Using epidermal layer of an apple, the effect of temperature upon the strength-duration curve of threshold electrical stimulation causing an action current of a certain definite strength was investigated. It was found that the chronaxie is prolonged in a regular manner by decrease of temperature in the region of 3°-25°C., showing an apparent activation energy of 9.9 kcal. On the other hand rheobase is less markedly and rather irregularly modified by temperature change; between 25°and 13°C. it is somewhat lowered and between 13°and 3°C. it is raised by the decrease of temperature.