130 



SPECIAL PHYSIOLOGY 



the capillary must be accurate and complete. It must not remair 

 short of or go beyond the mark desired, and air must not be allowec 

 to enter the pipette. If any of these errors take place the pipett( 

 must be recleaned, dried, and filled again. 



When properly filled, any blood adhering to its outer surfac( 

 must be completely removed before proceeding farther. It is bette] 

 to have a large drop of blood at first than to use two or three smal 



drops, as there is less liability of getting 

 air into the capillary and of the blooc 

 clotting. 



FIG. 66 



I. THE COUNTING OF THE BLOOD 

 CORPUSCLES. 



Introductory. In health the numbe] 

 of red cells in the blood is quite constant 

 The variations that occur are quite smal 

 and are due to normal processes. In the 

 male there are about 5,000,000 red celL 

 in each cubic millimetre. In the female 

 there are about 4,500,000 red cells. An^ 

 deviation from normal health quickly 

 causes a diminution in the number o: 

 red cells. In fact, simple unhygienic 

 surroundings or habits are sufficient t( 

 speedily reduce the number of red celL 

 without other demonstrable pathologica 

 conditions. 



The life of the red cell is probably o: 

 about two weeks' duration. There an 

 approximately in the normal male's blooc 

 200,000,000,000 red cells. Then accord- 

 ing to the length of the lifetime of th< 

 cells about 14,000,000,000 red cells di( 



and mugt be disp()sed Q f each day< A cor . 

 Y i * 



responding number must be manuracturec 

 each day in order to keep the numbe] 

 It will be readily seen that such an im- 

 mense process, which depends upon perfect elimination as well as 

 assimilation, can be disturbed very easily. It is important that thij 

 fact about the blood be thoroughly understood. Even though the 

 physician may not estimate the number of red cells in every case 

 yet he must recognize the fact that every disturbing element in the 

 normal body must disturb the number of red cells contained therein 

 There are, then, two objects to be gained by actually counting the 



The Thoma-Zeiss blood-counter. 

 The pipette for use in counting the 

 red corpuscles. 



within its normal limits. 



