An improved acriflavine-Feulgen method.

The acriflavine-Feulgen method for the histochemical demonstration of deoxyribonucleic acid was modified by staining hydrolyzed cells with 0.01% acriflavine dissolved in 90% ethanol. This method offered the following advantages: (a) it simplified the preparation of the acriflavine-Feulgen reagent; (b) it left the cytoplasm essentially unstained while staining the nuclei bright green in hydrolyzed cells and left the cytoplasm and nuclei essentially unstained in unhydrolyzed cells; (c) it eliminated poorly defined reagents from the staining solutions. Because of these staining properties, this technique may be especially useful in the quantitative determination of deoxyribonucleic acid by cytofluorometry.