192 



THE AMERICAN NATURALIST 



[Vol. LI 



On page 333 Dr. Castle writes : 



In typical blending inheritance the determiners of contrasted parental 



acter, the gametes formed by an individual being practically as uni- 

 form in character as those of either parent. Blending is illustrated in 

 the inheritance of ordinary size-differences in birds and animals. 



No one who knows the work of Punnett and Bailey (cited in 

 Hoshino's paper) on chickens, in which they found not only in- 

 dividuals in as small as the smallest parent and as large as 

 the largest, but even individuals lighter than the lightest parent 

 and heavier than the heaviest, could maintain that ordinary size- 

 inheritance in birds is blending. The gametes formed by the 

 Hamburg X Sebright hybrids, or by our Leghorn X fighting 

 bantam certainly were not as uniform as those of any of the four 

 parental strains ! 



We are perfectly in accord with Castle when he reasons that 

 if once we admit a contamination of genes and qualitative 

 changes in genes, we do not need to assume that flowering-time 

 in peas is influenced by two genes, in the cases studied by 

 Hoshino. In such a case the difference in one gene would suffice. 

 Indeed, we would go one step farther than Castle and declare, 

 that, on the assumption of qualitative changes in genes, we need 

 not assume a genotypic difference between the parent varieties 

 at all. Where we differ from Dr. Castle is in the fact that we 

 do not believe in qualitative variation of genes. Surely more 

 than ten genes must influence the beginning of flowering in the 

 pea, else there could not be so many varieties differing in the 

 time of flowering. All the genes which influence stature, shape 

 of flowering axis, color, must necessarily influence the onset of 

 flowering. And we need not look for coupling between color 

 factors and flowering-time factors, because the factors influencing 

 color influence the metabolism of the whole plant, and thus the 

 period at which it starts flowering. 



If we compare Hoshino's paper with Tschernack's extensive 

 experiments on the subject, we find nothing in it, which would 

 make us assume contamination of genes by crossbreeding, or any 

 qualitative variability of genes. 



A. C. Hagedoorn, 

 A. L. Hagedoorn 



December 19, 1916 



