ELECTROKINETIC STUDIES OF MARINE OVA. VI. THE EFFECT OF SALTS ON THE ZETA POTENTIAL OF THE EGGS OF STRONGYLOCENTROTUS PULCHERRIMUS

¹ Misaki Marine Biological Station, Misaki, Kanagawa-ken, and Zoology Department, Faculty of Science, Tokyo Imperial University, Tokyo

1. The electrokinetic potentials of the unfertilized eggs of Strongylocentrotus pulcherrimus were measured in mixtures of various ratios of isotonic NaCl and CaCl₂ and of NaCl and CeCl₂.

2. In the Na-Ca series, as the concentration of Ca-ions in the mixture was raised, the absolute magnitude of the negative potential of the eggs decreased. In the Na-Ce series, with the increase in concentration of Ce-ions, the sign of the zeta potential was reversed.

3. At the isoelectric point, the eggs agglutinated.

4. The course of the potential change can be attributed to the adsorption of the cations.

5. The existence of a covering layer and its dissolution in the absence of Ca-ions such as were seen in Arbacia eggs have not been found in Strongylocentrotus eggs.