Different Potentialities of Male and Female Skin in Reeves Pheasants. ∗

Abstract

The extraordinary similarity of feathers produced by male and female fowls after gonadectomy has led to the idea that the skin in the 2 sexes is potentially the same. This inference seems to be supported by the effects of endocrine injections and the results of skin transplantation. It is further strengthened by the fact that, although between different races there is much variation in response to endocrines, the 2 sexes of any one race react rather consistently. Nevertheless, there are frequently detectable, though generally slight, differences between feathers produced by birds that were originally male and those that were originally female. This suggests that the genotype of the male and that of the female may condition slightly different responses when all other factors are held constant.

A search for some form in which this problem could be approached more satisfactorily than in the common fowl revealed that the Reeves pheasant (Syrmaticus reevesi) is very satisfactory for the purpose. It is a species which breeds true to a standard type and has a plumage that is distinctive and varied, with none of the feathers of one sex duplicated by those of the other. The birds are rather expensive when purchased from dealers, but may be raised from eggs with relative ease.

Homoplastic skin transplantation immediately after hatching was chosen as the method affording the most delicate and dependable test. The procedure has the disadvantage of requiring a wait of several months between the beginning of an experiment and attainment of the final result. It also involves certain losses due to incompatibility of tissues of donor and host. But in many cases no incompatibility is revealed and the grafted skin appears to behave normally in every respect, functioning as an integral part of the host.