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

NEURO-PHYSIOLOGY. 45
at which the nerves themselves act as electrical conductors.
At present the weight of evidence, as I have
said, is opposed to the idea of the oneness of these two
modes of motion.
The property of being excited, which, following Lewes,
Yulpian calls newility, is common to all nerves. Sensitive,
motor, reflex, nutritive, or sympathetic filaments, all alike
have one and the same property, with no greater difference
than exists between the physiological properties of diiierent
muscular tissues.
There seems, indeed, to be every probability that however
aroused and whenever, in sensitive or motor nerves
the vis nervosa does not vary in its nature. As regards the
nerve fibres themselves, it is likely that their anatomical
similarity, which is very great, whatever be their function,
represents a greater likeness in physiological effects
than would at first sight seem possible. We are well
aware that the sensitive and afferent nerves when irritated
or normally stimulated seem to carry messages only
in a centripetal direction, while of motor nerves the
reverse holds true. There are, however, many facts
which tend to show that irritation of any portion of
either a motor or sensory nerve is propagated alike in
both directions, central and peripheral, so that the nerves
only appear to carry messages in one direction, because
only at one end is either set provided with organs which
have the power to announce the reception of an impression.
It is probable, therefore, that if in any nerve of
mixed function we could suddenly connect the sensitive
fibres with the motor centres at one end and the muscles
at the other, that we should still have these latter effectively
called into pla}^ while of the motor fibres a like
statement would hold equally good.
This view, which might for a long while back have been
sustained on theoretical grounds, has received positive