510 
me. f. gotch oft the electromotive properties 
Excitation of nerve 25 millims. from organ. 
Closure .... 
•011"--012 
•011"--013" 
Deflection 
+ 20 
+ 220 
The mean of these readings gives '0055" as the time occupied by transmission down 
40 centims. of nerve—that is to say, the nervous impulse travels down the trunk of 
the electrical nerve at the rate of 7‘3 metres per second. 
This is practically the same result as that obtained by Jolyet (27) with vigorous 
summer fish, and gives substantial confirmation of his statements as to the slow rate 
of transmission in the electrical nerves of the Torpedo. 
Experiments upon the Time of Delay. 
When we have made the necessary deduction for transmission time, we find that an 
interval between excitation of nerve and response of organ still remains. In the 
particular experiments just given this amounts to '006". This is the “ temps perdu,” 
or time of delay, and we now pass to experiments having reference to the influence 
upon the length of this period of varying conditions of the organ itself. The principal 
conditions which affect the response in this respect—that is to say, which affect its 
commencement—may be considered under three heads :—(1) The temperature of the 
organ ; (2) the strength of the nerve stimulus which evokes the response ; (3) the 
vigour of the particular organ under investigation, and thus the vigour and size of the 
fish. 
(1.) Influence of temperature—A. ready means of altering the temperature of the 
organ was secured by the use of a long water-box, through which water at different 
temperatures could be run, and which supported on its surface the organ preparation. 
To prevent any galvanometric disturbance through the metal of the box, the metal 
was covered with thin paper soaked in melted paraffin. 
A nerve-organ preparation was made from a large Torpedo, 50 cm. X 34 cm., and 
placed upon the tubes in such a way that, whilst the organ rested upon the warming 
apparatus, the nerve hung free in air. Rheotome observations were made every 
five minutes, so as to allow time for shifting the keys, it being necessary to catch 
the beginning of the response. The organ was at 5° C. at the commencement; it 
was warmed to 20° C. by allowing water at 45° to flow through the apparatus, 
and when the quickening-up of the response had ceased it was re-cooled. The result 
is given in the following Table. In the first experiment the nerve was excited 
45 millims. from the organ, so that yyo-y” must be deducted from the interval 
as transmission time. With this deduction the time of delay is only yyyyo” with an 
organ at 20° C., whereas it is tooo // to t ( yj f' when the same organ is at 5° C. 
In Experiment 2 the time of delay is to be reduced to Tfio'd ' a t a temperature 
of 20° C., from yoyo” at a temperature of 5° C., the transmission time being -0005'. 
