Agronomy and Horticulture Department


Date of this Version



The American Naturalist, Vol. 44, No. 528 (Dec., 1910), pp. 739-746


Copyright 1910 R. A. Emerson


Some years ago Lock reported a cross of a tall race of maize with a shorter race which produced an intermediate height in F1 and exhibited no segregation in F2 when crossed back with one of the parents. Castle's results with rabbits are very similar to those of Lock with maize. Castle summarizes his results in part as follows:

A cross between rabbits differing in ear-length produces offspring with ears of intermediate length, varying about the mean of the parental ear-lengths. . . . A study of the offspring of the primary cross-breds shows the blend of the parental characters to be permanent. No reappearance of the grand parental ear-lengths occurs in generation F2, nor are the individuals of that second generation as a rule more variable than those of the first generation of cross-breds.. . It seems probable that skeletal dimensions, and so proportions of skeletal parts, behave in general as blending characters. The linear dimensions of the skeletal parts of an individual approximate closely the mid-parental dimensions.