The principle and results of XXX staining are basically the same as Rachel's staining, XXX staining solution has stronger coloring power for cytoplasm, which can better show the degree of basophilicity of cytoplasm, especially for the asphaltenophilic, acidophilic and basophilic particles in blood and bone marrow cells, which are clearly stained, but the coloring of the nucleus is deep, and the nuclear structure is poorly stained, therefore, XXX staining is often used in conjunction with Rachel's staining. Eosinophilic particles are alkaline proteins, combined with acidic dye eosin, stained pink, known as eosinophilic substances; nucleolar proteins and lymphocyte cytoplasm are acidic, combined with alkaline dye Meilan or azurite, stained violet-blue, known as basophilic substances; neutral particles are in an isoelectric state and eosin and Meilan can be combined, stained mauve, known as neutral substances. Staining of blood cells: The XXX dye contains two dyes, methylene blue and eosin, the former basic and the latter acidic, which have different affinities for the various substances in the cells, thus giving them different shades of color for identification.