64 MANUAL OF CATTLE-FEEDING. 



classes of nutrients and supplementing tlie sali\a, tlio 

 gabtric ]nice, and the bile. 



Intehtlnal fluid. — It is commonly stated tliat, in addi- 

 tion to tlie bile and pancreatic juice, the food is acted on 

 by a third fluid secreted by numerous little glands, known 

 as Lieberkuhn's glandjs, in the mucous membiane of the 

 intestines. The statements regaiding the composition of 

 this fluid and its action on the food are very conflicting, 

 doubtless owing in part to the difficulty of obtaining it un- 

 mixed witli the other digestive fluids, and there seems to 

 be considerable doubt of its existence, which at any rate 

 cannot be regarded as proven. 



Recapitulation. — We see, then, that the whole process 

 of digestion is simply a conversion of tlie solid matteis of 

 the food into forms which are soluble in water or in the 

 digestive fluids and can theretoie pass into the circulation, 

 Thib is accomplished, in case of the albuminoids by the gas- 

 tric juice in the stomach and the pancieatic juice in the 

 intestines, in case of starch, etc., by the saliva and the pan- 

 creatic juice,, and in ease of the fats by the bile and pan- 

 creatic juice. In what part of the alimentaiy canal, or by 

 what seeietion, cellulose is digested, is not known. Possi- 

 bly the pancreatic juice, which acts so powerfully on the 

 other carbhydrates, is the agent of its solution, but this is 

 only a conjecture. i 



The latest view regarding the digestion of cellulose is 

 that it is not accomplished by any specific digestive fluid, 

 but that in the extensive digestive canal of the herbivora 

 it undergoes a sort of fermentation, caused by the innu- 

 merable bacteria and other low organisms there present, 

 and yields marsh gas, carbonic acid, hydrogen, and various 

 soluble products. 



By the action of these various digestive fluids, the chjmae 



