CH. I.J METAMORPHOSES OF INSECTS. 23 



furnished with the same number of breathing pores 

 as the caterpillar, and, from the experiments of 

 Reaumur and De Geer upon chrysalides, placed in 

 water, oil, the receiver of an airpump, &c., there 

 appears every reason to consider that the theory of 

 Reaumur adopted by Kirby and Spence is correct, 



A fanciful idea has recently been started, that the 

 nearest analogy which exists among the other class- 

 es of animals with the inactive state of the chrysa- 

 lis is that of an ox torpid, when reclining in a 

 meadow to ruminate and digest the grass he had 

 just been devouring, " for the pupa, though it does 

 not chew the cud like the ox, assuredly rests for 

 the purpose of digesting or (if the term be preferred) 

 of assimilating the cruder fluids stored up by the 

 caterpillar, and forming or perfecting therefrom the 

 organs and members of the mature nisect." 



Unless, however, it be intended by this statement 

 to imply that in the chrysalis state the insect is 

 employed in digesting the food of the caterpillar, 

 there can be no ground for the analogy ; and that 

 such a supposition is erroneous is evident from the 

 following remark of Swammerdam : — " When the 

 caterpillar has fed sufficiently it rests some time ; in 

 this period all the food it has taken is thoroughly 

 digested; it then forms a pretty strong web." 

 Hence it is evident, that if there be any analogy at 

 all between an insect and an ox while chewing the 

 cud, it must be daring the period mentioned by 

 Swammerdam, and not while in the chrysalis state. 



When the insect has remained under the form of 

 a chrysalis for a sufficient length of time to bring 

 all the various organs to a proper state of consist- 

 ence, the period of bursting through the walls of it^ 

 prison may often be easily ascertained -, the golden 

 colour becomes indistinct, and, in those chrysalidea 

 whose skin is sufficiently thin, the form of the legs, 

 antennae, and tongue, and the colours of the wings 

 of the enclosed butterfly, become visible through the 



