METAMORPHOSIS. 219 



larval stage that the organism acquires the potential 

 energy that keeps the species alive. 



The above explanation seems to me to account 

 not only for insect metamorphosis, but also for the 

 curious cases of extremely long larval life and very 

 brief maturity, such as the Ephemera and seventeen- 

 year locust (Cicada septemdecim). The great length 

 of the larval life of the latter is probably due to the 

 unchanging conditions of its existence underground, 

 especially the sameness of temperature and the dark- 

 ness. In this connection, another curious fact sug- 

 gests itself, namely, that the wings of certain ants 

 drop off after the hymeneal flight, a few hours after 

 the completion of development, which is ended by 

 the emergence of the young ants from their cells. 

 Apparently, the wings are developed through the 

 strength of the hereditary impulse.- Long-continued 

 habit has made it necessary for the ants to fly up in 

 the air for the act of reproduction. For this, wings 

 are necessary, and, by virtue of their powerful associa- 

 tion with the reproductive act, they are still retained 

 among the associations of the hereditary impulse, 

 though they are otherwise degenerate organs, and 

 not developed by the worker ants. That they should 

 drop off immediately after the hymeneal flight, seems 

 to be a curious case of the transference of a degen- 

 eration backward as far as possible without interfer- 

 ing with the reproduction of the species. 



