36 NATURAL HISTORY. [cH. I*. 



but the fact is, that there are numerous distinct spe~ 

 cies among these white butterflies, varying in the 

 time of their appearance and distinctive marks. 



When we consider, moreover, that it is during the 

 caterpillar state that the insect takes its chief nour- 



ishment, and that in the butterfly state it sips only 

 the nectar of flowers, it will be evident that no in- 

 crease of size could be expected to take place in the 

 latter portion of its life. It is true that by various 

 circumstances (such, for instance, as depriving the 

 caterpillar of its proper supply of food), a butterfly 

 may be prevented from acquiring the full size of the 

 species to which it belongs ; but as soon as its 

 wings are expanded it has acquired its full size, and 

 would not grow a single hair's breadth wider or' 

 larger if it were to live as many months as its dura- 

 tion in the perfect state is confined to days. 



