Electric Impedance of Fertilized Arbacia Egg

In previous work on the alternating current impedance of Arbacia punctulata egg suspensions (Cole and Cole, 1936b), it was found that the unfertilized egg had a static membrane capacity of 0.73/~f./cm. ~ which was independent of the frequency. On fertilization, the low frequency membrane capacity increased to 3.1/~f./cm. 2 and at intermediate frequencies there was evidence of another capacity element. I t was suggested that the fertilization data could be interpreted either by an increased plasma membrane capacity which varied with frequency or by an added high capacity of the fertilization membrane. The latter picture was considered the more probable one, and diagrams of the current flow were subsequently published (Cole, 1937). The present work was undertaken to determine whether or not this explanation was correct.