114 



PHYSIOLOGY. 



decomposition of the blood. If haemoglobin itself or substances which 

 are capable of separating the coloring matter from the red corpuscles 

 be injected into the portal blood, there is a proportionate increase in 

 bile-pigment. Biliary acids are not preformed in the blood, for upon 

 extirpation of the liver there follows no appearance of them in the 

 blood. Evidently the hepatic cells must exert some functions as yet 

 not understood. 



The composition of human bile is approximately as follows : 



Water ., . 982^ 



Solids 



( Mucin and pigments 1.5 



' Bile-salts . . 7.5 



Lecithin and soaps 1.0 



Cholesterin 0.5 



Inorganic salts 7.5 



18 



> parts in 1000. 



Fig. 30. Glycocholic Acid. (DuvAL.) 



Bile=mucin. 



The latest investigations show that human bile contains real 

 mucin. 



Bile-salts. 



There are two salts of bile, both having sodium as a base. These 

 are glycocholate and taurocholate. These two acids are very closely 

 related to each other, for, on boiling with stronger acids, a common 

 nonnitrogenous body is obtained called cholalic acid, and an amido- 

 acid which contains nitrogen. The glycocholic acid gives glycin and 

 the taurocholic acid gives taurin, which contains sulphur. Taurin, 

 from its sulphur-content, must be a result of the metabolism of the 

 proteids, and, according to Friedmann., it comes from cystin. Hence 



