COMPOSITION OF HUMAN BILE. 443 



chemistry. "We shall study the composition of the bile very closely, and shall show that 

 it contains two classes of constituents : one class elements of secretion which is reab- 

 sorbed ; and another an element of excretion which is discharged in a modified form 

 in the faeces. The latter involves a newly-described function of the liver, but our infor- 

 mation is much more positive and definite concerning it than with regard to the digestive 

 action of the bile. In treating of the subject of digestion, we have already indicated 

 some of the difficulties, which have been but imperfectly overcome, in the study of the 

 action of the bile as a true secretion, or a recrementitious fluid. The reason why the 

 same obscurity has prevailed with regard to the function of the bile as an excretion is 

 that physiologists have regarded what are known as the biliary salts as the only really 

 important constituents ; and these salts have eluded chemical investigation after the dis- 

 charge of the bile into the small intestine. Our recent positive knowledge of the excre- 

 mentitious function of the liver is due to the recognition of cholesterine, an invariable 

 constituent of the bile, as one of the most important of the elements of excretion. 



Composition of Human JSile. (Robin.) 



Water 916-00 to 819-00 



Taurocholate, or choleate of soda 56'60 " 106'00 



Glycocholate, or cholate of soda traces. 



Cholesterine 0'62 to 2'66 



Biliverdine 14-00 " SO'OO 



Lecithene. . 



O.OA SI "00 



Margarine, oleine, and traces of soaps.. r 



Choline. . . , traces. 



Chloride of sodium 2'7Y to 3*50 



Phosphate of soda 1'60 " 2'50 



Phosphate of potassa 0'75 " 1-50 



Phosphate of lime 0'50 " 1'35 



Phosphate of magnesia 0'45 " 0'80 



Salts of iron 0'15 " 0'30 



Salts of manganese traces " 0*12 



Silicic acid '. 0'03 " 0'06 



Mucosine traces. 



Loss 3-43 to 1-21 



1,000-00 1,000-00 



There are no peculiarities in the composition of the bile, as regards its inorganic con- 

 stituents, which demand more than a passing mention. It contains no coagulable organic 

 principle, except mucosine, and all of its constituents are simply solids in solution. The 

 quantity of solid matter is very large, and the proportion of water is relatively small ; but, 

 in comparing its proportion of water with that of other fluids in the body, as the blood- 

 plasma, lymph and chyle, milk, etc., it must be remembered, as is suggested by Robin, 

 that all of these contain water entering into the composition of their coagulable prin- 

 ciples ; so that their proportion of water, as it is ordinarily given, is really not greater 

 than in the bile. Among the inorganic salts, we find chloride of sodium in considerable- 

 quantity and a large proportion of phosphates. We also note the presence of salts of 

 iron, of manganese, and a small proportion of silicic acid. 



The fatty and saponaceous matters demand hardly any more extended consideration. 

 A small quantity of margarine and oleine are held in solution, partly by the small pro- 

 portion of soaps, but chiefly by the taurocholate of soda, These principles sometimes 

 exist in larger quantity, when they may be discovered in the form of globules. The pro- 

 portion of soaps is very small. Lecithene, a phosphorized fat, is mentioned by Robin and 

 others, but its constitution is not definitely settled. All that is known of this principle 



