NERVOUS SYSTEM. 163 
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 umited, 
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 sirength. 
* See Monro’s Anatomy, vol. iii. p. 113. 
