. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. a removal of the effect of the cerium ions, and not to the secondary effects of thecerium ions themselves, is shown by the following facts :— 1. The increase of the conductivity in the alkaline solution is much too rapid to beaccounted for by the secondary effect of the cerium ions. 504 ME. J. GRAY ON THE ELECTKICAL CONDUCTIVITY OF ECHINODERM EGGS, Eggs from same Female Sphcerechinus in Experiments A and B. A. Resistance of normal unfertilised eggs in sea-water ...
. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. a removal of the effect of the cerium ions, and not to the secondary effects of thecerium ions themselves, is shown by the following facts :— 1. The increase of the conductivity in the alkaline solution is much too rapid to beaccounted for by the secondary effect of the cerium ions. 504 ME. J. GRAY ON THE ELECTKICAL CONDUCTIVITY OF ECHINODERM EGGS, Eggs from same Female Sphcerechinus in Experiments A and B. A. Resistance of normal unfertilised eggs in sea-water .... 125 ohms. Resistance of same unfertilised eggs in 0*0001 Ce-- . . 153Resistance of same unfertilised eggs in alkaline sea-water (50 s-w +0-75 N/10 NaOH) 124 „ „ 12 55 after 4 mins. 55 55 5 B. Resistance of normal unfertilised eggs in sea-water .... same „ ,, 0*0001 Ce*** . . 0-0001 Ce- . .0-0001 Ce- . . * After each reading the Ce-* solution was changed. 55 55 55 LilU 55 55 5? 5) 55 55 55 55 112-5 55 141-0 55 55 6* „ 150-0 55 55 12* „ 147-0 55 55 29* „ £ o I60 I50 Cg <D I40 O §130 £IZO. Spliaerechnius granulans o 5 10 15 zo Z5 30 35 40 45 5o 55 60 65 lo Time in minubes Fig. 10.—Illustrating the antagonistic effects of alkaline sea-water and trivalent positive ions. 2. It has been shown that the secondary increase in the conductivity of eggs incerium solutions is unchanged by the presenceof a fresh cerium solution round theeggs. If, however, the primary effect of a cerium solution is removed by alkali,then, on addition of a fresh cerium solution, the conductivity of the eggs is againdecreased. The complete antagonism between cerium ions and alkali is shown bythe following experiment:— Resistance of normal unfertilised eggs (Sphcerechinus) in sea-waterResistance of same unfertilised eggs (Sphcerechinus) in— 0-0001 Ce- Normal-sea-water Alkaline sea-water (50 + 0*5 N/10 NaOH) 0-0001 Ce- . . . Alkaline sea-water (50 + 0*75 N/10
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