322 COLLOIDS IN BIOLOGY AND MEDICINE 



There are two important facts established by H. J. HAMBURGER * 2 

 and GIRARD.* The former showed that it was possible to prepare 

 membranes that were more permeable from one side than from the 

 other. As a result of this experiment of H. J. HAMBURGER we may 

 state that crystalloids pass from the lumen of the intestine toward the 

 periphery and yet no crystalloids of the blood may diffuse back into 

 the lumen of the intestine. It remains an open question, whether 

 the small quantities of NaCl found in the intestine in absorption 

 experiments come from the secretion of the intestinal glands, or 

 whether the semipermeability of the intestinal membrane is limited 

 in the direction of the lumen of the intestine. 



Of the greatest general importance are the investigations of 

 GIRARD. The exhaustive theoretical discussion of their basis would 

 lead us too far afield. The following experiment is suggested: if a 

 salt solution is suspended in a pig's bladder in water, the rate of 

 diffusion depends on whether the salt solution is neutral, slightly 

 alkaline or slightly acid. The cause of this is found in the fact that 

 the membrane is the seat of an electromotive force. We conclude 

 from this that by changing the reaction on both sides of the intestinal 

 membrane the rate of diffusion may be changed or regulated; so 

 that, e.g., with an alkaline reaction which occurs in the intestines, 

 the diffusion is very strongly increased. 



Hitherto we have started from the assumption that the intestinal 

 wall is of uniform texture. This is not the case, as a view of a micro- 

 scopic section and simple consideration shows; the intestine is com- 

 posed of cells as is every other organ, and we know that cells are 

 only permeable for crystalloids to a limited extent. Accordingly, 

 there must exist an easier way for the absorption of crystalloids than 

 through the cells; it must occur intercellularly. It is different in the 

 case of lipoid-soluble substances; they are absorbed intracellularly, 

 e.g., ethyl alcohol is absorbed much more rapidly than salt solution. 

 Numerous experiments of R. HOBER have established in general the 

 correctness of this view. 



The colloid-chemical study of intestinal absorption has already 

 yielded results for pathology. 



E. MAYERHOFER and E. PRIBRAM,* in a series of valuable inves- 

 tigations, have tested the condition of swelling and the ability to 

 swell of the normal and the pathologically changed intestine. 

 They found that the normal and especially the acutely inflamed 

 intestine were much swollen and the latter possessed an increased 

 permeability for crystalloids. The chronically inflamed intestine, 

 which already showed a connective tissue atrophy, had a very small 

 swelling capacity, so that a much more limited passage was afforded 



