Wilson — The Multiple Coupling of Mendelian Factors. 371 



And the further fact that Belgian cocks have not the power of leaving all 

 their progeny Belgian is also clear evidence that the Englisli type is dominant 

 to the Belgian. 



Thus, putting E for English type and b for Belgian, the Belgian breed 

 of fowl may be represented factorially so far as type is concerned, thus : — 



Males. Females. 



MM 

 b b 



M\F\ 



b \e\ 



The male birds of English type which appear occasionally among Belgian 

 stock may therefore be represented by , jp, and the mothers of sucli birds 



must have carried the factors 



M\F\ 

 E \e\' 



That the silver colour is dominant to the gold and the factor for gold 

 coupled witli that for femaleness is brought out by several results mentioned 

 in Mr. Jones's pamphlets ; for, when silver males are mated with gold females 

 the progeny are all silver, but when gold males are mated with silver females 

 only half the progeny are silver, while the other half are gold. Besides, the 

 silver progeny are all males, wliile the gold progeny are all females. The 

 factor for gold colour is thus coupled with that for femaleness. 



The factorial representation of the Belgian and English Gampines becomes 

 therefore : — 



silver 

 males. 



MM 



b b 

 S 8 



Belgian Belgian 



English 

 silver 



MM 

 b b 

 9 g 



M 



9 



EngUsh 

 silver 

 females. 



M M 31 \p 

 E E e\e 



8 S 8 \fi 



English 

 gold 



MM 

 E E 

 9 9 



Although it is unnecessary, for the above hypotliesis is clear as it stands, 

 it might be well to show how it can be confirmed by a selection from 

 Mr. Jones's experiments. 



I. 



English 

 silver 

 male. 



MM 

 E E 



8 8 



and gold 



Belgian 



gold 

 female. 



should 

 give 



English 

 silver 

 males. 



b E 



8 g 



and 



English 

 silver 

 females. 



Mr. Jones got 6 English silver males and 8 English silver females 



