. Electro-physiology . FIG. 188.—Effect upon excitability, of local treatment with salt at the kathode. Transition from descending closure twitch to closure tetanus. tetanus (Fig. 188) at every closure of the current in the direc- tion indicated, which at first disappears again completely on opening the circuit, but is persistent at later stages of the NaCl effect, when of course further observations are impossible. At a time when, after application of NaCl to the electrode proximal to the muscle, a weak descending current already discharges a vigorous closure tetanus, the closure of the same
. Electro-physiology . FIG. 188.—Effect upon excitability, of local treatment with salt at the kathode. Transition from descending closure twitch to closure tetanus. tetanus (Fig. 188) at every closure of the current in the direc- tion indicated, which at first disappears again completely on opening the circuit, but is persistent at later stages of the NaCl effect, when of course further observations are impossible. At a time when, after application of NaCl to the electrode proximal to the muscle, a weak descending current already discharges a vigorous closure tetanus, the closure of the same current in the opposite direction yields, as a rule, only a simple twitch, which cannot in time-relations or magnitude be distinguished from the closure twitches discharged under the same experimental con- ditions by local application of NaCl. This fact is by no means without interest, since it shows that, as regards the magnitude of final result from the excitation of any point of the nerve, it is a matter of indifference whether the " excitatory wave " discharged passes through a tract of nerve already in a condition of heightened excitability, or no. The opening of weak ascending currents has, as a rule, no effect after local application of NaCl at the anode, although on
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