[43] ‘Bull. de La Soc. Imp. d’Acclimat.,’ tom. viii. p. 351.
[44] See an account of Mr. Gregson’s experiments on the Abraxus grossulariata, ‘Proc. Entomolog. Soc.,’ Jan. 6th, 1862: these experiments have been confirmed by Mr. Greening, in ‘Proc. of the Northern Entomolog. Soc.,’ July 28th, 1862. For the effects of food on caterpillars, see a curious account by M. Michely in ‘Bull. De La Soc. Imp. d’Acclimat.,’ tom. viii. p. 563. For analogous facts from Dahlbom on Hymenoptera, see Westwood’s ‘Modern Class. of Insects,’ vol. ii. p. 98. See also Dr. L. Moller ‘Die Abhängigkeit der Insecten,’ 1867, s. 70.
[45] ‘The Principles of Biology,’ vol. ii., 1866. The present chapters were written before I had read Mr. Herbert Spencer’s work, so that I have not been able to make so much use of it as I should otherwise probably have done.)
[46] Professor Weismann comes to the same conclusion with respect to certain European butterflies in his valuable essay, ‘Ueber den Saison-Dimorphismus,’ 1875. I might also refer to the recent works of several other authors on the present subject; for instance to Kerner’s ‘Gute und schlechte Arten,’ 1866.
[47] ‘Proc. Acad. Nat. Soc. of Philadelphia,’ Jan. 28th, 1862.
[48] See Mr. B. D. Walsh’s excellent papers in ‘Proc. Entomolog. Soc. Philadelphia,’ Dec. 1866,, p. 284. With respect to the willow, see ibid., 1864. p. 546.
[49] See his admirable ‘Histoire des Galles’ in ‘Annal. des Sc. Nat. Bot.’ 3rd series tom. 19 1853 p. 273.)
[50] Kirby and Spence’s ‘Entomology,’ 1818, vol. i. p. 450; Lacaze-Duthiers, ibid., p. 284.
[51] ‘Proc. Entomolog. Soc. Philadelphia,’ 1864, p. 558.
[52] Mr. B. D. Walsh, ibid., p. 633, and Dec. 1866, p. 275.