102 



CHAP. IX. 



MIGRATION OF BIRDS. SWALLOW SUBMERSION AND 



MIGRATION. THE CUCKOO. THE STORK. THE 



NIGHTINGALE. STARLINGS ON THEIR RETURN 

 FROM MIGRATION. MIGRATION IN THE INSECT 

 WORLD BUTTERFLIES. THE LOCUST. CONTEM- 

 PORANEOUS PHENOMENA. INSTINCT. CONCLU- 

 SION. 



THE migration of some birds is a very curious part 

 of their natural history, and it is an essential one : 

 the fact is indubitable, but the solution of the 

 problem, in reference to the predisposing cause,, is not 



" Who bids the stork, Columbus-like, explore 



Heavens not its own, and worlds unknown before ? 



Who calls the council, states the certain day, 



Who forms the phalanx, and who points the way ? " 



As is the case with torpid animals which cannot 

 migrate, migratory birds retire before the severe season 

 has chased the insect race into their cocoons and 

 chrysalis forms. They take their departure while 

 warmth yet animates the atmosphere, and insects 

 dance in the sunbeam or flutter over the mantled pool, 

 the excitement, therefore, must proceed from 

 some subtile principle, and yet the change of clime 

 must be linked with the question of a supply of 

 food. " Not one of these is forgotten," before HIM 

 without whose permission " not a sparrow falls." 

 Such a presentiment, therefore, was essentially neces- 



