DIGESTIVE APPARATUS 59 



two sets of muscle fibers, one set encircling the esophagus, the 

 other placed lengthwise. 



In cattle and sheep, the esophagus terminates at the opening 

 between the first and second stomachs in the trough-like ' ' esopha- 

 geal groove. ' ' This groove is about six inches long and connects 

 with the first, second and third stomachs. It controls the move- 

 ment of food and water to the several stomachs. When food is 

 first swallowed, it passes mainly into the cow's first stomach 

 although some of it usually goes to the second. Liquids, includ- 



Fig. 30. — Stomach of the Cow. 



A, A, and B, B, different portions of the paunch or rumen; C, termina- 

 tion of the esophagus; D, second stomach (reticulum) ; E, third stomach 

 (omasum) ; F, F, fourth stomach (abomasum) ; G, small intestine, just 

 beyond the pylorus; H, esophagus. 



ing soluble foods, pass on to the second and third, the overflow 

 even passing into the fourth. 



Stomach. — The stomach is located in the anterior portion of 

 the abdominal cavity. Its function is to receive food and 

 furnish the gastric juice to aid in digestion. 



The horse's stomach shows two distinct portions. The mu- 

 cous membrane which lines the interior on the left side is light 

 colored, firm, and tough, like the mucous membrane of the 

 esophagus, of which it is a continuation. On the right side of 

 the stomach the mucous membrane is soft and red. Thus the 

 horse has a partially double or two-cavity stomach as compared 

 with the four-cavity stomach of the cow and the sheep. The 



