47 



TABLE SHOWING COMPARATIVE DIAMETER OF RED 

 CORPUSCLES. 



In man and the mammals the red corpuscles present neither a nucleus 

 nor a cell wall, and are universally of a small size. They can be readily 

 distinguished from the corpuscles of birds, reptiles and fish, in which they 

 are larger, oval in shape and possess a well-defined nucleus. 



The red corpuscles are exceedingly numerous, amounting to about 

 5,000,000 in a cubic millimetre 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. 



CHEMICAL COMPOSITION OF RED CORPUSCLES. 



Water, 688.00 



Globulin, 282.22 



Haemoglobin, 16.75 



Fatty matter, 2.31 



Extractives, 2.60 



Mineral salts, 8.12 



Haemoglobin^ the coloring matter of the corpuscles, is an albuminous 

 compound, composed of C. O. H. N. S. and iron. It may exist either in 

 an amorphous or crystalline form. When deprived of all its oxygen, 

 except the quantity entering into its intimate composition, the haemoglobin 

 becomes dark in color, somewhat purple in hue, 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-hemo- 

 globin. The amount of oxygen absorbed is 1.76 c.cm. ( r 7 ^ cubic inch) for 

 I milligramme (^ : ? grain) of haemoglobin. 



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 pulmonary air and 

 becomes oxy-hcemoglobin, scarlet in color, and the blood becomes arterial. 

 When the arterial blood passes into the systemic capillaries, the oxygen 



