Role of Eosin in Romanowsky Staining of Malaria Nucleus

Abstract

ACCORDING to Baker¹, the nucleus of the malaria parasite was seen for the first time in 1891. This was made possible by Romanowsky's invention of eosinate of methylene blue. Later other workers brought out modifications of this compound dye. They came to be known collectively as Romanowsky stains. All of them were prepared from eosin and methylene blue. Two or three of them were definite compounds formed by the interaction of methylene blue, a basic dye with eosin (tetrabromofluorescein disodium salt), an acid dye. Others (for example, Leishman stain) were prepared by the interaction of a polychrome methylene blue (prepared under controlled conditions) with eosin. The polychrome methylene blue is a hybrid mixture of azurs A, B, C, with methylene violet (Bernthsen) base and chloride with lower oxides of methylene blue. The latter make up the bulk of the polychrome methylene blue while the azurs and methylene violet are present only in minute quantities.