176 PHYSIOLOGY AT THE FARM. 



intestines consist of three coats, like the stomach namely, the 

 internal or mucous, the middle or muscular, and the external 

 or serous, which is derived from the shut sac of the abdominal 

 peritoneum. 



The duodenum is fixed to the liver near the pylorus, but its 

 lower part hangs free in the abdomen. The valvulse conniventes 

 of the duodenum, formed by plicse of the mucous membrane, 

 are placed in a longitudinal direction. The caecum makes turns 

 upon the ilium. The colon, furnished with a circular valve, is 

 small and short, and, without making any circuitous turn, goes 

 directly across the abdomen to form the rectum. It is nearly 

 uniform throughout, and has no cells. 



The internal surface of the small intestine is beset with 

 numerous long, thickset villosities, diminishing considerably 

 in size from before backwards, and disappearing entirely in the 

 great intestine. 



The glandular patches of Peyer are very distinct in the dog ; 

 they are of great size, numerous, sunk deep, and elongated. 



The mesentery, as in other similar animals, is a fold or 

 doubling of the general shut sac of the peritoneum, supporting 

 the small intestines as in a sling ; while the blood-vessels, 

 nerves, and absorbents, together with the mesenteric glands, 

 are contained between the two laminae, at the continuation of 

 which the one into the other the intestine hangs. What 

 has been already said under the horse (p. 55) and the ox 

 (p. 106) nearly applies to the organs contained between the 

 laminae of the mesentery in the dog. 



The omentum, also a part of. the general shut sac of the 

 peritoneum, exists in the dog as in mammals in general. It 

 is of considerable extent in the dog, and, like the great omen- 

 tum in man, descends from the stomach to return upon itself 

 and enclose the transverse part of the colon. 



Liver. The liver in the dog is in the right hypochon- 



