negative expression, but the nervous energy generated flows freely and directly to the organs which are to do service, without greatly impairing general function. Fear thus acts at first simply and advantageously; but in its later history fear becomes greatly complicated, and instead of freely issuing in serviceable action with not excessive heightening or depressing of any function, its outlet seems as it were choked, and the nervous energy spends itself within the body in violent disturbances of vital organs. Fear becomes then decadent and loses its place as evolutionary factor, becoming impediment rather than aid to progress. Negative expression must then be considered as especially notable in the later exhibitions of an emotion when concentration becomes morbid and ineffective, losing its advantageousness, and the emotion is being supplanted by other psychic factors. Great injury and death itself may result from the abnormal action of fear and other primarily useful psychoses. Besides the particular organs to serviceable activity with the subsidiary physiological functioning, and the indirect depression, we must still note other principles which may control expression. Nervous energy under the incitement of emotion is often in excess of the demand for the required action, and it will then overflow into correlated activities along the line of least resistance. Also when the suitable action is checked for any reason, its motive force backs up and overflows in new channels. Indefinite and purposeless movements of various kinds thus result which may be expressive of the emotion of which they are incidentally the result. Any one who has watched an Irish setter tracing game must have remarked the wavings of the tail becoming more rapid when the scent becomes stronger. When the dog is running very fast, the tail-waggings are less noticeable than when moving slowly, although the interest may seemingly be the same in both cases. It is obvious that a fast run uses to a large extent the superfluous energy which was discharging in tail movements, and when the useful running is checked the tail motion recommences with greater force, serving as a safety-valve. The frisking of young animals and children is also largely due to diffusion of so-called superfluous nerve-force, and is expressive of general sensations of pleasure. All feeling is motor in its natural value and tendency, and unless the resulting energy is fully used in some special serviceable action, it will discharge itself along the easiest and most habitual lines laid down by inheritance. Thus the peculiar ancestral experience of animals is always expressed by their spontaneous diffusive activities. It will be remarked that the principle of diffusion is the reverse of negative expression, being an overflow of force as opposed to withdrawal. Excessive generation of energy is certainly uneconomical, and we must consider that at first emotion