EXPERIMENTS ON INSECT LIFE. 335 



and say if life be computed by the amount of actual living, by 

 state, which, to mind, often annihilates and stands in the place 

 of time, by spiritual measurement instead of by finger calcula- 

 tion whether the balance of longevity, in its proper sense, 

 may not incline rather to the span of twenty than of sixty years. 



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-travellers. 

 The larva of an aphidivorous fly, placed by Kirby under a 

 glass, where 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 unin- 

 terrupted 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 can 

 abbreviate instead of prolonging the term of existence. En- 

 closing his chrysalides in the interior of a glass egg, Reaumur 

 called in the assistance of a brooding hen to hatch the butter- 

 flies he willed into a prematurity of perfect form, some of which 

 appeared, accordingly, in four, instead of fourteen, days. 



From experimental facts and philosophical deduction, the 

 lively French naturalist wanders into imaginative speculation 

 on the probable results of some such life-influencing power in 

 its application to the human race. First, in the case of abbre- 

 viation : " A child," he remarks, " would have little reason to. 



K K 



