48 HUMAN PHYSIOLOGY. 



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

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

 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-hsemo- 

 globin 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. 



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 ^sVtf f an inch m 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 amoeba, 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 

 resembling the white corpuscles. The spleen is the organ in which they 

 are finally destroyed. 



The white corpuscles originate from the leucocytes of the adenoid tissue, 

 and subsequently give rise to the red corpuscles and partly to new tissues 

 that result from inflammatory action. 



COAGULATION OF THE BLOOD. 



When blood is withdrawn from the body and allowed to remain at rest, 

 it becomes somewhat thick and viscid in from three to five minutes ; this 

 viscidity gradually increases until the entire volume of blood assumes a 

 jelly-like consistence, which occupies from five to fifteen minutes. 



As soon as coagulation is completed, a second process begins, which 

 consists in the contraction of the coagulum and the oozing of a clear, straw- 



