DIGESTION ig 9 



laminae of the deeper system. These leaves take no part in 

 emptying the omasum ; their function is to advance and meet 

 the incoming matter, then to raise it to the system of channels 

 formed by the series, and finally, by means of their papillae, to 

 further grind down and reduce insufficiently remasticated food. 

 This grinding or rasping down is effected by the leaves becoming 

 shorter, thicker, and stiffer ; the processes on them are drawn 

 through the mass like the teeth of a harrow. The movement of 

 the leaves is not simultaneous, but successive ; while one is 

 passing in one direction, its fellow is travelling in the opposite 

 direction, so that rasping of the food is continually going on, 

 and this is evident from the fact that the contents are much finer 

 at the abomasum end than at the reticulum end of the organ. 

 Ellenberger, therefore, speaks of the third compartment as a 

 triturating apparatus, a masticatory stomach, the contents of 

 which are dry because the fluid part is being constantly 

 strained off. 



With illness rumination ceases, and the chief supply of fluid 

 to the omasum is then cut off — viz., the saliva, which is re- 

 swallowed during rumination, and as no fresh ingesta is entering 

 the omasum, the contents rapidly become dry and caked. 



The Abomasum is the true digestive stomach, and is the only 

 compartment secreting gastric juice. In the abomasum proteins 

 are converted into peptones, the region of the cardia being in 

 this respect more active than the pylorus. Ellenberger states 

 that starch is also digested, and that this precedes protein 

 digestion. In the fourth stomach of the calf a milk-curdling 

 ferment (rennin) exists, which has already been dealt with. 



Stomach Digestion in the Pig. 



The stomach of the pig is peculiar ; it is a type between the 

 carnivorous and ruminant, and is divided by Ellenberger and 

 Hofmeister into five distinct regions, which do not all possess 

 the same digestive activity. 



The gastric juice of the pig contains for the first hour or two 

 of digestion lactic, and afterwards hydrochloric, acid ; pepsin is 

 present, and, it is said, a ferment which converts starch into 

 sugar. In the pig, according to the above observers, the process 

 of digestion is not the same in all regions of the viscus ; one 

 may contain hydrochloric acid, another lactic ; one may be 

 abundant in sugar, while this may be absent elsewhere. The 

 first stage of digestion is one of starch conversion ; the second 

 is the same, only more pronounced ; the third stage is one of 

 starch andfprotein conversion, both processes occurring at the 

 cardia, but only protein conversion taking place at the fundus ; 



