THE DIGESTION OF THE FOODSTUFFS 135 



split up. Till recently it was maintained that only a small 

 part of the fat is split up and that the large residue was 

 emulsified by the soap formed (see page 24) and absorbed 

 in the form of emulsion. Recently it has been supposed 

 that all the fat is split up before it is absorbed. After the 

 extirpation of the pancreas the absorption of fat is decreased. 

 In this case, however, fats are still split up by putrefaction 

 in the intestine. 



B. The function of bile in the digestion. Bile contains no 

 ferment, hence it does not digest, but aids in the processes 

 of digestion. 



1. By aiding in neutralizing the free hydrochloric acid. 

 This stops the action of the pepsin upon the trypsin. 



2. By aiding the action of pancreatic ferments. 



3. By dissolving the free fatty acids. 



Besides this, bile plays an important part in the absorption of 

 fats (see Chapter X). 



Some authors .ascribe an antiseptic action to bile, but others 

 deny this. 



C. Digestion by the intestinal juice. Intestinal juice con- 

 tains, besides a diastatic ferment, an inverting ferment which 

 changes cane-sugar into dextrose and levulose. Intestinal 

 juice also splits up lactose, this not being absorbed as such. 

 This action of the intestinal juice is supposed to be due to 

 a ferment called lactase. 



The accounts of other ferments in the intestinal juice are 

 contradictory. 



The intestinal juice, by its alkalinity, favors the action of 

 the pancreatic ferments and, by its mucin, favors the move- 

 ments of the chyme and the formation of faeces. 



4. PUTREFACTION IN THE INTESTINE 



In the intestinal canal, especially in the lower part of the 

 small intestine, processes of putrefaction, due to micro- 

 organisms, take place. These processes change the con- 

 tents of the intestine chemically. 



