156 GRAMMAR OF ENTOMOLOGY. 



CHAPTER XL 



CONCLUDING OBSERVATIONS. 



589. THE transformation (metamorphosis) of 

 insects requires a few words : every insect has at 

 least three distinctly marked stages of life ; the 

 egg, or fcetal ; the larva, or adolescent ; and the 

 imago, or adult. 



590. There is a fourth state which occurs in 

 many, the pupa, chrysalis, or quiescent state of 

 the larva ; these changes are accompanied by a 

 casting of the skin. 



591. In the changes which insects undergo, 

 not only is the external appearance altered, but 

 the organs of support, motion, sensation, digestion, 

 and generation are also altered, and frequently 

 those of respiration. 



592. The organs of support in insects are 

 mostly external ; they are not bones, but perform 

 the functions of bones ; no experiments have yet 

 proved that they possess the least sensitiveness to 



