194 Peculiar Pigme7itation of the Silky Fowl 



the constitution ffPPII or ffPPIi and suppose that in the presence 

 of a double dose of the pigmentation factor the effects of the inhibitor 

 are in considerable measure overcome in the younger stages. In cor- 

 roboration of this view we may state that we reared several of these 

 deeply pigmented ^^ and that they all became far less heavily pig- 

 mented in appearance as they approached maturity. In external 

 appearance indeed they showed little more pigmentation than the F^ 

 cocks. This explanation is the natural one if we regard the constitu- 

 tion of the slightly pigmented F^ % as FfPpIi, and further evidence 

 (p. 198) in favour of this view will be adduced from an entirely 

 different set of experiments. 



3. fj X Brown Leghorn. 



(a) Brown Leghorn $ x F^ (f. 



[Nature of mating, FfppIi x ^Ppli.] 



On our hypothesis this form of mating should give a specific result, 

 for while the ^^^^ should all be either without, or with comparatively 

 little, pigment, one quarter of the $ $ should be fully pigmented 

 (cf. Figs. 3 and 4). We have bred a considerable number of birds 

 (nearly 700) in this way, and the figures given in Table V show that 

 this expectation is closely realised. None of the 336 (^(^ produced 



TABLE V. 



Males Females 



Reference Nature of mating FuU Some None Full Some None 



1906 Pen 9, 207 Brown ? x i^^i <? — 28 8 29 



,, 33, 248 



„ 33, 159 



1907 „ 11, 203 



„ 12, 264 



,, 12, 159 



8 11 



13 5 18 



34 8 24 



13 3 8 



19 3 18 



„ 15, 347 Br.L. ?xFic? — 34 11 37 



„ 16 ? ?Br.L. Brown? xFiS — 18 2 14 



„ 20, 129 „ ' — 22 7 19 



„ 22, 101 „ _ 42 8 28 



„ 23, 98 „ — 24 7 18 



1908 ,, 5, 101 „ _ 17 3 20 

 „ 16, 345 Br. L. SxjPjc? — 20 7 16 

 ,, 22, 129 Brown ?xFi<f — 40 8 31 



1909 „ 20, 347 Br.L.^xFiJ— 4 1 4 



Total — 336 82 280 



Expectation — 336 90-5 271-5 



