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awake. Sleep is the universally necessary period of repose and rehabilitation. It is a question whether, viewed from its psychic side, it implies the abolition or only the iminution of consciousness. Locke maintained the former, Hamilton the latter thesis. The truth probably is that consciousness may be represented under the similitude of a conical figure. To be wide awake, is to be aware of all that can be embraced by its largest circumference, the base; to be fast asleep, is to be aware of nothing, or the contents of its smallest circumference, really a circumference no longer except by courtesy, the point which constitutes its apex. Between these extremes there is room for every possible degree of consciousness as testified to by the personal experience of various witnesses. But all testimony upon the continuity of consciousness is subject to the important qualification that, if there were a lapse of consciousness for a period of any length whatever, it would not be an element of conscious memory. In cases of syncope the thread of conscious experience is resumed exactly where it was broken off, so that a sentence, begun before a railroad accident, has been completed weeks after its occurrence, the injured person in the meantime lying apparently lifeless in a hospital. That some persons believe themselves to be continuously conscious, even during sleep, is, therefore, a fact easily explained. It seems paradoxical to say that we are conscious of our unconsciousness, but this is not the position of him who denies continuity so much as of him who assumes that if we were unconscious we would be conscious of it. The only true test must be objective, and judging by this we must conclude that, although insomnia may be protracted in abnormal cases, it is never manifested in normal experience as a strictly continuous consciousness, and even in abnormal cases is by no means so complete as the patient fancies. The foregoing are the leading physiological conditions of consciousness. It needs only to be added that the integrity of the cerebral organ in general is essential for normal consciousness. Whatever tends to destroy this, whether the agent be toxic or mechanical, disturbs the unity and harmony of the psychic life and, if carried to an extreme, ends in