ADRENAL INSUFFICIENCY AND BLOOD-DISINTEGRATION. 115 



A logical conclusion suggests itself in the presence of these 

 facts: i.e., that the changes undergone in the liver are a part of 

 a cycle with the intestine as a starting-point. And so it must 

 be, since, again using Garrod's words, "it seems to be clearly 

 established that absorption from the intestine does take place, 

 and that, of the urobilin so absorbed, some is excreted with the 

 bile and some with the urine." 



Bilirubin, from which at least a portion of the urobilin 

 found in the urine and faeces is derived, is not found in either 

 of these excreta. It disappears on its way down the intestine 

 and is replaced by large quantities of urobilin. When, how- 

 ever, bilirubin does, under certain morbid conditions, escape 

 with the faeces, urobilin does not appear in the latter. How 

 does this transformation in the intestine occur? Garrod states 

 that the radical change involved is attended with the elimina- 

 tion of nitrogen, and that there is much evidence to show that 

 it is brought about by bacteria. Bile inoculated with faecal 

 matter and placed in an incubator, for example, yields urobilin 

 rapidly, while the bilirubin simultaneously disappears. F. 

 Miiller, A. Schmidt, and Esser also "obtained urobilin by 

 cultivating intestinal bacteria in broth to which an alkaline 

 solution had been added." The same results were obtained by 

 Garrod and Drysdale, but only when oxygen was present. 

 While the absolute identity between this and the natural pig- 

 ment has not as yet been established, the artificially produced 

 urobilin was found to possess the chief properties of the latter. 



In the body the change chiefly occurs in the upper part 

 of the large intestine, the contents of which are alkaline, while 

 those of the small intestine are acid. This is a feature of con- 

 siderable importance evidently, since Esser found that "acidity 

 of the culture-medium inhibited the change which took place 

 under the influence of bacteria in alkaline broth." Garrod fur- 

 ther states that the green stools occasionally seen in typhoid 

 fever are always distinctly acid in reaction, and are urobilin- 

 free, the urobilin also disappearing from the urine. When 

 alkalinity recurs, urobilin likewise reappears. Yet, the intes- 

 tinal area in which the urobilin is formed from bilirubin varies 

 greatly in different individuals, sometimes extending to the 

 jejunum; but experiments by Vaughan Harley suggest that the 



