Dunn: Color Inheritance In Fowls 



29 



The first g-eneration Duckwing' males 

 v.-ere backcrossed with Cohimbian fe- 

 males (Fig. 12) and were also tested 

 by crossing with buff females. The 

 results are given in Table 2, crosses 4 

 and 5. By the Columbian females 

 these males produced equal numbers 

 of black and non-black chicks (40 :39) ; 

 while of the non-black chicks thirty- 

 three w^ere Columbian and six were 

 buiY. Of the buffs four lived and 

 proved to be females, while two which 

 died young were dissected and also 

 foimd to be females. Both sexes were 

 present in the black and Columbian 

 classes. By the buff females the first 

 generation males produced also ap- 

 proximated equal numbers of black 

 and non-bl'ack chicks (19:22). Of the 

 non-black chicks approximately half 

 were Columbian and half were buff. 

 The sexes were equally represented in 

 all classes. 



It is plain from these facts that a 

 single factor affecting the development 

 of black pigment differentiates the 

 black from the Cohmibian coloration. 

 The factor for self-black or extension 

 is dominant over its recessive allelo- 

 morph in the Columbian type in which 

 black develops to a limited extent in 

 the v/ing, hackle, and tail feathers. 

 Segregation takes place in the gametes 

 of the first generation male, and when 

 crossed with a non-extended type, 

 black (extended) and non-black (re- 

 stricted) chicks appear in a normal 

 monohybrid ratio. However, an addi- 

 tional factorial difference between 

 black and Columbian is necessary to 

 explain the dissimilarity in the adult 

 patterns of the hybrids from recipro- 

 cal crosses, and the appearance of a 

 new type, huff, when the hybrid males 

 are crossed with the Columbian par- 

 ent. This difference is apparently the 



same as that which distinguishes buffs 

 from Columbians. The Columbian 

 males transmit the gene for silver or 

 inhibition of buff to both sons and 

 daughters and even in the presence of 

 extended black this gene is able to 

 express itself in the silvering which 

 appears in both sexes from this cross. 

 The Cohmibian female transmits it (as 

 we have found above) only to her 

 sons ; and these in the crosses with 

 black are silvered in the Duckwing 

 pattern ; while her daughters never 

 receive it and are self-black like their 

 father. Moreover, when the first gen- 

 eration Duckwing males are bred to 

 Columbian females we should expect 

 that a certain number of off'spring 

 should receive neither silvering nor 

 extension. Since the Columbian fe- 

 male transmits silvering to all sons, 

 but never to daughters, while the first 

 generation Duckwing male transmits 

 it to half of his sons and half of his 

 daughters we should expect that the 

 only individuals not receiving silver 

 from this source should be females. 

 It was found that all buffs resulting 

 from this cross were females and this 

 is undoubtedly the double recessive 

 class showing neither extension nor 

 silvering. The genotypes of parents 

 and the numbers of progeny produced 

 on these assumptions should be as fol- 

 lows : 



Let E"^ := Extension of black to all 

 parts of plumage. 



Let e"" == Restriction of black to 

 wings, tail, etc. (Buff or Columbian.) 



Let S = Silvered (Columbian, Duck- 

 wing, etc.). 



Let s — Not silvered (Buff). 



— denotes the W chromosome of 

 the female which has not yet been 

 found to carry any factors. 



Genotypes 



Adult Colors : 

 Down Colors 

 Ratio: 



Black 9 



Em Ems — 



Columbian $ X Duckwing $ 

 emgmS — EmemSs 



X 



Columbian $ 

 ememSS 



EmemSS Eme'nS- 



EmgmSs Emems- 



Duckwing $ Birchen $ 

 Black 

 4 



EiuemS— 



ememSS 

 ememSs 



Columbian $ Columbian $ 

 Columbian 

 3 



Birchen $ 

 eiuemS— 



euiems — 



Buff 9 

 Buff 

 I 



