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

40 INJURIES OF NERVES.
study of this seuse has been made, it is impossible to carry
such comparisons further. In the lower animals the dorsal
skin seems, in some cases, to possess little or no feeling,
so that I have actually made incisions through this part
in dogs and rabbits without seeming to produce any pain
whatsoever. The interior organs are variably provided,
as to the pain sense, some of them appearing to have little
or none of this form of sensibility ; yet in all, even in the
bones and intestines, lie remote capacities for torture
which seem capable of development in the presence of
diseased states.
Are we to suppose that there exist always
in these
organs pain nerves, and that only once, perhaps, in a lifetime
these filaments are to be aroused into activity
?
Or,
as regards the skin, how shall we deal with the like difficulty
if we choose to believe that everywhere are peculiar
nerve fibres devoted only to transmitting painful sensations?
The skin, in this view of the case, must have a
set of nerves so rarely used that it is. diificult to comprehend
how they can sustain their organic life uninjured,
and ready to awaken into functional activity at long and
irreo-ular intervals.
I am unwilling, in view of these facts, to look upon pain
as a distinct sense with afferent tracks peculiar to itself;
and when we consider also how sensory impressions made
on nerves purely of special sense may rise to the height
of being painful, it becomes more and more probabte that
pain is the central expression of a certain grade of irritation
in any centripetal nerve.
There is, indeed, every probability that the sensory
nerves are competent to carry inward a variety of impressions,
which, owing to the peculiar nature of the excitations
they cause in the nerve, are capable of appreciation
only by the separate centres devoted to their perception,
so that pain, touch, and thermal excitations may need, in