24 The Bible of Nature 



level we marvel at an instinctive skill whose ex- 

 pression is unconscious art; finally, we are face to 

 face with an intelligent behavior which seems at 

 once a caricature and prototype of our own con- 

 duct. 



Let us recall, for a moment, just one of the 

 wonders of animal behavior the wonder of mi- 

 gration. There is the migration of those birds 

 that "know no winter in their year," "wild birds 

 that change their season in the night, and wail 

 their way from cloud to cloud down the long 

 wind." What journeys they take the Arctic Tern 

 was found by the "Scotia" explorers in the Far 

 South! How swiftly they fly, how confidently 

 across the pathless sea, at night, at a great alti- 

 tude. How strange that the young birds usually 

 fly away first in the autumn, without waiting for 

 those who have made the journey before. How 

 striking the fact proved for some birds that 

 they may return from their winter-quarters to the 

 garden where they spent the summer. 



Or take as another instance of migration the 

 life-history of the common European eel. It be- 

 gins its life below the 500 fathom line on the floor 

 of the deep sea in that dark, cold, calm, silent, 

 plantless world; it passes to the surface as a 

 flattened, transparent larva and lives an open-sea 

 life for over a year, not eating anything, and grow- 

 ing rather smaller as it grows older; it becomes a 



