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through every one of them I could moft plainly dillinguilh all 

 iurrounduig objeds. 



Fig. 12, EFG, reprelents a fmall portion of the tunica cornea 

 in the eye of a fly, in which thofe protuberant parts or optical or- 

 gans were not fewer in number than in the eye of the dragon-fly. 

 And to fliew the incredible perfed;ion of each of thefe optical or- 

 gans, I took a large grain of common fcowering fand, and I mult 

 fay, that above a thoufand of thofe protuberances, in the eye of a 

 fly, taken together, were not equal to the fize of that grain of fand. 



What I have here faid, refpedling the eye of a fly, mutl alfo be 

 underflood of the eye of a gnat, regard being had to the compara- 

 tive fmallnefs of the gnat's eye. 



About the time of my making thefe obfervations, I found it af- 

 ferted in the writings of a certain author, when treating of ants 

 and moths, that ants have no eyes in their heads, on account of 

 their fmallnefs; but, meeting with fome ants in my garden, I found, 

 upon difledling them, that each of their eyes contained fifty optical 

 organs ; and in the brains of thofe creatures I faw, with admiration,- 

 the wonderfully minute blood-veflels they contained. 



Refuming the examination of the eyes of the dnigon-fly, I was 

 defirous to know whether the tunica cornea in them confilled of 

 many fcaly particles laid one on another, as I have in another place 

 defcribed to be the formation of it in the eyes of men and quadru- 

 peds. This difledion, after fome difficulty, I accomplilhed ; but I 

 obferved that the leafl: alteration made by difl'eclion in the tunica 

 cornea, prevented my diftinguifliing objeds through it: I, however, 

 difcovered that it was in reality compofed of many particles or 

 fcales, laid one on another, of which I could diflincily count thir- 

 teen feries. 



Now, if we confider the multitude of parts of which thefe fcales 

 or flcins mufl: be formed, which efcape our relearches and our fight, 

 and moreover, how clofely and exactly they muft be laid together, 

 to give free paflage to the light, we fliall be loll in wonder at fuch 

 perfedion in the eyes of fuch infignificant creatures as thefe flies : 



