154 NERVE FORCE. CHAP. XI. 



of the manifestation of electric action in the nervous 

 tissue during nerve action, if nerve action be, as it 

 is supposed to be, merely the result of the electric 

 force of the tissue being converted into current 

 force. 



Let us not hastily conclude that nerve force is 

 totally distinct from electric force, or that it bears 

 no relation to it or the other polar forces, such as 

 magnetism, for example. We appear to be in a 

 position somewhat similar to the physical philo- 

 sophers prior to the discovery of Faraday of magneto- 

 electricity. So long as they confined their experi- 

 ments to the mere application of the electrodes of 

 the galvanometer to the two ends of the magnet, 

 no result was obtained ; the necessary evidence, the 

 connecting link, was wanting ; and we may now be 

 in a somewhat similar position. I am not now sup- 

 posing, or going so far as to say, that it must be by 

 means of the galvanometer that this necessary evi- 

 dence, the connecting link, is to be obtained ; it may 

 be by some other fact totally unconnected with the 

 galvanometer that the connection will be shewn. 

 We have sufficient evidence, however, to shew, that 

 an intimate connection exists between nerve force and 

 electric force, viz. in the development of the electric 

 force in the fish, in the dependence of the former 

 upon the will of the latter. We may also refer to 

 the relation that exists between nerve force and 

 muscular force. We have strong evidence for be- 

 lieving that muscular force is a polar force; the 



