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