72 THE PLAY OF ANIMALS. 



Be that as it may, we may explain by such degenera- 

 tion of instincts the countless cases which have caused 

 such men as Wallace to doubt whether there is any in- 

 stinct at all. In his chapter on The Philosophy of Birds' 

 Nests, Wallace has collected observations intended to 

 prove that birds do not come into possession of their 

 songs by inheritance, but learn them individually. Bar- 

 rington caged young linnets with singing larks, whose 

 song they learned so well that, even when placed with 

 other linnets, they did not change them. A bullfinch 

 sang like a wren and without any of the characteristics of 

 its own kind, and similar results were obtained from the 

 wheat-ear, fallow-finch, nightingale, and woodpecker. 

 " These facts," says Wallace, " and many others which 

 might be quoted, render it certain that the peculiar notes 

 of birds are acquired by imitation, just as a child learns 

 English or French, not by instinct, but by hearing 

 the language spoken by its parents." * This sounds 

 very convincing, but it is first to be considered that the 

 use of the voice is instinctive, and then that imitation 

 itself is instinctive, of which more is to be said below; 

 and, finally, that the experiment failed with young birds 

 taken from the nest when only a few days old, for they 

 could never be infiuenced again in the same way by later 

 experiences. The song of birds is no doubt a mixed 

 phenomenon in which instinct and experience blend, f 



Such advancement of the evolution of intelligence 

 as we have been considering is favoured also by play, as I 



* Wallace, Contributions to the Theory of Natural Selection, 

 in loc. 



t [This conclusion is strongly supported by the researches of 

 Lloyd Morgan. See his Habit and Instinct.] There is evidence, 

 too, that complicated songs are produced without teaching. Sim- 

 ple calls like those of the cuckoo and quail are purely instinctive. 



