Dunn : Color Inheritance In Fowls 



25 



The numbers of chicks produced by 

 these crosses are given in Table 1. It 

 is at once apparent that as regards 

 the difference between buff and white 

 ground color the reciprocal crosses 

 give different results. Columbian is 

 transmitted by the Light Brahma male 

 to both sons and daughters and is 

 almost completely dominant. Colum- 

 bian females, however, transmit the 

 character only to their sons ; their 

 daughters are buff like the father. 

 The first generation Columbian fe- 

 males when backcrossed to pure buff 

 males produced approximately equal 

 numbers of buff and Columbian chicks. 

 All of the buffs were females and all 

 of the Columbians were males. The 

 first generation Columbian males bred 

 to buff females, on the other hand, 

 ])roduced equal numbers of buff males 

 ar.d females and Columbian males and 

 females. The buffs extracted from 

 these backcrosses when bred intcr-se 

 produced only buff chicks of both 

 sexes. These results indicate that the 

 white Columbian coloration is due to 

 a single dominant sex-linked gene, 

 (called Silver), the recessive allelo- 

 morph of which is buff. The gene for 

 silver when present singly in the 

 zygote, apparently prevents the de- 



T 



Buff Female 



Columbian Female 

 COLUMBIAN AND BACKCROSS 



:n. In the backcross of the first generation Duckwing male 



emales, Columbian males and females, and a new type, buff, 



:wing type, but the females were unmarked black like their 

 ross (Figures 13 and 14). 



velopment of buff pigment in the 

 plumage, as Sturtevant and Punnett 

 have concluded from other cases. 



The other heredity (as far as it con- 

 cerns plumage color) of the Colum- 

 bians and buffs used by us is appar- 

 ently very similar, with the exception 

 that these two varieties differed also 

 in the extent to which black was de- 

 veloped in the feathers of the wing, 

 hackle and tail. The Columbians had 

 much l)lack in these parts ; the buffs 

 had almost none, while the hybrids had 

 an intermediate amount. Later genera- 

 tions showed that factors governing 

 the amount of black pigment were 

 transmitted independently of sex and 

 of the ground color of the plumage. 

 These "darkening" modifiers were 

 probably numerous in the Columbian 

 and few in the pure buff type. (See 

 Fig. 15 showing variations in amount 

 of black in the wings and tails of both 

 Columbian and buff' types.) 



From these experiments it appeared 

 that the Columbian and buff colora- 

 tions differed in one gene determining 

 the presence or absence of buff in the 

 plumage, and also represented two 

 stages in the development of black in 

 the plumage. The localization of 

 black was similar in the two varieties, 

 being restricted in each tyj^e to 

 the feathers of the wing, hackle 

 and tail. 



Columbian and Black 



Further experiments were un- 

 dertaken to study the expression 

 of the silver gene when introduced 

 into fowls in which much black 

 l)igment was present, as in self- 

 black varieties. We hoped also to 

 learn something of the genetic 

 constitution of the blacks with 

 regard to the presence or absence 

 of the silver gene and to study the 

 transmission of the pattern in 

 which black is restricted to the 

 wings and tail. 



Reciprocal crosses were made 

 between Light Brahmas as the 

 Columbian pattern parents, and 



