various excitants, the contraction of each particular one of these little muscles. Again, by observing those ready-made experiments which we call diseases, he learned what takes place when some of these muscles contract while others are inactive. In this way he has been enabled to see, most clearly, that the contraction of each muscle of the face determines a certain invariable expression; that is to say, that each passion seems to have at its command a facial muscle which contracts so soon as the soul is moved by this passion. M. Duchenne discourses as follows about the muscle of suffering (souffrance), as he calls the muscle whose contraction indicates pain. "From the very outset I had observed that the partial movement of one of the motor muscles of the eyebrow always produced a complete expression in the human face. For instance, there is one muscle which expresses pain—the superciliary muscle. On causing this to contract by electricity, not only did the eyebrow assume the form expressive of pain, but the other parts and features of the countenance, particularly the mouth and the naso-labial line, seemed also to undergo a profound modification, so as to harmonize with the eyebrow, and, like it, to give expression to this painful state of the soul." So, then, other muscles appear to share with the superciliary in the expression of suffering. M. Duchenne, however, believes that he is authorized by his experiments in holding that the muscular region of the face directly modified by a single passion is very circumscribed. But this modified region acts by a sort of sympathy on the adjacent regions precisely as one color modifies the tint of the colors all around it; and, just as, in the latter case, there is caused an optical illusion, the result of what Chevreul calls the simultaneous contrast of colors, so with the muscular movements of the face there is produced a kind of mirage which modifies, complicates, and seems to dilate a movement whose real sphere is very restricted. However this may be, M. Duchenne has succeeded in reproducing, by contractions called forth in a certain number of the facial muscles, nearly all those expressions which answer to the inner states of the soul, and he has thus been enabled to assign to each muscle a psychological in addition to its physiological name. Thus, the frontal muscle is the muscle of attention, surprise, wonder, and alarm, and each of these emotions excites it in a different way. The great zygomatic and the inferior orbicular muscles are the muscles of joy, while the pyramidal muscle of the nose is the muscle of aggression, and so on. In general, the muscles of the eye are adapted to expressions of the higher order, and those of the mouth to expressions of a more gross and material kind. The purely self-satisfied and sensual smile calls into play only the zygomatic muscle. It is the contraction of the inferior orbicular that gives to the expression of contentment and pleasure a character of good-nature and benevolence. Besides the primary expressions resulting directly from the play of one muscle, M. Duchenne finds that several
