Abstract
From the reports of Matsumoto Masao and others, it will be assumed that there would be no refractory period about the cathodic contraction of a single muscle fiber. But there is no work, which intended to assure this problem experimentally. The author, therefore, carried out the experiment to determine if the cathodic contraction would have any refractory period or not.
In the experiment, a single fiber separated from M. sartorius etc. of the bullfrog was used and was fixed in the so-called Sugi' s isolating vessel. The stimulating current was led to the Ringer's solution of both sides in the isolating vessel by means of non-polarisable electrodes. The experimental results are : (1) When two induction shocks were applied successively with nterval of 1, 0 msec, then the contraction grade was compared with that of for single shock. So it was shown that the.contraction height was always greater in the former case than in the letter. Thus the refractory period would be smaller than 1, 0 msec, if it existed. (2) A single fiber was stimulated with two right auglar currents having same intensity but different duration (0, 01 and 0, 05 sec). So the contraction grade for the current of long duration were greater than that of for the short duration. The current of long duration can be considered as two currents which whrch were given successively with zero intervai. Accordingly, it is, possible to conclude that there is no refractory period.
On account of these experiments, it was cleared that there was no refractory period on the cathodic contraction of a single muscle muscle fiber.
