I9 PHYSIOLOGICAL CHEMISTRY. 



putrefaction. In addition to this the work of the bacteria is 

 hindered by the accumulation of the products of their own 

 production. Some of these products have to a certain degree 

 a bactericidal action and tend to check the more rapid bacterial 

 development. It follows therefore that when the rectum is 

 reached in the downward progress of the intestinal contents 

 there may still be present remains of putrescible matters which 

 might have been broken down if all the conditions had been 

 favorable. 



This brings us to a consideration of the final remains or 

 the feces, but first a word must be said about the absorption of 

 certain products in the lower stretches of the intestine. Not 

 only are the normal digestive products taken up from both 

 intestines, from the small intestine mainly, but various prod- 

 ucts of the bacterial reactions referred to follow the same 

 course. The importance of this fact is very great from two 

 directions at least. The excessive production of such a body 

 as indol is always a consequence of increased bacterial activity 

 which is often a pathological phenomenon. The indol may 

 escape partly with the feces, but a portion is always absorbed 

 and is oxidized in the tissues, the liver probably, from which 

 it passes into the blood and later into the urine, where it is 

 recognized in the form of indican. The amount of indican 

 and certain similar substances detected in the urine is a meas- 

 ure then of the extent of putrefactive changes going on in the 

 intestine. In this oxidation an atom of oxygen is taken up 

 and indoxyl is formed : 



This indoxyl, like other basic substances, always finds sul- 

 phuric acid to combine with to yield indoxyl sulphuric acid 

 or a salt of the form 



CsHeN\ 



K/ 53 



or indican. 



Phenol is another product of intestinal putrefaction and in 

 part passes also into the circulation from the lower intestine 



