102 Professor xigassiz on the 



which have been more generally admitted by English writers 

 than by those of the Continent of Europe. 



Fabricius introduced an entirely new view of the subject, 

 dividing the insects according to the structure of the organs 

 by which they take their food, and the various structures and 

 degrees of complication of the jaws became the foundation 

 of his system, which he not only applied in a general manner, 

 but worked out in all its details, assigning even to the smaller 

 divisions characters derived chiefly from the peculiar form of 

 those parts. 



More recently the metamorphosis of insects has been made 

 the foundation of their classification, and they have been 

 grouped according to the extent of changes they undergo from 

 the egg, and according to the condition in which the young 

 animal remains for a time before it has arrived at its com- 

 plete perfect growth. 



According to these views, those insects that are hatched 

 from the egg with a form very similar to the full-grown per- 

 fect animal, and which undergo slight or only partial changes 

 during their growth, such as the additional development of 

 wings, or which remain active throughout their metamor- 

 phosis, have generally been considered as belonging to one 

 and the same great division, and have been brought together 

 as insects without metamorphosis, or with imperfect meta- 

 morphosis. On the other hand, such insects as are hatched 

 from the egg in the form of a maggot, grub, or caterpillar, 

 resembling worms in their earlier period of life more than 

 they resemble the perfect insects which are to grow out of 

 them, and from that condition passing into the state of im- 

 movable mummy-like pupoe, or chrysalids, and during this 

 period taking no food, but afterwards giving rise to a winged, 

 perfect fly, beetle, or butterfly, have been considered as in- 

 sects with perfect metamorphoses, and on that account have 

 been brought together in one great division. 



A glance at the classification resting upon such considera- 

 tions will shew, that each of these fundamental divisions 

 contains insects, which, in their perfect condition, chew their 

 food with powerful jaws, and others which are provided with 



