PBOOESSES OF DIGESTION 115 



starch and cellulose is effected in the intestines. The 

 pancreatic juice has a powerful hydrolysing action on 

 starch, maltose being produced. In the intestines the 

 maltose is converted into dextrose. Cane sugar is 

 converted into dextrose and loevulose, and milk sugar 

 into dextrose and galactose, or into lactic acid, before 

 absorption takes place. Cellulose is dissolved in the 

 colon by a fermentative process, due to the action of 

 bacteria, in which acetic and butyric acids, carbonic 

 acid and a little marsh gas (methane) are the products. 



The albuminoids of the food are attacked by the 

 gastric juice of the stomach (the fourth stomach 

 of ruminants) and converted into peptones, bodies 

 similar to albuminoids in composition, but which, 

 unlike them, are diffusible through a membrane. The 

 pancreatic juice of the small intestines also converts 

 albuminoids into peptones, and partly into amides 

 (leucine and tyrosine). 



The digestive agents in saliva, gastric juice, and 

 pancreatic juice, are commonly known as ptyalin, 

 pepsin, and trypsin, but the number of enzymes 

 present is doubtless more considerable. 



Fat, liquefied by the heat of the body, is probably 

 capable of absorption without change. The digestion 

 of fat in large quantities is greatly assisted by the 

 bile and pancreatic juice. 



The absorption of the dissolved constituents of the 



but the possibility of the digestion of cellulose by this means must 

 not be overlooked. Cellulose digested in this manner would have a 

 higher feeding value than cellulose broken up by bacterial fermenta- 

 tion. German writers teach that digestible cellulose is of more value 

 to ruminant animals than to a horse ; the solution of cellulose in the 

 paunch is thus apparently of practical importance to the animal. 



