No. 646] SHORTER ARTICLES AND DISCUSSION 465 



The females from the reciprocal crosses are unlike in adult 

 plumage. From the cross of Black male by Columbian female, 

 the daughters are self black. From the cross of Columbian 

 male by Black female, the daughters are black with white bor- 

 ders on the feathers of head, hackle, and upper breast. They 

 resemble the pattern known as Birchen. 



When backcrossed with Columbian females, the F^ males have 

 produced black, Columbian and huff chicks in the ratio of 4: 

 3 : 1 ; or approximately equal numbers of chicks with extended 

 and restricted black pigment. When crossed with buff females 

 the same F^ males have produced chicks in approximately the 

 ratio 2 black: 1 Columbian: 1 buff; again showing equality be- 

 tween the extended and restricted dasses. The F^ black fe- 

 males crossed with buff males have produced equal numbers of 

 black and buff chicks, while the F^ Birchen females have pro- 

 duced, when crossed with buff males, black, Columbian and buff 

 chicks in a ratio approximating 2 : 1 : 1. The ratios as quoted 

 above have all been obtained and will be reported in full when 

 the adult classifications have been completed. All of these 

 crosses represent matings of fowls heterozygous in extension 

 (^rngTO) ^yn^ fowls recessive in extension (e"'e'"). The expecta- 

 tion is equal numbers of black (extended) and non-black (re- 

 stricted) chicks. The experimental numbers at present are 99 

 black {E"^) : 98 non-black (Columbian or buff e'"). A clear 

 monohybrid segregation is evident between extension {E'") and 

 restriction (e"') of black pigment. 



The above results are all explained on the following hypothe- 



1. The black fowls have the dominant allelomorph of an auto- 

 somal gene (E"') which determines the extension of black pig- 

 ment to all parts of the plumage. The recessive allelomorph 

 (e"*) of this gene is present in the Columbian and buff fowls. 



2. The black fowls contain the recessive allelomorph of the 

 dominant sex-linked gene S (silver). This dominant gene in- 

 hibits the production of buff ground color and causes the pro- 

 duction of silver or white ground color;' - it is known to be 

 present in Columbian f(^\U. wlii'o ilir recessive allelomorph 

 characterizes the butts. A. ; , : ■ t;..„. two genes the blacks 

 used in thes,' e.xpcr ir. i- E"'E'"ss in composi- 

 tion, tlie Cnlnnibians , , - . , female), and the 



