CHAP. VIII. LAUGHTER. 197 clapped her hands, and the colour mounted to her cheeks." On other occasions she has been seen to stamp for joy.2 Idiots and Imbecile persons likewise afford good evi- dence that laughter or smiling primarily expresses mere happiness or joy. Dr. Crichton Browne, to whom, as on so many other occasions., I am indebted for the results of his wide experience, informs me that with idiots laughter is the most prevalent and frequent of all the emotional expressions. Many idiots are morose, pas- sionate., restless, in a painful state of mind, or utterly stolid, and these never laugh. Others frequently laugh in a quite senseless manner. Thus an idiot boy, incapa- ble of speech, complained to Dr. Browne, by the aid of signs, that another boy in the asylum had given him a black eye; and this was accompanied by " explosions of laughter and with his face covered with the broadest smiles." There is another large class of idiots who are persistently joyous and benign, and who are constantly laughing or smiling.3 Their countenances often exhibit a stereotyped smile; tlieir joyousness is increased, and they grin, chuckle, or giggle, whenever food is placed before them, or when they are caressed, are shown bright colours, or hear music. Some of them laugh more than usual when they walk about, or attempt any muscular exertion. The joyousness of most of these idiots cannot possibly be associated, as Dr. Browne remarks, with any distinct ideas: they simply feel pleasure, and express, it by laughter or smiles. With imbeciles rather higher in the scale, personal vanity seems to be the commonest cause of laughter, and next to this, pleasure arising from the approbation of their conduct. 2 F. Lieber on the vocal sounds of L. Bridgman, * Smith- sonian Contributions,' 1851, vol. ii. p. 6. 3 See, also, Mr. Marshall, in Phil. Transact. 1864, p. 526.