MUSCLES, NERVES, AND ELECTRICAL ORGANS. 199 



In a third communication Matteucci returns to the extrapolar 

 electrotonic currents, and there, as usual, repeats his statements 

 on this subject many times with all kinds of variations 1 , through 

 which it is useless to follow him. On the polarisability of nerves, 

 however, he founded his conception of extrapolar electrotonus cur- 

 rents as being escape-currents, which spread from the anode along 

 the anelectrotonic tract externally, and reach the kathelectrotonic 

 tract by the axis cylinder, along the outside of which they return 

 to the kathode : all of this he imitated by a platinum wire covered 

 by a moist coating. If such a wire is laid on a pair of electrodes, 

 extrapolar diffusion of current occurs according to the law of 

 electrotonus, but is absent when zinc wire covered by a coating 

 steeped in sulphate of zinc has been employed. As is well known, 

 this is the theory which has since been taken up by Hermann, to 

 whose experiments on internal polarisation of nerves we now come. 



15. Hermann's Researches on Nerve Polarisation. 



In his paper of the year 1867, in which Hermann first advanced 

 his necrosis hypothesis, he gave a philosophical 2 explanation of 

 electrotonus in connection with this hypothesis, according to which 

 a current opposed to the polarising current predominates in the 

 intrapolar tract, which is comparable to Peltier's counter current 

 in a thermopile through which an external current is passing. In 

 this supposed coincidence Hermann saw a striking confirmation of 

 his speculation and a new support of his view 3 . 



In my confutation I contented myself with exposing a flaw 

 in the series of conclusions by which Hermann believed that he 

 could connect his conception with the law of the conservation of 

 energy 4 . I had reasons for not withdrawing the veil from the whole 

 subject of the secondary electromotive actions of nerves with which 

 only I- and a few initiated people, such as Pfliiger, were acquainted. 



1 Comptes rendus etc., 16 September, 1861, vol. liii. p. 503; 20 Avril, 1863, vol. 

 Ivi. p. 760 ; 22 Juillet, 1867, vol. Ixv. pp. 131, 195 ; Annales de Chimie et de Physique, 

 3 me Serie, vol. lix. p. 385 ; Electro-Physiological Eesearches, Eleventh Series, Philo- 

 sophical Transactions, etc., 1861, p. 363 ; Proceedings of the Eoyal Society, vol. xi. 

 p. 384; Philosophical Magazine, etc., 4th Series, vol. xxiv, October, 1862, p. 311 ; 

 Corso di Elettro-Fisiologia in sei Lezioni, date in Torino ec., Torino, 1861, 



P. 59- 



2 [The word used is ' naturphilosophisch,' which cannot be rendered in English. (Tr.)] 

 s Weitere Untersuchungen zur Physiologic der Muskeln und Nerven, Berlin, 1867, 



p. 40. 

 4 Gesammelte Abhandlungen, vol. ii. p. 341. 



