Breeding Experiments in Poultry. 



179 



dulled owing to the development of minute spots of pigment. At 

 the same time, faint bars developed in some birds though they 

 were wanting in others. F 2 contains white, black, gray and barred 

 chicks, the last exactly like those of Barred Plymouth Rocks. 



B. Peculiarities in Inheritance of Brown Leghorn Color in Rela- 

 tion to Sex. 



Experiment I. — Brown Leghorn females X White Plymouth Rock males gave 

 both sexes barred. The males are splashed with Brown Leghorn color, which is 

 lacking in the females. 



Experiment II. — White Plymouth Rock females X Brown Leghorn males gave 

 barred males like those of Experiment I. The females are either nearly black with 

 orange hackle or else approach fairly closely the color of a Brown Leghorn female. 

 The White Plymouth Rock females appear then to be heterozygous for barring, and 

 the Brown Leghorn females for some factor for color or pattern. 



Experiment III. — Fi, females from Experiment I, bred to their father gave 27 

 white and 26 barred chicks. Even the males that were reared showed no trace of 

 Brown Leghorn color. 



Experiment IV. — White Plymouth Rock females X a male from Experiment I 

 thus far have given I black, 14 white, 6 barred, 2 Brown Leghorn. 



Experiment V. — Fi, females (Experiment I) X brown Leghorn male has given 12 

 barred, 5 black, 11 Leghorn, 4 modified Leghorn. 



Experiment VI. — Fi, females (Experiment 1) X White Langshan male (gametic 

 constitution unknown) is giving black, white, barred and red chicks. The reds 

 probably come from the father. 



Experiment VII. — F2, barred females (Experiment III) X White Langshan male 

 is giving white, black and barred chicks. 



Experiment VIII. — F2, white females (Experiment III) X White Langshan male 

 is giving only whites. 



Experiment IX. — Fi, females (Experiment II) X White Langshan is giving 

 white, black and reddish chicks. 



Experiment X. — Fi, females (Experiment II) X White Rock is giving barred and 

 white chicks. 



Since Experiment III produced no Brown Leghorn chicks and 

 since such occurred in Experiment IV, we are justified in believing 

 that the Brown Leghorn color exists in a heterozygous condition 

 in the female but not in the male, thus confirming Bateson's 

 theory of sex. As this color pattern is nearly, if not quite identical 

 with that of Gallus bankiva, it will be interesting to know if the 

 heterozygous condition is common to all the domestic races of 

 poultry bearing this ancestral color. Hagedoorn has described 

 such a case, but also describes the reverse, i. e., heterozygous 

 males and homozygous females. 



