270 THE MECHANICAL FUNCTIONS. 



for the manifest purpose of obtaining greater me- 

 chanical strength and elasticity than if they had 

 remained detached pieces, joined only by mem- 

 branous connexions. A long flexible body, such 

 as that possessed by the Myriapoda, could not 

 easily have been transported through the air ; for 

 every bend would have created a resistance, and 

 have impeded its advance during flight. Hence 

 the body of the insect, which is to be ultimately 

 adapted to this mode of progression, has been 

 shortened by a reduction in the number of its 

 segments, and rendered more compact. The seg- 

 ments destined to support the wings have been 

 expanded for the purpose of lodging the powerful 

 muscles which are to move them ; and rendered 

 dense and unyielding in order to support their 

 action. 



Nature has farther provided insects with instru- 

 ments adapted to different kinds of external actions. 

 They consist of articulated levers, variously com- 

 bined together, and forming legs, claws, pincers, 

 oars, palpi, and, lastly, wings, calculated for exe- 

 cuting every variety of prehension, of progression, 

 or whatever other action their wants and neces- 

 sities require. 



§ 3. Developement of Insects. 



It would appear as if the final accomplishment of 

 objects so numerous, so widely different, and so 

 liable to mutual interference, could be attained 

 only by the animal being subjected to a long series 

 of modifications, and passing through many inter- 



