Last year I said: "There is a growing sentiment that many diseases not heretofore regarded as nervous (and perhaps all diseases) are of nervous origin." This truth, that all pathologico-histological changes in the tissues of the body are degenerative in character, and, whether caused by a parasite, a poison, or some unknown influence, are first brought about by or through a changed innervation, is one that is being accepted very largely by the best men in the profession, and the accumulation of facts is increasing rapidly, and the acceptance of this great truth will prove to be little short of revolutionary in its influence on the treatment of the disease. This is the outgrowth of the study of disease from the standpoint of the evolution hypothesis. Derangements of function precede abnormalities of structure; hence the innervation must be at fault before the organ fails. Hence the art of healing should aim at grappling with the neuroses first, for the local trophic changes, perverted secretions, and structural abnormalities are the effects or symptoms, not the causes of the disease. Dr. J.L. Thudicum has studied the chemical constitution of the brain, and he holds that, "When the normal composition of the brain shall be known to the uttermost item, then pathology can begin its search for abnormal compounds or derangements of quantities." The great diseases of the brain and spine, such as general paralysis, acute and chronic mania, and others, the author believes will all be shown to be connected with special chemical changes in neuroplasm, and that a knowledge of the composition and properties of this tissue and of its constituents will materially aid in devising modes of radical treatment in cases in which, at present, only tentative symptomatic measures are taken. The whole drift of recent brain inquiry sets toward the notion that the brain always acts as a whole, and that no part of it can be discharging without altering the tensions of all the other parts; for an identical feeling cannot recur, for it would have to recur in an unmodified brain, which is an impossibility, since the structure of the brain itself is continually growing different under the pressure of experience.