PHYSIOLOGICAL H&MATOLOGY. 267 



than with the small bore pipette. Remember to thor- 

 oughly clean and dry the pipette after using. 

 Observations. 



(1) Estimate the number of white corpuscles per cubic 

 millimeter in several apparently normal individuals. 



(2) What is the proportion of white to red corpuscles 

 in each individual ? 



(3) Is there considerable variation in number of white 

 corpuscles in different individuals? 



(4) Is there considerable variation in the proportion be- 

 tween white and red corpuscles in different individ- 

 uals? 



(5) What may cause the variation ? 



