OF THE ELECTRICAL ORGAN OF TORPEDO MARMORATA. 
525 
Another strip, 30 mm. long and 4 mm. in thickness. 
Polarising current. 
Duration. 
1 // 
4 
1" 
2 
1" 
4 
A" 
4 
1// 
¥ 
6 Groves ( + ), gal- 
+ 150 
- 40 
+ 110 
+ 30 
- 120 
variometer T q 
- 20 
The strip was now pared down in the direction of the columns, so as to reduce it to 
a long strip only 2 mm. in thickness. 
Polarising current. 
Duration. 
i" 
1'/ 
¥ 
1// 
¥ 
1'/ 
¥ 
6 Groves ( + ), gal¬ 
vanometer T u 
+ co 
+ 400 
- 100 
- 160 
Polarising current. 
Very short. 
Very short. 
6 Groves ( + ), galvano¬ 
meter -jL 
+ 220 
- 50 
In all these cases further experiments with (+) currents gave only (—) after-effects. 
It is obvious that, whereas the ( + ) after-effect obtained with ( —) currents was only 
the ordinary change of electrolytic polarisation, the ( + ) after-effect following (-)-) 
currents was something of a different nature, and was the effect noticed by du Bois- 
Beymond (38). In order to obtain it with more distinctness, it was necessary to use 
stronger polarising currents, but unfortunately more than 6 Groves were not obtainable. 
In considering the question of its production, and especially the characteristics of the 
current which produced it, the essential feature is seen to be the necessity of using 
polarising currents of short duration and great intensity. The reason is probably that 
with these the ordinary phenomena of electrolytic polarisation are not developed in an 
overwhelming degree. If the polarising currents are long, the polarisation after-effects 
are so marked as to swamp every other electromotive change. This being the case, 
the use of strong induction currents at once suggested itself. The experiments of 
du Bois-Beymond with repeated induction currents (39) gave every hope of success, 
and, as the ordinary electrolytic phenomena would be reduced to a minimum, the 
confusion between polarisation and other changes would be largely avoided. 
