BENZIDIN-POLYCHROME STAIN FOR BLOOD
FRANK A. McJUNKIN · JAMA · 1920
For the accurate identification of endothelial leukocytes in blood smears, I have published an earlier report1of a staining method employing the so-called "oxydase or peroxidase" reaction. In this method the reagent employed was alphanaphthol, which brings out a blue granulation in the cytoplasm of the reactive leukocytes. Since the granulation is blue, a red nuclear stain was chosen; and the fact that the dilute basic fuchsin solution colors nuclei rather lightly detracts from the value of the stain. A second disadvantage of this earlier method is that the differential coloring of the blood elements in general which has brought the polychrome blood stains (Wright's and others) into universal use is not obtained. The greater accuracy in the identification of the leukocytes secured by the benzidin-polychrome combination, together with the preservation of the blood picture that hematologists now are so accustomed to, will, it is believed, make it of