

THE ABSORPTION OF THE FOOD-STUFFS 129 



still more freely. We might picture the situation in the 

 intestine somewhat as follows: The blood flows steadily 

 beneath a rather complex cellular wall, the other surface 

 of which is bathed by the mixed products of digestion and 

 the digestive secretions. Peptones and amino-acids, su-^ 

 gars, soaps, and glycerin, being formed in relative abun- 

 dance in the intestine, diffuse into the blood, which contains 

 little of these bodies. If the blood were to stand still the 

 small volume in direct relation with the absorbing surface 

 would accumulate digestive products until it held them in 

 the same concentration in which they exist in the canal. 

 Then a state of equilibrium would be established and no 

 further transfer to the blood would occur. 



Detailed observation shows that the facts of absorption 

 cannot be expressed in this simple manner. It has already 

 been hinted that large allowance must be made in such a 

 case for the fact that the membrane under examination is 

 alive. Its cells may discharge material at one surface 

 quite unlike that which they receive at the other. They 

 probably have a considerable metabolism. This means 

 that energy is set free within their borders and a share of it 

 may be applied to the moving of the absorbed food. We 

 have previously called attention to the parallelism be- 

 tween secretion and absorption. 



Before we can go further with this discussion something 

 must be said concerning the place of absorption and the 

 minute anatomy of the structures involved. There is a 

 measure of absorption from the stomach. Until rather 

 recently this organ was not credited with any marked 

 powers of this kind, unless it were in the case of alcohol. 

 This is a highly diffusible compound and its prompt 

 entrance into the circulation is noteworthy. When one 

 says of a glass of wine, "This goes to my head," the state- 

 ment is literally true. The alcohol strikes through the 

 walls of the stomach at once and is borne to all parts of the 

 body, including the brain. On the other hand, water is 

 not at all freely absorbed when it is taken into an empty 

 stomach. It is known to pass the pylorus in practically 



