Genetic Linkage in Size Inheritance-A Reply

Abstract

Castle''s extra-chromosomal interpretation of the association in heredity between quantitative characters and a qualitative, brown coat color, in a mouse interspecific cross, which was observed by the author and interpreted as genetic linkage, is considered. Castle''s assumptions that the recessive qualitative characters tend to remain together in their parental association and that whatever causes them to go together also causes the larger size of the recessive parent to go with them, are not substantiated by the data. F2 and back-cross animals show only free assortment, thus weakening his 1st assumption, while the validity of the 2nd is diminished since triple recessive animals (larger parent type) are no larger than those with the recessive gene for brown coat color in other combinations. It is still believed that genetic linkage offers the best explanation for the observations.