THE CHARACTERISTICS OF INSECTS. 33 



formation ; the only change analogous to that of 

 metamorphosis heing the appearance of additional 

 segments, which do not exist in their earliest stage ; 

 otherwise, they have from the first the form they 

 are destined to retain, and in the development of 

 which they grow like other classes of animals, 

 while true insects never grow after they have once 

 received their final forms. 



In different classes of insects there are different 

 degrees of completeness of metamorphosis, which, 

 as I have said, once formed hases upon which it 

 was attempted to found a system of classification, 

 among which the following may be particularized : — 



Hemipterous insects, for instance, have the 

 rudiments of wings in their earliest stages, which 

 develop themselves by degrees along with other 

 changes of form. This was considered a semi-com- 

 plete metamorphosis. 



Other classes of insects, as some Bees, Ants, and 

 all Beetles, undergo a direct change of form from the 

 grub state, without being encased in one general 

 shell like the chrysalis of the Moth, but cachp art 

 being separately encased in its new covering as it 

 is developed, and becoming hardened by degrees. 

 Many kinds of beetles are thus quite soft for some 

 time after they come forth in their perfected state. 



D 



