x] The Silky Fozul 183 



their offspring, whether male or female, are never more 

 than moderately pigmented. Just as in the making of F^ 

 therefore, the pigmentation must come in from the male 

 side in order that it may appear to any full degree in the 

 offspring. 



(2) The F^ males from both kinds of mating are 

 identical in composition so far as pigmentation and their 

 powers of transmitting it are concerned. When they are 

 bred with Brown Leghorn hens they produce one bird in 

 eight, on an average, deeply pigmented, and these are always 



females. 



This result was exceedingly definite and regular. A 

 long series of matings between F^ ^s from Brown Leghorn 

 hen X Silky cock as fathers and unpigmented hens gave 

 205 birds with various degrees of pigmentation from 

 moderate to nil, and 31 fully pigmented hens. Using F^ ^s 

 from Silky % x Brown Leghorn ^ the numbers of these two 

 classes were 170 and 23, the 23 fully pigmented birds being 

 again all hens. The total, 375 to 54, is 7 to i. 



(3) The F^ cock has only been tried once with a Silky 

 hen, and the offspring consisted of 7 males and 8 females, 

 showing all the different degrees of pigmentation, but from 

 so few no quantitative conclusions can be drawn. 



(4) When the deeply pigmented F^ hens are bred with 

 the pure Silky cock, all the offspring of both sexes are 

 deeply pigmented. 



(5) From a slightly pigmented F^ hen (offspring 

 namely of Silky ? x Brown Leghorn f) bred with a pure 

 Silky cock only a few birds have yet been bred. 



As a test of the distribution of the factors among the 

 gametes of the hen this mating is one of the most important 

 and many critical questions can be answered by it. The 

 numbers are as yet too small to be of much significance. 

 They are 8 hens all deeply pigmented, and 5 cocks ranging 

 from deeply pigmented to intermediate. 



The F^ results are so complicated that until they h.ue 

 been obtained on a very large scale it would be premature 

 and useless to describe them in any detail. In general 

 terms the F„ families contain both males and females of 

 the deeply-pigmented, the slightly pigmented, and the 



