anaerobes, and its main incidence is on the muscles, which rapidly become infiltrated with gas that spreads throughout the whole extent of the muscle, disintegrating its fibres and leading to necrosis.  The gangrenous process spreads with appalling rapidity, the limb becoming enormously swollen, painful, and crepitant or even tympanitic.  Patches of coppery or purple colour appear on the skin, and bullae containing blood-stained serum form on the surface.  The toxaemia is profound, and the face and lips assume a characteristic cyanosis.  The condition is attended with a high mortality.  Only in the early stages and when the infection is limited are local measures successful in arresting the spread; in more severe cases amputation is the only means of saving life.

#Cancrum Oris# or #Noma#.—­This disease is believed to be due to a specific bacillus, which occurs in long delicate rods, and is chiefly found at the margin of the gangrenous area.  It is prone to attack unhealthy children from two to five years of age, especially during their convalescence from such diseases as measles, scarlet fever, or typhoid, but may attack adults when they are debilitated.  It is most common in the mouth, but sometimes occurs on the vulva.  In the mouth it begins as an ulcerative stomatitis, more especially affecting the gums or inner aspect of the cheek.  The child lies prostrated,