SENSATION AND PAIN. THE limits of a singIe lecture are too small to give any adequate idea of the complicated structures and processes by which we experience what we call sensation and pain. But my primary object being to obtain some practical deductioils froin certain basic facts connected with thc phenomena of sensation and pain, rather than to entertain you with a detailed exposition of the subject, I must beg your attention while I give, as necessary to a proper understanding of conclusions which will be ultimately arrived at, a brief outline of some of the main and primary facts of nerve-structure and nervous action. In doing this, I shall not enter any debatabIe ground, as between physiologists and metaphysicians, but shall simply lead you a little way over a very common road.