growth, soon obliterate all traces of the primitive arrangement of the tissues. Making a thin cross-section of the stem, and magnifying strongly, we find bounding the section a single row of epidermal cells (Fig. 94, _A_, _ep._) whose walls, especially the outer ones, are strongly thickened. Within these are several rows of thin-walled ground-tissue cells containing numerous small, round chloroplasts. The innermost row of these cells (_sh._) are larger and have but little chlorophyll. This row of cells forms a sheath around the ring of fibro-vascular bundles very much as is the case in the horse-tail. The separate bundles are nearly triangular in outline, the point turned inward, and are connected with each other by masses of fibrous tissue (_f_), whose thickened walls have a peculiar, silvery lustre. Just inside of the bundle sheath there is a row of similar fibres marking the outer limit of the phloem (_ph._). The rest of the phloem is composed of very small cells. The xylem is composed of fibrous cells with yellowish walls and numerous large vessels (_tr._). The central ground tissue (pith) has large, thin-walled cells with numerous intercellular spaces, as in the stem of _Erythronium_. Some of these cells contain a few scattered chloroplasts in the very thin, protoplasmic layer lining their walls, but the cells are almost completely filled with colorless cell sap. A longitudinal section shows that the epidermal cells are much elongated, the cells of the ground tissue less so, and in both the partition walls are straight. In the fibrous cells, both of the fibro-vascular bundle and those lying between, the end walls are strongly oblique. The tracheary tissue of the xylem is made up of small, spirally-marked vessels, and larger ones with thickened rings or with pits in the walls. The small, spirally-marked vessels are nearest the centre, and are the first to be formed in the young bundle. The epidermis of the leaves is composed of irregular cells with wavy outlines like those of the ferns. Breathing pores, of the same type as those in the ferns and monocotyledons, are found on both surfaces, but more abundant and more perfectly developed on the lower surface of the leaf. Owing to their small size they are not specially favorable for study. The epidermis is sparingly covered with unicellular hairs, some of which are curiously branched, being irregularly star-shaped. The walls of these cells are very thick, and have little protuberances upon the outer surface (Fig. 93, _E_).