CHEMISTRY OF THE LIVER. 



319 



older data on this subject were obtained by methods which are 

 open to serious objection. 



Composition of Bile. Qualitatively bile is characterized 

 by the presence of certain acids and coloring matters which 

 are not found elsewhere in the body. The acids are tanro- 

 cholic and glvcocholic, and the coloring matters are bilirubin 

 and bilivcrdin, which have been referred to already in their 

 relation to the coloring matter of blood from which they are 

 derived. In addition to these substances several others are 

 present which, while important, are not characteristic. These 

 include cholesterol, fats, soaps, inorganic salts and mucin. 

 The quantitative composition is extremely variable as shown 

 by the analyses below which are frequently quoted. The 

 results are in parts per i ,000 : 



The figures under i, 2, 3 and 4 were obtained by analyses of 

 secretions from the gall bladders of persons executed or acci- 

 dentally killed. They therefore represent normal products. 

 No. 5 is bile from a fistula; it is seen to be much poorer in 

 solids than the other biles, which result is confirmed by many 

 other analyses. It follows from this that the secretion in the 

 bladder undergoes a concentration by absorption of water. 



Analyses have been made of bile from different animals 

 with the object of connecting composition with the food of 

 the animal or its habits. The results are not very definite. 

 Human bile contains more glycocholic than taurocholic acid, 

 while in carnivorous mammals, birds and fishes taurocholic 

 acid is the more abundant. Hog bile contains largely glyco- 



