428 THE LIVER. 



completely exhausted with strong alcohol, filtered, and the alcohol entirely 

 evaporated from the filtrate. The residue is extracted with ether and" 

 dissolved in water, and filtered if necessary, and the solution precipitated 

 by basic lead acetate and ammonia. The washed precipitate is dissolved 

 in boiling alcohol, filtered while warm, and a few drops of soda solution 

 added. Then evaporate to dry ness, extract the residue with absolute 

 alcohol, filter, and add an excess of ether. The precipitate now formed 

 may be used for PETTENKOFER'S test. It is not necessary to wait for 

 cystallization; but one must not consider the crystals which form in the 

 liquid as being positively crystallized bile. It is also possible for needles 

 of alkali acetate to be formed. In this connection it must be remarked 

 that a confusion with phosphatides, which also give PETTENKOFER'S 

 reaction, is not excluded, and a further testing and separation are advisable. 



Bile-pigments. The bile-coloring matters known thus far are rela- 

 tively numerous, and in all probability there are still more of them. Most 

 of the known bile-pigments are not found in the normal bile, but occur 

 either in post-mortem bile or principally in the bile concrements. The 

 pigments which occur under physiological conditions in human bile are 

 the reddish-yellow bilirubin, the green biliverdin, and sometimes also 

 urobilin (and urobilinogen) or a closely related pigment. The pigments 

 found in gall-stones are (besides the bilirubin and biliverdin) choleprasin, 

 bilifuscin, biliprasin, bilihumin, bilicyanin and (choletelinf). Besides 

 these, others have been noticed in human and animal bile by various 

 observers. The two above-mentioned physiological pigments, bilirubin 

 and biliverdin, are those which serve to give the golden-yellow or orange- 

 yellow or sometimes greenish color to the bile; or when, as is most fre- 

 quently the case in ox-bile, the two pigments are present in the bile at 

 the same time, they produce the different shades between reddish-brown 

 and green. 



Bilirubin. This pigment has the formula, CioHis^Os, or according 

 to ORNDORFF and TEEPLE and KUSTER/ more correctly C32H36N4O6, 

 and is designated by the names CHOLEPYRRHIN, BILIPH^EIN, BILIFULVIN, 

 and H^EMATOIDIN. It occurs chiefly in the gall-stones as calcium bilirubin. 

 Bilirubin is present in the liver-bile of all vertebrates, and in the bladder- 

 bile especially in man and carnivora; sometimes, however, the latter 

 may have a green bile when fasting or in a starving condition. It also 

 occurs in the contents of the small intestine, in the blood serum of the 

 horse, in old blood extravasations (as hsematoidin) , and in the urine and 

 the yellow-colored tissue in icterus. 



On reduction with sodium amalgam MALY obtained a reduction 

 product, which he called hydrobilirubin, with the formula, C 



1 Orndorff and Teeple, Salkowski's Festschrift, Berlin, 1904; Klister, Zeitschr. f. 

 Physiol. Chem., 59. 



