Abstract
1. Minute starch grains are formed in every tissue of rice flower soon after its differentiation and the size of the grains become larger as the tissue grows older. However, these grains are consumed abruptly for rapid elongation of the tissues which contain them and thereafter most of the maturing tissues do not restore any starch. Only rachilla, where many vascular bundles branch into many flower parts, stores transitory starch for longer period, which might be utilized for the elongation of other organs such as empty glumes and glumes (Fig. 1-4, PL. I) 2. The date of rapid glume elongation when starch stored there disappear, may coincide with the time when polysaccharides in the transitory tissue of anther disappear and the divisions of pollen mother cells predominate. 3. Pericarp of ovary begins to store grains soon after fertilization and the size of the grains becomes gradually larger with the time (Fig. 8, PL. II-IV) About 10 days after fertilization, however, they diminish in amount and are completely consumed within 2 weeks. 4. Nucellus and outer-integument cells begin to be collapsed and absorbed 3∼4 days after fertilization. On the 5th day, most of the nucellus cells are absorbed up except near the nucellar projection where they persist longer (PL. III). 5. Four to five days after fertitization endosperm cells begin to store compound starch grains simultaneously, which then rapidly grow into large grains (Fig. 8, PL. V). Most cells of matured embryo contain minute starch grains, the largest one in the scutellum. 6. From anatomical observations, the pathways of foods into caryopsis are assumed through the dorsiventral vascular bundles to the nucellar epidermis and to the nucellar projection; (Fig. 5-6, PL. II-IV).
