318 THE CONSTITUENTS OF THE BILE. 



(e) Biliprasin (bilirubin + water + oxygen) has also been found under like 

 conditions. 



(/) The yellow pigment finally obtained by the continued oxidizing effect of 

 the nitric-acid mixture upon all of the biliary pigments is the choletelin of Maly, 

 C 16 H 18 N 2 O 6 ; it is amorphous, and soluble in water, alcohol, acids and alkalies. 



(g) With addition of hydrogen and water in the intestine through 

 the agency of bacteria bilirubin passes over into the hydrobilirubin of 

 Maly, C 3 2H 40 N 4 07. The same result can be brought about artificially by 

 treating an alkaline aqueous solution of bilirubin with actively reducing 

 sodium-amalgam. Hydrobilirubin is but slightly soluble in water, 

 more readily in salt-solutions or alkalies, alcohol, ether and chloroform, 

 and it exhibits an absorption-band at F. This body, which, according 

 to Hammarsten, occurs even in normal bile, is a constant pigment of 

 the feces, from which, after acidulation with sulphuric acid, it can be 

 extracted by absolute alcohol. Probably it is identical with the pigment 

 of the urine, the urobilin of JafTe. Hydrobilirubin is formed in the 

 intestine from ingested bile, being in part absorbed and excreted from 

 the portal circulation through the bile. 



Hydrobilirubin to which a drop of sulphuric acid and some potassium nitrate 

 are added again yields Gmelin's reaction. Fresh fecal matter, broken up in a 

 porcelain dish in a concentrated solution of mercuric chlorid, yields a red color as 

 the reaction of hydrobilirubin, while admixture of bilirubin causes a green color. 



Cholesterin forms transparent rhomboid plates (Fig. 92, d), is in- 

 soluble in water, but soluble in hot alcohol, in ether or chloroform. 

 In the bile it is kept in solution by the salts of the biliary acids. Choles- 

 terin is not a secretory product of the liver, but a product of the disinte- 

 gration of the epithelial cells of the biliary passages. 



It is most easily obtained from the so-called white gall-stones, which not 

 rarely consist principally of almost pure cholesterin, by boiling the triturated cal- 

 culi with alcohol. The crystals that separate on evaporation of the alcohol 

 become red in color from the edges on addition of sulphuric acid (five volumes to 

 one volume of water), and blue, like cellulose, on addition of sulphuric acid and 

 iodin. Dissolved in chloroform, one drop of concentrated sulphuric acid produces 

 a deep-red color. Moistened with a deep wine-yellow, alcoholic solution of iodin, 

 the crystals exhibit green, blue and red coloration after addition of sulphuric apid. 

 Dissolved in glacial acetic acid, addition of sulphuric acid produces first a rose- 

 red, then a blue color. 



Other Organic Substances. Lecithin, or its decomposition-products, 

 neurin and glycerin-phosphoric acid; palmitin, stearin, olein, as well 

 as their sodium-soaps; . diastatic ferment; traces of urea, at times 

 ethereal sulphuric acids ; acetic and propionic acids and traces of myris- 

 tinic acid in the bile of cattle. 



Fat reaches the bile from the liver and, conversely, fat is in turn absorbed 

 from the bile in the biliary passages (epithelial cells of the gall-bladder). Fresh 

 unboiled bile decomposes hydrogen dioxid. Bacteria introduced into the blood- 

 stream are in part eliminated by the bile. 



The inorganic constituents of the bile (from 0.6 to i per cent.) include 

 sodium chlorid, potassium chlorid, 0.2 per cent, soda, alkaline sodium 

 phosphate, calcium and magnesium phosphate, and an abundance of iron. 

 The last yields the usual reactions of iron even in fresh bile, so that 

 iron must be present in the bile in one of its oxygen-combinations. 

 Finally, some manganese and silica are present. Freshly secreted bile 

 from the dog contains more than 50, from the rabbit 109, volumes per 

 cent, of carbon dioxid, in part combined with alkalies, in part absorbed, 

 the latter being almost completely absorbed within the bladder. 



