328 INSECTA. 



short feet, six of which are anterior, scaly, and pointed, the rest varying 

 in number and membranous, being attached to the posterior annul i. 

 These animals, called Caterpillars, live in this state for a certain 

 period, and repeatedly change their skin. An epoch, however, arrives, 

 when from this skin of a caterpillar issues a totally different being, of 

 an oblong form and without distinct limbs, which soon ceases to move, 

 and remains a long 'time apparently desiccated and dead under the 

 name of a chrysalis. By close examination we may discover on the 

 external surface of this chrysalis, lineaments which represent all the 

 parts of the Butterfly, but under proportions differing from those they 

 are one day to possess. After a longer or shorter period, the skin of 

 the chrysalis splits, and the Butterfly, humid and soft, with flabby 

 short wings, issues from it a few moments, however, and it is dry, the 

 wings enlarge and become firm, and the perfect animal is ready for 

 flight. It has six long legs, antennae, a spiral proboscis, and compound 

 eves in a word, it has no resemblance whatever to the caterpillar, from 

 which it has originated, for it is ascertained that these various changes 

 are nothing more than the successive development of parts contained 

 one within the other. 



This is what is styled the metamorphosis of Insects. In their first 

 condition they are called larvae, in their second pupae, nymphs or chry- 

 salides, and in the third perfect insects. 



All Insects do not pass through these three states. Those which are 

 apterous, issue from the ovum with the form they are always to pre- 

 serve : they are said to be without a metamorphosis. Of those that have 

 wings, many experience no other change than that of receiving them : 

 these are said to undergo a semi-metamorphosis. Their larva resembles 

 the perfect insect, with the single exception of the wings, which are 

 totally wanting. The nymph only differs from the larva in possessing 

 stumps or rudiments of wings, which are developed at its final change 

 of tegument, and render the animal perfect. Such are the Cimices, 

 Grylli, &c. Finally, the remaining Insects provided with wings 

 that are said to undergo a complete metamorphosis, are at first larvce, 

 resembling Caterpillars or Worms, and then become motionless 

 nymphs, but presenting in that state all the parts of the perfect insect 

 contracted, and as if wrapped in a bandage. 



In the nymph of the Coleoptera, Neuroptera, Hymenoptera, &c., 

 these parts, though closely approximated and in contact with the body, 

 are free ; but they are not so in that of the Lepidoptera and of many 

 Diptera. An elastic or solid skin is moulded over the body and its 

 external parts, forming a kind of case for it. 



