144 ANATOMY FOR NURSES [Chap. IX 



these organs, but others consider that it takes place in the blood 

 in any part of the system. 



Number of red corpuscles. — The average number of red cor- 

 j)uscles in a cubic niillinietre of healthy blood is given as 5,000,000 

 for men and 4,500,000 for women. Even in health this number 

 varies and in disease it may be greatly reduced. An increase in 

 temperature hastens the destruction of red corpuscles, and in this 

 way causes a reduction in number. The condition known as 

 anemia may be due to a diminished number of red corpuscles, which 

 means a diminished supply of ox^'gen, and a consequent inter- 

 ference with the processes of metabolism. 



White corpuscles. — The white corpuscles are masses of proto- 

 plasm containing a nucleus, sometimes even two or three nuclei, 

 and they have no cell wall. Their form is very various, but when 

 they are carried along in the blood current, or when the blood is 

 first drawn, they are rounded or spheroidal. Measured in this 

 condition, they are about osVcr of an inch (0.010 mm.) in diameter. 

 The white corpuscle may be taken as the type of a free animal 

 cell. 



Number of white corpuscles. — The average number of white 

 corpuscles in a cubic millimetre of healthy blootl is from 7000 to 

 9000, or in the proportion of 1 white to 500 or 600 red. A marked 

 increase in number is designated as leucocytosis, a marked decrease 

 as leiicopenia. Under various normal conditions, such as digestion, 

 exercise, or cold baths, leucocytosis occurs. It also occurs under 

 abnormal conditions, and a knowledge of the variations under 

 pathological conditions is an important aid in diagnosis. 



Varieties of white corpuscles. — At least five varieties have 

 been studied and described. They are classified under two main 

 groups : — 



(1) Leucocytes. 



(2) Lymphocytes. 



The most marked difference is in the nuclei and in the amount 

 of amoeboid movement exliibited. The difference is said to be 

 due solely to the age of the corpuscle — the lymphoc\'te being the 

 more recently formed, and in time will change into a leucocyte. 

 Each of these groups may be subdivided into two or more 

 subgroups, and some authorities hold that each variety has some 

 special function, but this has not been proven. 



