206' EXPRESSION OF JOY: CHAP. VIII. If! must be large; and it is perhaps to gain this end that the corners are retracted and the upper lip raised. Al- though we can hardly account for the shape of the mouth during laughter, which leads to wrinkles being formed beneath the eyes, nor for the peculiar reiterated sound of laughter., nor for the quivering of the jaws, neverthe- less we may infer that all these effects are due to some common cause. For they are all characteristic and ex- pressive of a pleased state of mind in various kinds of monkeys. A graduated series can be followed from violent to moderate laughter, to a broad smile, to a gentle smile, and to the expression of mere cheerfulness. During excessive laughter the whole body is often thrown back- ward and shakes, or is almost convulsed; the respira- tion is much disturbed; the head and face become gorged with blood, with the veins distended; and the orbicular muscles are spasmodically contracted in order to pro- tect the eyes. Tears are freely shed. Hence, as for- merly remarked, it is scarcely possible to point out any difference between the tear-stained face of a person after a paroxysm of excessive laughter and after a bitter cry- ing-fit.15 It is probably due to the close similarity of the spasmodic movements caused by these widely different emotions that hysteric patients alternately cry and laugh with violence, and that young children sometim.es pass suddenly from the one to the other state. Mr. Swin- hoe informs rne that he has often seen the Chinese, when suffering from deep grief, burst out into hysterical fits of laughter. 15 vSir ,T. Reynolds remarks (* Discourses,' xii. p. 100), " It is cxiriotis to observe, and it is certainly true, that the extremes of contrary passions are, with very little varia- tion, expressed by tbe same action." He gives as an in- stance the frantic joy of a Bacchante and the grief of ,a Mary Magdalen.