446 The Outline of Science 



admirable Wild Creatures of Garden and Hedgerow. To a 

 young thrush which she has brought up by hand she offered 

 some wood-snails (Helix nemoralis), but he took no interest 

 in them until one put out its head and began to move about. 

 The bird then pecked at its horns, but was bewildered when the 

 snail retreated within the shelter of its shell. This happened 

 over and over again, the bird's inquisitiveness increasing day by 

 day. The thrush often picked one up by the lip, but no real 

 progress was made till the sixth day, when the thrush beat a 

 snail on the ground as it would a big earthworm. At last on the 

 same day he picked up a shell and hit it repeatedly against a 

 stone. He tried one snail's shell after another, until after fifteen 

 minutes' hard work he managed to break one. After that all 

 was easy. He had cracked his first snail. After long trying he 

 had found out how to deal with a difficult situation. We may 

 say, then, that while a certain predisposition to beat things is 

 doubtless inborn, the use of the anvil is no outcome of a specialised 

 instinct, it is an intelligent acquisition." 



The general impression that one gets in regard to the clever- 

 ness of birds in such activities as nest-building, capturing booty, 

 and dealing with food is that on an instinctive basis, varying in 

 definiteness, there is built up a superstructure partly due to easy 

 education and subsequent imitation, and partly due to an intelli- 

 gent appreciation of the lessons of experience. But an apprecia- 

 tion of the relative importance of "nature" and "nurture" requires 

 careful observation and experiment. 



BIBLIOGRAPHY 



BEEBE, The Bird (1907). 



CLARKE, Studies in Bird Migration (1912). 



HEADLEY, The Flight of Birds (1912). 



HUDSON, British Birds. 



KIRKMAN and others, The British Bird Book (1911-13). 



MATHEWS, Field Book of Wild Birds and Their Music (2nd ed., 1921). 



NEWTON, A Dictionary of Birds (1896). 



