270 INFECTIONS OF THE DIGESTIVE TRACT 



The occurrence of free indol in the urine is certainly 

 a very exceptional phenomenon even hi cases of ex- 

 perimental poisoning with indol. In the combined 

 cyanide and indol experiments of Richards and How- 

 land it was found that a trace of indol sometimes appeared 

 in the urine. It is, however, noteworthy that in the 

 experiments in which examinations were made for the 

 detection of free indol in a loop of intestine (after poison- 

 ing with considerable quantities of indol) much more 

 indol was found to be excreted by the intestinal loop 

 than was excreted into the urine. This fact points 

 decisively to a relatively difficult excretion of indol by 

 the kidney. The tests employed for the identification 

 of the indol included Ehrlich's dimethylamidobenzalde- 

 hyde and the /3-napthaquinone-sodium-monosulphonate 

 reactions. The latter reaction, as already explained, 

 is absolutely distinctive for indol. 



Although it is thus apparent that the conditions re- 

 quired to bring about the excretion of free indol in the 

 urine must be such as seldom occur spontaneously in 

 human beings, it cannot be denied that traces of indol 

 may sometimes appear in the urine in the course of ex- 

 treme indicanuria. In a few instances distillates from the 

 urine contained a body which strongly suggested indol. 

 But the actual proof of the occurrence of free indol in the 

 urine in these cases of extreme indicanuria. does not, I 

 think, exist at present. It seems probable that a con- 

 siderable concentration of indol in the blood is nec- 

 essary to bring about the phenomenon of indoluria, and 

 such a concentration as will insure this leakage into the 



