Most cases of scarlatina are complicated either by acute parenchymatous or diffuse nephritis. Some confusion has arisen from the attempt to describe scarlatinal nephritis as if it was one disease, while really there are two anatomical forms of nephritis which occur as complications of scarlatina. When we try to fix the time during the course of scarlatina when the kidney lesions are developed, we meet with the same difficulty--that statistics have been compiled on the supposition that there is only one form of scarlatinal nephritis. If we take all the cases together, we find that kidney symptoms may be developed from the very first day of scarlet fever to the end of the ninth week--that the largest number of cases develop symptoms on the fourteenth day, the next largest on the twenty-first day, and next to this on the seventh day (Tripe). It seems probable that parenchymatous nephritis belongs to the first weeks of the disease, diffuse nephritis to the later weeks. SYMPTOMS.--The urine is diminished in amount, and may be suppressed. Its specific gravity is low, its color is bloody or smoky; it contains blood, large amounts of albumen, and numerous hyaline, granular, and epithelial casts. The patients lose their appetites, and suffer from nausea and occasional vomiting. There is a febrile movement, usually not very severe, pain in the back and limbs. They become unnaturally peevish and irritable and complain of headache, the irritability alternating with drowsiness. In the more severe cases delirium, convulsions, and coma are developed. The color of the patients is changed, the skin and mucous membranes becoming pale. Dropsy is developed--sometimes only a little puffiness of the face, hands, or feet, sometimes general anasarca. Synovitis and muscular rheumatism are frequent complications, while pericarditis, pleurisy, and pneumonia occur less often. The disease runs its course within a moderate length of time, although the changes in the urine often persist long after all the other symptoms have disappeared. The ordinary cases recover after from one to three weeks; the very bad cases die at the end of a few days. In a few cases the symptoms continue and the patient develops chronic diffuse nephritis. PROGNOSIS.--The prognosis is quite good. The larger number of the cases recover completely. In the more severe cases, however, the patients may die with cerebral symptoms, or all the symptoms will continue and the patient die after several weeks. TREATMENT.--The indications for treatment are the same as in the idiopathic form of acute diffuse nephritis. Chronic Diffuse Nephritis. This is the most common and the most important form of kidney disease. It has been described under a variety of names--chronic Bright's {85} disease, croupous, catarrhal, interstitial, tubal, and parenchymatous nephritis; fatty, granular, atrophied, cirrhotic, and large white kidney.