If for no other reason than that the gross and minute pathological anatomy of gastroenterocolitis is the same through the mammals and birds (aside from a few specific lesions like enterohepatitis, typhoid fever, etc.), while the food and bacteria vary, it would seem probable that the ultimate cause is the same, a poison which can be formed alike in the carnivorous and herbivorous gut, and not dependent upon bacteria, but upon the chemistry of the food or of the intestinal mucosa. To put the matter more simply, the lesions being the same under nearly all conditions is not the cause the same, and is it not a poisonous product from food or the intestinal lining. It is profitable here only to mention the marked similarity of enteric lesions under the differing conditions and in different orders. We shall study chartwise, the various forms of inflammation from the cardia to the anus in terms of their anatomical diagnosis and most probable etiology in an attempt to throw light upon the matter, and later present the physiology. System requires, however, some attention first to anatomical order so that a brief review of the esophageal and pharyngeal conditions is indicated. PHARYNX. The buccal-pharyngeal cavity in mammals is used chiefly as a passage way for food and as the place where some of them triturate and insalivate the bolus. Certain orders, Primates, rodents and marsupials, use this cavity thoroughly at the first mastication, others use it little at first but may ruminate, the ungulates, while strict carnivores use it very little. The Aves use their pharynx almost exclusively as a passage, and, despite the presence of a certain amount of salivary gland tissue, probably do not digest any substance in this cavity. The crop or ingluvies is a sac to permit of salivary digestion but is really a storehouse to allow rapid feeding without overfilling of the proventricle. The esophagus extends from the pharynx to the cardiac opening of the stomach in mammals and widens into the glandular stomach or proventricle in birds, the upper end of which lies in front of the lower third of the left lung behind the heart.