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INTRODUCTION TO 
exhibited by pupae previous to the disclosure of the 
perfect insect will be afterwards given in the particu- 
lar history of the Orders, to which we therefore refer. 
Imago or Perfect insect. When an insect quits its 
puparium, it is said to he complete or perfect, be- 
cause it has then gone through all its changes, has all 
its parts fully matured and developed, and is capable 
of executing all the functions peculiar to its nature. 
The sexual distinctions, in particular, are now mani- 
fested, and the species become capable of continuing 
their kind. The wings are unfolded, and by their 
means they may almost be said to become inhabitants 
of a new element. It is now, in short, that, consi- 
dered collectively, they exhibit in an especial man- 
ner all that diversity of form, peculiarity of structure, 
beauty and variety of colouring and ornament, as 
well as those singular instincts and modes of life 
for which the class is so remarkable. 
In considering the perfect insect in this place, we 
propose to give a view of its external and internal 
structure — in other words, of the exterior crust and 
organs as they appear to the eye, and of the internal 
parts as ascertained by dissection, or the anatomy 
properly so called. In so doing, we must necessarily 
render our account as general as possible, reserving 
the details of the modifications which the various parts 
undergo, till we come to treat of the separate orders ; 
for it is, in fact, by these modifications that the various 
orders are constituted, and a review must, therefore, 
be taken of all the most important parts of struc- 
ture as introductory to each, before it can be fully 
