500 
MR. F. GOTCH ON THE ELECTROMOTIVE PROPERTIES 
preceding ones. It was immersed in hot water for two seconds, and the difference 
two minutes afterwards was found to be + '0192 R. 
This experiment left no doubt as to the possibility of producing effects comparable 
with those of thermal section by an analogous mode of injury, and it is to be remarked 
that the electromotive change produced is the greater, the longer the columnar strip. 
This is due to the fact that the number of electromotive elements operated upon is 
proportional to the length of the strip. 
Another experiment was made upon a strip cut from a medium-sized Torpedo, and 
measuring 25 mms. in length and 3 mms. in thickness and breadth. This strip was 
kept in the cold for one hour and then examined; the difference was found to be 
+ '0021 Pt. It was now immersed for a few seconds in hot water and re-examined, 
when the difference had increased to as much as + '0226 Pi. 
Since the effect is produced by injury of the plates, which injury causes an electro¬ 
motive change in the plates such that the ventral aspect of the plate is negative to the 
dorsal, it must follow that, whether the injury extends along a whole column or only 
along a small portion, the effect is always of similar direction and character. 
The electromotive plates respond to the local excitation of injury as they do to 
nerve excitation, but the response in the former case is comparatively feeble, and 
is very prolonged. Wherever the injury may be, the effect must, therefore, be that 
the dorsal surface of the column is positive to the ventral surface. If, for instance, the 
dorsal half of a column be immersed in hot water, the effect must be of similar 
character to that produced by total immersion, and the same must be the case if the 
ventral half be immersed. The difference between partial and complete immersion is 
merely a difference in the amount, not in the direction of the effect produced, the 
amount being proportional to the number of electromotive elements affected. 
Thine strips were cut from the organ of a large Torpedo, each measuring 20 mms. in 
length of column, and 3 mms. in thickness and width. The first strip, when examined 
half-an-hour after its preparation, showed a difference of + '0091 R. The dorsal half 
of the strip was immersed in hot water for two seconds, and the difference rose to 
+ '0209 It. The second strip showed a difference of + '0084 R.; the ventral half of 
this was immersed, and the difference rose to + ’0254 R. The third strip was wholly 
immersed, and the difference amounted to '0340 R. 
In another experiment upon a strip cut from a medium-sized Torpedo, the columns of 
which measured 25 mms. in length, the strip was found to show a difference, an hour 
and a half after its preparation, amounting to -f- ‘0007 R. The dorsal fourth of the 
strip was immersed for two seconds, and the difference rose to -f- '003 R.; as soon as 
possible the ventral fourth of the same strip was immersed, and the difference rose to 
+ '00G5 R. ; the whole strip was now immersed, and the difference rose to + '0228 R. 
These results justify the statements which preceded them, and show that, whatever 
the part injured, the effect is the same, the organ-current being always similarly 
directed through the columns, namely, from the ventral to the dorsal surface. 
