220 ELECTRICAL INFLUENCE 



upon each other. It has been thought that the structure 

 of the brain presents an analogy to that of the galvanic 

 battery, and the nerves represent the conducting wires. 

 Although, however, some of the conditions appeal- 

 similar, there are many which have no representatives 

 in either the mechanical structure or the physical 

 properties of the brain, so far as we know it. That the 

 brain is the centre, the source, and termination of sen- 

 sation is very clearly proved by physiological investi- 

 gations. That the nerves are the media by which all 

 sensation is conveyed to the brain, and also the instru- 

 ments by which the will exerts its power over the 

 muscles, is equally well established. But to say that we 

 have any evidence to support the idea that electricity 

 has aught to do directly with these great physiological 

 phenomena, would be a bold assertion, betraying a want 

 of due caution on the part of the investigator. That 

 electric effects are developed during the operations of 

 vitality is most certain. Such must be the case, from 

 the chemical changes taking place during respiration 

 and digestion, and the mechanical movements by which, 

 even during external repose, the necessary functions of 

 the body are carried on. Whether electricity is the 

 cause of these, or an effect arising from them, we need 

 not stop to examine, as this is, in the present state of 

 our knowledge, a mere speculation. We have no evi- 

 dence that electricity is an exciting power, but rather 

 that it is one of those forces which tend to establish 

 the equilibrium of matter. When disturbed when its 

 equilibrium is overset it does, in its efforts to regain 

 its stability, produce most remarkable effects. An 

 electrical machine must be rubbed to exhibit any force. 

 In all galvanic arrangements, even the most simple, 

 dissimilar bodies are brought together, and the latent 

 electricity of both is disturbed ; and, even in the magnet, 

 it is only when this takes place that its electrical powers 

 are developed. In the Gymnotus, electricity appears to 



