In rice plants the lateral root originates in the pericyclic cells of the crown root opposite to a protophloem and between two protoxylems. Before the initiation of such root primordium the nuclei in a group of pericyclic cells gather in a certain zone (Fig. 3B, "R") and the density of the protoplasm around it becomes higher (Fig. 3). Similar phenomenon is also found in the adjacent endodermal cells (Fig. 4 and 5). After that, this group of the pericyclic cells undergoes anticlinal division (Fig. 6) followed by periclinal division (Fig. 7-10). The same phenomenon is also observed in the cells of the endodermis (Fig. 12 and 13). In this stage, the cells derived from such division in the endodermis are divided into two sets, one forms "Tasche" and the second forms the epidermis of the basal part of the lateral root primordium (Fig. 12, 13 and 17.20). In the crown roots of rice plants two kinds of lateral roots are recognized, one is thicker in diameter than the other. The thick one is different from the thin one in, the number of cell layers in the cortex, and the organization in the stele. Both primodia in the early stage are much alike anatomically, but at a certain stage of development they are markedly different in thickness (Fig. 17-20). This difference is mainly contributed to the periclinal division which takes place in the endodermis of one more than the other.