In this series of papers, the writer has traced the vascular strands of the spikelet (1940a), the male inflorescence axis (1939), the axillary shoot (1958), the leaf (1940b) and the adventitious root (1958) to the mother axis with a view to examine their behaviours, and he has also studied the origin and structure of the nodal plexus (1942) and the developmental order of the vertical bundles of the stem (1946). Consequently general consideration to the vascular construction has been given in this paper with special reference to the vascular connection of the lateral organs with their mother axis.<br>As pointed out previously (1940b, 1942), two systems of vascular bundles, one inside of the other and independent without being directly connected with each other, are distinguished throughout the cauline axis: the outermost peripheral bundles and the compound ones constitute respectively an outer system and an inner system at rather peripheral regions of the axis. The trace bundles from the lateral organs, i. e. the spikelet, the secondary inflorescence axis, the axillary shoot, the leaf and the adventitious root, are equally connected with those two bundle systems of the mother axis. Although in the case of the lateral shoot subtended by a foliar leaf, the behaviour of branch trace strands are greatly modified and complicated, owing to a large number of bundles, the presence of leaf traces and the development of nodal plexus, the fundamental pattern of the vascular connection with the mother axis is interpreted to be homologous to the case of dicotyledonous plants, if the horizontal vascular plexus is left out of consideration. The only significant difference of vascular construction between maize and dicotyledonous plants is that the vascular system in maize is of dicyclic construction from the first foliar node upwards to the pedicel of the spikelet.<br>The lateral organs of phyllome nature, except the floral phyllomes, bring about the multilacunar nodal structure of the mother axis, while those of cauline nature bring about the unilacunar, regardless of their vascular constructions which are complicated as in the axillary shoot or simple as in the pedicel of the spikelet