240 Proceedings of Boy al Society of Edinburgh. [sess. 
These results suggested that it might he still better to put elec- 
trodes B and C in contact, so as practically to make them one elec- 
trode. Of course it was here necessary to attend to compensation 
even more strictly than before ; for the danger of a direct escape 
of current was greater than before ; hut so long as the galvanometer 
circuit was fully compensated, even such an escape would introduce 
no error. 
Experiment 5 gives an example of this method. 
Experiment 5. 
Polarising Current. 
Stimulation 
Effect. 
1 D Rh. 1000 cm. f 
- 80 
1 D Rh. 100 t 
+ 6 
After 30" closure. 
- 18 
„ T „ 
- 22 
„ 2' „ 
- 28 
} 5 ^ , , 
- 35 
„ 4' „ 
- 38 
„ 5' „ 
- 43 
15" after opening polarising current. 
2Df 
-110 
-133 
30" after opening. 
3 D t 
? 
Owing to unsteadiness, difficult to 
read amount, but certainly less 
than - 100. 
3 D l 
-117 
20" after opening. 
+ 255 
-215 
Another reading. Current kept 
closed for 5' before readings taken. 
+ 48 
30" after opening. 
With 1 D Rh. 100 f a small positive deflection was got. I 
have a good many times observed that when the nerve is perfectly 
fresh, the polarising current very weak, and the reading taken very 
soon after closure, a positive stimulation effect is got on the side of 
the cathode. This would suggest that the conductivity around the 
cathode is not reduced immediately on closing such a current, hut 
may even he increased. This agrees with what I saw occasionally 
when stimulating in the middle of the intrapolar area, with the 
muscle attached. Sometimes with weak currents the descending 
was more favourable than the ascending for. getting Contraction. 
This never happened when the currents were fairly strong. 
Werigo also, in his experiments on intrapolar stimulation, quite 
