Many of the well-known pathological appearances found in the brain in insanity will, I doubt not, be found to have much more significance than they are thought to have at present, when the general physiology and pathology of the organ is better understood. It cannot be that such serious and enduring marks of morbid action in the parts supplied by the internal carotid and vertebral arteries as thickened and condensed cranial bones, adherent and thickened membranes, congested and toughened vessels, pia mater adherent to convolutions, and atrophied convolutions; all appearances, one or other of which are found in the majority of the insane, and treated almost as matters of course in the asylum dead house—could have arisen without intense disturbance in the working of the delicate neurine that those structures envelop and subserve. We as yet don't fully know what those things mean, as regards the previous condition of the brain. We talk of over-action, congestions, and brain excitement, but such terms are but vague expressions when we closely analyse what they mean. I think we are entitled to conclude that if such things are the accompaniments and effects of the storm on the bulwarks and sails of the vessel, the state of matters in the ship itself, while the tempest was at its height, must have been disturbed enough, could we only have had the means to see it. I have scarcely any patience in arguing with those who will say that there are no pathological changes left in the brains of those who have died insane, when such things are commonly met with, and can be seen by any tyro. It is our capacity to draw conclusions from such things that is at fault; and our means of observation as to the real condition of the minute brain structure. Conceive what dynamical disturbances must have occurred in the working during life of a most highly organised, yet infinitely delicate, jelly-like convolution supplied by a twig of a meningeal artery, during the long period when that twig was becoming thickened in its coats, overstrained at one time by intense congestion, its perivascular space alternately blocked up by débris, and by the overloaded vessel, its blood current now rushing at twice its usual speed, and then in a state almost of stasis. It is vain for anyone to say that such conditions can lead to an organic alteration in the coats of the vessel, and yet that the neurine may be left normal. The fact that all those vascular disturbances and changes were, probably, the result of the morbid vital action in the nerve tissue, and not its cause, were the result of the mere straining of the supply pipe from the irregular demands of the part supplied, should make us realize very vividly the intensity of the pathological disturbance that goes on in the convolutions of a brain that is acutely maniacal.