Chapter IV: The Origin of Metamorphoses

Origin of Metamorphoses.--Views of Messrs. Kirby and
Spence.--Nature of the question.--Young animals often more
similar than mature.--Views of Darwin, Herbert Spencer,
Johannes Müller, Fritz Müller, and Agassiz.--Effect of size of
egg.--Insects leave the egg in a more or less developed
condition.--Consideration of pupal condition.--Quiescence of
pupa.--Period of quiescence at each moult.--Changes not so
abrupt as generally supposed.--Change in
mouth-parts.--Difficulty in reference to Darwinian
theory.--Mouth-parts of _Campodea_ and Collembola, as
intermediate between the mandibulate and haustellate
types.--Change in mouth-parts as connected with pupal
conditions.--Origin of wings.--Use of wings under
water.--Connection of metamorphoses with alternation of
generations.--Parthenogenetic larvæ of _Cecidomyia_.--In
alternation of generations one form always agamic.--Dimorphism
and Dieidism.--Summary and Conclusions _page_ 62-81