Dissimilar Staining Properties of Purified and Certified Toluidine Blue

Certified toluidine blue (National Aniline Co.). applied to sections of frog blastulae, stained the nuclei light blue and left the yolk platelets either unstained or light blue. Purified toluidine blue (also National Aniline Co.) stained the nuclei a deep blue and the yolk platelets a brilliant pink with deep blue borders. Some of the observations suggest that this difference in staining behavior is due to the presence of an inhibitor in the certified dye, which suppresses the metachromatic staining of the platelets and reduces the intensity of the nuclear staining. Unsuccessful attempts were made to remove the inhibitor by salting out the certified dye and washing it with alcohol or by extracting it with chloroform. Details of these attempts, and of other experiments designed to identify the stainable substrates in the yolk platelets are given in the text.