INTRODUCTION 23 



If we examine the brush instead of the open wood 

 we meet animals just as interesting and characteristic ; 

 and instead of the field we might have taken the 

 meadow, the moor, or the quarry. 



So the life of the pond differs entirely from the life 

 of the brook and the great river. Nay, we might even 

 confine ourselves to the tiniest compass, and examine 

 only a drop of water hanging from the moss. We 

 should find that even in this little realm there are 

 hunters and hunted, and that countless living things 

 find the conditions of their life within these narrow 

 limits. 



Every animal seeks what it needs for its maintenance, 

 if not exclusively, at all events mainly, in the particular 

 region in which it lives. The wood-pecker will not 

 leave the wood, for this alone provides him with 

 food in its trees and a sure place for nesting ; nor are 

 river-fishes ever found in ponds. 



But all animals are not confined to one region. The 

 deer leaves the thicket in the evening to feed in the 

 green meadows ; the partridge seeks cover at times in 

 the wood ; the water-beetle of the pond may alight in 

 running water in its nocturnal flight. 



Other animals have a different habitation at different 

 periods of life. 



The young frogs swim about merrily in the water, 

 and resemble fishes in appearance and habits. After- 

 wards the long oar-like tail is lost, the feet sprout out, 

 and the frog assumes the form of a land- animal. It 

 lurks for flies at the edge of the pond, and only leaps 

 into its earlier element on the approach of danger. 



