iv.] METAMORPHOSES OF INSECTS. 63 



Aphides which certainly are not among the least 

 voracious, and which grow and breed at the same 

 time. There are also many scavengers among 

 other groups of animals such, for instance, as the 

 dog, the pig, and the vulture which undergo no 

 metamorphosis. 



It is certainly true that, as a general rule, growth 

 and reproduction do not occur together; and it follows, 

 almost as a necessary consequence, that in such cases 

 the first must precede the second. But this has no 

 immediate connection with the occurrence of meta- 

 morphoses. The question is not, why an insect does 

 not generally begin to breed until it has ceased to 

 grow, but why, in attaining to its perfect form, it 

 passes through such remarkable changes ; why these 

 changes are so sudden and apparently violent ; and 

 why they are so often closed by a state of immo- 

 bility that of the chrysalis or pupa ; for undoubtedly 

 the quiescent and death-like condition of the pupa is 

 one of the most remarkable phenomena of insect- 

 metamorphoses. 



In the first place, it must be observed that many 

 animals which differ considerably in their mature state, 

 resemble one another more nearly when young. Thus 

 birds of the same genus, or of closely allied genera, 

 which, when mature, differ much in colour, are often 

 very similarly coloured when young. The young of 

 the lion and the puma are often striped, and the foetal 

 Black whale has teeth, like its ally the Sperm whale. 

 In fact, the great majority of animals do go through 

 well-marked metamorphoses, though in" many cases 

 they are passed through within the egg, and thus do 



