CHAPTER XXXVI 



A PERSISTENT PARASITE 



members of the animal kingdom change 

 their form in the course of their existence, 

 and with the new structure adopt also a new way of 

 living. Thus the caterpillar and the butterfly, for 

 example, are in reality the same creature, but very 

 different in shape and habits. The caterpillar drags 

 itself heavily over the plant, gnawing the foliage; 

 the butterfly, furnished with light and graceful 

 wings, flies from flower to flower, imbibing a sugary 

 liquor from each with its long proboscis. The 

 cherry worm grows in the midst of the juice that 

 feeds it; after attaining full size it falls from the 

 tree with the damaged fruit and hastens to bury 

 itself in the ground, there to undergo its transforma- 

 tion. Next spring it comes forth in the form of an 

 elegant fly that lives on honey from the flowers and 

 never again touches a cherry except to deposit its 

 eggs therein, one by one. In the same way, again, 

 the nut worm, after finishing its growth, bores a hole 

 in the firm shell, emerges from its fortress, and 

 buries itself for a time in the soil. There it becomes 

 a beetle with a long proboscis, the so-called nut 

 weevil, which leaves its subterranean retreat in the 

 spring and takes up its quarters on the foliage of a 



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