744 URINE. 



4 per cent nitrogen. Still H. FISCHER l has now found that the stercobilin 

 has a lower nitrogen content because of a contamination with cholesterin 

 or bile acids, and it is possible that also the low nitrogen content of the 

 urine-urobilin may be caused by contamination with non-nitrogenous 

 substances. 



These possibilities bane, it is sure, have not been tested; but the 

 unequal nitrogen content of the two pigments does not positively exclude 

 the identity of urobilin and hydrobilirubin. FISCHER and MYER-BETZ 

 have in fact shown that the hemibilirubin, which forms about one-half 

 of the mixture called hydrobilirubin (see page 429) is identical with the 

 urobilinogen from human urine. 



The possibility of the formation of urobilinogen and of urobilin from 

 bile pigments is assured and many physiological as well as clinical observa- 

 tions 2 support the view that this transformation of the bile pigments 

 occurs by means of putrefactive processes in the intestine. Of these 

 observations we must mention the regular appearance in the intestinal 

 tract of stercobilin, undoubtedly derived from the bile-pigmets; the 

 absence of urobilin in the urine of new-born infants, as well as on the com- 

 plete exclusion of bile from the intestine, and also the increased elimina- 

 tion of urobilin with strong intestinal putrefaction. On the other hand 

 there are investigators who, basing their opinion on clinical observations, 

 deny the enterogenous origin of urobilin and claim that the urobilin is 

 derived from a transformation of the bilirubin elsewhere than in the 

 intestine, by an oxidation of the bile-pigment or by a transformation of 

 the blood-pigments. 3 



Urobilin or urobilinogen dees not occur in the urine of all animals, 

 and according to FROMHOLDT it is absent in the urine of rabbits. The 

 correctness of this statement is denied by GAUTIER and Rosso. In nor- 

 mal human blood they seem to be absent, while according to BiFFi 4 

 urobilin and urobilinogen occur sometimes in disease and in cadaver blood. 



1 Hopkins and Garrod, Journ. of Physiol., 22; Fromholdt, Zeitschr. f. exp. Path., 

 u. Ther., 7; H. Fischer, Zeitschr. f. physiol. Chem., 73. 



2 See Fr. Miiller, Schles. Gesellsch. f. vaterl. Kultur, 1892; D. Gerhardt, " Ueber 

 Hydrobilirubin und seine Bezieh. zum Ikterus " (Inaug.-Diss., Berlin, 1889); Beck, 

 Wien. klin. Wochenschr., 1895; Harley, Brit. Med. Journ., 1896; Fischler, Zeitschr. 

 f. physiol. Chem., 48. 



3 In regard to the various theories as to the formation of urobilin, see Harley, 

 Brit. Med. Journ., 1896; A. Katz, Wien. med. Wochenschr., 1891, Nos. 28-32; Grimm, 

 Virchow's Arch., 132; Zoja, Conferenze cliniche italiane, Ser. la, 1; Hildebrandt, 

 Zeitschr. f. klin. Med., 59; Biffi, Boll. d. scienc. med. di Bologna (8), anno 78, 7; Troisier,, 

 Compt. rend. soc. biol., 66 and Tsuschija, Zeitschr. f. exp. Path. u. Ther., 7; Fromholdt 

 and Nersessoff, ibid., 11. 



4 Fromholdt, Zeitschr. f. physiol. Chem., 53; Cl. Gautier and Russo, Compt. rend. 

 BOC. biol., 64; Biffi, Folia hsematol., 4, and 1. c. Boll., 78. 



