. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. c agent. But whereas theeffect of the spermatozoon on the electrical resistance of the egg is quite irreversible,that of sodium citrate is partially or entirely removed if the eggs are transferred tonormal sea-water. That the two phenomena are related would appear from the fact that exposure tocitrate solution, as it were, anticipates a part of the fall in electrical resistancecaused by the spermatozoon. 3 Y 2 516 ME. J. GRAY ON THE ELECTRICAL CONDUCTIVITY OF ECHIN
. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. c agent. But whereas theeffect of the spermatozoon on the electrical resistance of the egg is quite irreversible,that of sodium citrate is partially or entirely removed if the eggs are transferred tonormal sea-water. That the two phenomena are related would appear from the fact that exposure tocitrate solution, as it were, anticipates a part of the fall in electrical resistancecaused by the spermatozoon. 3 Y 2 516 ME. J. GRAY ON THE ELECTRICAL CONDUCTIVITY OF ECHINODERM EGGS, Table XXIV. Eggs. Resistance. Unfertilised. I In La* solution. 250 In Citsolution. Fertilised at once in normal sea-water. (Resistance 4 mins. after fertilisation.) Echinus acutus >> j? jy 33 • * * • * * * 225255 163 130122170 In other words the effect of fertilisation upon— Normal eggs is to reduee their existence by ... .Citrated eggs Lanthanum eggs 250 ?? ?? J5 5? 5? J? ISOMO Echinus acutus 1 r >i. •oooimol fcziirizo% sod. cit. xz«;ULL* 1 Sea-water 50 120 L 32*9 per cent. 25-245-5 ??. *- O 5 xo 15 ZO ZS 30 35 40 45 50 55 60 Time in minutes Fig. 14.—Illustrating the effect of fertilisation upon the resistance of eggs of Echinus acutus whichhave been treated with trivalent negative ions and trivalent positive ions respectively. AND ITS BEARING ON FERTILISATION AND ARTIFICIAL PARTHENOGENESIS. 517 oO o Z60 Z40 ZIO zoo 190 180170<2 160150140130 120 IIO IOO 90 80 O C « ID CO o t\ . I * ? • I Eckiiius acutu; 1 La*-00 01 mol. _ Fer t. in f vlu ( 20% sod. cit. iz-ScTcT^1 Sea-water 50 rb. i __. \Fe n Sr\ N. T !_£** ? JJCi. A \( s^C it. 11 —.. „ o 5 10 15 zo z$ 30 35 40 45 50 55 60 65 Time In minubes Fig. 15.™Illustrating the effect of trivalent ions on the resistance of fertilised eggs of Echinus acutus. The Effect of Sodium Citrate Solutions upon Fertilised and Unfertilised Eggs, A. Fertilised Eggs.—The general effect
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