102 



MENDELISM 



CHAP. 



We may now construct a scheme for comparison with 

 that on page loo to show how these assumptions explain 

 the experimental results. The original parents were lacti- 

 color female and grossulariata male, which on our assump- 

 tions must be Ffgg and ffGG respectively in constitution. 



Ffgg[9] ffGG[^] 



gametes ■{ / > 



(fG 

 XfG 



[c?]ffgrg 



!}-■< 



1 — 



Ffgg 



[2] 



FfGg[f] ffGg[^] 



Hfgg [9] 



ffGg 



Ffgg FfGg ffGg ffGG FfGg Ffgg ffGg ffgg 

 [9] [?] W] W] [?] [9] W] i6\ 



Fig. i8. 



Scheme of inheritance in the Fi and Fg generations resulting from the cross of lacHcolor 

 female with grossulariata male. The character of each individual is represented by the 

 sex signs in brackets, the black being grossulariat in appearance and the light ones lac- 

 ticolor. 



Since the female is always heterozygous for F, her gametes 

 must be of two kinds, viz. Fg and fg, while those of the 

 pure grossulariata male must be all fG. When an ovum 

 Fg is fertilised by a spermatozoon /G, the resulting zygote, 

 FfGg, is heterozygous for both F and G, and in appearance 

 is a female grossulariata. The zygote resulting from the 

 fertilisation of an ovum/g by a spermatozoon /G is hetero- 

 zygous for G, but does not contain F, and therefore is a 

 male grossulariata. Such a male being in constitution 



