62 



INHERITANCE OF CHARACTERISTICS IN DOMESTIC FOWL. 



evidence is found in a careful study of table 55, keeping constantly in mind 

 this fundamental principle that the recessive condition alone in the parents 

 can never give rise to the dominant; for the recessive condition implies 

 entire absence of the dominant factor. But the pure dominant condition will 

 vary in the direction of the recessive condition; such a result implies only 

 a partial failuz'e of the factor to develop completely; and we should not be 

 surprised if occasionally the failure were complete. This implies no " rever- 

 sal of dominance," but rather an arrested development of the factor. 



At the outset, then, we find (table 55) that even pure races with high 

 nostril (Polish, Houdans), when bred together, vary much in the height 

 of nostril (in perfection of dominance) and, in 2 per cent of the offspring, 



Table 50. Distribviion of frequency of grades of "openness " in offspring when one parent is heterozygous and the 



other an original dominant {DRxD, originals). 



Table 51. Distribution of frequency of grades of " openness" in offspring when one parent is heterozygous and the 



other an extracted dominant (DBxDD, extracted). 



