[2] The chief general collection of data (not here drawn upon) concerning homosexuality among animals is by the zooelogist Prof.  Karsch, “Paederastie und Tribadie bei den Tieren,” Jahrbuch fuer sexuelle Zwischenstufen, vol. ii.  Brehm’s Tierleben also contains many examples.  See also a short chapter (ch. xxix) in Hirschfeld’s Homosexualitaet.

[3] H. Sainte-Claire Deville, “De l’Internat et son influence sur l’education de la jeunesse,” a paper read to the Academie des Sciences Morales et Politiques, July 27, 1871, and quoted by Chevalier, L’Inversion Sexuelle, pp. 204-5.

[4] M. Bombarda, Comptes rendus Congres Internationale de l’Anthropologie Criminelle, Amsterdam, p. 212.

[5] Lacassagne, “De la Criminalite chez les Animaux,” Revue Scientifique, 1882.

[6] Steinach, “Utersuchungen zu vergleichende Physiologie,” Archiv fuer die Gesammte Physiologie, Bd. lvi, 1894, p. 320.

[7] Fere, Comptes-rendus Societe de Biologie, July 30, 1898.  We may perhaps connect this with an observation of E. Selous (Zooelogist, May and Sept., 1901) on a bird, the Great Crested Grebe; after pairing, the male would crouch to the female, who played his part to him; the same thing is found among pigeons.  Selous suggests that this is a relic of primitive hermaphroditism.  But it may be remembered that in the male generally sexual intercourse tends to be more exhausting than in the female; this fact would favor a reversion of their respective parts.

[8] E. Selous, “Sexual Selection in Birds,” Zooelogist, Feb., 1907, p. 65; ib., May, p. 169.  Sexual aberrations generally are not uncommon among birds; see, e.g., A. Heim, “Sexuelle Verirrungen bei Voegeln in den Tropen,” Sexual-Probleme, April, 1913.

[9] See Moll, Untersuchungen ueber die Libido Sexualis, 1898, Bd. i, pp. 369, 374-5.  For a summary of facts concerning homosexuality in animals see F. Karsch, “Paederastie und Tribadie bei den Tieren auf Grund der Literatur,” Jahrbuch fuer sexuelle Zwischenstufen, Bd. ii, 1899, pp. 126-154

[10] Muccioli, “Degenerazione e Criminalita nei Colombi,” Archivio di Psichiatria, 1893, p. 40.

[11] L’Intermediare des Biologistes, November 20, 1897.

[12] R.I.  Pocock, Field, 25 Oct., 1913.

[13] R.S.  Rutherford, “Crowing Hens,” Poultry, January 26, 1896.

[14] This has now been very thoroughly done by Prof.  F. Karsch-Haack in a large book, Das Gleichgeschlechtliche Leben der Naturvoelker, 1911.  An earlier and shorter study by the same author was published in the Jahrbuch fuer sexuelle Zwischenstufen, Bd. iii, 1901.

[15] See a brief and rather inconclusive treatment of the question by Bruns Meissner, “Assyriologische Studien,” iv, Mitteilungen der Vorderasiatischen Gesellschaft, 1907.