BILE PIGMENTS. 405- 



THE DETECTION OF BILE-ACIDS IN ANIMAL FLUIDS. To obtain the 

 bile-acids pure so that PETTENKOFER'S test can be applied to them, the 

 protein and fat must first be removed. The protein is removed by 

 making the liquid first neutral and then adding a great excess of alcohol, 

 so that the mixture contains at least 85 vols. per cent of water-free alcohol. 

 Now filter, extract the precipitated protein with fresh alcohol, unite all 

 filtrates, distill the alcohol, and evaporate to dryness. The residue is 

 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 dryness, 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 crystal- 

 lization ; 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 reac- 

 tion, 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 ki the normal bile, but occur 

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

 pigments which occur under physiological conditions are the reddish- 

 yellow bilirubin, the green biliverdin, and sometimes also urdbilin (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 choletelin?) . 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 some- 

 times greenish color to the bile; or when, as is most frequently the case 

 in ox-bile, the two pigments are present in the bile at the same time r 

 they produce the different shades between reddish-brown and green. 



Bilirubin. This pigment has the formula Ci 6 Hi 8 N2O3, or accord- 

 ing to ORNDORFF and TEEPLE and KtisTER, 1 more correctly C3 2 H 36 N 4 O 6r 

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

 and KLEMATOIDIN. 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, 



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

 Physiol. Chem., 59. 



