oys ZOOLOGY. 



the end of about twelve days of seclusion, if the time be warm. 

 they leave the envelope in the perfect state. 



536. Finally, there are also insects which do not un- 

 dergo a metamorphosis, and which are born with all the 

 organs they are ultimately to possess; but it is always 

 the apterous insects which offer us this mode of development. 

 The podurella (Fig. 352), already spoken of, and the louse 

 (Fig. 405), offer examples of this. 



537. Insects so remarkable by their organization, are 

 still more so by their habits, and by the admirable instinct 

 which nature has bestowed on so many of them. The arti- 

 fices they employ to procure their food, or to withdraw them- 

 selves from their enemies, and the industry they display in 

 their labours, astonish all who have witnessed them; and 

 when we see them unite into numerous societies, to make up 

 for their individual feebleness, assist each other, divide amongst 

 them the works necessary to the prosperity of their commu- 

 nity, provide for their future wants, and frequently even regu- 

 late their actions according to the accidental circumstances in 

 which they may be placed, one remains confounded to find, in 

 these beings, so small and apparently so imperfect, instinct so 

 varied and so powerful, and intellectual combinations which 

 so strongly resemble reasoning or judgment. The subject 

 would not become exhausted, if we felt inclined to relate here 

 examples of these curious phenomena, but the narrow limits 

 of these lectures do not permit us to consecrate at this mo- 

 ment more time to this subject ; and we can only refer our 

 readers to what we have already said whilst treating in a 

 general way of the actions of animals ( 317 to 339). 



538. Classification of Insects. If we now endeavour 

 in a few words to sum up the more important differei nv> 

 which insects present, we shall find that these differences 

 depend especially on the structure of the mouth, which regu- 

 lates the regime of these animals ; in the disposition of the 

 organs serving for aerial locomotion, a function which gives 

 to the entire class one of its most prominent characters; finally, 

 on the kind of metamorphoses which these beings undergo 

 when young. Now, after what we have said elsewhere re- 

 specting the essence of natural classification, it is evident that 

 it ought in consequence to be in the modifications of the 

 buccal apparatus, of the wings, and of their mode of develop- 

 ment, that the zoologist should look for the basis of a metho- 

 dical distribution of these animals. In fact, it is in this way 



