370 PHYSIOLOGICAL CHEMISTRY. 



SEYLER). To these humin bodies developed by the action of acid 

 in normal urine when exposed to the air must be added the 

 UROPHAIN of HELLER, the various UROMELANINS, and other 

 bodies described by different investigators (PLOS'Z, THUDICHUM, 

 SCHUNCK). Indigo-blue (UROGLAUCIN of HELLER, UROCYANIN, 

 CYANURIN, and other coloring matters of older investigators) is 

 split off from the indoxyl-sulphuric acid or indoxyl-glycuronic acid. 

 Red coloring matters may be formed from the coupled indoxyl 

 and skatoxyl acids, and UROHODIN (HELLER), URORUBIN (PLOS'Z), 

 UROH^IMATIN (HARLEY), and perhaps also UROROSEIN (NENCKI 

 and SIEBER) probably have such an origin. 



We cannot enter into too many details of the different coloring 

 matters obtained as decomposition products from normal urine; 

 and as the preformed physiological coloring matters of urine have 

 not been closely studied, we can only discuss the most carefully- 

 investigated urinary pigment, urobilin. 



TTrobilin was first prepared from urine by JAFFE. This color- 

 ing matter occurs in urine especially in fevers, and it is therefore 

 designated FEBRILE UROBILIN by MACMUNN. The urobilin 

 occurring in normal urine is somewhat different from an optical 

 standpoint from the above, and is called NORMAL UROBILIN by 

 MAcMuNN. As above stated, a mother-substance of urobilin, a 

 UROBILINOGEN, occurs in the urine, from which urobilin is pro- 

 duced by the action of the air. 



Many investigators claim that urobilin is identical with hydro- 

 bilirubin (MALY) and corresponds to the composition C 32 H 40 lSr 4 7 . 

 Also, that urobilin is formed by a reduction- of bilirubin in the 

 intestine. The correctness of this view is disputed by others 

 (MAcMuNN, LE NOBEL). According to MAcMuNN, hydrobiliru- 

 bin and the urinary urobilin are not identical bodies, because he 

 obtained normal urobilin by the action of peroxide of hydrogen 

 upon a solution of haematin in alcohol containing sulphuric acid. 



Coloring matters similar to urobilin, though not identical, have 

 been obtained from the biliary and from the blood coloring mat- 

 ters. Besides the hydrobilirubin prepared by MALY from bilirubin, 

 STOKVIS obtained a choletelin from a biliary pigment, cholecyanin, 

 by the action of zinc chloride and tincture of iodine, or by boiling 



