induced by the current, which assisted the propagation of the excitatory disturbance in a selected direction. On the cessation of this inducing force, there may be a rebound and a temporary reversal of previous molecular arrange- ment, with concomitant reversal of the conductivity varia- tion. The immediate after-effect of a current flowing in a particular direction on conductivity is likely to be a tran- sient change, the sign of which would be opposite to that of the direct effect. The after-effect of a heterodromous current may thus be a temporary depression, that of a homodromous current, a temporary enhancement of con- ductivity.
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Fig. 47. — Direct and after-effect of heterodromous and homodromous currents. Fu-st two records, N, N, normal. 1, enhanced transmission under heterodro- mous current; i arrest of conduction as an after-effect of heterodromous current. Next recoid f shows arrest under homodromous current. Last record •' shows enhancement of conduction greater than norma), as an after- effect of homodromous current. (Dotted arrow indicates the after-effect on cessation of a given current. ^ homodromous and | heterodromous current).
Experiment 43. — This inference will be found fully justified in the following experiment : — The first two re- sponses are normal, after which the heterodromou.-; current
