532 



NERVE. 



the algebraic sum of two electromotive changes, and the isolated com- 

 ponents must be inferred from the time relations of the whole effect. 



The curves a, b, c, and d, e t f, marked by thin lines in Fig. 271, repre- 

 sent the proximal and distal change respectively. They would produce 



by their combination the 

 observed diphasic effects 

 indicated by the strongly 

 marked lines enclosing 

 the shaded area. In the 

 diagram the abscissae 

 represent time, and the 

 ordinates the extent of 

 galvanometric deflection 

 when the circuit was 

 closed at different mo- 

 ments after excitation. 

 It is noteworthy that in all Hermann's results the distal electromotive 

 change and the proximal one are slightly different ; these differences are 

 such that the total area of the two curves, a, b, c, and d, e, f, are the 

 same, but the forms of the two are not absolutely identical. 1 



In the non-medullated nerves of Octopus and Eledone, the slower 

 rate of transmission has enabled Boruttau to observe similar diphasic 

 effects with the rheotome method of galvanometric observation. The 



1 The analysis of such electrometer curves as those outlined in Fig. 270, 7, IV, 211, 

 gives the following results : 



FIG. 271. After Hermann. 



