CHAP. XX. 



HELIGOLAND. 



259 



impulse, to which the descendants of migratory birds 

 were subject in spring and autumn, which has during 

 the lapse of ages acquired a force almost, if not quite, 

 as irresistible as the instinct to breed in spring. Ou the 

 other hand, the direction in which to migrate appears to be 

 absolutely unknown to the young birds in their first autumn, 



VIEW OF HELIGOLAND. 



and has to be learnt by experience. The idea that the 

 knowledge of where to migrate is a mysterious gift of Nature, 

 the miraculous quality of which is attempted to be con- 

 cealed under the semi-scientific term of instinct, appears 

 to be without any foundation in fact. It appears that each 

 individual bird has to find out its proper winter quarters for' 



. 



