This is, fortunately, a very rare disease, as it is almost always fatal. It chiefly occurs in children whose constitutions are enfeebled by bad or insufficient food, bad air, filth, or other unhygienic conditions, and, according to Niemeyer, is often caused by the use of mercury. The disease is characterized by a low form of inflammation, giving rise to extensive sloughing, or gangrene, which begins on the inside of the cheek, extends to the gums, the lips, and the tongue; exposes the bones of the jaw, causing the teeth to drop out and the separation of portions of bone. Finally the disease may extend to the face, the whole cheek and even the nose becoming black and sloughy. When recovery takes place it is very slow, the lost parts being built up by granulation. The only remedies which do any good are those which, like the actual cautery, destroy the diseased tissues and thus excite a healthy action.