206 Proceedings of Royal Society of Edinburgh, [april 18. 
polarising stream, a curve be constructed whose ordinates correspond 
to amount of change of the polarisation, the abscissae representing 
time of flow, this curve is found to have a maximum ; i.e ., when 
the current is kept constant, the effect first increases with the time, 
and then diminishes. Here the stimulus is, of course, also kept 
constant. 
3. The effect increases, within limits , ivith the density of the 
polarising stream. — The curve plotted with current density as 
abscissa, and amount of stimulation effect as ordinate, also reaches a 
maximum, when the time of flow is kept constant. 
4. The effect is less, as might be expected , the longer the interval 
between breaking the polarising current and closing the galvanometer 
circuit. — The persistency of it is sometimes, however, astonishing. 
5. The effect increases with the strength of the stimulus. — Result 
No. 1 has an important bearing on Hermann’s explanation of the 
apparent diminution of resistance in a tetanised nerve, which I 
propose to discuss at another time. 
I must add that, in the case of a strong current, result No. 4 does 
not always hold, the nerve apparently requiring some time to regain 
its maximum of excitability. 
