MiSADKLlAN EXPERIMENT ON FOWLS. 



177 



all the colonred being heterozygous and carrying pile. The 

 total number of chicka in these four broods was 26, of which 

 12 were pile and 14 coloured. In Broods I &, II only one chick 

 survived to maturity in each, and that in Brood I was coloured. 

 F. II 3 $ was a hen with much brown on breast. The male 

 parent of F, II, namely F^ VIII 2 r? , had also, before the sexual 

 change of colour took place, much brown on breast. In the piles 

 of the other two broods there was brown on the breast of the 

 hen or yellow on the back of the cocks in all cases, but no very 

 distinct evidence of increase over the previous generation. 

 Owing to my visit to Aiistralia in 1914, I was not able to 

 examine these two broods for colour till they were three or four 

 months old, when the males were already losing the colour on 

 the breast and developing it on the back, and the colour on the 

 back is never more than light j^ellow, while in the hens it is a 

 much deejjer brown on the breast. 



F, III was the offspring of F^ VIII 6 $ and F^ VIII 7 J , both 

 dark-coloured birds with silky plumage. As these were both 

 heterozygous for plumage-colour there were some piles among 

 the ofispring, the numbers being 5 coloured and 3 recessive. Of 

 the latter one died in the down stage, and the other two were 

 both males Avhicli had brown on the breast when first fledged. 

 F, V was the offspring of F^ VIII 8 d x F, IV 3 $ , both coloured. 

 Only one F^ V 7 was pile, and this when first fledged had mode- 

 rate brown on the breast. 



The birds kept from F. for breeding again were : — 



Fg II 3 5 , pile with much brown on breast. 



Y- V 5 d" , coloured. 



F^ III 1 & 2 $ , dark silky. 



Fj VI 1 c? , coloured, dark. 



F-VII 1 c?, coloured. 



F', V 2 & 4 ? , coloured, light. 



Fj IV 3 5 , pile with brown on breast. 



f' VI 2 $ , coloured dark. 



F- VI 3 $ , coloured light. 



fJv 7d,pile. 



Fg V 6 $ , coloured light, silky. 



F^ Generation^ 1915. 



In the Fg generation eleven broods were hatched. Of these 

 six were from matings of pile with coloured, and of the chicks 

 produced by these 24 were coloui'ed and only 9 pile. This is very 

 far from the expectation of equality, and the difference is greater 

 than in F^ or F,. In F,. several of the broods were small, as 

 though fertility had decreased, ;ind it is possible that more of the 

 recessives were either unfertilized or died before hatching. In 

 all these piles of F^ as well as in those produced by matings of 

 heterozygous coloured birds together, brown colour was present 

 on the breast in the first feathering, disappearing in the cocks as 



Proc. Zool. Soc— 1919, No. XII. 12 



