[287]. The clear recognition of individual objects is said to show itself in average cases from about the sixth month (Tracy, op. cit., pp. 15-16).
[288]. With the smile there ought perhaps to be taken the infantile crow.
[289]. Darwin puts the first true smile on the forty-fifth day. The first quasi-smiles are probably quite mechanical and destitute of meaning.
[290]. See above, p. 195 and p. 308.
[291]. Compare what was said above, p. [201].
[292]. Darwin tells us that his boy uttered a rude kind of laugh when only one hundred and ten days old, after a pinafore had been thrown over his head and suddenly withdrawn. C.’s sense of humour was hardly as precocious as this.
[293]. Preyer’s boy perfected the action in the fifth month. For differences in precocity here, see F. Tracy, The Psychology of Childhood, pp. 12, 13.
[294]. This should be read in connexion with Study V.
[295]. This rather bald account of early vocal sounds should be contrasted with those of Preyer and others referred to in Study V.
[296]. Perez speaks of both the affirmative and negative movement of the head appearing about the fifteenth month (First Three Years of Childhood, Engl. transl., p. 21). Darwin finds that the sign of affirmation (nodding) is less uniform among the different races of men than that of negation. According to Preyer, while the gesture of negation appears under the form of a turning away or declining movement as an instinct in the first days of life, the accepting gesture of nodding (which afterwards becomes the sign of affirmation) is acquired and appears much later (see his full account of the growth of these movements, Die Seele des Kindes, p. 242).