The embryo sac formation of Hemerocallis middendorffii var. esculenta (Koidz.) Ohwi proceeds in the manner of Polygonum type classified by Maheshwari (1950). The cytochemical characteristics of the mature embryo sac were as follows: The antipodal nuclei have thick thread-like chromatin deeply stained with methylgreen and Feulgen reaction. Other nuclei consisted of fine chromatin which shows faint pyroninophilia and very weak Feulgen reaction. This fact suggests that the antipodal nuclei are of a polytene nature or polyploidy. The cytoplasm of the antipodal cells contained some bodies which, like the nucleolus, revealed dense pyroninophilia and were strongly positive to the protein reaction. Consequently, these bodies are called "nucleolus-like bodies" (NLBs) in the present study. Considering that the antipodal cells have a rich cytoplasm and many NLBs, it is inferred that they play an important role in the embryo sac development. The egg cell had a number of starch grains around the nucleus, and the filiform apparatus, having grown sufficently at the micropylar end of synergids, was strongly positive to both PAS reaction and methylgreen.