On the Question of Equipotentiality of the Spurs in the Leghorn Fowl. ∗

Abstract

In previous communications^{1, 2} it has been shown that the spurs of the two sexes do not react equally to the sex hosts once the chick is hatched. Spurs from either sex grafted to the male host were for the most part of the male type but on the female each was characteristic of its sex. This might be explained either on the basis of a conditioning of the male spur by the male hormone prior to the time of hatching or on the basis of a genetic difference in the spurs of the two sexes.

In an effort to determine whether the spurs of the female can be conditioned by the male hormone and whether a spur will continue to develop in the presence of the female hormone after growth has begun as maintained by Goodale 3 and Domm, 4 spurs from females were grafted to male hosts and after varying periods were transplanted back to the original donors. Complete records are available for 9 experiments, 7 between infant chicks and 2 between adult birds. Of the experiments between infant chicks, one spur was taken from a chick the day of hatching, 4 from day-old chicks, one from a 2-day old chick, and one from a 4-day old chick. These were allowed to grow on male hosts during periods varying from 14 to 24 days before they were transplanted back to the original donors. Between the adults, the one spur was allowed to remain on the male host 8 weeks, during which time it increased 3.0 mm. in length; the other remained 14 weeks, during which time its length increased by 3.5 mm. In all the experiments between the infant chicks, the spurs developed into normal female spurs.