258 LECTURE XII. 



with sufficient certainty in urine. It is even problematical whether 

 skatoxyl occurs in urine. The suggestion has been made that it is present 

 in combination with glucuronic acid. At any rate, its presence is only 

 indirectly established. Indoxylsulphuric acid is found as an alkaline salt 

 in urine. It is the source of most of the urine indigo. Jaffe 1 was the 

 first to discover that indoxylsulphuric acid resulted from the combination 

 of indole and indoxyl with sulphuric acid. He injected in dole subcuta- 

 neously into dogs, and then found large amounts of indoxylsulphuric acid 

 in the urine. The suggestion has also been advanced that the indoxyl- 

 sulphuric acid in the urine is not only produced by intestinal putrefaction, 

 but that indole and indoxyl are also formed in the tissues. The researches 

 of A. Ellinger and M. Gentzen 2 have made this improbable. These 

 authors showed first of all that tryptophane, which is skatoleaminoacetic 

 acid, is the antecedent of indole, and the latter is formed from it during 

 putrefaction. When tryptophane was introduced directly into the small 

 intestine of rabbits, large amounts of indoxyl quickly appeared in the 

 urine. When, however, the tryptophane was injected subcutaneously, 

 no indoxyl could be detected in the urine. That the excretion of indoxyl- 

 sulphuric acid in the urine is very intimately connected with the intestinal 

 putrefactive changes, is shown by the fact that when there is an intestinal 

 stoppage, especially in the small intestine, the quantity quickly increases. 

 Observations with fasting carnivorous animals have shown that the elimi- 

 nation of indoxyl continues, and the inference was drawn that indole and 

 indoxyl were also produced by the tissues. F. M tiller 3 has, however, 

 shown that, during fasting, only the intestinal contents gave an in- 

 tense indole test, whereas the organs showed this only to a slight extent. 

 He, therefore, concludes that indole in the urine is exclusively of intestinal 

 origin. A limitation is certainly necessary, and this applies also to the 

 phenols. Putrefactive products can, of course, also be formed in other 

 parts of the organism, aside from the intestines, wherever putrefactive 

 processes are at work; for instance, in putrid empyema, decomposing 

 tumors, etc. 



If we add to urine an equal amount of hydrochloric acid containing a 

 little free chlorine or ferric chloride, a blue coloring matter is produced, 

 which can be shaken out with chloroform. This is indigo-blue: 



x co x x co x 



C = C 



N NH X 



1 Jaffe": Z. med. Wiss. 1872 and 1875. 



2 A. Ellinger and M. Gentzen: Hofmeister's Beit. 4, 171 (1903). 



3 F. Miiller: Mit. Wiirzburger med. Klinik, 2, 1886; A. Ellingsr: Z. physiol. Chem. 

 39, 44 (1903). 



