CH. XIV.J EPHEMERA OR MAYFLY. 211 



gin to extricate themselves from their skin is inva- 

 riably the same ; and there is another hour fixed, 

 later than which it is not permitted them to com- 

 mence their task. In less than two hours these 

 insects quit the water, form immense clouds, fall in 

 thick and continuous showers, and then leave the 

 air. It is in vain to venture to conjecture on the 

 nature of these influences, which act on such myr- 

 iads of living beings simultaneously. The fact that 

 the wonderful and complicated organs of such myr- 

 iads of isolated insects should be set into motion at 

 once for purposes which are evident, incontestably 

 excludes ail idea of chance, and proves order and 

 design." 



No insect executes an operation at once so im- 

 portant and laborious with equal celerity. We do 

 not draw our arms from the sleeves of a coat more 

 quickly than the ephemera extricates its body, 

 wings, legs, and the long caudal appendages, from 

 a sheath in which these various parts are folded 

 and cramped up. We could hardly expect that an 

 insect, which, when perfect, is so frail and delicate, 

 could exert in its imperfect state so much force as 

 the act of getting rid of its larval skin appears to 

 demand. It would seem, however, that the address 

 and strength necessary to effect its emancipation, is 

 supplied at the moment of need by a power inde- 

 pendent of the will of the insect. Swammerdam's 

 experiments prove that every part of the body of the 

 insect is in itself capable of its full development. 

 He detached a wing still enclosed within its larval 

 skin r it immediately unfolded itself, and attained 

 all the natural dimensions which it would have ac- 

 quired had it still remained in its natural situation, 

 communicating with the vessels of the insect's 

 body. Reaumur crushed the head of these crea- 

 tures while in the very act of transformation ; nev- 

 ertheless the metamorphosis was performed with 

 the same celerity as if the cruelty had not been 



