2l6 PHYSIOLOGICAL CHEMISTRY 



Indican may be decomposed by treatment with concentrated hydro- 

 chloric acid (see tests on page 404) into sulphuric acid and indoxyl. 

 The latter body may then be oxidized to form indigo-blue thus: 



CO OC__ /\ 

 ! | +2H 2 



c\A/ 



NH NH 



Indigo-blue. 



This same reaction may also occur under pathological conditions 

 within the organism, thus giving rise to the appearance of crystals of 

 indigo-blue in the urine. 



Skatole or methyl indole possesses the following structure: 



C(CH 3 ) 



CH 

 NH 



In common with indole it is changed within the organism and eliminated 

 in the form of a chromogenic substance. Skatole is, however, of less 

 importance as a putrefaction product than indole and ordinarily occurs 

 in much smaller amount. The tryptophane group of the protein mole- 

 cule yields the indole and skatole formed in intestinal putrefaction, but 

 the reasons for the transformation of the major portion of this trypto- 

 phane into indole and the minor portion into skatole are not well under- 

 stood. Indole is more toxic than skatole. 



Phenol occurs in fairly large amount in certain abnormal conditions 

 of the organism, but ordinarily the amount is very small. It is probably 

 derived from the tyrosine group of the protein molecule. Phenol is 

 conjugated in the liver to form phenyl potassium sulphate and appears 

 in the urine in this form (Baumann and Herter). Para-cresol occurs 

 in the urine as cresyl potassium sulphate. 



Regarding the claim of Nencki that methyl mercaptan is formed 

 as a gas during intestinal putrefaction it is an important fact that 

 Herter 1 was unable to detect the mercaptan in fresh feces. He was, 

 therefore, not inclined to accept the theory that methyl mercaptan is 

 formed in (ordinary intestinal putrefaction but believed that it may be 

 formed in exceptional cases. Hydrogen sulphide is, however, formed in 

 all cases of intestinal putrefaction. 



It has been demonstrated that putrefaction processes in the human 

 intestine may be retarded by the ingestion of a carbohydrate diet. 2 The 

 putrefactive organisms are facultative organisms and prefer a carbo- 



1 Herter: "Bacterial Infections of the Digestive Tract, p. 227." 



* Kendall; Jour. Afed. Res., 24, 411, 1911; also Pediatrics, 23, No. 9, 1910. 



