202 Pemdiar Pigmentation of the SiJlij Fowl 



Silky crosses other than with the Brown Leghorn. 



During the course of our experiments we have crossed the Silky 

 with other fowls beside the Brown Leghorn, but as the crosses with 

 the last named promised the most definite results our attention and 

 resources were mainly devoted to these. We may however mention 

 a few points of interest wliich have arisen in connection with some of 

 the other crosses. 



Our original Silky ^ was mated in 1906 to a white Rosecomb 

 bantam. All the chicks (5 (^ ^ and 7 $ $) were deeply pigmented 

 on hatching though as they reached maturity the pigment became less 

 marked in the cockerels. A few cases are already on record in which 

 a Silky was crossed with another breed and all the resulting offspring 

 of both sexes were deeply pigmented'. It is worthy of note that in 

 such cases the breed with which tlie Silky was crossed possessed dark 

 shanks. This was certainly so for the Spanish used by Tegetmeier and 

 Darwin as well as for the Rosecombs used by ourselves; and we iufer, 

 though this is not explicitly stated, that it was also true for the frizzled 

 fowls used by Davenport. 



We may mention two cases from our experiments which are con- 

 sistent with this view. When a Silky J' was mated with a dark- 

 shanked mongrel % (F.. ex White x Brown Leghorn) 2 out of the 13 

 male chicks produced were fully pigmented. The remaining 11 male 

 chicks exhibited a varying amount of pigment, while all the 11 female 

 chicks showed the full pigmentation (1906, Pen 18, 150). lu the other 

 case an F^ </, ex Silky $ x Brown Leghorn J", was also crossed with 

 a dark-shanked mongrel Legliorn hen bred similarly to the last (190C, 

 Pen 9, 604). Out of the 19 male chicks from this mating two were 

 deeply pigmented, while with light-shanked hens the cock gave the 

 usual result (cf. p. 194). W^e must suppose therefore that the factor 

 or factors upon which shank pigmentation depends can influence the 

 factors concerned with the development of the pigment found in the 

 Silky fowl, but at present we do not know sufficient about the nature 

 of these factors to make any more definite statement. 



Though our experiments have led us to infer that the strain of 

 Brown Leghorns with which we worked was homogeneous in respect 

 of the factor modifying pigmentation we nevertheless have evidence 



1 Cf. Tegetmeier, The Poultry Book, 1873, p. 268 ; Darwin, Animals and Plants, 2nd 

 edit., 1899, p. 2.53 ; Davenport, Inheritance in Poultry, 1906, p. 60. 



