That besides this gradual extinction of the primitive history, a
FALSIFICATION of the record preserved in the developmental history takes
place by means of the struggle for existence which the free-living young
states have to undergo, requires no further exposition. For it is
perfectly evident that the struggle for existence and natural selection
combined with this, must act in the same way, in change and development,
upon larvae which have to provide for themselves, as upon adult animals.
The changes of the larvae, independent of the progress of the adult
animal, will become the more considerable, the longer the duration of
the life of the larva in comparison to that of the adult animal, the
greater the difference in their mode of life, and the more sharply
marked the division of labour between the different stages of
development. These processes have to a certain extent an action opposed
to the gradual extinction of the primitive history; they increase the
differences between the individual stages of development, and it will be
easily seen how even a straightforward course of development may be
again converted by them into a development with metamorphosis. By this
means many, and it seems to me valid reasons may be brought up in favour
of the opinion that the most ancient Insects approached more nearly to
the existing Orthoptera, and perhaps to the wingless Blattidae, than to
any other order, and that the "complete metamorphosis" of the Beetles,
Lepidoptera, etc.
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