1. The growth of wheat plants at two depths of planting, from seed in which embryo size and endosperm size were varied independently was studied.
2. Embryo size was shown to have a negligible effect on growth, whilst endosperm size had a considerable effect; the influence of neither embryosize nor endosperm size appeared to be in any way modified by depth of planting. It is suggested that the relationship between seed size and plant size is governed by the amount of reserve material present in the seed.
3. During the first 6 days of growth small embryos had a higher relative growth rate than large ones, apparently regardless, within wide limits, of the amount of reserve material in the seed. Thereafter until the exhaustion of reserves growth appeared to be related to the amount of reserve material present.