as the red cell. Frequently, too, platelets are 

 surrounded by what looks like a definite clear 

 outline, but a closer examination will show that 

 the resemblance to a parasite is only superficial. 

 The mass is granular throughout, a parasite is 

 not. The staining is uniformly reddish or blotchy, 

 blue and red, it is not divided as in the parasite 

 between a definite blue area and a definite red 

 dot or dots. 



Leucocytes, we have said, are also not 

 uncommonly taken for the larger forms of parasites 

 (e.g., gametes), but only a beginner could possibly 

 make such a mistake, as the leucocytes have a 

 large densely staining mass of red (the nucleus) 

 forming a considerable proportion of the whole 

 cell mass, whereas in the gametes there is only a 

 patch or- so of red amidst the blue. 



Dust on the eye piece is at once detected by 

 rotating the eye piece when the body shifts its 

 position. 



The Normal Constituents of the Blood 



Normal blood should be carefully studied in^ 

 fresh and stained specimens. 



I . The Red Cells. — With Romanowsky's stain 

 these are only faintly stained reddish (Method 2), 

 greenish or bluish in colour (Method i). Their 

 apparent size, i.e., the area they occupy when flat- 

 tened out, depends upon the thickness of the film ; 

 in well-made thin films they are large, and stain 

 with beautiful uniformity. In fresh specimens 

 (wet films) they ought to appear as perfect, 

 uniformly straw-coloured discs ; if crenated, it is 

 impossible for the beginner to detect parasites. 



