THIRD CHAPTER. 



PARTIAL ORISMOLOGY 



46. 



HAVING thus concluded the examination of the general differences 

 observed in all, or the majority of the organs, it now remains for us, as 

 the subject of the following chapter, to describe the insect body in its 

 separate periods of existence, and all the thence perceptible differences 

 of its various organs. The illustration of its several stages of develop- 

 ment first claims our attention. 



47. 



Commencing our investigation with the first beginning of insects, we 

 may lay it down as a universal law, that all insects originate from EGGS 

 (ova). With the exception of the few instances, wherein the egg is 

 hatched in the body of the mother, and the young thus born more fully 

 developed, a species of propagation to which the ancients applied the 

 name of Insecta ovo-vivipara (Musca carnaria, &c.), all insects are 

 truly animalia ovipara. We must here indeed mention a second 

 exception, comprising those Diptera which are retained in the body 

 of the mother, until transformed into pupae, and are excluded in an 

 apparent egg-shell, but which is, in fact, the pupa-case. This species 

 of developement is peculiar to a single family, which has thence received 

 the name Diptera pupipara. Exclusive of these very rare anomalies, 

 we may observe four distinct periods of existence in every insect, 

 namely, those of the EGG, the LARVA, the PUPA, and the IMAGO, or 

 PERFECT INSECT. In each of these states they are subject to manifold 

 differences, arising from the various groups to which they belong, and 

 to the contemplation of which we now pass. 



