OHAP. XI. CONCLUDING EEMAEKS. 155 



electric condition of the tissue and the development 

 of the force during contraction is in favoui- of the 

 supposition. We are not compelled to assume that 

 any peculiar force exists, or is associated with the 

 muscle distinct from this electric force ; only that the 

 mode in which it exists is brought about by other 

 agencies than those that occur in the inorganic 

 kingdom, viz. by nutrition. It is in these intimate 

 relations and- connections in the dependence of the 

 developement of electric force in the fish, and of 

 muscular contraction upon nerve action, that the 

 strongest evidence for the polar character of nerve 

 force is manifested, and not so much upon the 

 electric condition of its tissue'. 



But, it may be asked, are we justified in sup- 

 posing that nerve force, in nerve action, is entirely 

 independent of the electrie force as it exists in the 

 nerve in its quiescent state? Do we not see, that 

 nerve force bears some relation to the state of the 

 vital powers of the animal, viz. its nutrition? as 

 nutrition is increased or diminished, does not 

 nervous energy increase and diminish in a cor- 

 responding ratio? and have we not emperimental 

 evidence to shew, that the electric state of the tissue 

 {the nerve current) is dependent upon, and varies 



' We must not overlook the oormection which exists between 

 nerve force and secretion. The latter is undoubtedly a polar 

 action, but the influence of nervous action over secretion, 

 although it undoubtedly exists, does not appear to be exerted in 

 so immediate and direct a manner as in the two instances I 

 have just quoted. 



