KiO Bulletin No. 155. — 1U13. 



Piock breed of fowls has, within the past two or three years, received 

 some consideration. 



The fact has long been noticed by observant poult rymen that the 

 progeny from crosses between Phmouth Rocks and dark non-barred 

 breeds varied with respect to the barred color-pattern, according as 

 the male bird belonged to one or the other race in question. Gush- 

 man (1803) was probably the first to report this circumstance. 

 'Diis writer made a large number of crosses between pure-bre<l fowls 

 witli the purpose of perfecting a good market roaster. Among his 

 (Tosses were Indian Game cf X Barred Plymouth Rock 9. Cush- 

 mnn (/, c.) gives a l)rief description of this cross and states that the 

 cockerels had barred plumage whereas the pullets were all black. 



It is probable that other poult r>'men have observ'ed similar results 

 from such crosses, but without recording their observations. Yet 

 tlie facts obs<Tve<l awakened little speculation until the attempt was 

 made to place u|>on them an interpretation agn^'ing with the Men- 

 (Iclian view of here<lity. Spillman (l908) then devised a Mendelian 

 hypothesis to account for the facts observed in the inheritance of 

 b.irring. This hypothesis may be briefly 8tate<i as follows: 



1. \Mien barring is present \n female birds, they are heterozygous 

 for this character; they arc also heterozygous for the female sex 

 character (F). 



'2. When barring is present in male birds, they may be either 

 hdcroziigous or homozygous for this character; the males are always 

 homozygous for the absence of the female sex character. 



3. Barring (li) and the character. '*f«'maleness" (F^. n«'Vor oxist 

 togeth'T in the same gamete. 



This may be represent e<l symbolically i\s follows: 



Let F represent the female sex character (9). 

 Let / represent the absence of femaleness, or the male sex character 

 (cf). 



liCt B reprcvHcnt the factor for barring. 



Ix;t b rr'pro«fMit tho aKsence of the barring factor. 



