Hadley: The White Leghorn 



151 



F=femalencss 



N= black pigmentation 



B = barring factor 



I = inhibiting factor No. 1 



I' = inhibiting factor No. 2 

 and the constitution of the male 

 written 



f2N2B2l2r2 



while the White Leghorn female being 

 heterozygous for three factors would be 



FfNsBbl.I'i'. 



Using these same symbols, the White 

 Dorking, another dominant white breed, 

 but lacking both the latent barring and 

 black would become, male, 



f2n2b2l2i'2 



and the female essentially the same, 



Ffnobol.i'o 

 The White Plymouth Rock, a reces- 

 sive white, which differs from the White 

 Leghorn only in the lack of the factors 

 for black pigmentation and for the 

 inhibitors I and I', would be represented, 

 male 



fon.Boioi'., 



and the female 



Ffn2Bbi2i'2 

 The White Silky with 



its 



black 

 would 



mesodermal pigmentation' (M) 

 be, male, 



f2M2n2b2i2i'2 

 and the female 



FfM2n2b2i2i'2. 

 These illustrations are sufficient to 

 indicate what is meant by standardizing 

 breeds of poultry. Of course the breeds 

 alluded to above have many other 

 characters that would also be listed 

 in the vStandard formulae, and other 

 breeds would possess their own char- 

 acter-complexes, or aggregations of unit 

 characters. But the main point is, that 

 if breeds were so standardized, and 

 listed, a poultryman would know what 

 he was purchasing when he acquires a 

 certain fowl. He would know not only 

 how the bird looked, but how that bird 

 will breed; and it seems as if this point 

 might be of interest and possibly of 

 importance to poultrymen who are 

 also poultry breeders. 



Plant Breeding Correlations 



Fundamental principles useful in apple breeding arc being studied particularly 

 at the Iowa state agrictdtural experiment station. One object is to determine 

 what features are of taxonomic value in distinguishing horticultural varieties with 

 certainty ; another is to find correlations which may be used in practicing intelligent 

 selection with young seedlings without having to grow each plant through to 

 maturity in order to determine its characters. A large factor in the success of 

 most great plant breeders has been their marvelous ability to judge by looking at 

 a small seedling, what it would be likely to produce when it reached maturity. 

 This ability has often seemed mysterious, but as a fact it must necessarily depend 

 largely on the observation of correlations not appreciated by the ordinary horticul- 

 turist, and perhaps not definitely formulated by the talented breeder himself. 

 The Iowa station wants to reduce this mystery to mathematical formulae and put 

 it in the reach of every one of intelligence; already hardiness has been found to 

 be correlated with structure and composition in a definite way. 



Johannsen to Visit America 



Dr. W. Johannsen of the University of Copenhagen, Denmark, is expected in 

 the United States this summer to join the faculty of the University of California 

 Summer Session at Berkeley. He has been invited to attend the meeting of the 

 American Genetic Association at Berkeley, August 2-7. Dr. Johannsen is one of 

 the pioneers in the application of mathematics to biological problems, and is 

 particularly well known in genetics for his enunciation of the theory of "pure 

 lines." 



