LEADING CHARACTERS OF INSECTS. // 



this would certainly be the case were not the difficulty ob- 

 viated in a manner as remarkable as it is perfect, namely, by 

 the periodical shedding of the external envelope, forced open 

 as it were, from time to time, by the internal organs, which 

 have increased in volume since the preceding moulting, 

 owing to the quantity of food taken by the creature. This 

 shedding of the covering of the body is very variable in its 

 effects upon the various groups of insects, in some consist- 

 ing of a mere throwing off of the outer envelope, without 

 any other change being effected, save that of an increase of 

 size ; in others, however, an increase of limbs is obtained ; 

 and in some, an entire change in the form of the body is 

 effected, and organs of flight acquired. These latter changes 

 are termed metamorphoses or transformations, and are more 

 especially applicable to the winged groups of insects. Another 

 important character distinguishing this tribe of animals is to 

 be found in the highly organized structure of the eyes in the 

 majority, although in some the organs of sight consist only 

 of a number of small tubercular lenses, which are moreover 

 found in some species which also possess the compound or 

 facetted eyes. The head is also furnished, in the majority 

 of the tribe, with a pair of articulated organs, varying in- 

 finitely in their construction, termed antennae, of which the 

 precise uses have not hitherto been decidedly ascertained. 

 Such are the leading characters of the great mass of animals, 

 to which Linnaeus gave the name of Insecta, but which 

 Latreille has changed into Condylopa, from the articulated 

 structure of the legs. The anatomical investigations of 

 foreign naturalists, about the commencement of the present 

 century, threw a great light upon the real nature of the 

 various groups of Linnaean insects, and upon the respective 

 value of the characters by which the orders into which they 

 had been divided were separated from each other. It was 

 thence at once discovered, that, although the winged orders of 



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