III. 



AFTER Peltier had demonstrated polarisation in muscle l , du Bois- 

 K-eymond in the year 1 856 showed that internal polarisability is 

 encountered as a widespread property of animal tissues, including 

 nerve and muscle 2 . Later (1867) he proved that this polarisability 

 is incomparably stronger in nerve and muscle than in other bodies 

 moistened with electrolytes, as well as that the strength of the 

 polarisation increases with the duration of the current, up to a 

 limit. This polarisation might arise in two ways. It might be 

 external, at the junction of the muscle with the clay of the elec- 

 trodes ; and it might be in the substance of the muscle itself. 

 He thought it unlikely that the first cause was here capable of an 

 appreciable action. On the other hand, he demonstrated internal 

 polarisability by so placing the electrodes of a galvanometer be- 

 tween those of the polarising current that the galvanometer 

 was not acted on by the muscle while the polarising circuit was 

 closed. After the polarising current had flowed through the 

 muscle a sufficient length of time, with the galvanometer circuit 

 open, the polarising circuit was opened and that of the galvano- 

 meter closed by a switch. A deflection ensued in the reverse 

 direction to that corresponding to the polarising current in the 

 muscle. Du Bois-K/eymond obtained similar experimental results 

 with nerves 3 . 



1 Du Bois-Eeymond, Untersuchungen iiber thierische Elektricitat, i. 1848, p. 376 

 foil. 



2 Ibid. Gesammelte Abhandlungen, i. p. 19. 



3 Ibid. ii. pp. 191-193. 



