Present researches were udertaken for the purpose to elucidate the appearance of potential difference of the apple skin, which has been used as the representative material among various vegetable inenihrane by niany investigators. For to lead the potential across the apple skin, we used Ringer's solution aid other salts solutions, and the potential defferences were mensured by Poggendorf's method utilizing the Lead-Nornhroup's potentiometer. Effects of concentrations of various ions upon the potential defference were observed and that results were not far from those of Beutner, Locb. Fuzita and Motokawa. We could ascertain the“independent effect of ion”which was discovered by Beutner concerning with his“Öl-Kette”, also in the case of apple skit. But it was failed to observe such effect when H _??_ or SCN' were used When we led the E. M. F. from the apple shin by NaCl solution, there oceured quasi-perzodieal change of the potential, which resembled to tie discovery of Ifashida, who found out that when Li _??_ was applied to th outer surface of the frog skin there appeared rhythinical chanbes of potential difference. In the cane of apple skin, the periol of such potential change induced by Na' was about 4.5 minutes.