214 Bulletin No. 155.— 1913. 



2. — The zygotic constitution of the W. L. cf with respect to barring 

 and the other factors concerned has thus been given provisionally as 

 C2B?f2l2, and the 9 as C2-B62F//2. To what extent the W. L. stock 

 of this country and Europe possesses this formula cannot now be 

 definitely stated. All that may be said on this point at present is 

 that the data presented in this paper are based on experiments which 

 made use of som.e of the best W. L. stock obtainable.* 



3. — The possible origin of the factor for barring in the W. L. has 

 not been considered in these pages and it is probably useless to 

 speculate on this point until we have more authoritative information 

 relating to the foundation of this breed and to the manner of pro- 

 duction of the various strains now scattered about the country. 

 Among them all there may exist several variations in zygotic constitu- 

 tion. 



4. — The result of the reciprocal crosses between the W. L. and W. S. 

 indicates that cf cf of the former breed (as is also the case with the 

 Brown Leghorn c^) possess a factor which inhibits Silky pigmenta- 

 tion (mesodermal). The 99 are heterozygous for this character, 

 which is sex-limited in its inheritance. These '' inhibiting factors," 

 apparently possessed by the Leghorn breed of fowls as a whole, are 

 of considerable interest and deserve further study. In the hands of 

 the intelligent breeder, they suggest an effective instrument for con- 

 trolling the manifestation of a variety of characters in poultry. 



5. — Finally it may be said that the data reported in this paper 

 explain certain curious results obtained by both Davenport and 

 Hurst {op. cit.) with respect to barred progeny. They furthermore 

 give an explanation for the interesting phenomenon occasionally 

 observed by poultrymen, — the appearance of '' cuckoo" progeny in 

 Fi or F2 from supposedly non-barred parents; also for the otherwise 

 unexplainable circumstance that barred 99 have arisen from 



♦Since the results presented in the body of this paper were secured, two other W. L. males have 

 been tested, one coming from Professor James E. Rice of the Cornell Agricultural College and 

 Experiment Station; the other from Professor Harry Lewis of the New Jersey Agricultural Experi- 

 ment Station. Both were found to possess the barring factor as indicated by the appearance of 

 barred feathers in the F^ individuals. 



