240 H^EMATOIDIN. 



in old blood-clots as of cerebral haemorrhages 1 , in corpora lutea, in the 

 urine in cases of transfusion of blood 2 and in cases of hsematuria 3 . 

 There is no doubt that as occurring in the above cases it is directly 

 derived from some metamorphosis of haemoglobin. Apart from the 

 similarity of crystalline form and colour it was further found that 

 hsematoidin crystals readily give the characteristic (Gnielin's) reaction 

 for bilirubin by treatment with nitric acid, and thus its identity with 

 bilirubin was at once asserted and supported by very convincing 

 evidence 4 . The identity was however for some time disputed, notably 



FIG. 40. H^HATOIDIN CRYSTALS. (Frey after Funke.) 



by Stadeler, and by others largely on the basis of inconclusive spectro- 

 scopic investigation of the two substances. There is however no doubt 

 that hsematoidin is really identical with bilirubin, so that now the 

 name is of interest rather from a historical point of view, and 

 physiologically as indicating the undoubted genetic relationship of 

 the pigments of bile to those of blood. 



BILE-PIGMENTS AND THEIR DERIVATIVES. 5 



The bile is in all animals a characteristically highly-coloured 

 secretion. The colour of the fresh bile is as a general rule golden-red 

 in man and carnivora, and more or less bright green in herbivora. 

 These colours are due to the presence of a pigment known as bilirubin 



1 Virchow first carefully described it as obtained from this source and named it 

 hzematoidin to indicate its undoubted derivation from the colouring matter of the 

 blood. Virchow's Arch. Bd. i. (1847), S. 419. 



2 Hoppe-Seyler, Pfliiger's Arch. Bd. x. (1875), S. 211. 



3 Ebstein, Deutsch. Arch. f. Klin. Med. 1878, S. 115. 



4 See among others E. Salkowski, Hoppe-Seyler's Med.-chem. Unters. Hf. 3, 

 1868, S. 436. 



5 See specially Maly in Hermann's Hdbch. d. Physiol. Bd. v. Th. 2. 1881. S. 154. 

 Also for history and literature, Heynsius u. Campbell, Pfluger's Arch. Bd. iv. (1871) 

 S. 497. 



