The outer layer of the seed coat, which is the modified epidermal layer of the ovule, is known as the Malpighian layer. (Pl. V, figs. 1 and 2.) The cells constituting this layer, commonly called palisade cells, are the most highly modified cells of the seed coat. They are very much elongated, their length varying in the different regions of the coat, and their outer tangential walls and the outer portions of their radial walls are so much thickened that their lumina are confined to the inner portion of the cells, sometimes occupying less than half the length of the cells. The inner tangential walls and inner portions of the radial walls are thickened just previous to the death of the cells, the thickening sometimes being only slight and sometimes so much as to leave only very narrow lumina. There is a very thin layer on the outer surface of the Malpighian cells which has been called cuticle by previous investigators, but the chemical composition of this layer and its perviousness to water indicate that there is very little cutin present. This layer is probably the primary epidermal cell wall rather than a deposit on the outer surface of the wall. To determine this a study of the development of the Malpighian cells is necessary. Beneath the so-called cuticle there is the much thickened outer portion of the Malpighian cells in which there are two rather distinct regions, one constituting the conelike structures and the other forming a continuous layer over the conelike structures, separating them from the cuticle and filling in between them. These two regions separate easily, and in cutting sections the outer region, called by some the cuticularized portion, often breaks away, leaving the entire surface of the cones exposed. The term "cuticularized layer" will be used to designate all of the thickening covering the cones, including that around the cones as well as the portion between the cones and the cuticle. This term is not entirely appropriate, for the region is practically free from cutin, but for the want of a better term it will be used. There are canals in the cuticularized layer and cones, which are easily seen when the sections are treated with chloriodid of zinc or sulphuric acid. A surface view of a section showing the cones and cuticularized layer when mounted in glycerin shows the canals as dark lines due to the air inclosed. The canals are most abundant along the lines where the lateral walls of the cells join, but many are within the cones and in the cuticularized substance between the cones. (Pl. V, fig. 5.)