Agronomy and Horticulture Department


Date of this Version



Science, New Series, Vol. 40, No. 1019 (Jul. 10, 1914), pp. 57-58


Copyright 1914 R. A. Emerson


Groth's preliminary note on the "golden mean" in the inheritance of sizes in SCIENCE of April 17, 1914, pp. 581-584, deserves the attention of geneticists. Its publication is of such recent date that I need only call attention to one or two points that seem to me of particular moment.

In brief, Groth's hypothesis is that the mode

of inheritance in Fl not only of surfaces and

volumes, but also of linear dimensions is to be

expressed by √ab rather than by a + b /2

where a and b are parent sizes. The hypothesis

is based upon measurements of a large

number of tomato fruits of parental and Fl

plants. It will certainly be worth determining

whether Groth's expression fits size characters

in other plants. A hurried examination of

data, both published and unpublished, derived

from my own studies of seed size in beans and

maize, indicates that Fl sizes are nearer the

average than the geometric mean of the parent

sizes. But my object now is not to lay stress

upon any possible agreement or disagreement

between my results and those of Groth. It is

rather with the relation of Groth's hypothesis

to the idea of multiple factors that I am here