[204] “Entwicklung der Dipteren.” Leipzig, 1864. [205] Lubbock concludes from the presence of thoracic legs in the embryonic larva of bees that these have been derived from a larva of the _Campodea_ type, but he overlooks the fact that the rudiments of the abdominal legs are also present; _loc. cit._, p. 28. [206] “Für Darwin,” Leipzig, 1864, p. 8. [207] Mem. Peabody Acad. of Science, vol. i. No. 3. [208] Verhandl. Wien. Zoolog. Botan. Gesellsch. 1869, p. 310. [209] Über Ontogenie und Phylogenie der Insekten. Eine akademische Preisschrift. Jen. Zeitschrift. Bd. x. Neue Folge, iii. Heft 2. 1876. [Some remarks by F. M. Balfour on the origin of certain larval forms have already been quoted in a previous note (p. 485). This author further states:--“The fact that in a majority of instances it is possible to trace an intimate connection between the surroundings of a larva and its organization proves in the clearest way _that the characters of the majority of existing larval forms of insects have owed their origin to secondary adaptations_. A few instances will illustrate this point:--In the simplest types of metamorphosis, _e.g._ those of the Orthoptera genuina, the larva has precisely the same habits as the adult. We find that a caterpillar form is assumed by phytophagous larvæ amongst the Lepidoptera, Hymenoptera, and Coleoptera. Where the larva has not to go in search of its nutriment the grub-like apodous form is assumed. The existence of such an apodous larva is especially striking in the Hymenoptera, in that rudiments of thoracic and abdominal appendages are present in the embryo and disappear again in the larva.... It follows from the above that the development of such forms as the Orthoptera genuina is more primitive than that of the holometabolous forms, &c.” Comparative Embryology, vol. 1, p. 352. R.M.] [210] [The _Aphaniptera_ are now recognized in this country as a sub-order of Diptera. See, for instance, Huxley’s “Anatomy of Invertebrated Animals,” p. 425, and Pascoe’s “Zoological Classification,” 2nd ed. p. 122. R.M.] [211] [This illustration of course only applies to the old arrangement of the Hymenoptera into _Terebrantia_ and _Aculeata_. See also note 201, p. 488. R.M.] [212] [Eng. ed. This law is perhaps a little too restricted, inasmuch as it is theoretically conceivable that the organism may be able to adapt itself to similar conditions of life in different ways; differences of form could thus depend sometimes upon differences of adaptation and not upon differences in the conditions of life, or, as I have formerly expressed it, it is not necessary to allow always only _one_ best mode of adaptation.] [213] [It must be understood that the word rendered here and elsewhere throughout this work as “transformation” is not to be taken in the narrow sense of metamorphosis, but as having the much broader meaning of a change of any kind incurred by an organism. Metamorphosis is in fact but one phase of transformation. R.M.]