220 THE CIRCULATORY APPARATUS 



under the oxygen pressure, with the air we breathe 

 into our lungs, the hemoglobin absorbs some of the 

 oxygen, through a chemical union (oxyhemoglobin) ; 

 immediately the blood becomes bright scarlet color 

 on leaving the lungs; as the tissues are reached by 

 this blood, when the oxygen pressure is low, the 

 oxyhemoglobin gives up some of its oxygen to the 

 tissues, and the blood becomes bluish in color (reduced 

 blood); whereupon it returns through the veins to 

 the lungs by way of the heart, to be oxidized again. 



The White Cells. The white cells, corpuscles, or 

 leukocytes are composed chemically of 90 per cent, 

 water, the balance solid matter, mostly proteins, e. g., 

 nuclein, nucleo-albumin, which contain phosphorus (as 

 much as 10 per cent.), cell globulin, also lecithin, fat, 

 glycogen, earthy and alkaline phosphates. 



The number of white corpuscles is much less than 

 the red corpuscles, thus in 1 cubic millimeter the 

 ratio is about 1 white to 700 red. The average number 

 of white cells in a cubic millimeter of blood is between 

 7500 to 8000. The number may be increased or reduced 

 by the following physiologic conditions: Taking of 

 food rich in proteins raises the number 30 to 40 per 

 cent.; in the newborn, 17,000 to 20,000 per cubic 

 millimeter; latter days of pregnancy they are as high 

 as 15,000 to 20,000; they are increased in various 

 pathologic conditions, such as abscess, peritonitis, 

 appendicitis, pneumonia. Starvation reduces the 

 number. 



The white cells as seen under the microscope floating 

 in the blood plasma, appear as grayish cells, about 

 2To"o mcn m diameter, adhering to the walls of the 

 vessel. 



The cell structure appears as a homogeneous mass 

 containing numerous granules consisting of fat, pro- 

 tein, and carbohydrate. A nuclei can be seen by 

 the adding of a mild acid. They are ameboid, that is, 

 they show movements similar to those seen in the 



