When acute gastritis exists (twenty cases) the animal seems uneasy but does not vomit. On one occasion I was called to see a monkey which was retching and seemed in pain. Lime juice was offered and taken, followed by gentian and cardamon, which seemed to give some benefit. Somewhat later this was repeated in another case, but observations where this might be useful are rare. The pathology of gastric conditions offers little to contrast with that of man. The enormous distensibility of the fundal pouch often suggests to the observer the rumen of ungulates. Acute gastritis of one kind or another and acute catarrhal enteritis are the most common lesions noted in the Primates. Involvement of the intestine or colon need not carry with it an increase of signs of illness, although at times one will see an evidently sick animal with diarrhœa. Anatomically the lesions are commonly restricted to the stretches of gut _above_ the ileum, it being rather rare that this division or the colon is affected. Pathologically the lesions are catarrhal with definite involvement of the follicles in about one-third of the cases. In this order toxic and pseudomembranous forms are quite rare and ulcerative lesions uncommon. Colonic disease as a sequel to inflammation higher up is sometimes seen in the follicular varieties, but takes a minor place compared to amœbic dysentery of which we have had several cases; this will be discussed under a separate heading. Degenerative disease of the skeleton is almost always accompanied by a low grade of enteritis but not necessarily gastritis or colitis. The pallor of the mucosa, while at times striking, may be relieved by follicular spots and petechia or pigmentation. Often, however, animals suffering from osteomalacia and rickets come to their end by an acute inflammation of the gut tract. The bacteriology at our disposal allows no conclusions. Aside from a case probably due to Ps. fluorescens and one with colon bacillus abscesses in the liver, no reliable data are at hand. Reference to Table 11 reveals the fact that among orders with sufficient autopsies to permit percentages, the alimentary tract in monkeys is in the group of low figures, that the intestinal section is relatively more often affected, and that the colon is more often diseased than in other mammalian orders, and is exceeded only by the gallinaceous birds.