INSECTA. 429 



principle takes upon it the power of receiving impressions, or becoming a 

 sensitive being. Here we have only one change, and of course two states. 



In another class of animals, viz. frogs, toads, &c, there are two 

 changes, and of course three states. They are first changed from the 

 foetus (their state in the egg or spawn) to the aquatic state ; and then 

 are changed from the aquatic to the land state, but this change from 

 the aquatic to the terrestrial is very little ; and it is a gradual change 

 from the one to the other, not so immediate as in the first, or from the . 

 foetal to the aquatic state. The second change in these animals is 

 mainly in the mode of respiration, from respiring water to breathing 

 air ; for, when in the aquatic state, they have a kind of gills fitted for 

 such a situation, and these are gradually lost, and the lungs as gradu- 

 ally come into play. Some other trifling changes take place in some of 

 this tribe and not in others : some parts are lost, as the tail in frogs ; 

 new parts are added, as the legs in the same : other parts are altered, 

 as the tails in some newts. But none of these changes are so complete 

 as in the insect ; none of .them going into a new state, in which they 

 are losing many of their first formed parts, and acquiring the second, — 

 a state in which it has neither the character of the preceding nor of the 

 succeeding animal. Perhaps it is one of the great characteristics of 

 this class of animals, these very changes which they go through before 

 they arrive at the adult or perfect state. 



This class of insects may be said to have two states of foetation and 

 two births, and therefore they have four different modes of life. The 

 first or fetus, while in the egg, is the stage of hatching, similar to the 

 chick in the egg, or the fetus in the womb ; save with this difference, 

 that in the chick or the child all the adult parts are forming, and they pass 

 into the last mode of life immediately upon being born ; while the insect 

 only goes into the larval or second state. This second state of birth, viz. 

 the caterpillar or maggot, is that in which the insect is increasing in 

 size in all its parts, whether they be those that are to remain or not ; 

 and is forming some new parts, as the parts of generation (as we see 

 in the silk-moth), fitting them for the condition of the adult state. 

 The third state, or the second fetation, is called the ' chrysalis,' when 

 they appear to live upon themselves, or on what they accumulated when 

 in the state of a larva. They now become intersected, whence they got 

 the name of 'insect;' and there are forming many parts necessary for 

 the adult, which were not necessary for the larva, as, e. g., eyes, legs, 

 wings ; and they now complete the parts of generation. The fourth 

 state is the consequence of the second birth, and forms the complete 

 animal. The fourth differs as much from the second state as any two 

 distinct genera of animals possibly can do. 



