124 



THE UNIVERSE. 



In certain caterpillars the digestive power is so great 

 that they swallow every day three or four times their own 

 weight of food. If the elephant and rhinoceros were to 

 feed on this scale, and Avere as numerous as the others, 

 they would only require a very short time to devour all 

 the vegetation on the globe. 



The first period of an insect's life is devoted to develop- 

 ment, to nutrition, and frequently it is only during this 



71. Head aiid Juws of the Caterpillar. — From Lyonet, "Anatomical Treatise on the 

 Wilhjw-eating Caterpillar." 



time that it cats in the gluttonous manner we have just 

 spoken of When it has reached adult age it seems to 

 have no other object in its existence than reproduction; 

 sometimes even the alimentary canal is obliterated, and 

 the animal takes no nourishment. The caterpillar, with 

 its destructive jaws, the perdition of our harvests, is trans- 

 formed into a butterfly, the harmless proboscis of which 

 only imbibes the nectar of flowers.^ In its last stage the 



^ See a more special reference to this form of metamorphosis at page 146. 



