300 INSECTA. 



which did not previously exist. In the dragon-fly, for example 

 (Jig- 104), when the cutis had become expanded to its mature 

 larva condition, it secreted from its surface the external epidermic 

 crust which gives form to the larva, B ; this outward integument 

 remains, of course, unchanged when once formed, and retains the 

 same appearance during the whole period of the existence of the 

 insect in its larva state : but underneath this cuticle, and con- 

 sequently concealed from observation, the growth of the living 

 dermis still goes on, and important organs begin to appear, which 

 had no existence when the last larva-investment was secreted. 

 The wings have sprouted as it were from the shoulders, and 

 already have attained to a certain growth ; the old integument of 

 the larva becomes useless, and a new one is wanted; the process 

 already described is repeated, the old cuticle becomes detached 

 from the surface of the body, and the cutis begins to secrete for it- 

 self a new covering moulded upon its own shape : the newly form- 

 ed wings, therefore, and other newly developed processes of the 

 dermis, secrete horny coverings for themselves in the same manner 

 as other parts of the surface of the body ; and thus, when the in- 

 sect leaves its old skin, and once more escapes from confinement, 

 it presents to view the wing-cases which distinguish the pupa. 



Whatever may be the form of the pupa, its covering is secreted 

 in a similar way ; it is the living and vascular skin which, though 

 concealed, continually grows more perfect in its parts, and the 

 cases secreted by it at distant intervals correspond in shape with 

 the different phases of its developement. 



(345.) After having attained the pupa state, the last steps of the 

 process are completed, and the dermic system becomes fully de- 

 veloped in all its parts. The oral apparatus attains its perfect con- 

 dition ; the wonderfully elaborate structure of the eyes is com- 

 pleted ; the antennae assume their full developement ; the legs en- 

 closed in those of the pupa attain their mature form ; and the 

 wings, which have been continually growing, although concealed in 

 the wing-cases of the pupa, acquire their ultimate size : the per- 

 fect insect is ready for liberation, and, enclosed in its last covering, 

 creeps out of the water in which it has so long resided to enter 

 upon a new state of existence. Fixing itself upon some plant in 

 the neighbourhood of its birth-place, the imprisoned dragon-fly splits 

 its pupa-case along the back (jig. 137, A), and slowly extricates 

 its head and body ; draws its wings from their coverings, and 

 its legs from those of the pupa as from cast-off boots ; and at 



