An anatomical study was carried out on the tissue differentiation and growth of lemma in Japonica paddy rice, cultivars Sachikaze and Reimei. Every kind of tissues composing lemma such as outer- and inner- epidermis, hypodermis, parenchyma and vascular bundles had initiated before the lemma's rapid growth. With the beginning of lemma's rapid growth, both sides epidermes undertook such cell differentiations as uneven mitosis of epidermal cells followed by initiation of macro- and micro-hairs, and formation of tubercles in outer epidermis, and as initiation of stomata and microhairs in inner epidermis. After the rapid growth remarkable schlerization was made especially in hypodermis and outer epidermis. First sign of the differentiation of tubercles was the accumulation of a kind of substance which was not so well stained by Delafield's haematoxylin as to nucleus at the contacts of four large epidermal cells, forming a dome-like protuberance in basal portion of which some "zig-zag shaped structures" were constructed. And later the protuberance was covered by translucent membrane. Multicellular macrohairs were newly observed in the outer epidermis besides needle like trichomes and microhairs. Although both macrohairs and microhairs initiated from small epidermal cells, they differed each other on their developmental processes. Those of macrohairs were that whole small cells expanded and elongated before the enlargement of tubercles, but those of microhairs were that a portion of the small cell's wallprojected at the point of which was extremely narrowed by tubercles situated at their both sides, followred by moving the small cell's nucleus into that protuberance. It was, therefore, clarified that developmental process of tubercles was differed from those of macro- and micro- hairs, and that histogenetical center of outer epidermal cell was on the macro- or micro- hairs which were situated at the concave of both sides tubercles. Judging from that multicellular macrohairs and microhairs initiated in the beginning of lemma's rapid growth and withered in almost the same time with the end of its growth, it was suggested on the physiological functions of those hairs that they might have some relations to the rapid growth of lemma. The fact that both stomata and microhairs initiated densely at the near of vascular bundles in inner epidermis was considered that there might be some physiological correlations among them.