223 THE ABDOMEN AND ITS CONTENTS, 



CUT OF THE INTRSriXE.-, 



a The commencement of the small intestines. '1 he ducts which convey the bile and the 



secretion from the pancreas are seen entering a little below. 

 I h The convolutions or winding of the small intestines. 

 c A portion of the mesentery. 

 d The small intestines, terminating in the CBecum. 

 e The caecum, or blind gut, with the bands running along it, puckering and dividing it into 



numerous ceils. 

 /The beginning of the colon. 

 g g The continuation and expansion of the colon, divided, like the caecum, into cells. 

 h The termination of the colon in the rectum. 

 t The termination of the rectum at the anus. 



The intestines of a full-grown horse are not less than ninety feet in length. The 

 length of the bowels in different animals depends on the nature of the food. The 

 nutritive matter is with much more difficulty extracted from vegetable than animal 

 substances ; therefore the alimentary canal is large, long, and complicated in those 

 which, like the horse, are principally or entirely fed on corn or herbs. They are 

 divided into the small and large intestines ; the former of which occupy about sixty- 

 six feet, and the latter twenty-four. 



The intestines, like the stomach, are composed of three coats. 



The outer one consists of the peritoneum — tliat membrane which has been already 

 described as investing the contents of the abdomen. By means of this coat, tlie 

 intestines are confined in their proper situations ; and, this membrane being smooth 

 and moist, all friction and concussion are prevented. Did the bowels float loosely in 

 the abdomen, they would be subject to constant entanglement and injury amid the 

 rapid and violent motions of the horse. 



The middle coat, like that of the stomach, is muscular, and composed of two 

 layers of fibres, one running longitudinally and the other circularly ; and by means 

 of these muscles, which are continually contracting and relaxing in a direction from 

 the upper part of the intestines to the lower, the food is propelled along the bowels. 



The inner coat is the mucous or villous one. It abounds with innumerable small 

 glands, which secrete a mucous fluid to lubricate the passage and defend it froiii irri- 

 tating or acrimonious substances; and it is said to be villous from its soft velvet- 

 like feeling. This coat is crowded with innumerable minute orifices that are the 

 commencement of vessels by which the nutritive part of the food is taken up; and 

 these vessels, uniting and passing over the mesentery, carry this nutritive matter ti,' 

 a proper receptacle for it, whence it is conveyed into the circulation, and distributed 

 lo every part. 



