EXPERIMENTS ON INSECT LIFE. 153 



the spring-time of our lives, and of the year, those especial 

 "times for feeling," when we can say with the poet, 



" One moment now may give us more 



Than fifty years of reason ; 

 Our minds will drink at every pore 

 The spirit of the season." 



Many curious experiments have been tried successfully in 

 the prolongation and curtailment of insect life. In some 

 cases, starvation, that agent, usually, of destruction, has been 

 , found, by retarding the completion of its accustomed stages, 

 to lengthen the journey of existence to our little fellow-trav- 

 ellers. The larva of an aphidivorous fly, placed by Kirby 

 under a glass, w r here it was left inadvertently without food, 

 was found alive three months afterwards, living eight times as 

 long as it would have done in the combined periods of its 

 usual uninterrupted stages. 



Cold was also an agent employed by the French naturalist 

 Reaumur to retard the emergence of butterflies from their 

 aurelian cases, and thus prolong the duration of their life if 

 we may apply the term to a state of apparent torpor. The 

 chrysalis of a nettle butterfly, which usually emerges in a 

 fortnight, being placed, with others, in a cellar, remained 

 two months before exclusion. 



On the other hand, by the agency of heat, the naturalist 

 who, through the exercise of this curious power over life 

 and death, would seem, in a measure, to command nature 



