112 



MENDELISM 



CHAP. 



i.e. in constitution ffppli, while the hen birds, though 

 identical in appearance so far as absence of pigmentation 

 goes, should not contain this factor but should be con- 

 stitutionally Ffppii. Crossed with the pure Silky, the FI 



[9] Ffppli ffppii 



gives gives 



gametes gametes 



[rf]ffPPii [9] Ffppii 



gives gives 



gametes gametes 



Ffppli [c?] FfPPiiff] 



gves 

 gametes 



gves 

 gametes 



fPi 



fpi 



f p 



FfPpii 



ffPpii FfPpli FfPpii ffPpli ffPpii 



FIG. 25. 



Scheme to illustrate the heterozygous nature of the pure Brown Leghorn hen. For 

 explanation see text. 



birds of opposite sexes should give an entirely different 

 result. For while the hens should give only deeply pig- 

 mented birds of both sexes, the cocks should give equal 

 numbers of deeply pigmented and slightly pigmented 

 birds (cf. Fig. 25). These were the results which the ex- 

 periment actually gave, thus affording strong confirma- 

 tion of the view which we have been led to- take of the 

 Brown Leghorn hen. Essentially the poultry case is that 

 of the currant moth. It differs in that the factor which 



