182 THE SURVIVAL OF THE UNLIKE. [vil. 



endeavor to occupy the vacant places. Weeds and 

 undergrowth come up thickly in the new clearing and 

 bluebirds and sparrows build where the woods' birds 

 once lived. But these disturbances have innumerable 

 secondary and remote influences, which grow fainter 

 as they recede, like the ripples which follow the cast- 

 ing of a stone. The felling of the trees not only de- 

 stroys the forest, but destroys ,the food upon which 

 certain animals live, and these animals may have been 

 the food of other animals, which must now decrease, 

 and this will allow the prey of these latter animals to 

 increase, and so the changes run on and on until lost 

 in complexity. Man is now the most disturbing ele- 

 ment upon the face of the earth. Wherever he goes, a 

 train of modifications and complications follows. We 

 need not be surprised, therefore, at Wallace's obser- 

 vation that the more old maids the heavier the clover - 

 seed crop, for the maids protect the cats which destroy 

 the mice which rob the nests of the bumble bees which 

 pollinate the flowers. 



We are now prepared to admit that this whole 

 question of enemy and friend is a relative one. It 

 does not depend upon right and wrong, but simply 

 upon our own relationship to the given animals and 

 plants. An insect which eats our potatoes is an enemy 

 because we want the potatoes, too; but the insect has 

 as much right to the potatoes as we have. He is 

 pressed by the common necessity of maintaining him- 

 self, and there is every evidence that the potato was 

 made as much for the insect as for human kind. Dame 

 Nature is quite as much interested in the insect as in 

 the man. "What a pretty bug!" she exclaims ; "send 

 him over to Smith's potato patch," But a bug which 



