336 



A YEAK IN SCIENCE 



numerous that between four and five million are present 

 in one cubic millimeter of blood. Like other cells they 

 are composed of protoplasm. They likewise w r ear out 



and must be replaced. 

 Some are produced 

 by the cells in the red 

 marrow of bones. 

 The color of the cor- 

 puscles is due to the 



presence of a sub- 

 Fig. 157. Blood corpuscles; A, red f Qr , rt0 V n r\ -or n QC 

 corpuscles from above; B, from the Stance Known as 

 side ; C, in chains ; D, white corpuscles. . _ 



hemoglobin. By 



means of this the corpuscle can perform its important 

 function of -carrying oxygen. 



When the blood passes through the small blood 

 vessels into the lungs, oxygen from the air in the 

 lungs is diffused into it. The hemoglobin then combines 

 chemically with the oxygen and forms an oxide of 

 hemoglobin. As the blood circulates through the body, 

 the oxygen is given up to the cells of the body where 

 it is needed. At the same time the blood loses its 

 bright red color, which had been due to the presence 

 of the oxide of hemoglobin. 



White corpuscles. The white bodies are not as 

 numerous as the red. There is one white to about 

 every six hundred red. They are larger, colorless, and 

 irregular, and change their shape rapidly. They are 

 not, as the red, restricted to the blood vessels. By their 

 movements they can get through the walls and flow 



