THE DIGESTIVE SYSTEM. 121 



rumen. These papillae secrete a mucous fluid which assists in 

 the process of digestion. Externally covering the second stom- 

 ach we find the peritoneum, under which is situated the muscu- 

 lar coat, composed of two separate layers of strong muscle fibres 

 criss-crossing each other. The opening into this stomach is of 

 some extent, the grooves forming it are the floor of the greater 

 portion of the oesophageal canal. The contents of this stomach 

 are more liquid than those in the others. Just before the end 

 of the entrance to the second stomach the oesophageal furrow 

 virtually ends in the third stomach, called the Omasum or Many 

 Plies, so called from its peciiliar internal make up, which is 

 formed by a number of unequally developed leaves of mucous 

 membrane filling and running the length of the cavity. These 

 leaves increase the internal surface of the organ ten fold; they 

 are studded with numbers of small papillae, which are harder 

 than those in the reticulum. Some of the papillae on the edges 

 of the leaves are in the shape of a bent cone pointing towards 

 the entrance of the stomach, the object of these being to retain 

 food for a certain period of time, and it has been found that iu 

 certain sheep, which were subject to scours and unable to 

 retain their food, that these cones were abnormally short. The 

 omasum has but one opening, which is in direct communication 

 both with the oesophageal furrow and the fourth stomach. In 

 appearance the third stomach is globular in form, possessing 

 muscular and mucous coats the same as the first two. Its con- 

 tents will generally be found to be hard, and much more so than 

 the contents of the other stomachs. The fourth stomach, or 

 Abomasum, is in fact the true stomach, corresponding to the 

 stomach of man, being that which secretes the gastric juice, 

 which, by its action on the food, converts it into chyme. This 

 juice is by nature acid. It is a clear watery yellowish liquid 

 having a specific gravity of 1005, as compared to water at 1000. 

 It contains solids to more or less extent, the main part of which 



