78 



In the greater part of insects of this class, the inci- 

 sions separate the body into three principal parts ; the 

 head, the stomach, the lelly : this division has a relation 

 to that observed in great animals. Some of the insects 

 of the first class are without legs ; others are furnished 

 with them. All the insects of the second class have 

 legs ; but some are winged, others not. 



There is such a diversity in insects, that it may be 

 questioned, if there is liot united in them every variety 

 to be met with throughout the animal world. And 

 what renders this variety still more surprising, is, that it 

 does not extend merely to the whole species, but like- 

 wise to individuals. The same insect has, at one time, 

 organs that are not to be found in him at another. The 

 same individual which, in his youth, belonged to the 

 first class, in a more advanced age, takes up his rank in 

 the second. From thence arise the difficulties attending 

 a proper distribution of these little animals. 



15. The bodies of almost all insects are formed of a 

 collection of rings, set in each other ; which, by con- 

 tracting or dilating, lengthening or shortening, contri- 

 bute to all the motions of the animal. 



The head, in many species, changes its form in an in- 

 stant. It contracts and dilates itself, lengthens and 

 shortens, appears and disappears, at the pleasure of the 

 insect. The flexibility of its folds enables it to make 

 these motions. In other species, the head is in one 

 constant position, and bears a greater resemblance to 

 that of the larger animals, by the hardness of its cover- 

 ing, which is scaly. 



The mouth is sometimes discovered to be a simple 

 circular aperture : but it is generally furnished with 

 hooks, or a kind of pick-axe; with teeth, or two indent- 

 ed shells, which they move horizontally ; with a trunk, 

 a very compact instrument, which serves to extract and 

 liquify, and raise up alimentary juice; or with a sting, 



