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not simply that sleep is partial and disturbed. Such a state, indeed, affects the character of dreams, and deepens their impression, and thus aids us in recalling them; but does not seem to be their cause.

A third fact looking to the same conclusion is the familiar one of talking in sleep, though the person on waking retains none of the impressions which occupied the mind. In such cases, mental activity is fairly shown to exist without corresponding recollection. The dog even will bark in his sleep, tickling the motor nerves with some tantalizing image of cat or rabbit.

Allied to this is the fourth general proof furnished by somnambulism in all its forms. In these cases, the mind acquires a partial control of the body, and, while leaving the senses chiefly at rest, guides and stimulates its muscular powers. The wonderful precision and daring with which this is sometimes done evince great calmness and activity of the faculties, enabling them to reach results impossible to the frightened, swimming senses. Of this character are those familiar instances in which the somnambulist passes through positions of great peril without failure or disturbance. A student in my own college class had been greatly interested and perplexed by a difficult problem. He could not hit upon its solution. He retired to rest, and, in the night, rose in his sleep, and wrought it out on the board in the room. There, to his astonishment, he found it in the morning, the whole labor having left not the slightest trace in the memory.

A fifth fact looking in the same direction, is that testified to by Sir William Hamilton, and open to anyone's verification: " I have always observed that when suddenly awakened during sleep (and, to ascertain the fact, I have caused myself to be roused at different seasons of the night), I have always been able to observe that I was in