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. 
