44 HUMAN PHYSIOLOGY. 



H&moglobin, 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 darker 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-hcemo- 

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

 i milligramme (^) grain of haemoglobin. 



It is this su^tance 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- hemoglobin, scarlet in color, and the blood becomes arterial. 

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

 is absorbed by the tissues, the haemoglobin becomes reduced, purple in 

 color, and the blood becomes venous. A dilute solution of oxy-hsemo- 

 globin gives two absorption bands between the lines D and E of the 

 solar spectrum. Reduced haemoglobin gives but one absorption band, 

 occupying the space existing between the two bands of the oxy-haemo- 

 globin spectrum. 



The Function of the red corpuscles 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. 



The White Corpuscles are far less numerous than the red, the proportion 

 being, on an average, about I white to 350 or 400 red ; they are globular 

 in shape, and measure the ^-Vo f an i nc h i* 1 diameter, and consist of a 

 soft, granular, colorless substance, containing several nuclei. 



The white corpuscles possess the power of spontaneous movement, alter- 

 nately contracting and expanding, throwing out processes of their substance 

 and quickly withdrawing them, thus changing their shape from moment 

 to moment. These movements resemble those of the amceba, and for this 

 reason are termed amoeboid. They also possess the capability of moving 

 from place to place. In the interior of the vessels they adhere to the inner 

 surface, while the red corpuscles move through the centre of the stream. 



The white corpuscles are identical with the leucocytes, and are found 

 in milk, lymph, chyle and other fluids. 



Origin of Corpuscles. The red corpuscles take their origin from the 

 mesoblastic cells in the vascular area of the developing embryo. 



In the adult they are produced from colorless nucleated corpuscles 



