In the previous papers, 8, 9) it was reported that the gross and internal morphology of leaves of Chinese cabbage changed according to temperature conditions, and the effect of temperature on the formation of the“small head” (embryonic head) was observed.In this paper the author undertook to clarify the effect of temperature on the morphology of the shoot apex and tiny projections composed of larger cells.7)Seedlings of Chinese cabbage (cv. Nozaki-kohai No. 3) were grown in phytotron, the temperature conditions of which were as follows: high 30-25°C, medium 23-18°C, and low 15-10°C, for day and night, respectively. For histological observations, slides were prepared from shoot apices collected at different growth stages of the plants by the paraffin microtechnique.The size of the shoot apices increased as the plants grew and changed according to temperature conditions; the lower the temperature, the larger the shoot apices. Organization of the shoot apices also changed with the plant growth and the temperature conditions. The number of tunica layers increased and zonation became clear as the plants grew. The number of tunica layers was larger and the zonation was more distinct at lower temperatures. It is thought that leaf initial (the first periclinal division) went deeper and the leaf primordium at its inception became larger as the number of tunica layers increased. It is reasoned that the difference in the age of the cells between adaxial and abaxial sides, which caused the hyponastic curvature of the leaf primordium, 9) becomes larger as the size of the leaf primordium at its inception increases.Growth of the tiny projections was slower at lower temperatures, whereas the vacuolation in the larger cells, as an indicator of aging, progressed faster. And, the size of nucleoli seems to vary according to temperature condition in figures. While the aging of leaf primordia was retarded until they grew larger at lower temperatures. There appeared significant contrast between the growth of tiny projections and the development of leaf primordia.Considering the characteristics of the tiny projection and leaf morphogensis9) in relation to temperature condition, a possibility was suggested that resolvents of DNA and RNA in large nuclei and nucleoli effected the development of leaf primordia as cytokinin and its work was more active at lower temperatures.