CHEMICAL FORMATION OF THE BILE. 417 



it must be recalled that the liver is an excretory organ for the bile-pig- 

 ments circulating in the blood. TARCHANOFF observed, in a dog 

 with biliary fistula, that intravenous injection of bilirubin causes a very 

 considerable increase in the bile-pigments eliminated. This statement 

 has been lately confirmed by the investigations of Vossius. 1 



Numerous experiments have been made to decide the question whether 

 the bile-pigments are only eliminated by the liver or whether they are 

 also formed therein. By experimenting on pigeons, STERN was able 

 to detect bile-pigments in the blood-serum five hours after tying the 

 biliary passages alone, while after tying all the vessels of the liver and also 

 the biliary passages, no bile-pigments could be detected either in the 

 blood or the tissues of the animal, which was killed 10-24 hours after 

 the operation. MINKOWSKI and NAUNYN 2 also found that poisoning 

 with arseniuretted hydrogen produces a liberal formation of bile-pig- 

 ments, and the secretion, after a short time, of a urine rich in biliverdin 

 in previously healthy geese. Ii} geese with extirpated livers this does 

 not occur. 



No such experiments can be carried out on mammalia, as they do 

 not live long enough after the operation; still there is no doubt that this 

 organ is the chief seat of the formation of bile-pigments under physiolog- 

 ical conditions. 



In regard to the materials from which the bile-acids are produced, 

 it may be said with certainty that the two components, glycocoll and 

 taurine, which are both nitrogenized, are formed from the protein bodies. 

 The close relation of taurine to the cystine group of the protein mole- 

 cule has been especially shown by the investigations of FRIEDMANN 

 (see Chapter III), and recently v. BERGMANN 3 has shown by feeding 

 dogs with sodium cholate and cystine that the animal body can trans- 

 form cystine into taurine and that the taurine of the bile originates 

 from the proteins of the food. In regard to the origin of the non-nitro- 

 genized cholic acid, which was formerly considered as originating from 

 the fats, nothing is positively known. 



The blood-coloring matters are considered as the mother-substances 

 of the bile-pigments. If the identity of haematoidin and bilirubin was 

 settled beyond a doubt, then this view might be considered as proven. 

 Independently, however, of this identity, which is not admitted by 

 all investigators, the view that the bile-pigments are derived from the 

 blood-coloring matters has strong arguments in its favor. It has been 

 shown by several experimenters that a yellow or yellowish-red pigment 



1 Tarchanoff, Pfliiger's Arch., 9; Vossius, cited from Stadelmann, Der Icterus. 



2 Stern, Arch. f. exp. Path. u. Phann., 19; Minkowski and Naunyn, ibid., 21. 



3 Hofmeister's Beitrage, 4. See also Wohlgemuth, Zeitschr. f. physiol. Chem., 40. 



