Constitution of the White Leghorn Breed. 211 



until data are obtained on a larger number of F2 birds than form the 

 basis of present comparisons. 



3. — On the nature of the factor I of the White Leghorn fowl. — Hereto- 

 fore in this series of experiments the inhibiting factor has been ob- 

 served only in its effect upon the factor (or factors) for black pigmen- 

 tation of the feathers, and (still unpublished) of the beaks and shanks 

 (epidermal pigmentation). Whether factor I has the power to 

 inhibit in all cases other colors, such as buff and red, cannot be stated 

 definitely at this time.* But one other point of interest has been 

 raised with reference to the factor / as a result of reciprocal matings 

 between the W. L. and W. S. breeds. The experimental data may be 

 presented as follows : 



From the cross, W. L. cf X W. S. 9 all the progeny were white with 

 the exception of a few minute black flecks and an occasional suffusion 

 of buff on the breast or wing coverts. The d^ d^ and 9 9 were 

 exactly alike in appearance, not only with respect to the pigmentation 

 of the feathers, beaks and shanks (epidermal), but also with respect 

 to the typical mesodermal pigmentation of the W. S. 



In the cross W. S. d^ X W. L. 9 the results were different: 

 With respect to plumage pigmentation, both cf cf and 9 9 were 

 heavily splashed with black. The pigmentation was perhaps more 

 apparent on the cf cf . With respect to the Silky type of pigmenta- 

 tion, the heavily pigmented birds (eyes, beak, shanks, wattles, 

 pleura, peritoneum, etc.), were invariably 99. It is apparent 

 that these results (so far as they relate to the inhibition of mesodermal 

 pigmentation in the c^ &), are in accord with the findings of Bateson 

 and Punnett (op. cit.) from observation of reciprocal crosses between 

 the Bro^vn Leghorn and W. S. 



The results obtained by the present writer make it appear that the 

 W. L. 9 , as well as the B. L. 9 , possesses in heterozygous condition a 

 factor for the inhibition of the Silky pigmentation; and that the 



*It can now be stated, as a result of later work, that the red of the Rhode Island Red breed, is 

 recessive to, and the buff of the Buff Leghorn and Buff Wyandotte dominant over, the white of the 

 White Leghorn. 



