320 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



edge of each fold. When the contents of this stomach are examined in 

 animals slaughtered in perfect health they are always found dry, and 

 there is a disposition for the epithelium to become detached in shreds 

 and adhere to the pulpy mass. In the hornless ruminants, such as 

 sheep, these folds are more or less rudimentary. 



The oesophageal canal communicates on the left with the paunch 

 and reticulum, and on the right with the manyplies. Its direction is 

 from above outward and backward, the anterior pillar entering the 

 honey-comb bag and the posterior the paunch (Figs. 136 and 13Y). The 

 lower angle is raised above the level of the third stomach, especially 

 during the action of the gullet, so that it is only when the pillars of the 



Fig. 136. — (Esophageal Canal, Open. Fig. 137.— (Esophageal Canal, Closed 

 (Colin.) by Suture. (Colin.) 



A, inferior extremity of the (Esophagus ; B, cardiac orifice ; C, superior orifice of the manyplies. 



canal are at rest, and liquids or soft foods are descending, or when the 

 contents of the first and second stomachs strike against the canal, that 

 any food enters into the omasum. 



The fourth stomach, or abomasum or rennet, corresponds in its his- 

 tological structure with the stomach of other mammals. Its mucous 

 membrane is arranged in numerous larger or smaller folds, on the 

 summits of which open the ducts of the gastric glands. It also is 

 supplied with muscular fibres, and with nerves, blood-vessels, and lym- 

 phatics. Its mucous membrane is arranged in folds, which are trans- 

 verse at the upper end, longitudinal in the middle, and graduallj' effaced 

 in the pylorus. The fourth stomach of the ruminant differs from that 

 of other mammals only in size and shape, and agrees in histological 



