70 METAMOEPHOSES OF MAN 



lifetime in the performance of those acts necessary to 

 the production of offspring. 



The greater number of insects differ more or less 

 from this general type. Most of them, even on attain- 

 ing their final condition, have still to maintain or com- 

 plete their organization, and hence must provide for 

 the nutrition of their bodies. Very many assume the 

 perfect condition on leaving the egg, and, like mam- 

 malia, have only to increase in size. Others are 

 entirely devoid of wings. These variations, however, 

 are limited, and certain characters present themselves 

 so constantly that there can be no question as to their 

 being fundamental. 



Every perfect insect is composed of a head, thorax, 

 and abdomen ; breathes by tracheao, and has three 

 pairs of legs. Looking at the insect class from our 

 point of view, we can group together all these differ- 

 ences and affinities by regarding them as the results 

 of a series of modifications of one and the same phe- 

 nomenon. In common with all entomologists, we 

 grant that metamorphoses may be either complete or 

 incomplete.* The former term applies to those 



# There may be also a sort of exaggerated metamorphosis, as M. 

 Fabre has shown in his interesting researches upon the develop- 

 ment of the meloes. The larva of this insect, before being con- 

 verted into the chrysalis, passes through four distinct stages, which 

 the author has termed first or primitive larva, second larva, pseudo- 

 chrysalis, and third larva. But these changes, which are simply a 

 series of moultings, are dependent upon the different conditions by 

 which the animal is surrounded, on account of its frequent migra- 

 tions, and have no reference to the internal organization of the 

 creature. Hence they are included in the expression complete meta- 

 morphoses. This has been fully understood by the author of the 

 remarkable papers upon " l'Hypermetamorphose et les Mceurs des 

 Meloides," Annales des Sciences naturelles, 1857-58. Siebold, in his 



