218 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



classes it is divided into two forms, the small and large intestines. The 

 small intestine is destined for the absorption of food-products, and for 

 the elaboration of the digestive secretions for the solution of food-stuffs 

 which have escaped the action of the gastric juice. We find its walls, 

 therefore, supplied with tubular glands secreting the so-called intestinal 

 fluid ; and emptying into the small intestine we find in all cases two large 

 glandular organs, the liver and pancreas, secreting alkaline fluids which 

 have a greater or less importance in digestion. In the small intestine of 

 mammals are also to be found special organs for assisting the absorption 



Pig. 77.— Stomach of Adult Sheep, Dried and Inflated ; One-fifth 

 the Natural Size. (Tlianhoffer.) 



B, rumen; R, reticulum ; S, omasum ; O, abomasum : r, cardia; p, pylorus; or, cesophatnis ■ co 

 cardiac valve; bo, oesophageal gutter; r, pillars of the rumen ; rn, opening of the reticulum ; on open- 

 ing of the abomasum, or fourth stomach ; b, valve between reticulum and omasum ; t, duodenum.' 



of food, the so-called villi, which are simply conical expansions covered 

 by mucous membrane, whose function, together with that of the folds of 

 the mucous membrane, is simply to give increased surface for absorption. 

 In the higher animals the small intestine is divided arbitrarily into three 

 divisions, the duodenum, or the portion of bowel directly in communica- 

 tion with the stomach, which is always curved and usually free from 

 mesentery. Following this we have the jejunum, so-called because ordi- 

 narily found empty, and following that the ileum. 



The intestinal canal is supplied with muscular fibres, arranged 

 longitudinally and in concentric rings, being red-striped muscular fibres 



