DIAGNOSIS OF MALARIA 525 



The writer 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 giij capacity containing distilled water ; 



2. Pipette bottle of about Jij to 3iij 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 inch x 4 inch. 



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. 



Drop from the pipette bottle just enough of the diluted Giemsa's 

 solution to cover the film. Allow it to act for about ten to twenty 

 seconds [if longer, especially in a hot climate, the alcohol evaporates 

 and precipitates the stain]. 



Then drop on as much distilled water as the slide will hold 

 that is, about eight times as much water as stain allow the stain 

 and distilled water to mix, and stain for the requisite time. 



It is better, however, in order to prevent the precipitation of the 

 stain, to pour off the diluted stain and water from the film on to 

 the surface of a piece of slightly curved plate-glass, and immediately 

 place the slide, film side downward, on this. The duration of 

 staining varies according to the temperature of the room and the 

 nature of the film generally speaking, ten to twenty minutes 

 give excellent results ; but a good plan is to remove the film, 

 flood off the stain with distilled water, and examine under low 

 power. If the nuclei of the leucocytes are of a ruby-red colour, 

 the staining is successful. If they are blue, the film is insufficiently 

 stained, and it should be replaced on the staining fluid ; if they 

 are blackish red, it is too deeply stained for most purposes, and all 

 that is required is to pour distilled water on the surface, watching 

 the effect (easily seen by holding the slide over a piece of white 

 paper), and as soon as the whole film is faintly pink the staining 



