AROMATIC DERIVATIES OF PROTEWS 471 



of the amount of intestinal putrefaction. In the case of indol 

 and skatol, which have no hydroxyl group, a preliminary oxi- 

 dation occurs, whereby indol is converted into indoxyl. 



C.OH 



>CH, 



and skatol into skatoxyl, 



\ 



and they are then combined with sulphuric or glycuronic acid, 

 as follows : 



C iOH + H|O SO 2 OK <^ y C O SOj OK. 

 / CH \ / CH (indican) 



By far the greater part of these aromatic substances, when 

 excreted in the urine, is combined with sulphuric acid, and 

 but a small part with glycuronic acid ; but in case the 

 amount of sulphuric acid available is too small to com- 

 bine with all the aromatic radicals entering the blood, a 

 large amount of the glycuronic acid compound appears in the 

 urine (e. g., after therapeutic administration of phenol, cresol, 

 thymol, camphor, etc.). Both the preliminary oxidation and 

 the combining with acids seem to occur chiefly in the liver, this 

 process constituting one of the most important of the many pro- 

 tective offices of that organ, since the resulting compounds are 

 much less toxic than are the original substances. Herter and 

 Wakeman 1 have shown that living cells have the power of 

 acting upon indol and phenol (and presumably upon the rest of 

 this group) in such a way that they cannot be recovered by dis- 

 tillation. Most active in this respect is the liver, then in order 

 come kidney, muscle, blood, and brain. The change seems to 

 be a loose chemical combination with the protoplasm of the 

 cells, and the power of the tissues to bring about this combina- 

 tion is not greatly decreased by serious pathological changes in 

 the organs (e. g., ricin poisoning 2 ). 



Indol. This is probably the most important member of this 

 group of substances, the striking color of its derivatives making 

 its detection in the urine easy, so that it is generally used as the 



1 Jour. Exper. Med., 1899 (4), 307. 



2 For further discussion of this topic, see " Chemical Defences against Poisons 

 of Known Composition," Chapter vii. 



