. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. uced by stronger solutions below the normal resistance of thetissue is quite irreversible (Osterhout). 3 u 2 500 MR. J. GRAY ON THE ELECTRICAL CONDUCTIVITY OF ECHINODERM EGGS, 300 28o .«(«.i.(lhin«iVim O 5 Z40tg_Z20 zio zoo190 J_i OX LJLX LUL O miliaris . 0-5- 10 15 20 zS 30 35 40 45 50 55 Time .in minutes Fig. 5.—Illustrating the effect of trivalent positive ions upon the resistance of unfertilised eggs of Echinus miliaris. Ce*** *0G01 moL I60 ISO 00£ o 140 O cto
. The Electrical Conductivity of Echinoderm Eggs, and Its Bearing on the Problems of Fertilisation and Artificial Parthenogenesis. uced by stronger solutions below the normal resistance of thetissue is quite irreversible (Osterhout). 3 u 2 500 MR. J. GRAY ON THE ELECTRICAL CONDUCTIVITY OF ECHINODERM EGGS, 300 28o .«(«.i.(lhin«iVim O 5 Z40tg_Z20 zio zoo190 J_i OX LJLX LUL O miliaris . 0-5- 10 15 20 zS 30 35 40 45 50 55 Time .in minutes Fig. 5.—Illustrating the effect of trivalent positive ions upon the resistance of unfertilised eggs of Echinus miliaris. Ce*** *0G01 moL I60 ISO 00£ o 140 O cto 120 «r -. Spl laere ^^w**-** LUS £ *raii .s •I C e** *o ooo — ?——— o 10 zo 30 40 50 60 70 80 90 100 no 120 130 140 150 Time in minutes Ftg. 6,-—Illustrating the effect of trivalent positive ions upon the resistance of unfertilised eggs of Sphmrechinus granulans. AND ITS BEARING ON FERTILISATION AND ARTIFICIAL PARTHENOGENESIS. 501 1,110IJOO cO *P90 ^ ipso ° ip^ ^060 £ ipso £ ipioipoo<990- O. 90 100 no 30 40 50 60 TO Time in minutes Fig. 7.—Changes in resistance of Laminaria tissue produced by 1 per cent, ether in sea-water. (From Osterhouts data.) Again, Mines (47) found that after a short period of rest the heart of Pecten maybegin to beat strongly in a perfusion fluid containing 0*0002 mol. Ce* (see Mines,p. 501). A. Trondle (53a) found that the effect of light upon the permeability ofcertain plant cells is not a progressive change, and the data of this author provideanother analogy to the effect of Ce upon the electrical conductivity of echinodermeggs. That the electrical resistance of tissues is increased during ansesthetisation has alsobeen shown by Aloock (l). He found that the resistance of the sciatic nerve of thefrog is increased by 51 per cent, during ansesthetisation in 50 per cent, ether vapour,and that the change is completely reversed on removal of the anaesthetic.
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