BILE 



205 



the predominant pigment in greenish bile and the bilirubin being the 

 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 



FIG. 55. BILE SALTS. 



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- 



FIG. 56. BILIRUBIN (HEMATOIDIN). (Ogden.) 



yellow rhombic plates (Fig. 56) upon the spontaneous evaporation 

 of its chloroform solution. The crystalline form of bilirubin is 

 practically the same as that of hematoidin. It is easily soluble in 

 chloroform, somewhat less soluble in alcohol and only slightly soluble 

 in ether and benzene. Bilirubin has the power of combining with 



