A very important degenerative disease of the liver is acute yellow atrophy or, better expressed, acute degenerative atrophy for it is a total destruction of the whole or large parts of the parenchyma. It is apparently toxic in origin being related to the toxemias of pregnancy, to certain organic and inorganic soluble poisons; some cases arise without discoverable cause. We have seen no cases in the mammal but two in birds. Both were females, one in active ovulation, while the other had no related pathology and the condition of the ovaries could not be determined since they had been destroyed after death by rats. The macroscopic and minute anatomy offers nothing new. Jaundice was present but not intense. HEPATITIS. True inflammatory lesions are to be defined as some form of parenchymatous change to which are added congestion, infiltration of round or polynuclear cells, stagnation in the bile ducts or perhaps actual degeneration of their lining cells. It seems necessary to stipulate these things because in the chronic forms, usually called cirrhosis, it is necessary to have all of them, plus efforts at regeneration, in order to determine it as a chronic progressive process. Acute hepatitis is a rare condition in mammals except when it is combined with septicemia or severe enteritis. In birds on the other hand the liver is, aside from the intestinal wall, perhaps the most frequent seat of pathology in the abdomen. This is because of its almost constant involvement in infective enteritis, and in such conditions as fowl cholera, fowl typhoid, coccidiosis and cecal amœbiasis, all of which we have sporadically. When one searches for special distribution among the orders, only one of them stands out as having a high percentage, the Galli, an order which seems to have a very vulnerable liver.