168 PTILOTA. 



out the body. The epidermis, all the external visible organs, 

 and even the mandibles and palpi, remain attached to the 

 old skin. This moulting is repeated several times. 



Various physiologists, and especially Dr. Virey, have en- 

 deavoured to trace an analogy between the transformations 

 of insects and the developement of some of the higher ani- 

 mals, attributing, as Mr. MacLeay observes in his Horn: 

 Entomologies, the metamorphoses of insects to the shedding 

 of an envelope analogous to that which contains the foetus 

 of the more perfect vertebrata ; and as every embryo, whe- 

 ther animal or vegetable, is inclosed in a tunic more or less 

 solid (its chorion), so proceeding with the analogy, they 

 conceive there must be some condition for every animal, 

 similar to the state of the foetus of the more perfect animals, 

 when surrounded by the amnios of this state, and which, in 

 the hexapod insects, they hold to be the larva, according to 

 which the true birth of the animal will be its exclusion from 

 the pupa case. This argument seems to have been derived 

 from an observation of Reaumur namely, that the larva of 

 insects ought to be regarded as an egg of an extraordinary 

 kind, endowed with organs of locomotion and nutrition; 

 and that this analogy is also retained during the period of 

 the insect's existence in the chrysalis state. When we con- 

 sider, however, that many species of insects are active in the 

 pupa state, and that on their exclusion therefrom they have 

 acquired their full size, and are fitted for the reproduction of 

 their species, we must admit that the former view of the 

 subject is scarcely maintainable ; and that the larva state, 

 which is especially that in which the digestive system pre- 

 dominates, and the greatest supply of food is taken, is more 

 strictly analogous to the period of infancy of the higher 

 animals. 



