ADRENAL INSUFFICIENCY AND BLOOD-DISINTEGRATION. 117 



bilin, the author, after reviewing the main hypotheses bearing 

 upon this point, says: "It will be seen that the above theories, 

 one and all, start with the assumption that urobilin is derived 

 from hcemoglobin, either directly or through the intermediate stage 

 of Ule-pigment" and refers to Thudicum as alone maintaining 

 that urobilin is a product of decomposition of urochrome: a 

 view which need not represent an exception, since this pigment 

 can likewise be traced back to haemoglobin. 



"The very small amount present in normal urine and its 

 complete absence from that of certain animals, such as dogs, 

 in whose intestines it is present in considerable quantity," says 

 Garrod, "suggest that the pigment is, in part, subjected to 

 change in its passage through the body, and is excreted in some 

 altered form." This is quoted merely to emphasize the fact 

 that the formation of any of the pigments referred to, even 

 stercobilin, is not followed by its immediate evacuation from 

 the organism, but that the transformation from bilirubin to 

 urobilin-stercobilin on the colon side of the ileo-caecal valve 

 probably represents but the first step of various transforma- 

 tions of a biochemical nature in which the tissues at large take 

 part, but of which certain organs are the primary seat. Uro- 

 bilin, as shown by Riva, when introduced into an isolated loop 

 of intestine undergoes absorption. This and other evidence 

 available distinctly indicates that this pigment enters the cir- 

 culation. 



We will assume, as a working hypothesis, that urobilin, far 

 from always representing a product of waste, some of it at 

 least, is constantly traversing the organism, fulfilling its 

 various missions and returning to the ileo-caacal neighborhood 

 via the liver. It will then become apparent that the state- 

 ment "Its disappearance from the urine when the bile is oc- 

 cluded . . . disposes of the theory that urobilin is formed 

 from bilirubin in the tissues at large, for, under such circum- 

 stances, although the tissues remain loaded with bilirubin, 88 the 

 excretion of urobilin is arrested" from Garrod's pen seems 

 to lose weight. If the above hypothesis obtains, complete oc- 

 clusion of the common bile-duct, as carried out by Friedrich 



The italics are our own. 



