82 



PRINCIPLES OF VETERINARY SCIENCE 



is held in position by the great mesentery. The bulk of the 

 small intestine lies in the upper part of the left flank, but is 

 changeable in situation, depending on the degree of fulness. 



About 6 inches from the stomach the 

 common opening of the bile and 

 pancreatic ducts pierce the intestine 

 at the diverticulum duodeni (Fig. 22) . 

 From the free surface of the mucous 

 lining numerous small projections, 

 termed villi, can be seen when a piece 

 of the membrane is placed in water 

 (Fig. 25). Each villus is covered 

 with the cells which line the intestine 

 and contains a network of capillary 

 blood-vessels that surround a central, 

 lymph- vessel or lacteal. Food nu- 

 trients in water-soluble form are 

 absorbed from the intestine through 

 these lymph and blood channels of 

 the lacteals (Fig. 26). 



The large intestine of the horse is 

 divided into the cecum, large colon, 

 small colon, and rectum. It is about 

 25 feet long and nearly twice the 

 diameter of the small intestine. For 

 the most part it is sacculated. 



The cecum has a capacity of 7 

 gallons and is about 3 feet long. It 

 has two blind ends, and resembles in 

 form an inverted comma. The larger 

 end is attached under the right 

 kidney, while the free end lies on the 

 abdominal floor, giving the organ a 

 downward and forward direction. 

 The two openings of the cecum are 

 placed close together in its crook. 

 The opening for the exit of food 

 material being higher up than the inlet, insures a thorough mix- 

 ing. The latter opening has a valvular arrangement to prevent 

 regurgitation of the ingesta. 



Fig. 26. — Diagrammatic 

 longitudinal section of a 

 villus to show essentials in 

 the structure of a villus. The 

 columnar cells lining the in- 

 testine are shown in section. 

 L, Lacteal or lymphatic sur- 

 rounded by a network of 

 capillaries. The connective 

 tissue, which actually exists 

 inside the villus, has been 

 ignored for the sake of sim- 

 plicity. (Stiles, Nutritional 

 Physiology.) 



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