DIGESTION AND ASSIMILATION. 71 



The small intestine begins at an opening on the right side 

 of the stomach. It is about 72 ft. long, and about i^ in. 

 in diameter. It terminates at the cacum, which is the first 

 portion of the large intestine, and which forms a 'cul-de-sac of 

 about 3 ft. in length and of an average capacity of about 7^ 

 gallons. The large intestine is about 20 ft. long, and ends at 

 the anus. 



According to Colin, the capacity of the large intestine is 

 about double that of the small one, and their united capacity is 

 more than ten times as great as that of the stomach. In cattle 

 the capacity of the stomach, of which there are four compart- 

 ments, is about 2y 2 times greater than that of the intestines. 



Under the heading of " organs of digestion*" must be placed 

 certain glands that secrete fluids which flow into the 

 alimentary canal, and which are respectively concerned in the 

 digestion of food. The principal glands in question are as 

 follows : The salivary glands, the most important of which 

 in the horse are the two parotid glands that respectively 

 occupy, on each side, the space where the head is joined to the 

 neck. The office of the salivary glands is to secrete saliva for 

 mastication. The gastric glands secrete gastric juice, which 

 flows into the stomach. The pancreas (sweetbread) secretes 

 pancreatic juice, which is carried out of the gland by a tube 

 that opens into the small intestine close to the stomach. This 

 tube also serves to convey into the small intestine bile, which 

 is secreted by the liver. The intestines are supplied with a 

 large number of small glands (intestinal glands) that secrete 

 a fluid which aids in digestion. 



GENERAL VIEW OF DIGESTION, ABSORPTION, 

 AND ASSIMILATION. 



The office of digestion is to dissolve the food, so that it can 

 be absorbed through the mucous membrane of the alimentary 

 canal, and to effect certain chemical changes in its constituents, 



