12 PHYSIOLOGICAL ÆSTHETICS.
and liver, considerable disintegration often takes place before
the patient experiences painfid sensations. Here we have
to deal with viscera mainly supplied with nerves from the
sympathetic ganglia, or possessing independent systems of
their own, and inasmuch as, in the vertebrata, the cerebro¬
spinal system is the sole seat of consciousness, it follows that
Pain can only be felt in these organs when the disintegration
reaches portions of them or of adjacent tissues which are
supplied with cerebro-spinal fibres. The inter-communica¬
tion between the two systems is, however, so intimate and
intricate that internal diseases exhibit the greatest apparent
capriciousness in their painful or painless character. Lastly,
direct experiment has shown that if the cut end of an
efferent nerve in unbroken connexion with the brain be
irritated, no consciousness of any sort ensues. We may
therefore add to our previous rough generalization the limit¬
ing clause—provided the tissue be supplied with afferent
cerebro-spinal nerves in unbroken connexion with the
brain.
But does this generalization include all classes of Pains,
and if not, to which particular species does it apply ? Pro¬
fessor Bain has well divided Pains into two main classes,
the Massive and the Acute. The former are those which
arise from affections of the whole organism, or large tracts
of it, and are weak in intensity: the latter, those which
arise from affections of special limited areas, and are strong
in intensity. Now the above enumerated Pains, which have
for their physical antecedent a disintegration of tissue,
belong for the most part to the Acute class. It is to this