THE BLOOD. 



187 



in the hepatic than in the portal vein. The bile-pigments are 

 formed by the liver-cells ; these coloring matters contain only traces 

 of iron, while the hepatic cells are rich with it. They give the char- 



Fig. 55. Blood-crystals of Man and Different Animals. (THAX- 

 HOFFEB and FREY.) 



1, Haemoglobin crystals: Mo, squirrel; Tr, guinea-pig; M, groundmole; 

 L, Horse; Em, man; H, Marmot; Ma, cat; T, cow; mv, from venous blood 

 of a cat. 2, Hsematin crystals; E, man; Y6, sparrow; M, cat. 3, Haemato'idin 

 crystals from an old extravasation of the blood in man. 



acteristic test for iron when treated with hydrochloric acid and 

 potassium ferrocyanide. 



Onlv traces of the iron are excreted as a constituent of the bile. 



