Now in all sleep there is more or less somnambulism, because the brain, according as the sleep is more or less profound, is more or less removed from the sphere of action. If this quiescent state of the brain is accompanied, as it frequently is in nervous and excitable persons, by an exalted condition of the spinal cord, we have the higher order of somnambulic phenomena produced, such as walking and the performance of complex and apparently systematic movements; if the sleep of the brain be somewhat less profound, and the spinal cord less excitable, the somnambulic manifestations do not extend beyond sleep-talking; a still less degree of cerebral inaction and spinal irritability produces simply a restless sleep and a little muttering; and when the sleep is perfectly natural, and the nervous system of the individual well balanced, the movements do not extend beyond changing the position of the head and limbs and turning over in bed. As regards the power of the spinal cord to supply the nervous force requisite for the performance of such actions as those specified, I do not think there can be any question. Much observation and many experiments have convinced me that the importance of the spinal cord as a center of intellection and volition has been unwarrantably ignored. It is of course not a matter for doubt that the faculty of consciousness is latent in the spinal cord so long as the brain is in a state of activity, and that the faculty of memory does not reside in it at all. When the brain acts, it ordinarily assumes the control of the cord; but there are times, especially during the course of certain diseases, when the latter obtains the mastery over the superior organ and dominates with terrible power. The actions initiated by the spinal cord are more or less automatic in their character--though not altogether so. The motions of a frog deprived of its brain, show a certain amount of intellection and volition. That they are not more extensive is probably due to the fact that all the organs of the senses, except that of touch, have been removed with the brain. In persons engaged in intense thought and performing actions not in accordance therewith, the impressions made upon the organs of the senses are not appreciated by the brain, but pass through its substance to the spinal cord with which they are in connection by continuity of structure, and which initiates the subsequent actions. In the somnambulic individual the brain is still more incapable of receiving sensorial impressions. Whatever sense is therefore exercised during the condition of somnambulism, owes its activity to the spinal cord; but in most cases of the state in question, the brain is so profoundly asleep that it does not even transmit impressions to the cord, and hence there are no sensations at all, except that of touch, unless the irritations capable of exciting them are extraordinarily great.