Microscopical Essays. 



37* 



rife from the exterior notches ; forae of thefe fcales, or plates, 

 are to be found fo exceedingly (lender, that it is not eafy to dip- 

 criminate them from hairs by the naked eye. The regular 

 arrangement of thefe plates, one befide, and partly covering the 

 other, as in the tiling of a houfe, is belt feen by examining the 

 wing in the opake microfcope. The prodigious number of fmall 

 fcales which cover the wings of thefe beautiful infecls, is a fure 

 proof of their utility to them, becaufe they are given by him 

 who makes nothing in vain. 



That the lively and variegated colours which adorn the wings 

 of the moth and butterfly arife from the fmall fcales, or plates, 

 that are planted therein, is very evident from this, that if they 

 are brufhed off from it, the wing is perfectly tranfparent ; but 

 whence this profufion and difference of colour on the fame wing ? 

 is a queflion as difficult to refolve as that of Prior, when he 

 afks, 



" Why does one climate and one foil endue 

 The blufhing poppy with a crimfon hue, 

 Yet leave the lilly pale, and tinge the violet blue ?"J 



The materials of the wings under thefe plates feem to be of a 

 talcy nature ; the wing is ftrengthened by feveral nerves, or 

 ribs, which run through it; the largefl fortifies the exterior edge 

 of the wing, while a fmaller one firengthens the interior edge. 

 When the moth immerges from the chryfalis, the wings are foft 

 and thick, and if they are examined at that time, they will be 

 found to confifl of two membranes, which may be raifed up, and 



Y y 2 then 



