CHAPTER X 

 ABSORPTION AND ASSIMILATION OF FOODSTUFFS 



1. GENERAL REMARKS ABOUT ABSORPTION AND 

 ASSIMILATION 



UNDER absorption we include the processes whereby the 

 dissolved foodstuffs and the emulsified fats are taken up from 

 the mucous lining of the stomach and intestine and are 

 brought directly or by means of the lymphatics into the 

 blood, by which they are carried to the organs and tissues, 

 of the body. 



By assimilation we understand the processes which the 

 absorbed foodstuffs undergo till as constituents of the cells 

 and tissues they are consumed in the activity of the tissues. 



As the insoluble and undialyzable food is rendered soluble 

 and dialyzable by digestion, it is probable that osmosis- 

 of the soluble substance plays an important part in absorp- 

 tion. Still there are certain facts about absorption which 

 cannot be explained by the laws of osmosis as known to us 

 at present. Absorption often takes place contrary to the 

 laws of osmosis. On the one hand, water is absorbed from 

 a sodium chloride solution placed in the intestine even though 

 of higher osmotic pressure than the blood, whereas, accord- 

 ing to the laws of osmosis, water ought to pass from the 

 blood or lymph into the intestine. On the other hand, 

 undialyzable substances, like proteid and emulsified fat, are 

 taken from the intestine by the blood. 



The force which causes this absorption contrary to the 



140 



