綠豆根端在發芽期間分生組織區之轉變

The establishment of the anatomical zonation in the root apex of Phaseolus radiatus

This study emphasizes the fact that dynamic changes occur in the apical meristem of the primary root in Phaseolus radiatus Linn. During its early stages of development which are associated with germination. The root apical meristem is composed of a group of common initial cells in its early stage. The diameter of these initials average from 24.70 to 31.20 µ in their different developing stages. Twelve hours after germination, it is gradually reorganized into central initials (transverse meristem) and peri-initials. The former gives rise to the stele and columella by transverse division, and latter gives rise to the cortex, epidermis and cap cells other than the columella by various planes of cell division. Slightly before the reorganization of the meristematic region, the root cap cells appear identifiable zonation, i. e., the formation of a columella.