NEKVOUS SYSTEM. 



it probably consists of different filaments, each acting their 

 peculiar part. This appears to be demonstrated in those 

 cases where a nerve, upon being cut, has afterwards united, 

 and, while capable of executing the action of volition, has 

 become unfit for that of sensation. 



It would be to no purpose to enquire into the nature of 

 that action which is excited in the nerve, either in sensa- 

 tion or volition, because the subject is yet in obscurity, 

 and its elucidation, perhaps, impracticable. The rapidity 

 with which the functions of the nervous system are exe- 

 cuted, have induced some to consider its action as per- 

 formed by means of some fluid similar to electricity, 

 secreted by the medullary matter, and restrained by the 

 tunics of the brain and nerves. All this may be true, but 

 it is without proof. Others, from contemplating the effects 

 of electricity, on the parts of dead animals, have conclud- 

 ed, that the nervous and electrical fluids were identical. 

 There is, however, one experiment, easily performed, which 

 proves the fallacy of this conclusion. The nervous energy 

 is suspended or destroyed by the compression or section of 

 the nerve, while the electrical matter is not arrested in its 

 progress, provided, in the latter case, the cut ends of the 

 nerve are brought in contact *. 



The effects of electricity on many of the organs concern- 

 ed in the vital functions, in exciting them to action, may, 

 at first sight, favour the supposition of its identity. Thus, 

 the action of the lungs, heart, and stomach, may be con- 

 tinued for a short time, after the natural nervous influence 

 has been removed. In these cases, however, although elec- 

 tricity can act on the irritability of the muscles, it is proba- 

 bly through the intervention of the nervous filaments, and 

 may be occasioned by exciting the languishing energies of the 

 inju red nerves, to expend the remainder of their strength. 



* See MONRO'S Anatomy, vol. iii. p. 113. 



