TSE STOMACH. 



393 



nerves are derived from the pneumogastrics and solar plexus, and in accom- 

 panying the vessels show microscopic ganglia in their course ; their mode 

 of termination is not known. 



Functions. — In the stomach is begun those transformations by which 

 alimentary matters are rendered capable of being assimilated. There the 

 food comes into contact with the gastric fluid, by whose action its principal 

 elements, and particularly the albuminoid substances, become soluble and 

 absorbable, after undergoing some isomeric changes. 



DIFFERENTIAL CHAEACTERS IN THE STOMACH OP OTHER THAN SOLIPED ANIMALS. 



The stomach is an organ that exhibits great diiferences in the various domesticated 

 animals. In the study of these differences, we will proceed from the simple to the 

 complex. 



1. The Stomach of the Fig. 



The Pig's stomach is simple, like that of the Horse, but it is less curved on itself, and the 

 cardia is nearer the left extremity ; the latter has also a small conical dilatation, which 

 has been compared to a cowl curved backwards. The oesophagus opens into the stomach 

 by a wide infundibulum, and the mucous membrane of that conduit is prolonged over 

 the gastric surface in a radius of from two to three inches around the cardia. Here 

 again we find a "trace of the division into two sacs," common to Solipeds. 



The capacity of the Pig's stomach averages from one and a half to two gallons. 

 (The muscular tunic is thicker in the right than the left extremity ; near the oesa- 

 pliagus the serous tunic shows some transverse folds.) 



2. The Stomach of Camivora. (Fig. 191.) 

 In the Dog and Cat the ventriculus is but little curved, and is pear-shaped, the 

 small extremity corresponding to the 



pylorus. The cardia is dilated like a *'S- ^^'■■ 



funnel, and is nearer the left extremity 

 of the organ than in other animals. The 

 oesophageal mucous membrane is not con- 

 tinued beypnd the margin of that orifice. 

 The simple stomach of Camivora forms 

 only a single sac, whose internal mucous 

 membrane presents, throughout its whole 

 extent, the same organisation as the 

 membrane lining the right sac of Soli- 

 peds. This membrane is remarkable for 

 the regular and undulated folds it forms 

 wheal the stomach is empty. Nothing 

 is more variable than the capacity of the 

 Dog's stomach, because of the great dif- 

 ferences in the size of this animal, accord- 

 ing to breed. M. Colin has found the 

 minimum to be IJ pints, and the maxi- 

 mum If gallons; he calculates the aver- 

 age to be about 2J quarts. In the Cat, 

 the average is from 2 to 2J gills. 



3. The Stomach of Ruminants. 

 These animals are distinguised from 

 the others by the faculty they possess 

 of swallowing their food after imperfect 

 comminution, and causing it to return 

 again into the mouth to submit it to a 

 second mastication, previous to final de- 

 glutition. The gastric apparatus is ad- 

 mirably arranged to effect this physio- 



regarded as so many stomachs. 



" STOMACH OF THE DOG. 



A, (Esophagus ; B, Pylorus. 



