MALARIA IQI 



the structure of malarial parasites, and for films containing other 

 protozoa, but may be used for differential counts instead of Jenner's 

 stain. Do not fix the film ; place a few drops of the stain on it, and 

 rock it so as to cover the surface. After half a minute drop on about 

 twice the volume of distilled water, and mix by rocking or by stirring 

 with a clean glass rod. Now stain for five minutes, and wash in 

 distilled water. If a more prolonged staining is required, as for the- 

 intimate study of the malarial parasite, staining spirochaetes, etc., the 

 process may be continued for an hour or more, the preparation being 

 kept covered to prevent drying up (an inverted watch-glass answers 

 perfectly), and in this case there may be a granular deposit. This 

 can be dissolved by washing the film momentarily in absolute alcohol, 

 getting rid of the latter by means of distilled water. If the red cor- 

 puscles are stained blue the film may be washed in very dilute acetic 

 acid (i in 1,000). 



When old films have to be stained it is best to cover the surface 

 with a film of fresh serum. Let this drain off, dry, and proceed as 

 before. 



Wright's stain is used similarly, but the water is added until an 

 iridescent scum appears on the surface, after which staining is com- 

 plete in about two minutes. 



Giemsa's stain requires previous fixation, and is used diluted with 

 distilled water (i drop to i c.c.). Fix the films in absolute alcohol 

 for twenty minutes, blot, and dry. Stain for a period varying from 

 fifteen minutes to twenty-four hours : in the latter case, immerse the 

 films face downward in the solution, covering it to prevent evapora- 

 tion. Wash in distilled water, blot, dry, and mount. Better staining 

 is got by using i in 1,000 solution of potassium carbonate for diluting 

 the stain instead of distilled water. 



A simpler stain is that recommended by Rees (Practitioner, 

 March, 1901), involving" the use of carbol thionin, prepared by 

 dissolving 1-5 grammes of thionin in 10 c.c. of absolute alcohol 

 and 100 c.c. of a 5 per cent, solution of carbolic acid. This is 

 to be kept for at least a fortnight, and diluted with four times 

 its bulk of distilled water immediately before use. Staining is 

 complete in about ten minutes. Ordinary carbol thionin 

 answers very well indeed. Thionin stains the red corpuscles a 

 faint green, nuclei blue, and the parasites an intense purple. 



In a suspected case of malaria the search should not be 

 abandoned in less than half an hour, or, in the case of an in- 

 experienced observer, much longer. 



A few notes on the life-cycle of the malaria parasite and 

 of the main differences between the different species must be 

 added. 



