530 
MR. E. GOTCH ON THE ELECTROMOTIVE PROPERTIES 
The effect entirely disappears when the tissue is immersed for 15" in hot water. 
The effect being obviously an excitatory one, it is conceivable that it is nothing 
more than the response of the organ to the excitation of the nerve branches contained 
in the tissue. A strip of organ contains a very large number of nerve fibres, which 
may be traversed by the induction shock, and, if so, may be excited ; on the other 
hand, the result may be due to excitation of the plates themselves. Any such 
confusion in the case of muscle and nerve is obviated by the use of curare, but this 
drug does not appear to be applicable to the Torpedo (40). In order, then, to deter¬ 
mine whether or no the after-effect is a nerve-organ response, its character must 
be determined precisely as that of the true nerve-organ response has been determined 
—namely, by the rheotome method. The presence of the induction shock during the 
first three hundredths of a second is, however, a serious difficulty in the prosecution of 
such rheotome experiments. It is, however, quite easy to determine the relative 
values of the effect as disclosed by closures of from •03" to '05" and from '05" to ‘07" ; 
and it appears that the effect is always visible during these periods, but, though quite 
appreciable, it is not so strong as the nerve-organ response would be at the periods in 
question, especially when we take into consideration the magnitude of the total effect. 
Thus the largest nerve-crgan response was imperceptible with the galvanometer 
(too shunt) after an interval of one second. In the experiment to be next given the 
after-effect was so large that after an interval of one minute it was perceptible with 
the galvanometer jJo shunt. There should, therefore, be a very large effect if the 
galvanometer circuit be closed for from •03"- - 05" after the excitation. As a matter 
of fact, the effect is small under these conditions. 
Strip of Tissue from Small Torpedo. Six Groves in Circuit of Primary Coil. 
. . . . + 420"j 
. . . . + 190 | 
. . . + 70 )• 15" readings. 
. . . . + 30 
.... + 10 
Closure. 
•03"--05" + 50 
■03"-07" + 250 
It had been ascertained that, with a closure of '03"-’05", the passage of the 
induction shock, through the electrodes only, produced no galvanometric effect; the 
deflections were thus undoubtedly due to the presence of the after-effect. The amount 
of the after-effect from •03"- - 07" shows that in this case there was an increase between 
‘05" and '07". This was, however, by no means a uniform result. In the first of the 
two experiments to be next referred to the after-effect was equal during the two 
periods, in the second it was greater during the earlier closure. 
Secondary coil, 9'5 cm. ( + ) G. T Xy 
„ 8 cm. ( + ) g. T y 
55 55 (T) 55 
