21 



To STAIN FILMS 



For the study of blood parasites some modification 

 of the Romanowsky stain as developed by Ziemann, 

 Leishman, Giemsa, etc., is by far the best, because by 

 these stains the chromatin of nuclei is stained red while 

 the protoplasm is stained blue and so a differentiation 

 is got which is given by no other stain. The red nuclei, 

 moreover, makes the detection of the parasite very easy. 



ROMANOWSKY STAINS 



The principle on which these stains are based is the 

 following. A solution of methylene blue that has been 

 acted upon by carbonate of soda or other reagents 

 becomes partly converted into various derivatives, e.g., 

 methylene azure and methylene violet. These bodies 

 also occur in old * ripe ' polychrome blues. These 

 bodies are in solution. When they are acted upon by 

 a solution of eosin there results a precipitate and this 

 precipitated body (or bodies) possesses the property of 

 staining nuclei an intense heliotrope red colour 

 (chromatin stain). 



The staining may be effected at the time of mixing 

 the ripened blue and eosin solutions, in the nascent state, 

 so to speak, as in method I ; or the precipitate may be 

 allowed to form, and subsequently be dissolved in a 

 solvent, e.g., methyl alcohol, as in the Leishman and 

 Giemsa stains ; and finally be precipitated out of 

 solution by the addition of water at the time of staining. 



I. Romanowsky.* Two stock solutions are made, 



* This method gives excellent results, and is not inferior to the Leishman or 

 Giemsa stains. The stain is easily made and is cheap, and the blue, if made up, 

 improves with age. 



