The direct dependence of sexual pigmentation on the primary sexual glands is well illustrated by a true hermaphroditic adult finch exhibited at the Academy of Sciences of Amsterdam (May 31, 1890); this bird had a testis on the right side and an ovary on the left, and on the right side its plumage was of the male's colors, on the left of the female's color.
See. e.g., Papillault, Bulletin Société d'Anthropologie, 1899, p. 446.
Guinard, Art. "Castration," Richet's Dictionnaire de Physiologie.