. Electro-physiology. Electrophysiology. IX ELECTRICAL EXCITATION OF NERVE 171 less pronounced but always perceptible delay in the entrance of the twitch ; (b) the dependence of the magnitude and form of the curve of the twitch upon duration of closure. Both are clearly seen in the graphic tracing of the opening twitch, as discharged with weak currents from the alcoholised nerve. The extent of the delay varies within a considerable range. At times it is hardly perceptible; in other cases the shortening of the muscle is much retarded. The determining factors are here duration and intensity of c
. Electro-physiology. Electrophysiology. IX ELECTRICAL EXCITATION OF NERVE 171 less pronounced but always perceptible delay in the entrance of the twitch ; (b) the dependence of the magnitude and form of the curve of the twitch upon duration of closure. Both are clearly seen in the graphic tracing of the opening twitch, as discharged with weak currents from the alcoholised nerve. The extent of the delay varies within a considerable range. At times it is hardly perceptible; in other cases the shortening of the muscle is much retarded. The determining factors are here duration and intensity of current—the " latent period " being usually reduced as these increase. The " latent period of the opening excitation" is also affected, in alcoholised nerve, by the degree of increase of. JL. FIG. 191.—Alcohol treatment of nerve. Method of experiment as in Fig. 190. Effect of duration of closure upon height of break twitch (II). Break twitch (I) appears quite independent of the same. excitability, so that it usually appears much greater at the beginning of a series of experiments than during their course, even if in this case the influence of the single stimuli following at short pauses (with constant duration of closure) is of more importance. As Pfliiger pointed out, " the phenomenon (of delay) alters after repeated closures, since the break twitch follows more and more closely upon opening, until finally no perceptible interval ; A glance at the opening twitches marked II in Fig. 191 shows the striking dependence of the break excitation upon duration of exciting current under the given conditions of experiment—comparatively slight modifications of current sufficing, on the one hand, to suppress the twitches altogether, on the other to discharge maximal contractions. So far the effect of electrical stimulation upon alcoholised nerve, and upon nerves of which the excitability has been heightened by partial loss of. Please note that th
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