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 Fj 



[9] Ffppli 



gives 

 gametes 



Fpi \ 

 fpl / 



ffppii [c^] 



g:ives 



fameti 



[fpi 

 I fpi 



g:ives 

 gametes 



[^]ffPPii [9]FfpP" 



ffppIiEd] 



gives 

 gametes 



fPi 

 fPi 



1} 



g-ives 

 gametes 



[Fpi 

 \fpi 



gives 

 gametes 



fpi\ 

 fpi / 



FfPPii[f ] 



gives 

 gametes 



/ FPi 



I fPp 



FfPpii 

 [?] 



ffPpii 

 LSI 



FfPpii 



[?] 



Fig. 25. 



FfPpii 



ffPpIi 



ffPpii 



> 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 )!vhile 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 



