CHAPTER III.

THE NATURE OF METAMORPHOSES.

The life history of an Insect must be considered as a whole.--Vagueness of the term Larva.--Some larvæ much more advanced than others.--Organs develope in different order, in different groups.--Suppressed stages.--Apod condition of _Phryganea_; of _Aphis_; of _Chrysopa_.--Libellulidæ.--_Donacia_.--Spiders.--Myriapods.--Apod stage of Homomorphous Insects once probably longer than now.--Suppression of embryonic stages.--Metamorphoses of Hydroida, Crustacea, Isopods, and Amphipods.--Echinoderms.--Variations in development induced by the influence of external conditions. _page_ 41-62