30 INHERITANCE IN POULTRY. 



IIA. Feathers mostly white, but some are sooty. The single comb is 

 cleft behind for about one-fourth of its total length. 



ISA. Feathers all white ; comb strictly single. 



The father, No. QA, also of unknown parentage, has a large rose comb 

 90 mm. long by 44 mm. broad at its widest part. The tubercles are very 

 irregular, but five rows of them can be discerned. The plumage is prevail- 

 ingly black, but many feathers of the back are tipped with white and several 

 primaries are almost or quite white. 



RESULTS. 



This series of experiments has been carried as yet through only the first 

 hybrid generation. 



1 . PLUMAGE COLOR. Eighty-three first hybrids were obtained of which 74 

 were white, either pure or with some black feathers, and 9 were deeply pig- 

 meuted. Females A and C yielded only white offspring. Female B, on the 

 other hand, produced chiefly dark birds, recorded as "blue" or "black- 

 and-white." She was the mother of the 9 pigmeuted birds just mentioned. 

 B's germ cells are probably mixed. The only two of B's offspring reared 

 to maturity are blue like the so-called "Andalusian breed" (fig. 54, pi. xvn). 

 Now blue is a combination of black and white and is a " heterozygous form." 

 If blue birds, one of which is male, the other female, breed together, both 

 pure black and impure white, as well as blues again, are to be expected in 

 the proportions of 1:1:2 respectively.* Of the white offspring of both A 

 and C it is noteworthy that the males are mostly pure white (i. c. , without 

 trace of black, although often suffused with yellow), while the females are 

 always specked with black. 



2. COMB FORM. Of 80 first hybrids 40 have single comb and 40 rose comb. 

 This result indicates first that the cock is a heterozygote and consequently 

 produces in its germ glands two kinds of germ cells, viz, those with the single- 

 comb and those with the rose-comb determinants and second, that rose comb 

 is dominant. Then : R single X DR rose gives 50 per cent DR rose and 50 

 per cent RR single. 



Bateson and Sauuders (1902, pp. 102, 103) find rose comb of Wyandotte 

 or White Dorking dominant over single comb of the Leghorn. Hurst 

 (1905, p. 134) crossed a White Leghorn with a Black Hamburgh (rose comb) 



*Tegetmeier (1867, p. 185) states that blue Polish bred together throw cuckoo, white or 

 speckled produce. Wright (1902, pp. 399-401) states that "Andalusians " constantly throw 

 black and also white chicks. Blue chicks are frequently produced by crossing black and 

 white. Wright (1902) mentions such a result from crossing black and white L,angshans 

 (p. 291) and Wyandottes (p. 318). Such blues also throw whites and blacks. Inher- 

 itance of blue is discussed by Bateson and Saunders (1902, pp. 131-132) and by Bateson 

 and Punnett (1905, pp. 118-119). In the latter paper it is stated that of 75 offspring of 

 Andalusians 17 were " white splashed, 36 blues, 22 blacks." A blue bred to a white pro- 

 duced 34 blue and 20 white splashed ; bred to a black it gave 27 blue and 19 black. 



