418 THE LIVER. 



can be formed from the blood-coloring matters, which gives GMELIN'S 

 test, and which, though it may not form a complete bile-pigment, is 

 at least a step in its formation (LATSCHENBERGER). A further proof 

 of the formation of the bile-pigments from the blood-coloring matters 

 consists in the fact that haematin on reduction yields urobilin, which is 

 identical with hydrobilirubin (see Chapter XV). Further, haBmato- 

 porphyrin (see page 288) and bilirubin are isomers, according to NENCKI 

 and SIEBER, and closely allied. The formation of bilirubin from the blood - 

 coloring matters is shown, according to the observations of several investi- 

 gators, 1 by the fact that the appearance of free haemoglobin in the plasma, 

 produced by the destruction of the red corpuscles by widely differing 

 influences (see below) or by the injection of haemoglobin solution, causes 

 an increased formation of bile-pigments. The amount of pigments in 

 the bile is not only considerably increased, but the bile-pigments may 

 even pass into the urine under certain circumstances (icterus). After 

 the injection of haemoglobin solution into a dog either subcutaneously 

 or in the peritoneal cavity, STADELMANN and GORODECKI 2 observed an 

 increase of 61 per cent in the secretion of pigments by the bile, which 

 lasted for more than twenty-four hours. 



If bilirubin, which contains no iron, is derived from hsematin, which 

 contains iron, then iron must be split off. This process may be repre- 

 sented by the following equation : C 3 2H34N4O 5 Fe + H 2 Fe = C 3 2H3 6 N 4 O 6 . 

 The question in what form or combination the iron is split off is of special 

 interest, and also whether it is eliminated by the bile. This latter does 

 not seem to be the case, at least to any great extent. In 100 parts of 

 bilirubin which are eliminated by the bile there are only 1.4-1.5 parts 

 iron, according to KUNKEL, while 100 parts hsematin contain about 

 9 parts iron. MINKOWSKI and BASERIN 3 also found that the abundant 

 formation of bile-pigments occurring in poisoning by arseniuretted hydro- 

 gen does not increase the quantity of iron in the bile. The quantity 

 apparently does not seem to correspond with that in the decomposed 

 blood-coloring matters. It follows from the researches of several investi- 

 gators 4 that the iron is, at least chiefly, retained by the liver as a 

 ferruginous pigment or protein substance. 



What relation does the formation of bile-acids bear to the forma- 

 tion of bile-pigments? Are these two chief constituents of the bile derived 

 simultaneously from the same material, and can we detect a certain 



1 See Stadelmann, Der Icterus, etc., Stuttgart, 1891. 



2 See Stadelmann, ibid. 



3 Kunkel, Pfliiger's Arch., 14; Minkowski and Baserin, Arch. f. exp. Path. u. 

 Pharm., 23. 



4 See Naunyn and Minkowski, Arch. f. exp. Path. u. Pharm., 21; Latschenberger, 

 I.e.; Neumann, Virchow's Arch., Ill, and the literature in footnote 2, p. 362. 



