Injuries of nerves and their consequences - Reflex Sympathetic ...

44 INJURIES OF NERVES.
now we remember that electricity travels at a rate of
462,000,000 feet per second, we shall see how difficult it
is to assimilate these two modes of motion. As regards
reflex impressions, the difficulty is still greater, because
most of these move slower than the excitations which
cause voluntary motions, and are often so much retarded
as to be capable of estimate by far coarser means than
those employed by Helmholtz and Donders.
I shall elsewhere have occasion to point out, when
studying nerve injuries, how this question of the rate at
which nerve force moves may come to possess practical
value in determining the possible seat of the originating
thus much of in-
lesion. Just now, the matter has only
terest. In certain pathological spinal conditions the speed
of nerve force is so strikingly lessened as to be capable of
rough estimate by a metronome beating quarter seconds.
In some instances, this slowing reaches at least five seconds,—
a deofree of retardation which no alteration of
conductors will enable us to realize as regards electrical
currents. So that if we had only this fact as to relative
speed, it alone would oblige us to believe that these two
forces are absolutely distinct, and that they possess only
such relationships as exist among the other natural forces.
The conclusions thus reached are sustained by the later
researches of Marey, who, however, puts the rate of nerve
force at about half of that assigned to it by Helmholtz.
He also sees in these facts an argument against the
unity of nerve and electric force, but remarks that Gaugain
has shown that electricity in passing through moistened
threads has so low a rate of movement as to make
him still hesitate concerning the question of possible
identity. In another place I have pointed out the need
for some such experiments on bad conductors with electricity
of low tension; but the problem can only be
definitely settled by a careful determination of the rate