150 



The Journal of Heredity 



inhibit! vc factor ( I') which acts ( possibly 

 in conjunction with the first inhibitor, 

 I) not only upon the black jjluma^e 

 pigment of ectodermal structure, but 

 also on the deeper mesodermal pig- 

 mentation. While the first inhibitory 

 factor mentioned does not appear to be 

 a sex-limited character, this second in- 

 hibitor does appear to be correlated 

 with sex. It is transmitted from the 

 male Leghorn to both male and female 

 progen\% but by the female Leghorn 

 it is givx>n to the sons only. 



OTHER COLORS HIDDEN. 



In addition to these inhibitors of 

 black pigmentation, the White Leg- 

 horn also possesses inhibitors for buiT 

 and red. These colors arc, however, 

 rej^ressed less perfectly than black; and 

 red, as might be expected, less per- 

 fectly than buff. Whether the factors 

 that inhibit these colors are identical 

 with the inhibitor of black cannot now 

 be stated. Nor would it be safe to 

 affirm that there are not still other 

 unrecognized factors modifying ]jattcrn 

 and jjlumagc color carried by this in- 

 teresting breed. In any case the above 

 facts are sufficient to show that the 

 White Leghorn is something of a mas- 

 querader. Her appearance gives us 

 little knowledge of what lies beneath her 

 clo^ik of white. And if the White Leg- 

 horn, after a little study of her constitu- 

 tion, gives us such new conce])tions of 

 her character complex, what shall we 

 ex]X'Ct of some other breeds, of which 

 we still know comparatively nothing r 



What the poultry world of toda>- 

 needs, in addition to the Standard 

 which tells how poultry ought to appear 

 is a Standard which will tell how the 

 varieties ought to breed. It would be a 

 great help to poultry breeders if each 

 different breed should have its zygotic 

 constitution re]jresented by a formula 

 designating, so far as ])ossible, all the 

 imjjortant characters ])ossessed by thai 

 breed, thus indicating the breeding 

 values. For instance, in the case of 

 the White Leghorn the following sym- 

 bols might be used to cover ilic 

 characters already mentioned. 



^ See Lewis, H. F. Jour, ftf tin- AnuT. AssfK-. of Instructors and Invcstijjators of I'oiiltrv 

 Husbandry. Vol. 1, No. 2, 191.S. 



^ See Bali'son, Wm. and PunnrtL, K. ('., jour, (nnctiis, Vol. 1, No. .^, I'Ml. 



in homozygous condition, Ijlack j^ig- 

 mentation is held completely in control; 

 when I is present in a heterozygous con- 

 dition, as in the Fi cross-breds. the 

 effect is diminished, and a little black 

 frequently shows as minute flecks in an 

 otherwise white plumage. 



This factor for the inhibition of black 

 is a])parently i)resent normally in both 

 male and female White Leghorns in 

 homozygovis condition, and is not sex- 

 limited in its manner of inheritance. 

 For the Imrring factor, however, the 

 White Leghorn male appears to be 

 homozygous and the female heterozy- 

 gous. The ]jresence of these two factors 

 exi)lains many curious results that have 

 been obtained by poultrymcn when 

 they have employed in crosses the 

 White Leghorn breed. 



Bvit these are not all the factors of 

 interest that the White Leghorn carries 

 in the germ cells but does not show 

 somatically. 



If a White Leghorn male be crossed 

 with a White Silky female, the dark 

 mesodermal Silky pigmentation of the 

 beak, shanks and face is reduce el in the 

 Fi cross-breds to an intermediate grade. 

 The ])lumage of such birds is white, 

 with a few black flecks, and the males 

 resemble the females not only in these 

 points but also in the color of the irides 

 which are lighter than in the Silky 

 parent and sometimes almost as much 

 of a bay as in the White Leghorn itself. 



If, hcnvever, in a cross of this sort, 

 the male jjarent is the Silky and the 

 female ]jarent is the Leghorn, the 

 results arc different. The males will be 

 found to show little of the Silky pig- 

 mentation in beak, shanks, eyes or face, 

 anel their plumage is almost a pure 

 white. But the females show the deeper 

 Silky i)igmentation in all these struc- 

 tures and the white feathers of the- 

 wings and back are heavily s]jlashed 

 with black. Similar results are obtained 

 when the White Leghorn is mated with 

 some other heavily jMgmented h)reeds 

 like the Black Langshan,' and when the 

 Brf)wn Leghorn is crossed with t he- 

 White Silky.-' 



Here then we have to do with ancAher 



