MENDELIAN EXPERIMENTS ON FOWLS. 359 



In this case the piles would be as before, and there would be no 

 improvement. 



But the pile might be 



XYxYS X XYXY. 



Gametes XYS + xYS + XY + xY x XY. 



Progeny ... XYXYS + XYxYS + XYXY -[- XYxY. 



Therefore half the Piles would be improved by being now 

 homozygous for the combination XY instead of heterozygous. 

 At the same time the effect on the Bln,ck-red recessives from the 

 cross agrees with what fanciers say of the inferiority of such birds 

 to the pure-bred Black-red, for half of these recessives are 

 heterozygous for the XY combination. 



EXPLANATION OF THE PLATES. 



Plate I. 



Fig. 1. Fo J, Pile cock from cross of White Leglioni liens with l^lack-reil Game 

 cock. Killed March 1921, hatched April 14th, 1920. 



Fig. 2. Fi 9 , P'lft licii, rather deeply coloured : back light brown or fawn colour, 

 " laced" but not quite regularly, some white at base of each feather. Neck 

 hackles white, with orange edges to feathers (" lacing") ; abdomen uniform 

 pale brown. Killed Dec. 1920, hatched April 2Sth, 1919. 



Plate II. 



Fig. 1> F-2 ?, coloured recessive. General colonr diluted black, i.e. grey. Neck 

 hackles laced with pale yellow ; feathers of back dark grey, laced "with pale 

 fawn ; tail dark grey ; abdomen like the back, but much paler. Killed 

 March 1921, hatched April 14th, 1920. 



Fig. 2. F, $ , coloured recessive. General colour sooty black, with no red. Neck 

 hackles black, with streaks of light brown ; back mostly black, with 

 slight lacing of pale brown or drab ; breast and abdomen pale grey; some 

 white on wings. Killed March 1921, hatched April 14th, 1920. 



