INFECTIONS OF THE DIGESTIVE TRACT 93 



intestinal tract. The correctness or incorrectness of this 

 view can only be established by experimental methods. 

 Still another influence of diminished function in con- 

 sequence of a pathological thinning of the epithelial 

 layers may be found in a diminished capacity on the part 

 of the intestinal epithelium to act upon products of 

 decomposition in the intestine. In experiments made 

 many years ago with indol, it was found that the epithe- 

 lium of the digestive tract possesses in a high degree 

 the capacity to bind indol in such a way that this sub- 

 stance cannot be recovered by distillation. I think it 

 likely that in cases where there is excessive production 

 and absorption of indol in the intestinal tract the epithe- 

 lium acts as a protective agency to the organism as a 

 whole. This action of the epithelial cells is certainly 

 not confined to indol. It seems not unreasonable to 

 suppose that where the epithelium has been very much 

 thinned, the organism suffers from the enfeeblement of 

 this function incidental to the loss of epithelium. Here 

 again experimental methods should throw more light 

 upon this protective action of the intestinal epithelium. 



THE PERMEABILITY OF THE MUCOUS MEMBRANE OF 

 THE INTESTINAL TRACT FOR BACTERIA 



Another function of the epithelial cells of the digestive 

 tract has to do with the protection of the body from 

 the invasion by bacteria within the tract. There exists 

 some experimental evidence indicating that an intact, 

 fully developed layer of epithelium is an important 

 barrier to the entry of at least some kinds of bacteria 



