At the April 16 meeting of the Biological Stain Commission the Board of Trustees voted that hereafter Giemsa stain will be certified in two varieties, namely “Giemsa stain, Azure B type, for malaria and blood work” and “Giemsa stain, Azure A type, for hematology and bacteriology”.
The Azure B type closely resembles tinctorially and spectroscopically the Grübler and Hollborn Giemsa stains of the 1930's and is the variety especially recommended to give the faintly greenish blue tint to parasite cytoplasm which contrasts well with the grayish or greenish blue background of the thick film stained at pH 7.0. This is recommended by many malariologists for thick film work.
The Azure A type gives darker red chromatin stains, grayer or more violet blue lymphocyte cytoplasm, and perhaps somewhat heavier staining of microorganisms. Its useful life is probably shorter under average tropical storage conditions. It is preferred by many American hematologists.