212 NATURAL HISTORY. [cH. XIV- 



practised. Neither did immersion in spirits of wine 

 prevent the completion of the change. The insect 

 burst through its trammels, and instantly perished. 



This operation must not be compared, however, 

 to the one by which we throw off a simple vest. 

 The aerial insect has no need of those implements 

 with which it dug its little cavern, and lived and 

 moved in the waters ; consequently all those parts 

 peculiar to the aquatic insect, such as teeth, pincers, 

 the air-fins, and all its wonderful play of organiza- 

 tion, are cast away in a moment by the prodigal 

 hand of nature. 



The females of the ephemera seem to be born 

 only to perpetuate their species, and accordingly, as 

 soon as they can use their wings, so soon they be- 

 gin to lay their eggs ; a creature whose life in a 

 perfect state is comprised in a iew hours, cannot 

 afford to waste the precious moments ; nature, 

 therefore, has foreseen and contrived that her ob- 

 ject should be thoroughly attained in the shortest 

 time ; and few insects are more prolific than the 

 ephemera. They lay about eight hundred eggs, 

 nevertheless they are deposited in a shorter time 

 than another insect would consume in laying only 

 one. The creature is so organized, that the whole 

 of its eggs are neatly arranged into two packets, 

 each a quarter of an inch long, and about one line 

 broad, and are glued together in each pocket by a 

 cement soluble in water ; and these are ejected at 

 the same moment. Is there no design manifested 

 in the arrangement of this part of the insect's or- 

 ganization, no forethought displayed in regulating 

 the exigences of its functions to the shortness of 

 its life 1 



These two bunches of eggs are deposited by the 

 parent in the water, where, from their greater specific 

 gravity, they sink to the bottom, and the grains sep- 

 arate ; so great, however, is tlie necessity of laying, 

 that instinctive selection does not appear to have 



