EXAMINATION FOR MALARIA 649 



(5-10) of the stain, which is spread by tilting, and in hot weather 

 the preparation should be covered with a capsule to prevent 

 evaporation. After a half to one minute distilled water is added 

 and mixed with the stain, in sufficient amount to produce an 

 abundant precipitate, and the mixture should appear pinkish ; 

 the water should be about double the amount of stain used, and 

 staining is continued for five, or in some cases for ten, minutes. 

 The staining should be continued until the nuclei of the leucocytes 

 are a rich purple when examined with a low power. The film is 

 then rinsed with distilled water, a little distilled water is left on 

 the film, which is watched under the low power until the red 

 corpuscles appear red ; this takes half a minute or more. The 

 water is now tilted off the film, and the slide on edge allowed to 

 dry, or it may be blotted and dried. Fresh films stain better 

 than old ones ; if the films are old, staining with the diluted stain 

 should be prolonged for ten or fifteen minutes and differentiation 

 with distilled water may take five minutes. Jenner's, Giemsa's 

 or May-Griinwald blood-stain may be similarly used. 



The author is indebted to Dr. A. C. Coles, of Bournemouth, for 

 the following method of staining blood-parasites. 



In order to obtain good stained films of blood containing para. 

 sites it is essential to have good slides, well cleaned, a film of blood 

 spread as uniformly as possible, and to avoid any precipitation of 

 the stain on the surface of the film. 



Slides are best cleaned with whiting or Creta preparata, made 

 into a paste with water, or with Windowlein, a preparation used 

 for cleaning windows. Rub the whiting thinly over the surfaces 

 of the slide, and when dry rub off with a clean cloth. 



The impedimenta required for staining the blood film are : 



1. Drop bottle of about ^iij capacity containing distilled 



water ; 



2. Pipette bottle of about 5ij to 5iij capacity for the staining 



solution ; 



3. Bottle of Giemsa's staining solution ; 



4. Bottle of Merck's pure methylic alcohol ; both well corked ; 



5. A Politzer's bag ; and preferably, though not essential, 



6. A curved piece of window glass, 8 in. x 4 in. 



Into the perfectly dry pipette bottle pour some of the Giemsa's 

 solution, and add about twice as much pure methylic alcohol ; 

 shake up and keep well stoppered. 



