1902.] Photographic Records of the Response of Nerve. 209 



represent the positions of the ends of the conductors in which a 

 wave of electrical activity originates at the points jh, P2 • • » - Pn 

 respectively. 



Then, neglecting the function /(V), which need not be here taken 

 separately into account, the time of initial change of P.D. between 

 the leads B and A will be t = (pi-b)/v for the wave-front, which 

 will continue moving onwards till t- 2 = (jh -qi)/v, where it will stop, so- 

 far as the conductor denoted by pi is concerned. 



But the P.D. due to the wave-front in those conductors which do 

 not reach the second lead, will not diminish until the tail of the 

 wave, or subsidence of the E.M F., begins at the first lead. This will be 

 when t{ — (pi — b + v9)/v, and since this expression does not contain q,. 

 the second or electro-negative phase begins at the same time for 

 regular as for non-regular bundles. But the second phase will end so far 

 as the conductor denoted by p\ is concerned when t{ = (jh ~ ?i + ^)M 

 the relation (p-q)/v determining whether there is zero between the 

 phases or not. 



It is evident, therefore, that in the case of a bundle of conductors 

 some of which do not reach the second lead, the difference of potential 

 due to the development of the E.M.F. will rise as rapidly as in a 

 regular bundle, but will fall off more slowly, so that the first or electro- 

 positive phase taken by itself may last longer and even be more 

 intense. 



But the second or electro-negative phase, due to the subsidence of 

 the E.M.F. while beginning at the same time as in a normal bundle, 

 will cease in each conductor as soon as it reaches q, causing the curve 

 to tail off in proportion to the number of conductors which come to 

 an end between A and B. 



The function / (tt) merely rounds off the abruptness of the change. 



III. On the Interpretation of the Photographic Records. 



Gathering together the results of the preceding investigation, we 

 find that the expression representing that portion of the P.D. due to 

 the development of the wave of E.M.F. in the bundle is of the form 



and that due to its subsidence, is of the form 



~$lf(% t,p, e,k.Tr, q), 



the time relations of the total P.D. between A and B, being repre- 

 sented symbolically by the sum of these functions, taking t as the 

 variable. 



The object of the present investigation is to find out how far it may 

 be possible under these exceedingly complicated conditions to determine 



VOL. LXX. Q 



