ORIGIN OF MIGKATIOX. Qi 



vital a part in tlic migration of birds, I liavc no explana- 

 tion to olfer. AVe know, however, that it exists n(jt only 

 in birds but in many other animals. It is this instinct, 

 aided by the ^'heredity of habit," which guides a l)ird 

 to its nesting ground. The Carrier Pigeon is taught its 

 lines of Hight by gradually extending its journeys; a 

 species establishes its routes of migration by gradually 

 extendini'" its ranu:e. 



