126 HUMAN PHYSIOLOGY. 



The red corpuscles are exceedingly numerous, amounting to about 

 5,000,000 in a cubic millimeter of blood. In structure they consist 

 of a firm, elastic, colorless framework, the stroma, in the meshes 

 of which is entangled the coloring-matter the hemoglobin. 



CHEMIC COMPOSITION OF RED CORPUSCLES. 



Water 688.00 



Globulin 282.22 



Hemoglobin >. 16.75 



Fatty matter 2.31 



Extractives 2.60 



Mineral salts 8.12 



1,000.00 



Hemoglobin, the coloring-matter of the corpuscles, is an albu- 

 minous compound, composed of C, O, H, N, S, and iron. It may 

 exist in either an amorphous or a crystalline form. When deprived 

 of all its oxygen, except the quantity entering into its intimate com- 

 position, the hemoglobin becomes purplish in color, and is known as 

 reduced hemoglobin. When exposed to the action of oxygen, it 

 again absorbs a definite amount and becomes scarlet in color, and 

 is known as oxy hemoglobin. The amount of oxygen absorbed is 1.76 

 c.c. ( T 7 ^ of a cubic inch) for i mg. ( -^ of a grain) of hemoglobin. 



It is this substance which gives the color to the venous and arterial 

 blood. As the venous blood passes through the capillaries of the 

 lungs the reduced hemoglobin absorbs the oxygen from the pul- 

 monary air and becomes oxyhemoglobin, scarlet in color ; the blood 

 becomes arterial. When the arterial blood passes into the systemic 

 capillaries, the oxygen is absorbed by the tissues ; the hemoglobin 

 becomes reduced, purple in color, and the blood becomes venous. 

 A dilute solution of oxyhemoglobin gives two absorption bands 

 between the lines D and E of the solar spectrum. Reduced hemo- 

 globin gives but one absorption band, occupying the space existing 

 between the two bands of the oxyhemoglobin spectrum. 



The function of the red corpuscle is, therefore, to absorb oxygen 

 and carry it to the tissues ; the smaller the corpuscles and the 

 greater the number, the greater is the quantity of oxygen absorbed, 

 and, consequently, all the vital functions of the body become more 

 active. 



