THE CORPUSCLES 127 



tened discs. Others which are translucent or ''white/' 

 are globular and have one or more small rounded granu- 

 lar bodies, the nuclei, within them. Still others are 

 smaller transparent discs. 



Red blood corpuscles. The blood owes its red color 

 to the yellowish-red discs, which are therefore called 

 red blood corpuscles. They consist of a clear jelly-like 

 substance, hemoglobin, which readily absorbs oxygen. 

 Their shape makes it possible for them quickly to take 

 up oxygen from the air and give it off to the tissue cells, 

 since they are so flat and broad that each one of them 

 exposes a comparatively large surface for absorption. 

 It has been calculated that in an adult there are 25,000,- 

 000,000,000 red corpuscles and that their total surface 

 equals about 35,000 square feet. In a healthy person. 

 5,000,000 red corpuscles are contained in a drop of 

 blood no bigger than a pin head (1 cu. mm.). 1 In bulk, 

 they constitute one -half of the blood. They are devel- 

 oped in the red marrow of the bones and when full 

 grown are set free in the blood current, in which they 

 are carried to all parts of the body. They are destroyed 

 in the liver and spleen. 



White blood corpuscles. The white blood corpus- 

 cles consist of granular protoplasm containing one or 

 more nuclei. They are nourished by the blood and 

 lymph and behave very much like amebse, in that they 

 are able to change their form and to lead an essentially 



1 In cases of anemia (literally, lack of blood), their numbers 

 may be diminished to two-thirds or one-half of this. Consequently, 

 the amount of oxygen necessary for full activity cannot be carried 

 to the tissues, and the result is pallor and weakness. In hook- 

 worm disease, which is common in the South and other warm 

 countries, the anemia due to the sucking of blood by parasitic 

 worms in the intestinal wall, may be so great that there are 

 but 1,000,000 cells in a cu. mm. of blood. 



