Case 3c. d^ -^ • '- r: — r~rT. r X Black 



Constitution of the White Leghoen Breed. 195 



Now how do the observed results compare with the expected? In 

 Table 10 (p. 174), have been presented the experimental results which 

 should test the present theory. It is there shown that of 6 birds 

 half were white and half dark; of the darks two were black and one 

 was barred. The number of individuals described is too small to 

 be of great value but it appears that the trend of the data is towards 

 the verification of tlie hypothesis which has been assumed to cover 

 these cases. 



( [White Leghorn d^ X Black Minorca 9 ] cf 

 Black Minorca 9 



Minorca 9 • — (Table 11, p. 175). Under the heading of Case 3b 

 (Table 10) it has been shown that the mating (W. L. X B. M.) cT 

 [C2Bhf2li] X Black Minorca 9 [C2h2Ffi2] gives one-eighth d^ d^ that 

 are heterozygous for barring and lack the black-inhibiting factor I. 

 Using as a breeding unit a d^ having the zygotic constitution C2Bhf2i2, 

 it should be possible, if the theoretical deductions are correct, to build 

 up a group of barred 9 9 possessing the barring originally derived 

 from the W. L. d^ . The first step in this process would be to demon- 

 strate that d^ 325B actually was heterozygous for the barring factor, 

 and would transmit this character to his offspring; then to produce 

 heterozygous 99, free from I, and a homozygous d^ possessing the 

 zygotic formula C2B2f2i2, — in other words, the constitution of the 

 pure-bred B. P. R. d^ . To accomplish the first step mentioned above 

 d^ 325B was mated with a number of black 99, including Black 

 Minorcas. Since these fowls have the zygotic constitution C2b2Ffi2, 

 compatible with the absence of barring, and of the inhibiting factor, 

 the cross should bring out a certain number of 99 manifesting 

 heterozygous barring. This has appeared to be the case. The 

 mating as made may be represented as follows : 



The d^ 325B, [C2Bhf2i2] may be assumed to form gametes, 



CBfi ' Cbfi 

 and the black 9 9 to form gametes, 



ChFi • Chfi. 



