THE GENETIC FACTOR FOR HEN-FEATHERING IN 

 THE SEBRIGHT BANTAM. 



T. H. MORGAN. 



Crosses between Sebrights and Game Bantams had shown 

 that the dominant gene for hen-feathering is inherited as an 

 alternative to cock-feathering, but the number of F, and back- 

 cross cocks that were obtained was too few to settle the ques- 

 tion whether one or two pairs of genes for hen-feathering were 

 involved. The situation has been recently discussed in my paper 

 on '"'The Genetic and Operative Evidence Relating to Secondary 

 Sexual Characters," Carnegie Publication, No. 285, 1919. I am 

 now able to add a small amount of new data to that previously 

 recorded, although I regret that even the combined data still do 

 not show clearly whether one or two factors for hen-feathering 

 are involved. 



During the summer of 1919, I back-crossed four hens (out of 

 Game by Sebright) to a pure Game Bantam cock bought from 

 the same breeder from whom the other Games had come. The 

 chicks were hatched in June and July, 1919, and the following 

 records were made on March 22, 1920, when the new birds had 

 fully attained their adult plumage. 



Five of the cockerels were hen-feathered, and three were cock- 

 feathered. There was no difficulty in separating the cockerels 

 into two classes. Only one bird fell within the group of hen- 

 feathered cocks that in my previous paper I sometimes spoke of 

 as " intermediate." This means only that some of the back and 

 saddle feathers were more pointed than are those of pure Se- 

 bright cocks. Their ends may show on each side of the tip a 

 narrow edging lacking barbules. Previously the same back-cross 

 gave two hen-feathered and seven cock-feathered males. The 

 two records together give, therefore, 7 hen-feathered and 10 

 cock-feathered males. 



For a single factor-difference the expectation for 16 birds 

 would be 8. hen-feathered and 8 cock-feathered birds. The num- 



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