CHAPTER n 



THE mSECT : ITS EXTERN' AI STRUCTURE 



Biii^iDg together the facts abi'u: insects alrea<h' stated, ire find that 

 an adult insect is a fatlata^alh' symmetiical animal amasin^ of a seiies 

 of segmeDts <Mie bdiind another, and that these segments aze groaped 

 into three lefftoats. the head in fnmt, f dOowed in order by the thorax and 

 the abdomea (F%. 10). Covering the anima] is a Skeleton, sheTl-Eke in 

 that it oidoees the body, bat homy in its nature. Attached to the s^- 



mentts aie three pairs of j<«ited legs, a pair of antenns, moath parts and 

 osDaltr two pairs of wings. It Iweathes throogfa air tabes, and the 

 lefKodoctiTe «gans c^ien near the hinder end <rf the body. 



The adnh insect does not aiiow all the segm ents of which its body is 

 composed. In the embryo eridences of 21 have been foond.- but as the 

 animal fHogxesses toward maturity scxne ci these fuse with others. The 

 head of the adnh, thou^ a{qiarently ccMisbting of only one segment, is 

 DOW bdKeved to be the prodaet of the fi^on ci six: the three foond in 

 the adult thmax seem to have always been that number; and the abdo- 

 mesL, composed of 12 segments in the eanbryo appears to have been re- 

 doeed in the adolt to a nwaaiber vaiyii^ frcxn three to 11. parth' by a 



' Soaae 'mtvMi f Ab oKs bd feie tibat 22 segBoeats are present, the head e u mwling of 

 aevem, bat thfe Tiew fe act mun g aaat By aceepted, 



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