EXTRACT XXXIX. A. 

 ON NERVE FORCE, OR ENERGY. 



NERVE energy is a form of force sui generis, yet difficult to 

 differentiate and distinguish from some other modes of 

 force, except that it can be produced in, and by, one form 

 of structure only, and, so far as we at present know, can 

 act or operate functionally through that structure only. 



In its essential nature it is different from, yet resembles, 

 electricity, and can, in some minor degrees, be replaced by 

 it, but in all essential respects it is, as we have said, a mode 

 of force sui generis. The principle of vitality, or life, is 

 inseparably bound up with it, although vitality, or life, is 

 observable over a large proportion of the animated world, 

 where nerve force, as nerve force, may, or can, be inferred, 

 but does not definitely exist. 



It may, however, be inferred from these remarks, and 

 the facts on which they are based, that the force animating 

 and sustaining the lower forms of life or those in which 

 no nervous system has as yet been developed or the 

 principle of vitality, is no other than the force which in the 

 upper regions of the organic world becomes concentrated 

 and focussed, so to speak, and requires for its production, 

 storage, and usage, a series of structures known as the 

 nervous system ; therefore, the nerve force can only be 

 vital force. 



In this connection, we have thought it likely that sensory 

 impressions conveyed from the periphery, if unexhausted on 

 arrival at the receiving nerve cells, may be conserved there, 

 as in a " Leyden jar," for future use, as motor impulse, 

 or " food for thought," or exhausted and used up in 



