Constitution of the White Leghorn Breed. 



199 



white 9 9 . From the mating in question one of each sort Uved to 

 maturity, black 9 325A and white 9 325E. A consideration of the 

 analysis presented on p. 177, made it seem probable that 325 A did 

 not possess the barring factor, its zygotic formula being 0262/^/^2. 

 The white 9 325E, however, might have had the zygotic constitu- 

 tion CiBhFfli (compatible with a barred plumage rendered obscure 

 by the presence of /) ; or the constitution C^^FfH (compatible with 

 the total absence of the barring factor). We may now consider the 

 details of these two matings, with the aim of demonstrating the actual 

 zygotic constitution of the black and the white female cross-breds 

 mentioned above, both being full sisters of cf 325B. 



First Instance. — cf 325B (barred) X 9 325 A (black): As in- 

 dicated above, 6^ 325B [C2Bbf 012] may be considered to form gametes 



CBfi • Cbfi 

 while the black 9 325 A (his sister) [0262^^2], forms gametes 



CbFi ' Cbfi 

 The mating would then be represented : 



9 CbFi • Cbfi X 

 cf CBfi • Cbfi = 



9 C2b2Ffi2, black 

 9 C2BbFfi2, barred 

 cf 0262/2^2, black 

 d^ C2Bbf 212, barred 



In other words, among every four birds two would be black and 

 two would be barred; and in each of these groups there would be one 

 cf and one 9 . Each of the barred birds would be heterozygous for 

 this character. The expectation m.ay be represented as follows: 



