DIGESTION. 213 



action and partly produce a lactic-acid and butyric-acid fermen- 

 tation. 



The maltose which is formed from the starch seems to be con- 

 verted into glucose in the intestine. The cellulose, especially the 

 finer and more tender, is undoubtedly partly dissolved in the intes- 

 tine ; the products formed hereby are not very well known. It has 

 been shown by TAPPENIER that cellulose may produce a marsh-gas 

 fermentation in the intestines caused by the action of a micro- 

 organism; but we do not know to what extent the cellulose is de- 

 stroyed and what part is valueless for the organism. 



Bile possesses the power of dissolving fats in so slight a degree 

 that it is scarcely worthy of mention. It is, however, without doubt 

 of greater importance that the bile, as NENCKI has shown, facilitates 

 the fat-splitting action of the pancreatic juice. This splitting of 

 the fats into fatty acids and glycerin is an important factor in the 

 absorption of the fats. The fatty acids combine with the alkalies 

 of the bile and most readily with the alkalies of the intestinal and 

 pancreatic juices, producing soaps which may be partly absorbed 

 as such and partly exercise a powerful action on the absorption of 

 the fats. There is no doubt that the chief part of the fats in the 

 foods is absorbed as a fine emulsion, and for this reason the soaps 

 are of such importance in the formation of this emulsion. 



If to a soda solution of about 2 p. m. N^COg we add pure, 

 actually neutral olive-oil in not too large quantity, we obtain, after 

 vigorous shaking, a transient emulsion. If, on the contrary, we 

 add to the same quantity of soda solution an equal amount of com- 

 mercial olive-oil (which always contains free fatty acids), we need 

 only turn the vessel over for the two liquids to mix and immediately 

 we have a very finely-divided and permanent emulsion making the 

 liquid appear like milk. The free fatty acids of the always some- 

 what rancid commercial oil combine with the alkali forming soaps, 

 which act to emulsify the fats (BRUCKE, GAD). This emulsifying 

 action of the fatty acids split off by the pancreatic juice is undoubt 

 edly assisted by the habitual occurrence of free fatty acids in the 

 food, and also by the splitting off of fatty acids from the neutral 

 fats by the putrefaction in the intestine. These fatty acids must 

 also combine with the alkalies in the intestine and form soaps. 



This emulsification of fats by means of the action of the pan- 



