Abstract
Embryo sac development of D. japonica THUNB. and D. quinqueloba THUNB. has been studied. In both species, the ovules are anatropous, bitegmic and crassinucellate. The development of the embryo sac is of the Polygonum type. The writer wishes to express his thanks to Prof. Dr. Sadao SUGAYA of the Tohoku University for his kind guidance and also to Dr. Chugai KIMURA of the same university for his valuable advice throughout this investigation.
