[1638] Wallace, ‘Darwinism,’ pp. 160, et seq.
[1639] Darwin, ‘The Origin of Species,’ vol. ii. pp. 44, &c. Cf. Godron, loc. cit. vol. i. p. 209.
[1640] The greater or less degree of sterility of hybrids, although, as Mr. Darwin remarks (‘The Origin of Species,’ vol. ii. p. 46), a very different case from the difficulty of uniting two pure species, yet, to a certain extent, runs parallel with it.
[1641] Geoffroy Saint-Hilaire, ‘Histoire naturelle,’ vol. iii. pp. 168, 169, &c.
[1642] Darwin, ‘Animals and Plants under Domestication,’ vol. ii. p. 180.
[1643] ‘Exodus,’ ch. xxii. v. 19. ‘Leviticus,’ ch. xviii. v. 23; ch. xx. v. 15. ‘Deuteronomy,’ ch. xxvii. v. 21. Pliny, loc. cit. book viii. ch. 42. Virgil, ‘Bucolica,’ Ecloga iii. v. 8.
[1644] Janke, loc. cit. p. 276. Mackenzie, ‘Voyages,’ p. xcvii. v. Kraft-Ebing, ‘Psychopathia sexualis,’ pp. 135, et seq.
[1645] See Darwin, ‘The Descent of Man,’ vol. ii. pp. 125, 126, 128.
[1646] Cf. Blumenbach, loc. cit. pp. 80, et seq.; Steller, loc. cit. p. 289, note.
[1647] Périer, ‘Essai sur les croisements ethniques,’ in ‘Mémoires Soc. d’Anthr.,’ vol. i. p. 216. Jacquinot, in Dumont d’Urville, ‘Voyage au Pole Sud,’ Zoologie, vol. ii. p. 92.