Having discussed the inflammatory conditions of the gastrointestinal tract we now come to the more or less definitely mechanical abnormalities, whether or not they depend upon preëxisting inflammation, and the subject of constipation will claim first attention. In the human being this condition is the result of bad habits more than any other one thing or all things together, I think it will be admitted. In the lower animals perhaps no such thing as habit of defecation exists so that one can with more certainty hold incorrect food, chronic catarrhs or physical obstruction as responsible. Veterinarians look upon excess of dry food and irregularity of work and food periods as the principal causes of constipation. These factors do not hold in zoological collections. As a matter of fact constipation is of minor importance in this menagerie, but a certain few cases are worthy of note. It has been mentioned in the diagnoses in only a little over 1 per cent. of the total, and of these the records indicate its importance only ten times (.2 per cent.); a few notes of these cases are appended. The first place of incidence is taken by marsupials (six kangaroos and one opossum), the second by ungulates (largely ruminants) and the third by Primates. It will be noted that with exception of the opossum, herbivorous mammals occupy the first places of incidence, carnivores falling well behind the orders named. This condition is quite infrequent in birds and is usually associated with the presence of seeds or parasites or with impaction in the ceca. Primates, almost exclusively feeders upon carbohydrate and soft protein food, have shown as causes of constipation two outstanding conditions. A low grade of colonic catarrh with excessive pouchings of this tube has had constipation associated with it three times. One of these cases had small coproliths in the diverticula, one other a fecal concrement in the cecum. Another group of these cases with evidence of delayed passage of feces shows chronic peritonitis with adhesions, one of which seems certainly due to filaria in the peritoneal sac. The seat of constipation in monkeys is practically always the colon. The carnivores while occasionally showing hard fecal masses packed into the colon, more often exhibit a constipation in the ileum. One case presented a nearly empty colon with a long scybalum just above the cecal valve. There is no peculiar associated pathology in the notes at my command. Ungulata, showing next to the highest incidence, has its stoppage chiefly in the colon, but the lowest stretch of the ileum may contain balls of feces. In nearly every case one finds some grade of colonic catarrh. In two instances, there being a proctitis, it seemed as if the animal voluntarily restrained from defecating because of pain. The caput coli is the seat of stoppage in the Rodentia.