364 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



and extends toward the pylorus and cesophageal portion, its extremities 

 being triangular. The mucous membrane in this region is very thick 

 and brownish-red in color, and contains the so-called fundus glands. 

 These are tubular in structure, longer, but subdivided to a less degree 

 than the pyloric glands. The ducts of these tubules are lined with epi- 

 thelium similar to that lining the cavity of the stomach, while the fundus 

 contains chief and associate cells similar to those found in the stomachs 

 of carnivora, with the exception that the associate cells lie in groups 

 external to the cylindrical cells. 5. The right or pyloric zone includes 

 the pylorus, as much of the lesser curvature as does not belong to the 

 cesophageal portion, and a small portion of the greater curvature. Its 

 mucous membrane is white in color, and in the pylorus very thin, 

 though much thicker at the entrance to the pylorus ; the submucosa 

 is sparsely developed. After death the pyloric zone is generally found 

 coated with a thick layer of mucus, stained yellowish from the bile. The 

 glands of this portion are considerably longer than those found elsewhere, 

 are subdivided and convoluted. Associate cells are entirely wanting in 

 the pyloric zone, the cells being cylindrical and granular or hyaline. 



As Ellenberger and Hofmeister pointed out, the stomachs of mam- 

 mals may be divided into two different .groups, in one of which cesoph- 

 ageal diverticula, and in the other diverticula of the stomach itself, 

 represent the mode of deviation from the simple gastric form. When 

 both forms of diverticula are present, the true compound stomach is 

 represented. The gastric formation, with a divert iculum formed from 

 the glandular stomach itself, is met with in many herbivora and omniv- 

 ora, and such carnivora as live on highly indigestible animal substances. 



In its simplest form the part near the pylorus is dilated into a 

 pouch-like expansion ; such a form is met with in the hog, but is still 

 further complicated by a saccular expansion at the cardiac extremity. 

 Such a formation evidently lengthens the period of retention of the 

 food within the stomach, and by an increase in the internal surface of 

 the stomach permits of a more continuous action of the gastric juice, 

 since it corresponds to an increase in the secreting surface. 



In the development of the compound stomach through the forma- 

 tion of cesophageal dilatations, the stomach of the hog represents the 

 first stage. 



The second stage is found in the stomach of the horse, where the 

 entire left half of the stomach may be regarded as an oesophageal 

 expansion ; and while the stomach of the horse from external view 

 resembles a simple stomach, internal examination shows that it is 

 practically a compound stomach. 



The highest degree of development of the cesophageal pouches is, 

 of course, seen in the stomachs of ruminants. 



