470 GASTRO-INTESTINAL "AUTOINTOXICATION" 



From the tryptophan are formed numerous important sub- 

 stances, as follows : 



/NH 2 



CH 2 CH COOH, 



)CH 



NH 



(tryptophan) 



readily yields, through splitting off the NH 2 group and addition 

 of H, indol propionic acid (formerly incorrectly called skatol 

 acetic acid), which is 



CH 2 COOH, 



X >CH 

 NH 



and from which in turn may readily be formed indol acetic acid 

 (erroneously called skatol carboxylic acid), which is 



Both of these substances have been found in the intestinal con- 

 tents. From these substances are formed the better known 

 skatol, 



and indol, 



H 



In dogs, but not in man, kynurenic acid, 



C.OH 



x Racoon, 



N=CH 

 is also formed from tryptophan. 1 



The greatest interest concerning these bodies arises from the 

 fact that after they are absorbed from the intestine they become 

 combined with sulphuric or glycuronic acid, and are excreted in 

 the urine as salts of these acids ; consequently the amount of 

 sulphuric acid appearing in the urine in such organic combi- 

 nation (" ethereal sulphuric acid ") is considered as an index 

 1 See Ellinger, Zeit. physiol. Chem., 1904 (43), 325. 



