Electrical polarity of the amphibian egg and its reversal through fertilization

Summary

• 1. The egg protoplasm of the unfertilized egg of the frog possesses a negative charge. A certain potential gradient exists in the egg cell along the polar axis, and possibly also along some other axes of the egg.

• 2. The vegetative pole of the unfertilized egg ofR. temporaria andarvalis is negative to the animal pole while in unfertilizedesculenta-eggs the sign of electrical polarity seems to be an opposite one.

• 3. A reversal of electrical polarity takes place intemporaria andarvalis after fertilization; the sign of polarity seems to remain constant througout the course of further development.

• 4. Reversal of electrical polarity seems to follow immediately activation of the egg.

• 5. Ether causes the same reversal of electrical polarity in unfertilized eggs of all the three species, and inesculenta distilled water acts likewisc.

• 6. An idea is advanced of some correlation existing between the physicochemical structure of the egg and its “morphogenetic” structure, both of them resulting from local differences in metabolic processes going on in the egg-cell.