VARIATIOX OF INSTINCT IN DEFINITE LINES. 225 



among animals, but it may be said in general that, as the 

 faculty of imitation depends on observation, it is found in 

 .greatest force, as we should expect, among the higher or more 

 intelligent animals — reaching its maximum in the monkeys, ' 

 where, us is well known, it passes into ludicrous extremes. 

 And in this connection it is interesting to observe that 

 a child begins to imitate very early in life, and that the 

 faculty goes on developing during the first year or eigliteen 

 months, after which it remains stationary for a time, and is 

 then of much service in developing language.* With growing I 

 intelligence, this faculty subsequently declines, and in after 

 life may be said to stand in an inverse relation to originality 

 or the higher powers of the mind. Therefore among idiots 

 below a certain grade (though of course not too low), it is 

 usually very strong and retains its supremacy through life, 

 while even among idiots of a higher grade, or the " feeble- 

 minded," a tendency to undue imitation is a very constant 

 peculiarity. The same thino- is conspicuously observaljle in 

 the case of many savages ; so that in view of all these facts 

 we must conclude that the faculty of imitation is one very 

 characteristic of a certain area of mental evolution, and there- 

 fore that within the limits of this area it must conduce in no 

 small degree to the formation of instinct.f 



* See Preyer, loc. cit., pp. 176-182, where a number of detailed obsei'- 

 vatioiis on this head are given. He says that the first imitative movement begins 

 as early as the fifteenth week in protruding the lips when anyone perform-; 

 this action before tlie child. [This action see ns to come naturally to young 

 children, and may I think probably have some hereditary connection with the 

 same movement as so strongly pronounced in the orang outang. For a picture 

 of such protrusion in this animal, see Darwin Expression of Emotions, p. 141.] 

 Towards the end of the first year imitative movements become more numerous 

 and more quickly leaimt, and the child takes active pleasure in their perform- 

 ance. At twelve months Preyer observed his child repeating in its dreams 

 imitative movements which had made a strong impression on it wliile awake-, 

 — e.g., blowing with the mouth. Later still, complicated imitative movements 

 are performed for mere amusement, as is apparently the case with monkeye. 



t With reference to imitation in connection with instinct, I think it is 

 desirable here again to express my opinion already given in Animal Intelli- 

 gence, on the theory published by Mr. WalLice, in his Natural Selection, 

 that" the nidification of birds is due to the young b rds consciously imitating 

 the structure of the nests in which they have themselves been reared — the 

 characterislic nidification of each species of bird being thus maintained. I 

 have advanced in Animal Intelligence sundry general considerations, which I 

 thought sutficient to negative this theory on a priori grounds ; but since theii 

 I have found among Mr. Darwin's MSS a letter which describes the results 

 of the test experiment which Mr. Wallai-e himself suggests. This experiment 

 is to rear young birds from the egg in an artificial nest or incul^ator unlike 



P 



