3 THE BLOOD 



globin) 87-95 P er cent.; (b) stroma, composed of fat, lecithin, 

 and cholesterin; (c) and salts, principally potassium chloride, 

 and potassium phosphate. 



Hemoglobin. Hemoglobin is the coloring matter of the 

 red cells, and is composed of (i) hematin, a pigment containing 

 iron; and (2) globin, a proteid. Hemoglobin is of great physio- 

 logical importance, because of its ability to unite with oxygen 

 and thus form oxyhemoglobin. By it the blood carries its 



FIG. 21. 



A, human colored blood corpuscles i, on the flat; 2, on edge; 3, rouleau of colored 

 corpuscles. B, amphibian colored blood corpuscles i, on the flat; 2, on edge. 

 C, ideal transverse section of a human colored blood-corpuscle magnified 5,000 

 times linear a, b, diameter; c, d, thickness. (Landois.) 



oxygen from the lungs to the tissues. It also unites to some 

 extent with carbon dioxide and it is thus that carbon dioxide is 

 brought from the tissues. We find oxyhemoglobin chiefly in the 

 arterial blood, while in venous blood we find both hemoglobin 

 and oxyhemoglobin. In asphyxiated blood we find only 

 hemoglobin. 



The stroma is the colorless framework of the corpuscles after 



