The data here reported include results of studies on (1) the histological display of the heading pro-cess of chinese cabbage, (2) the effect exerted by the artificial supplement of the growth substance on the behavior of the leaves, (3) relationships between the native auxin and carbohydrates and nitrogenous constituents with regard to heading. 1. The leaves of chinese cabbage plants incurve as they are brought into the dark place. The in-curving portion consists of vigorously growing tis-sues and it is observed that the cells of the dorsal side of the incurved portions are much more elon-gated than the cells of ventral side of the leaves. It seems that the incurving process of the leaves is of hyponastic nature responding to shading. 2. As the hyponastic development seemed to be brought about by the hormonal displacement, the artificial supplement of auxin to the plant body by means of the naphthaleneacetic acid applied in various ways, was conducted for the purpose of detecting the response of the leaves as influenced by the applied growth substances, compared with the incurving development arising in natural sequence. a) The leaf blade responds to the supplement of the growth substance more sensitively than the leaf petiole, and wider expands the leaf area, the more active is the response. b) The tips of the leaf blade responds most sensitively to the supplement of the growth substance, being followed by the middle and the basal part in the order decreasing sensitiveness. c) The trend of the incurving response to the supplement of the varied concentrations of naph-thaleneacetic acid shows that there is the optimal -concentration for incurving. d) The hyponastic development of the leaves rich in carbohydrate content is much invigorated, and weakened, however, when the leaves arerich in nitrogen content. 3. It was proved that native auxin in the leaves of chinese cabbage was indoleacetic acid by means of paperchromatographic color tast and avena straight growth test. a) The native auxin content is high in the leaf blade and less in the petiole. b) The native auxin content of leaves varies with the phyllotactical order. The inner leaves are more rich in the auxin content than the outer leaves. The higher concentration of auxin is found in the leaves which compose the outermost part of the head. The etiolated leaves folded in the head, however, show less auxin content than the green leaves. 4. The results of the chemical analysis of the leaves show that both the nitrogenous constituents and carbohydrates increase phyllotactically inwards and the carbohydrate content is so much that the ratio of carbohydrate to nitrogen increase inwards. 5. It may be concluded that the head formation of chinese cabbage is brought about by the incurv-ing development of hyponastic nature under the shaded condition. The outer rosette-typed, green and broad leaves shade the later developing inner leaves, which incurve and compose the head. It was proved by the authors in the previous ex-periment that the defoliation of the outer leaves inhibited the incurving development of the inner leaves and sometimes the latter did even expand outwards. Accordingly, auxin activity in the leaves is the most essential internal factor responsible for the heading process togather with the nitrogenous constituents and carbohydrates. The higher the auxin and the carbohydrate content, the auxin activity is enforced more vigorously. It is observ-ed that the heading movement arises in the leaves, most abundant in the auxin content and favored with higher carbohydrate ratio to nitrogen.