OF NATURAL HISTORY. I?? 



however inflgnliicant thefe creatures may appear to inatten-f 

 tive obfervers, Nature has been equally provident in the for- 

 mation of their bodies, and in the means of preferving the 

 different individuals, according to their kinds, as in the 

 larger animals, which have the appearance of more import- 

 ance in the fcale of being. To infe<Sts fhe has denied lungs 

 iimilar to thofe of men, quadrupeds, birds, and fiihes ; but, 

 as the tranfmiilion of air into their bodies was necefTary to 

 continue the principle of life, fhe has furnilhed them with 

 peculiar inftruments and apparatus for accomplifliing this in- 

 difpenlible purpofe. 



Air is conveyed into the bodies of infefts by inftruments 

 called tracheae or Jl'igmata, The tracheae, or wind-pipes, are, 

 in many infedls, long tubes protruding externally from differ- 

 ent parts of the body. In fome, they proceed from the 

 pofterior part, and have the appearance of one, two, or three 

 tails J in others, they arife from the back or fides. The 

 iligmata are fmall holes, generally of a different colour from 

 the reft of the body, and run along the fides of many cater- 

 pillars in regular and beautifully dotted lines. That theie 

 tracheae and ftigmata are deftined for the tranfmiilion of air, 

 has been proved by repeated experiments ; for, when ftopped. 

 up by the application of oil, or other unduous fubftances, the 

 animals foon loofe their exiftence. 



In contemplating the parts of animals, when the ufes of 

 thefe parts are not apparent, we are apt to deceive ourfeke* 

 by rafhly fuppofing them to anfwer purpofes for which they 

 were never intended by Nature. Impreffed with this idea, 

 M. de Reaurhur was not fatisfied with the notion of Goedart 

 and others, that the long tails of certain worms were intend- 

 ed to keep them fteady in their motions, and to prevent 

 them from rolling. Reaumur obferved, that thefe worms 

 or grubs could lengthen or fliorten their tails at pleafure, 

 but that they were always longer thaii the animal's body. 



