The succeeding paragraphs will reveal in comparison to other organs only a small number of cases of degeneration, inflammation and tumors. This has been ascribed to the freedom of blood supply and the power of tryptic digestion. An expression of this relative immunity to pathologic change is met in analyzing the data upon the simplest lesions, degenerations, to be expected in many states of disease. Only a small number of cases present themselves, and they are under expected conditions, namely in association with acute general infection, sometimes definitely septicemic in nature. About half of them were discovered microscopically, affecting the islands of Langerhans in vacuolization or granular disintegration. Focal necroses of the organ were met four times, three turkeys and a cockatoo. It is noteworthy that all these birds had some involvement of the liver, twice a complete acute hepatitis and twice a cholangitis. This is the more interesting since we shall learn that the liver is less often involved in avian than in mammalian pancreatitis. Hemorrhages occur occasionally in the pancreas in acute general infections and are seen in acute inflammations of the intestines; the percentage incidence with the latter is, however, very small. Pancreatic apoplexy proper has not occurred, for all the instances of large hemorrhage into the organ have been combined with changes forcing a classification of acute pancreatitis. PANCREATITIS. Pancreatitis in the acute form is divided by many writers into exudative, hemorrhagic and necrotizing, while for the chronic variety an inter- and intra-acinus form has been described. It is questionable whether it is fair in acute cases to focus attention by special nomenclature on different macroscopic pictures, unless it be for descriptive purposes solely, since there is nothing at hand to indicate that differing agents cause one kind every time. The physical findings seem to depend rather upon the speed of operation of the causation than upon its essence. Sudden obstruction of the pancreatic duct is believed to produce necrotizing processes to which hemorrhage may be added by digesting of blood vessels. Exudative cases seem due to extension of ulcerative inflammation, from a perforated gastric ulcer for example, to which digestive pancreatitis may be added. The interacinus chronic inflammations are usually considered as due to obstruction or infection through the biliary or pancreatic ducts whereas vascular disease produces intra-acinus connective tissue overgrowth. Analysis of the records of this laboratory would seem to indicate that necrotizing and hemorrhagic processes belong together, exudative in a class by themselves, and that chronic disease may be either interlobular or intra-acinar without regard to associated pathology. I have therefore studied our cases from this standpoint.