ELECTRICAL BREAK-EXCITATION. 103 



Although Peltier attributes to this secondary polarisation-current 

 the excitatory effect on breaking- the original, primary current, 

 this hypothesis was discredited by the authority of du Bois- 

 Reymond, and first became known to me on reading through the 

 literature of the subject after I had reached, on the above- 

 mentioned grounds, my conclusions as to the nature of the 

 break-excitation. ' In what way Peltier meant to explain the 

 break-contraction by means of this fact,' says du Bois-Reymond, 

 'it is not easy to understand, since these charges require to all 

 appearances a closed circuit to produce a current through the 

 nerve ; this condition however is lost at break.' 



Now this main objection is no longer valid ; for I convinced 

 myself that in the above-mentioned experiments breaking the 

 nerve-circuit allowed the nerve-current to come into existence by 

 being closed through certain paths in the nerve, and so caused 

 excitation. Although, so far as I know, there are no other 

 similar observations on the excitatory effect of a current whose 

 circuit lies wholly in the nerve, yet it was generally assumed that 

 nerve-currents partly close themselves within nerves 1 . It therefore 

 seemed to me quite incomprehensible that no significance with 

 regard to the break-excitation had been attributed to this secondary 

 polarisation-current, and the more so that this polarisation-current 

 had been recently investigated by various observers under the 

 name of secondary electromotive phenomena 2 . I have lately 

 turned my. attention to this polarisation-current, since in it is to 

 be found, as it seems to me, the real cause of the break-excitation. 

 The results of my investigations may be summed up in few words. 



Unpolarisable electrodes were applied to a nerve or muscle 

 (curarised sartorius) at indifferent points 6-10 mm. apart, and so 

 connected with a Pohl's reverser without cross-wires that in the 

 one position of the reverser the polarising current, of from a given 

 fraction of a Daniell up to three Daniells at the highest, flowed 

 through the nerve, while in the other position the secondary 

 current generated in the nerve flowed through a Wiedemann's 

 galvanometer. Turning over the reverser occupied a fifth of a 

 second on an average. 



I observed, in full agreement with Tigerstedt, that (i) the 

 secondary polarisation- current increases correspondingly to, and 

 approximately in proportion to the strength of the polarising 



1 Of. Hermann, Handbuch der Physiologic, ii. p. 180. 



2 Ibid. ii. p. 164. 



