458 



THE DIGESTIVE APPARATUS IN MAMMALIA. 



the fulness of the organ. The left extremity, suspended to the sublumbar region 

 by the aid of a very short serous ligament — a portion of the great omentum — is 

 related to the base of the spleen, the left extremity of the pancreas, and, less 

 directly, to the anterior border of the left kidney. The right extremity, lower 

 than the left, touches the right lobe of the liver and the above-mentioned 

 intestinal curvatures. 



Interior. — When a stomach is opened to study its interior, one is at first 

 struck by the different aspect its internal membrane presents, according as it is 

 examined to the right or the left. To the left, it has all the characters of the 

 oesophageal mucous membrane, in being white, harsh, and even resisting ; it is 

 covered by a thick layer of epithelium. To the right, it is thick, wrinkled, 

 spongy, very vascular and follicular, has a reddish-brown tint that is speckled 

 by darker patches, loses its consistency, and is only covered by a very thin 

 epithelial pellicle. It is not by an insensible, but a sudden transition that the 



mucous membrane of the stomach is thus 

 divided into two portions ; and their separation 

 is indicated by a salient, more or less sinuous, 

 but sharply marked ridge. This ridge, then, 

 divides the stomach into two compartments — 

 a division already indicated externally, by the 

 circular depression observed in the majority 

 of subjects. The left sac or compartment is 

 considered as a dilatation of the oesophagus. 

 The riijlit sac constitutes the true stomach of 

 Solipeds ; as on it alone devolves the secretory 

 function which elaborates the gastric juice, the 

 essential agent of digestion in this organ. 



The interior of the stomach (Fig. 260) 

 offers for study two apertures : the cardiac and 

 pyloric. The cardiac, or asopJiageal orifice, is in 

 the lesser curvature of the left sac of the 

 stomach. Its arrangement have given rise to 

 numerous discussions, as in it has generally been sought the reason why Solipeds 

 vomit with such extreme difficulty. At one time there was described a semilunar 

 or spiroidal valve, which is opposed to the retrograde movement of the food ; and 

 at another time it was the oblique insertion of the oesophagus, resembling that 

 of the ureters into the bladder, and which, by a mechanism analogous to these, 

 proved an obstacle to the return of aliment into that oesophagus. Both suppo- 

 sitions are wrong. When we attentively observe the manner in which the 

 oesophagus comports itself at its termination, it will be noticed that it is inflected 

 downwards, after traversing the right pillar of the diaphragm, and is inserted 

 almost perpendicularly into the lesser curvature of the stomach. In opening 

 into this viscus, the oesophagus does not widen into an infundibulmn, as in other 

 animals ; on the contrary, its calibre is here narrower than elsewhere, and its 

 cardiac or stomachal orifice, completely obstructed by the folds of mucous 

 membrane, only occupies an infinitely small portion of the internal surface of 

 the stomach. 



With regard to the pylorus, it represents a large aperture formed at the 

 bottom of the right sac, and furnished with a thick circular ring ; this opening 

 can be completely closed through the action of the powerful sphincter surrounding 



INTERIOR OF THE HORSE'S STOMACH. 



A, Left sac ; b, right sac ; C, duodenal 

 dilatation. 



