[Giemsa stain's 100th year].

Research work associated with the development of Giemsa stain is revived, with emphasis on the methylene blue polychromes. A short biographical sketch of Dr. Berthold Gustav Carl Giemsa is presented, along with the composition of his original formulation and its mec. HPLC analyses of his azur II indicated the following composition: methylene blue 63.6%, azur B 28.6%, azur A 4.4%, azur C 1.4%, thionin 1.9%. Azur I was not "pure", but rather a mixture of thionin and all of its 3 and 7 N-methylated derivatives. Lillie inferred that it was probably prepared by an acid oxidation process. Applications of Giemsa stain reported in the last 32 years are tabulated.