. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. ns . in sol 152 55 5 55 125 55 33 55 152-5 5) 6 55 129-5 55 19 55 In normal sea-water recovery from the effects of trivalent positive ions is muchslower and not always so complete as that in alkaline sea-water. A further proof that the effect of cerium ions upon the conductivity of the eggs isdue to their electrical charge is furnished by the antagonistic effect between theseions and the trivalent negative ions of sodium citrate. AND ITS BEARING ON FERTILISATION AN
. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. ns . in sol 152 55 5 55 125 55 33 55 152-5 5) 6 55 129-5 55 19 55 In normal sea-water recovery from the effects of trivalent positive ions is muchslower and not always so complete as that in alkaline sea-water. A further proof that the effect of cerium ions upon the conductivity of the eggs isdue to their electrical charge is furnished by the antagonistic effect between theseions and the trivalent negative ions of sodium citrate. AND ITS BEARING ON FERTILISATION AND ARTIFICIAL PARTHENOGENESIS. 505 1. Resistance of normal unfertilised eggs of Sphcerechinus in sea-water Resistance of same unfertilised eggs of Sphcerechinus in— 0*0002 M Ce- . . 0-14 MCit 0-0002 MCe- 2. Resistance of normal unfertilised eggs of Sphcerechinus in sea-waterResistance of same unfertilised eggs of Sphcerechinus in— 0-UMCit 0-14 MCit . 0-0001 MCe-. 0-14 MCit . . 3£Or 117 ohms. 172 j? after 4 mins 105 55 55 2 55 125 55 55 4 55 115 55 103 55 55 7 55 95- 5 55 55 14- 5 55 115 55 55 5 55 102 55 55 11 55. 17 O — —— — - O 5 • lO 15 20 25 30 35 40 45 Time in minutes Fig. 11.—Illustrating the antagonistic effects of trivalent positive and negative ions on the resistance of the unfertilised eggs of Echinus miliaris. Before commenting on the above experiments, it is necessary to describe the effectof a prolonged treatment of the eggs with a solution of sodium citrate or alkalinevant HoflPs solution. If unfertilised eggs are treated with an alkaline vant HofFssolution for about an hour, the conductivity of the eggs is practically unaffected bythe presence of cerium ions. vol. ccvit.—b. 3 x 506 MR. J. GRAY ON THE ELECTRICAL CONDUCTIVITY OF ECHINODERM EGGS, Resistance of normal unfertilised eggs of Spcerechinus m neutral vant Hoffs solution 145 ohms. Resistance of same unfertilised eggs of Sphmrechinus in— Alkaline vant HofFs (50 + 0 • 25 N
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