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The liver is the hirgest secreting gland in the body, weighing 

 from 10 to 12 pounds. Its shape is very irregularly elliptical, 

 thick in the center, gradually becoming thinner at the borders. 

 It is situated immediately behind the diaphragm and secretes a 

 fluid called bile, which is emptied directly into the small intes- 

 tines, as the horse is not provided with a gall bladder. 



The pa nci^eas (sweetbread) is situated behind the stomach and 

 in front of the kidneys. It is of a reddish cream color, and 

 weighs about 17 ounces. Its function is to secrete pancreatic 

 fluid, which is poured into the duodenum. 



The abdominal cavity, or belly, is a large and somewhat oval 

 cavity, bounded superiorly by the muscles of the back, inferiorly 

 by the abdominal muscles, anteriorly by the diaphragm; poste- 

 riorly it is continuous with the pelvic cavity. 



PHYSIOLOGY OF DIGESTION. 



The food is received into the digestive or alimentary tube; 

 there it is subjected to a series of agencies by which it is, in 

 greater or less part, digested and worked up to a condition in 

 which it can be sucked up by the appropriate vessels, and, while 

 this portion is absorbed by the circulation, the effete remainder 

 passes on and is discharged. 



The digestive tube, beginning at the mouth, is continued to 

 the stomach by the throat and esophagus or gullet, while the 

 stomach is succeeded by the small and large intestines. 



In its passage along this tract (tube) the food is subjected to 

 both mechanical and chemical processes. The food is taken into 

 the mouth by the lips, where it is masticated (or chewed) and 

 mixed with saliva; it is then swallowed, passed into the stomach, 

 acted upon by the gastric juice, and when thoroughly macerated 

 (rolled, mixed, and soaked) it enters the first portion of the 

 small intestines, and is acted upon by the secretions of the liver 

 and pancreatic gland (bile and pancreatic fluid) ; from this point 

 onward the food, having been brought in contact with and thor- 

 oughly mixed with the several fluids above mentioned, is now 

 ready for the nutritive portions to be absorbed into the circula- 

 tion for the nourishment of the animal, which is accomplished 

 by little villi, situated in the mucous membrane lining the intes- 

 tines. The villi are small projections of the mucous membrane 

 of the small intestines. 



