CLASS INSECTS. 437 



as it were, to stop en route, and never come to possess wings. 

 Fleas are in this case, and, leaving the egg, they have no 

 feet, and have the form of small worms, of a whitish colour. 

 These larvae are very lively, and roll themselves into a circle 

 or spiral. Soon they become reddish, and after having lived 

 in this state a dozen days, they shut themselves up in a small 

 silky cocoon of extreme fineness, to be transformed into a 

 nymph; then, at 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 undergo 

 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 podu- 

 rella (Fig. 430), already spoken of, and the louse (Fig. 491) 

 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 

 community, provide for their future wants, and frequently 

 even regulate their actions according to the accidental circum- 

 stances in which they may be placed, one remains confounded 

 to find, in these beings, so small and apparently so imper- 

 fect, instinct so varied and so powerful, and intellectual com- 

 binations 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 moment 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 In sects. If we now endeavour 

 in a few words to sum up the more important differences 

 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 



