Abstract
1. Employing toad's myelinated nerve fibres as material and TASAKI-FRANK'S method of action potential recording, examinations were made on the action potential of single nodes of Ranvier in NaCl-, LiCl-and mixed solution.
2. In pure NaCl or LiCl solution, the size of the action potential increases simply and similarly with concentration, while, in a mixed solution where NaCl concentration is fixed, a maximum appears in the size at a certain LiCl-concentration. The maximal value is incomprehensively large.
3. The threshold is higher and the spike duration somewhat prolonged in the neighbourhood of the maximum.
4. Positive after-potential was observed occasionally in normal ionic condition, and much more clearly in mixed solutions.
5. It was supposed that the mechanism of action potential production must be much more complicated than believed usually.
The author wishes to express her sincere gratitude to Prof. K. YAMAGIWA and Prof. M. ICOMKA for useful advices and constructive criticisms throughout the present study, and for their kind help in preparing the manuscript.
