[30] Darwin, Origin of Species, chap. i.
[31] On this homology of hair and teeth, see Brandt, "Über ... eine mutmassliche Homologie der Haare und Zahne" (Biol. Centralblatt, vol. xviii., 1898, especially pp. 262 ff.).
[32] It seems, from later observations, that the transformation of Artemia is a more complex phenomenon than was first supposed. See on this subject Samter and Heymons, "Die Variation bei Artemia Salina" (Anhang zu den Abhandlungen der k. preussischen Akad. der Wissenschaften, 1902).
[33] Eimer, Orthogenesis der Schmetterlinge, Leipzig, 1897, p. 24. Cf. Die Entstehung der Arten, p. 53.
[34] Eimer, Die Entstehung der Arten, Jena, 1888, p. 25.
[35] Ibid. pp. 165 ff.
[36] Salensky, "Heteroblastie" (Proc. of the Fourth International Congress of Zoology, London, 1899, pp. 111-118). Salensky has coined this word to designate the cases in which organs that are equivalent, but of different embryological origin, are formed at the same points in animals related to each other.
[37] Wolff, "Die Regeneration der Urodelenlinse" (Arch. f. Entwicklungsmechanik, i., 1895, pp. 380 ff.).
[38] Fischel, "Über die Regeneration der Linse" (Anat. Anzeiger, xiv., 1898, pp. 373-380).
[39] Cope, The Origin of the Fittest, 1887; The Primary Factors of Organic Evolution, 1896.