A saturated aqueous solution of picric acid is used to differentiate paraffin sections and smeared pollen-mother-cells stained in Heidenhain's and Delafield's hematoxylins. The method proceeds as usual, except that the iron alum in the destaining process is replaced by picric acid. Mixtures of picro-sulfuric acid and dilute Delafield's hematoxylin and mixtures of picric acid and aqueous hematoxylin have also been tested, of which the latter yields the better result, but is not as good as the other method described here.