The simpler gastrointestinal tract is possessed by the Perissodactyla, and by the following families of Artiodactyla, the Phachocœridæ, Suidæ and Tayassuidæ. This consists of a stomach with a single cavity (some Peccaries have partitions but no true septa with strict histological differences) divided into esophageal, cardiac, fundal and pyloric areas, dependent upon the nature of the lining epithelia and the absence or presence of glands, as well as the nature of the tubules. The duodenal section is ample and may be sacculated while the intestines are small in calibre and rather sturdy in wall. The cecum is relatively very large, well supplied by longitudinal bands and sacculations; the colon is relatively short but quite capacious and sacculated. The ruminants and other remaining members of the Artiodactyla have a compound stomach suited to the separation of coarse and fluid foods and the retention of water, and so arranged that boluses of different densities are distributed as needed. These divisions are histologically as well as grossly different. The first three, comparable to the esophageal section of the simpler stomach, are reservoirs or channels, while the fourth or true digestive section, is divided into areas corresponding to fundus and pylorus, possessing the appropriate type of gland. The duodenum in this group is narrow, as is the rest of the small gut, and has delicate walls. The cecum proper is short and of variable width, but never as great as in the group first discussed, while the colon, an intricately wound tube, is narrow and very long. Certain of the first group (Peccaries) have a colon of this type, but it is not so complicated as in true ruminants. These complications seem designed to permit of a long retention of coarse food of low nutritive value per bulk for a time sufficient for full digestion; reverse adaptation of large size of stomach and colon may be explained on the same basis. Let us now examine these two groups to discover their pathological reactions and the nature of the lesions.