430 THE LIVER. 



figuration exists already formed in these two bodies, and that the above- 

 mentioned tetrasubstituted acid, which is not obtained from bilirubinic 

 acid, must come from a special third pyrrol nucleus in the bilirubin and 

 hemibilirubin. Hsematinic acid (KUSTER from bilirubin) and methyl- 

 ethylmaleic imide (H. FISCHER and MEYER from hemibilirubin) have 

 been obtained from the two other pyrrol nuclei. Haematinic acid as 

 well as methylethylmaleic imide have also been obtained from biliru- 

 binic acid. 



FISCHER and ROSE 1 have earlier obtained, from hemibilirubin as 

 well as from the above-mentioned bodies and from bilirubin, by reduc- 

 tion with hydriodic acid, glacial acetic acid, a new crystalline acid, 

 the bilirubinic acid, CirH^^Os. This acid, to which PILOT Y and 

 THANNHAUSER'S bilinic acid stands in close relation, yields hsematinic 

 as well as methylethylmaleic imide on oxidation. By changing the 

 method of reduction FISCHER and ROSE 2 have obtained cryptopyrrol 

 and isophonopyrrolcarboxylic acid from bilirubin. The bilirubinic acid 

 also yielded the same products. 



The close relation of the blood pigments to the bile pigments was 

 first shown by KUSTER when he obtained the two hsematinic acids (as 

 imide) as oxidation products of these. This close relation is further 

 shown by the investigations given above although it is perhaps too 

 early to draw positive conclusions in regard to the structure of the two 

 groups of pigments and the differences existing between them. 



Bilirubin is sometimes amorphous and sometimes crystalline. The 

 amorphous bilirubin is a reddish-yellow or reddish-brown powder; the 

 crystals have a reddish-yellow, reddish-brown, or more reddish color, 

 and sometimes they have nearly the color of crystalline chromic acid. 

 The crystals, which can easily be obtained by allowing a solution of bili- 

 rubin in chloroform to evaporate spontaneously, are reddish-yellow, 

 rhombic plates, whose obtuse angles are often rounded. On crystalliz- 

 ing from hot dimethylaniline it forms, on cooling, broad columns with 

 both ends sharply cut (KUSTER 3 ). On dissolving in chloroform both 

 kinds of crystals are converted into long needles or whetstones. 



Bilirubin is insoluble in water, behaves like an acid, and occurs in 

 animal fluids as soluble alkali bilirubin. It is very slightly soluble in 

 ether, benzene, carbon disulphide, amyl alcohol, fatty oils, and glyc- 

 erin. It is somewhat more soluble in alcohol. In cold chloroform it 

 dissolves with difficulty, and is much more readily soluble in warm chloro- 

 form. Its solubility varies, and supersaturated solutions are readily 

 formed (ORNDORFF and TEEPLE). The varying solubility of bilirubin 



^ - - - , _.- - _.--.--. .-_- 



1 Zeitschr. f. physiol. Chem., 82. 



2 Ber. d. d. chem. Gesellsch, 45. 



1 Ibid., 30 and 35, and Zeitschr. f. physiol. Chem., 47. 



