BLOOD. 



475 



The most important constituent of the red blood-corpuscles, both in 

 quantity and function, is the " haemoglobin." Haemoglobin, or the blood 

 coloring-matter, is a complicated, crystallizable albuminoid body 

 containing iron, and forms about 90 per cent, of the red blood-cells. 

 When separated from the corpuscles, haemoglobin readily crystallizes out 



Fig. 176.— Blood-Crystals of Man and Different Animals. (Tlianhoffer and Prey.) 



1, haemoglobin crystals ; Mo, squirrel ; Tr, guinea-pig ; U, ground-mole : L, horse ; Em, man ; H, 

 marmot; Ma, cat; T, cow; mv t from the venous blood of a cat. 2, hajmatin crystals ; E, man; V6, 

 sparrow ; M, cat. 3, hsematoidin crystals from an old blood extravasation of man. 



of its solutions in serum when concentrated. These cr}'stals have dif- 

 ferent forms in different species of animals, depending, apparently, on 

 varying amounts of water of crystallization. In the domestic animals they 

 belong to the rhombic system ; those of the squirrel are hexagonal. The 



