Transmission of action potentials inBiophytum

By cooling or by electrical stimulus an action potential, (60 to 100 mv negative) was propagated throughout the length of a pinna-rachis or a peduncle ofBiophytum sp. A cutting stimulus evoked a series of two to four transmission of actions of action potentials. The transmission did not pass through the base of the leaf or peduncle. The velocity of the transmission in the rachis and penduncle was about 0.2 cm/sec, and no difference in the velocity was found between the acropetal and basipetal directions. In the stimulated site a local response (a negative bulge of potential) was seen with threshold stimulus. The absolute refractory period for the transmission of action potential was estimated at 20 to 50 sec, and the relative one at 30 to 70 sec. The mechanism of the transmission seemed to be similar to that inMimosa pudica.