THE DIGESTION OF THE NUTRIENTS 53 



with the production of maltose. The sahva contains also a 

 small amount of maltase, which may change some of the 

 maltose to glucose. These actions may continue after the 

 masticated feed has reached the stomach, until it is rendered 

 acid by the flow of the gastric juice. In case of ruminants, 

 some digestion may take place in the rumen by fermenta- 

 tions, with the production of acetic and butyric acids, and 

 carbon dioxide and methane gases. However, the principal 

 digestion of starch takes place in the small intestine. Here 

 the enzyme, pancreatic amylase of the pancreatic juice, 

 acts upon starch, converting it to maltose. The enzyme, 

 maltase, of the intestinal and of the pancreatic juices then 

 acts upon the maltose, converting it to the simple sugar 

 glucose. 



Sucrase, another enzyme found in the intestinal and 

 pancreatic juices, acts upon any sucrose or cane sugar, 

 spHtting it up into the simple sugars, glucose and fructose. 



Lactase, the third sugar-spUtting enzyme of the intestinal 

 and pancreatic juices, acts upon lactose or milk sugar with 

 the formation of the simple sugars glucose and galactose. 



The starches and sugars are absorbed in the form of the 

 simple sugars, glucose, fructose, and galactose, glucose 

 being predominant. These sugars are absorbed by the villi 

 of the small intestine and pass into the capillaries, through 

 the hver, and into the general circulation of the blood. 



Some digestion, both by enzyme action and by bacterial 

 fermentation, may take place in the large intestine, the 

 products of which are absorbed there by the capillaries. 



Crude Fiber. — Crude fiber probably is digested only 

 by the action of bacteria, as no special enzyme for the diges- 

 tion of crude fiber or cellulose has been found. In ruminants, 



