CHAP. IX.] SUMMARY OF THE ACTIONS OF THE INTESTINAL JUICE. 417 



progress of proteolysis by trypsin. The capital objection to Bunge's 

 conception of the part played by the intestinal juice is that, as will 

 be subsequently shewn, the alkaline carbonate which it contains is 

 more than neutralised by the lactic acid which is formed by the 

 action of micro-organisms, so that the reaction of the contents of the 

 small intestine is not alkaline, but acid. Whether it plays any part 

 whatever in furthering their absorption, the action of the intestinal 

 juice on fats is, doubtless, insignificant, when compared with the part 

 which the intestinal enzymes and ferments play in the digestion of 

 the carbohydrates. 



The intestinal mucous membrane and its secretion 

 have thus been shewn to exert no chemical action on 

 the P roteid constituents of food, but to play a great 

 part in the digestion of the carbohydrates of the 

 economy, completing, if necessary, the conversion of starch into 

 soluble products, splitting up saccharose and lactose into glucoses, 

 but above all, converting maltose into grape sugar. When we con- 

 sider the large proportion of carbohydrates which herbivorous animals 

 consume, the great importance of this function to the economy will 

 be manifest. 



summary of 

 the actions of 



27 



