THE LIVER III 



cholic acid and glycocholic acid (the biliary salts), cholesterin, 

 bilirubin, lecithin, fats, soaps, mucin and various inorganic 

 salts, such as sulphates, carbonates, phosphates, etc., and a 

 quantity of carbon dioxide. The quantity of bile secreted in 

 twenty-four hours is about two and a half pounds. 



In human bile sodium taurocholate largely predominates 

 over glycocholate. These are formed as acids by the liver cells, 

 are absorbed in their passage down the intestine, and are pre- 

 sumably those parts of the bile which are concerned in its digestive 

 action, particularly in the absorption of fats. So far as these 

 constituents are concerned, the bile is a typical secretion. 



Cholesterin, on the other hand, seems to be simply removed 

 from the blood by the liver cells, and is discharged in the feces, 

 where, however, it exists in a slightly changed form, stercorin. 

 It is thought to be held in solution by the bile acids, glycocholic 

 and taurocholic. So far as this constituent is concerned, there- 

 fore, the bile is a typical excretion. It is produced in many of 

 the body tissues, and no function has been discovered for it. 



Bilirubin is the characteristic coloring matter of the human 

 bile ; that of herbivorous animals is biliverdin, and a little of this 

 latter is also present in human bile. These pigments originate 

 from hemoglobin. It is supposed that when the red corpuscles 

 break down, "the hemoglobin is brought to the liver, and then 

 under the influence of the liver cells is converted into an iron-free 

 compound, bilirubin, or biliverdin." (Howell.) 



The lecithin is probably an end product of physiological 

 activity in the tissues, and is apparently an excretion. 



The mucin gives the fluid its viscid character. 



The production of bile is continuous, but this does not mean 

 that its discharge into the duodenum is continuous, for in the 

 intervals of digestion it is not admitted (freely at least) into the 

 intestine, but regurgitates from the ductus communis choledo- 

 chus through the cystic duct into the gall bladder, which acts as a 

 reservoir until its contents are needed. The secretion is more 



