208 



PHYSIOLOGICAL CHEMISTRY 



ents. The following have been isolated: bilirubin, biliverdin, bili- 

 fuscin, biliprasin, bilihumin, bilicyanin, choleprasin, and choletelin. Of 

 these, bilirubin and biliverdin are the most important and predominate 

 in normal bile. The colors possessed by the various varieties of normal 

 bile are due almost entirely to these two pigments, the biliverdin being 

 the predominant pigment in greenish bile and the bilirubin being the 



FIG. 61. BILE SALTS. 



principal pigment in lighter colored bile. The pigments, other than 

 the two just mentioned, have been found almost exclusively in biliary 

 calculi or in altered bile obtained at post-mortem examinations. 



Bilirubin, which is perhaps the most important of the bile pigments, 

 is apparently derived from the blood pigment, the iron freed in the 



t 



FIG. 62. BILIRUBIN (HEMATOIDIN). (Ogden.) 



process being held in the liver. Bilirubin has the same percentage com- 

 position as hematoporphyrin, which may be produced from hematin. 

 It is a specific product of the liver cells, but may also be formed in other 

 parts of the body. The pigment may be isolated in the form of a 

 reddish-yellow powder or may be obtained in part, in the form of reddish- 



