OF THE GALVANIC CURRENT ON THE MOTOR NERVES OP MAN. 
971 
pretation is likewise a supposition tliat the phenomenon signifies invasion of katelec- 
trotonic by anelectrotonic region (physiological) with increasing strength of the 
galvanic current. The increased excitability is in the peripolar region, the excitation 
is in the polar region in which excitability is diminished. The difficulty with which 
this phenomenon is brought into evidence, in comparison with its converse, is accounted 
for by the supposition that in the converse case we have to deal with the invasion of 
peripolar anelectrotonic by polar katelectrotonic region, and in the present case with 
invasion of polar anelectrotonic by peripolar katelectrotonic region. The difficulty is 
due to the pain caused by the strong galvanic current required, and to the tetanus 
which such a current evokes, so that the increase appears only when the conditions 
are exceptionally favourable to electrical density in the peripolar region as compared 
with density in the polar region ; we noticed in effect that when this increase was 
brought about, kathodic polarization of increasing strength effected increase in the 
effect of the induction anode without preceding diminution. The difference between 
the augmentation of the faradic anode under the influence of the galvanic kathode and 
that of the faradic kathode under the influence of the galvanic anode may be formally 
stated as follows. 
10. The increasing effect of the combined faradic anode and galvanic kathode takes 
place with a weaker galvanic current than that of the combined induction kathode and 
galvanic anode; the increase is greater and more rapid in the former case than in 
the latter\ 
We record finally, under these statements relating to the break induction current, 
an observation relating to the make induction current, because it was a salient feature 
in our experiments with the ordinary arrangements of the coil, and because its mention 
emphasises the superiority of the kathode of the make induction current combined 
with the kathode of the galvanic current, over all other combinations of the two poles. 
11. With the ordinary arrangement of the coil used there was no contraction to the 
make induction current with all combinations and all strengths of the induction arid 
galvanic currents , except the combined anode of the break induction current (i.e., kathode 
of the make induction current) and kathode of the galvanic current. 
The interpretation of this fact is identical with that for the kathode of the break 
induction current when also kathode of the galvanic current. Excitation thus coincides 
with increased excitability in the polar region. 
B. Polar alterations of excitability tested by the make induction current 
In order to use make induction currents as the test of excitability, we modified 
the coil after the method of Henry, using 30 Leclanche cells and a resistance of 
100 ohms in the primary circuit; the results differed in no respect from the results 
previously obtained with break induction currents, and it is therefore only necessary 
to add that we have verified all the above statements for the make as well as for the 
