Constitution of the White Leghorn Breed. 209 



presence of X and Y together would determine pigmentation, but 

 this would be obscured by /, althougn in heterozygous condition. It 

 is conceivable, however, that li might permit a small amount of 

 black to appear in the early feathering of Fi; and this condition was 

 actually found to occur as also pointed out by Goodale (1910). In 

 this paper it has been shown to hold for Fi in nearly all of the White X 

 Black crosses. 



In the production of F2 of the cross under discussion, a cf Fi white 

 cross-bred \E2f2liXxYy\ would form gametes of 8 sorts: 



BJIXY • Bfixy • BfIXy • BfixY 



Bfixy • BfiXY • BfIxY • BfiXy 

 w^hile Fi cross-bred 9 [BbFfliXxYy] would form 16 kinds of gametes: 



BfIXY • Bfixy ' BFIXY ■ hFixy 



BfIXy • BfixY ' hFIXy ' hFixY 



BfIxY • BfiXY ' hFIxY • hFiXY 



BfIxy • BfiXy • hFIxy • hFiXy 

 This mating would give 128 individuals possessing 27 different 

 zygotic constitutions as follows : 



cf Combinations. 



52/2/2X272 (1), white B2f2l2X2Yy (2), white 



B2j2liXxYy (8), white 52/2/2X2F2 (1), white 



^2/2/2X2 72/ (2), white B2f2lix2y2 (2), white 



B2f2liXxY2 (4), white ^2/2/20:22/2 (1), white 



52/2/2X^72/ (4), white -62/212^^22/2 (1), white 



^2/2/1X272 (2), white B2f2i2X2Yy (2), white 



52/2/2X0^72 (2), white 52/222X22/2 (1), white 



B2f2liX2Yy (4), white 52/2/2X0:2/2 (2), white 



52/2/2X0:2/2 (4), white B2f2i2X2Y2 (1), white 



52/2/2X22/2 (1), white 52/222X0:72/ (4), barred 



52/2/2X0:2/2 (2), white 52/222X0:72 (2), barred 



52/2/2X22/2 (2), white 52/222X272 (1), barred 



52/2/20:272/ (4), white 52/222X272/ (2), barred 

 52/2/20:272 (2), white 



