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better perhaps are the mediums of changes which give rise to two distinct results, one of feeling one of motion. Hence they are termed sensor and motor nerves. Yet the action of a sensor nerve is most frequently not accompanied with a sensation. The distinction seems to lie in the different termini of the two sets of fibres, closely united as they are in their sheaths and indistinguishable in structure. The sensor nerve starts in a sensor surface, and ends in the gray matter of a ganglion; the motor nerve starts in the same gray matter, and ends in a muscle. The inscrutable changes which take place in a nerve in the transfer of an impression have no more likeness to the sensor or motor result than have the electric states of a wire of a telephone to the sounds at the termini. The simplest action of a nervous system is termed reflex. It is the immediate response along the same bundle of nerves to irritation, by action in the part irritated. Thus the foot is tickled, and immediately withdrawn. The response to stimuli is usually much more complex. A blow is aimed at the face, the attitude is changed, the head turned aside, the arm upraised, the pulse quickened, the eyes closed. There is a consensus of actions in one end. These responses may, without the intervention of consciousness, under organic stimuli, become very complex, the distribution being determined by that plastic power accumulated along the entire line of development. "When these actions pertain to the interplay in functions of the organs of the body, they belong to the organic life. It is the office of this life to institute and sustain these relations. If they pertain to movements directed toward external objects, and still arise from organic stimuli, they belong to the instinctive life. This life has the same base as the organic life, and is hardly more than it. If consciousness intervenes, stimuli pass into sensations, while the responsive actions become still more extended and complex.