140 INSECT TRANSFORMATIONS. 



yellow, or green colour, and apparently analogous to 

 tilt in the larger animals*. This furnishes, as is fur- 

 ther supposed, a store of nutriment for promoting the 

 growth of the butterfly t- 



This brief sketch will serve to give the reader a tole- 

 rable notion of the internal structJire of caterpillars, 

 and the manner in which their food is elaborated into 

 nutriment ; but when we know that Lyonnet wrote a 

 large quarto volume on the structure of a single cater- 

 pillar, and that Maipighi, Heroldt, Ramdohr, Spren- 

 gel, and Marcel de Serres, are little less voluminous, 

 it will be understood, that we give it merely as a 

 sketch which we could easily have extended, had it 

 appeared, as it does not, to be suitable to our plan. 

 It will prove more interesting, we think, to pass now 

 to the external structure and appearance. 



It will be obvious from what we have said re- 

 specting the colours of eggs, that we are not in- 

 clined to adopt in all its extent the theory of many 

 naturalists, which maintains the peculiar colours and 

 forms of animals to be given them by nature for the 

 purpose of concealment from their enemies. As in 

 the instance of caterpillars this theory meets us again 

 in full force, w^e shall mention a few facts which ap- 

 pear not only to be at variance with it, but show, we 

 think, that the facts of the theorists may stand as 

 appropriately for exceptions as for a general rule. 

 Since caterpillars form the staple food of soft-billed 

 birds and of the young of most hard-billed birds, not 

 to mention the parasite-grubs of ichneumon-flies, 

 which destroy grtat numbers. Nature has provided an 

 immense abundance of them beyond what is requisite 

 for continuing the race. Were it maintained, there- 

 fore, that they were all by design so formed and 

 coloured as to deceive the eyes of birds and ichneu- 



* Lyonnet, Anat. de hi Chemlle, 106. 

 f Reaumur, Mem. i. 145. 



