222 INSECTS. 



transverse jaws, with lips, a kind of teeth, a tongue; 

 and palate : it has also, in most instances, four or 

 six palpi, or feelers.; Insects have also moveable 

 antennae, proceeding generally from the front part of 

 the head, which are endowed with a very nice sense 

 of feeling. 



In a minute examination that has lately been 

 made in this class by Cuvier, one of the most accu- 

 rate observers of nature now living, neither a heart 

 nor arteries have been detected ; and this gentle- 

 man says that the whole organization of insects is- 

 such as one would expect to find, if they had been 

 actually known not to be provided with such organs. 

 Their nutrition, therefore, would seem to be carried 

 on by immediate absorption, as is evidently the case 

 with the polypes, and other zoophytes, which are 

 considerably below insects in the perfection of their 

 organization*. 



Nearly all insects (except Spiders, and a few 

 others of the apterous tribe, which proceed nearly 

 in a perfect state from the egg) undergo a meta- 

 morphosis, or change, at three different periods 

 of their existence. 



The lives of these minute creatures, in their per- 

 fect state, are in general so short that the parents 

 have but seldom an opportunity of seeing their 

 living offspring. Consequently, they are neither 

 provided with milk, like viviparous animals, nor 

 are they, like birds, impelled to sit upon their eggs 



* He excepts the Crabs and Lobsters, which he arranges in a class 

 by themselves, and denominates Crustaceous animals. 



