Distribution of Intercellular Material in the Apical Part of Pea Seedlings

Abstract

AbstractThe sections from the upper part of the third internode, counted from the seed, in etiolated pea seedlings are studied for the distribution of two types of Intercellular spaces: the transparent and the dark. The transparent spaces represent the result of the water logging of passages originally water‐lined, while the dark spaces are lined with a lipid‐containing substance which may be impregnated with melted paraffin and which forms a ramifying network within the tissue. The intercellular material of the dark spaces has the appearance of a tube, since it concentrically lines the intercellular space, leaving a lumen for air or gas. It is a plastic, isotropic subslance which may be cut transversely and identified in successive sections of the inlernode as belonging to the same continuous material from the intercellular space. The dark and the transparent spaces have a distinct pattern of distribution in the growing internode, and the relative quantity of dark spaces present at different levels of the internode may be measured. The dark spaces predominate in those parts of the stem with a greater potential for growth, while the transparent spaces are located in the regions where growth has ceased or subsided. Since the paraffin is infiltrated instantaneously throughout the network of dark intercellular spaces, it is possible that these may represent a channel for the translocation of substances.