220 



Photographic Records of the Response of Nerve. [Feb. 11, 



firmed by the shape of the curve, which shows a zero pause of about 

 0'0005 second, during which time the wave must have been wholly 

 between the electrodes. 



Accordingly the rise of the electro-positive potential difference is 

 due to the passage of the wave-front (development of E.M.F.) past the 

 first electrometer lead, and the fall of it to the end of the wave 

 (subsidence of E.M.F.) passing the first lead. 



Similarly the first part of the second or electro-negative phase is due 

 to the arrival of the front of the wave at the second lead, and the second 

 part to the cessation of the E.M.F. under the second lead. Hence it 

 may be inferred since (q) is eliminated, that the distance from maximum 

 electro-positive to maximum electro-negative represents the time 





















































































■ 































•OO/s. OOZs 003s. OOfs. -OOSs. -Oo6s. -OOfs. -OOifs. -OQJs. O/Os. -O/te. 0/2-&. 



Fig. 18. — Nerve excited at distallend to eliminate effect of nerve fibres which pass 

 only under one lead. T = 5° C. Leads 3'1 cm. apart. 



required for the response to travel from one lead to another. This 

 gives a velocity, v, of about 1000 cm. per second, and since there is a 

 zero pause of at least 0*0005 second, the whole wave of electrical 

 response from beginning to end cannot have been more than 2 '6 cm. 

 long, and the duration of the electrical effect at each point may have 

 been about 1/400 second. 



It should be noticed that the first part of the electro-positive phase 

 and the first part of the electro-negative last a much shorter time than 

 the end of the electro-negative and the end of the electro-positive. 

 This agrees with what has been already stated about the rapid develop- 

 ment and slow subsidence of the E.M.F. The shape of the second 

 phase indicates that the nerve had been slightly injured near the 

 proximal lead. The smaller E.M.F. is partly accounted for by the 

 fact that although / (q) is eliminated, the short-circuiting due to the 



