1902.] Photographic Records of the Response of Nerve. 219 



And analyses of other photographs — of which examples were given 

 in our paper — show that no new development of E.M.F. takes place 

 until the previous one is over. 



The electrical phenomena of excited nerve and those of the electrical 

 organ of Malapterurus are thus similar as regards these two points, 

 namely, (1) the relative duration of development and of subsidence ; 

 (2) incapacity to show a second electromotive change while the first is 

 in progress. 



Farther confirmation is thus afforded of Professor Gotch's view, that 

 the electrical phenomena of such fish are of nervous origin.* 



Elimination of Fibres ivhich do not reach the Second Lead. 



The function / (q) may be investigated by taking advantage of the 

 fact that a nerve may be excited at either end. If two pairs of exciting 

 electrodes are placed, one at each end of a long nerve, and a pair of 

 electrometer leads between, as far apart as the length of the preparation 

 will admit, the resulting curves will differ according to which end is 

 excited. For when the electrodes at the proximal end are used, every 

 fibre of the nerve is excited, but in the other case only those that reach 

 the distal end are affected. Accordingly, the latter curve though 

 smaller, is more symmetrical, and represents a simpler condition, from 

 which / (q) is eliminated. 



When the proximal end is excited, as in the majority of experiments,, 

 the results are curiously complicated by conditions depending on the 

 rate of propagation, the distance between the electrodes, and in addi- 

 tion their actual position on the nerve. For the ends of the fibres are 

 not evenly distributed along the nerve, but occur in groups wherever a 

 branch has been cut, and the effect of some of these groups can occa- 

 sionally be distinctly recognised in a series of curves from the same 

 preparation. 



When the distal end is excited the resulting curves confirm the 

 conclusion arrived at from my analyses that the development of the 

 E.M.F. at any point is more rapid than its subsidence. A typical 

 illustration of this is given in fig. 18, the analysis of the response of a 

 kept nerve, with leads 3*1 cm. apart, at a temperature of 5° C. 



A complete interpretation of this analysis cannot be given, as the 

 commencement of the response is masked by the movement of the 

 meniscus due to escape of the exciting induction shock, and there are 

 not sufficient data to determine the rate of propagation, v, with 

 accuracy. 



But from other examples it may be inferred that the length of the 

 wave was less than the distance between the electrodes. This is con- 



* See Schafer, 'Text Book of Physiology,' vol. 2, Article by G-otch, "On the 

 Physiology of Electrical Organs," p. 591. Edin. and London, 1900. 



