Gonadectomy in Relation to the Secondary Sexual Characters of Some Domestic Birds

Gonadectomy in Relation to the Secondary Sexual Characters of Some Domestic Birds

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Gonadectomy in Relation to the Secondary Sexual Characters of Some Domestic Birds

Gonadectomy in Relation to the Secondary Sexual Characters of Some Domestic Birds

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Excerpt

It has been long known that an intimate relation exists between the primary sexual organs of certain animals and their secondary sexual characters. Until recent years, however, there has been considerable doubt as to the interpretation of many of the effects of castration -i. e., as to whether the effect tended toward the appearance of characters belonging to the opposite sex. In particular, there has been a dispute as to whether certain characters, such as the small comb of the capon, were to be considered juvenile or female. In birds the occurrence of individuals with the plumage and other characters of the male, but having the sexual organs of the female, have attracted a great deal of attention. Recently, Guthrie (1910) has described a hen with male plumage following ovariotomy, while Fitzsimons (1912) has reported like results in the ostrich.

Very often, and perhaps always, the records state that the ovaries of male-plumaged females occurring in nature have degenerated to a greater or less degree, and from this it has been inferred that the occurrence of the male plumage was in some way or other associated with the degeneration of the ovary. On the other hand, the sporadic occurrence of birds with the external characters of the female and the internal sexual organs of the male is relatively uncommon in races such as pheasants or domestic fowl. As a rule such males, whose primary sexual organs are perfectly normal, exhibit only one or two female characters, the remainder of their secondary sexual characters being those of the normal male. Female characters may also be normal to the juvenile male. Moreover, it has been shown in the case of henfeathered males of the domestic fowl that this character is inherited in a definite fashion. The occurrence of male birds with the secondary sexual characters of the female, where these characters are distinct from those of the juvenile male, are extremely rare. It seems highly probable that, except in the very rarest of instances, female-feathered males are in an entirely different category from male-feathered females. (However, cf. Morgan, 1915.) Nevertheless, races exist, such as the bobolink, in which the males may become nearly or quite indistinguishable from the females at certain seasons of the year.

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