132 A Manual of Veterinary Physiology. 



The food which newly arrives in the stomach mixes at 

 once with that already there, and undergoes, in the pre- 

 sence of saliva and the water consumed, a peculiar macera- 

 tion which suits it for remastication. Cellulose is also 

 digested in the rumen through the presence of ferments, 

 and the amount of conversion which can thus occur has 

 been estimated at between CO per cent, and 70 per cent. 



Ellenberger's views on the function of the rumen and 

 reticulum are as follows : 



In the rumen the food is mechanically divided through 

 the motion of the walls of the organ, and a thorough 

 incorporation occurs ; owing to the quantity of fluid found 

 in this stomach, softening and maceration of the food 

 substance takes place ; carbo-hydrates are digested through 

 ferments contained in the food itself ; in this way starch is 

 converted into sugar, cane-sugar into maltose, and cellulose, 

 especially in the sheep, undergoes decomposition ; further, 

 proteids are slowly converted into peptones through food 

 ferments, not through a true peptic ferment ; the rumen is 

 the seat of fermentation and gas production. 



The reticulum has the same function as the rumen, and 

 it regulates the passage of food from the first to the third 

 stomach, and from the first stomach into the mouth. 



In young ruminants digestion principally occurs in the 

 fourth stomach, as the others are almost rudimentary. It 

 is remarkable, however, how soon they develop, and how 

 easily the process of remastication is acquired in young 

 animals placed on solid food. 



The Omasum, or third stomach, is peculiar. Its physiology 

 has been elaborately worked out by Ellenberger. This 

 authority says that it possesses no secreting power, that its 

 function is to compress and triturate the food, which it 

 crushes between its powerful muscular loaves, and rasps the 

 ingesta down by means of its papillae. The contents of this 

 stomacli arc always dry, due to the fluid portion being 

 squeezed off and flowing into the fourth stomach by the 

 action of gravity and the pressure exercised bj the viscus. 

 Normally it possesses no reaction ; if found arid, it is due to 



