Microscopical Essays. 



189 



f, Aptera. Thefe have no wings, as fpiders, lice, acari, 

 &c. 



Of the Transformation of Insects. 



Infects are further diflinguifhed from other animals by the 

 wonderful changes that all, except thofe of the aptera clafs, pafs 

 through. Moft animals retain, during their whole life, the fame 

 form which they receive at their birth; but infects go through 

 .wonderful exterior and interior changes, infomuch that the fame 

 individual, at it's birth and middle ftate, differs effentially from 

 that under which it appears when arrived at a ftate of maturity ; 

 and this difference is not confined to marks, colour, or texture, 

 but is extended to their form, proportion, motion, organs, and 

 habits of life. 



The ancient writers on natural hiftory were not unacquainted 

 with thefe transformations, but the ideas they entertained of 

 them were very imperfect, and often erroneous. It was not till 

 towards the latter end of the laft century that any juft conception 

 of this fubject was formed, and the my fiery was then unveiled by 

 thofe two great anatomifts Malphigi and Swammerdam, who 

 obferved thefe infects under every appearance, and by differing 

 them at the time juft. preceding their changes, were enabled to 

 prove that the moth and butterfly grow and flrengthen them- 

 felves, and that their members are formed and unfolded, under 

 the figure of the infect we call a caterpillar ; and they alfo (hewed, 

 that it is not difficult to exhibit in thefe all the parts of the future 

 moth, as it's wings, legs, antennas, &c. and confequently that 

 the changes which are apparently fudden to our eyes, are gra- 

 4 dually 



