BILIVERDINE. UROCHROME. 99 



of the bile. Bilirubine, if exposed to the atmospheric air in alkaline 

 solution, becomes oxidized and assumes a green color, being converted 

 into another closely related substance, namely, biliverdine. 



Biliverdine, C 16 H 20 N 2 5 . 



In addition to bilirubine, the bile contains also a green coloring 

 matter, namely, biliverdine; and its varying tint in different specimens 

 depends on the different proportions in which the two substances are 

 present. In many species of animals, as in the ox, sheep, rabbit, and 

 vegetable feeders generally, the bile presents a strong green or greenish 

 color, due to the comparative abundance of biliverdine. Biliverdine 

 is insoluble in water, ether, and chloroform, readily soluble in dilute 

 alkaline solutions and in alcohol. It is also soluble in glacial acetic 

 acid, and is deposited from the evaporated solution in the form of an 

 imperfect crystallization. It is often found in human gall-stones, and 

 in the dog is abundantly deposited along the edges of the placenta. 



There is every reason to believe that biliverdine is formed from bili- 

 rubine by a process of oxidation, the elements of water entering at the 

 same time into combination. The nature of this change is shown by 

 the following formula: 



Bilirubine. Biliverdine. 



C 16 H 18 N 2 3 + H 2 + = C 16 H. 20 N 2 5 . 



The prompt conversion of the color of ruddy or reddish-brown bile 

 into green by the action of various oxidizing agents, or even by ex- 

 posure to the air, and the evident chemical relationship between the 

 two substances, leave no doubt that this is the mode in which bili- 

 verdine originates in the animal body. Both bilirubine and biliverdine 

 are discharged with the bile into the alimentary canal, but they become 

 undistinguishable toward the lower end of the small intestine. Beyond 

 that point they are replaced by the brown coloring matter of the feces, 

 and are finally discharged from the body under this form. 



Urochrome. 



The coloring matter of the urine has been repeatedly studied by 

 competent and laborious observers, but thus far with only partial suc- 

 cess. The substances which have been extracted from the urine by 

 various methods, and which have been regarded as representing, more 

 or less exactly, its natural coloring principle, are known by the dif- 

 ferent names of Urochrome, Urosine, Urosacine, Hemaphaeine, Uro- 

 hematine, Uroxanthine, Urobiline, and Hydrobilirubine. They are all 

 probably modifications of the same substance, variously altered by dif- 

 ferent methods of extraction, or obtained in different grades of purity- 

 The fresh, normal urine has a light yellowish or amber color, while 

 specimens of unusually high specific gravity, and particularly specimens 

 of febrile urine, often exhibit a distinct reddish hue. Normal urine, 

 which, when fresh, is only amber-colored, will often, by exposure to 

 the air, acquire a jiftge? tff iec^ The substance obtained by Thudi- 



