Tests for lignin occasionally showed slight traces in the Malpighian cells below the light line. When treated with reagents for pectic substances, the cuticle, cuticularized layer, cones, and all cell walls below the light line gave a definite reaction. The reaction of the cones and cuticle was more pronounced than the cuticularized layer. Tests for callose gave no reaction except in the upper part of the light line. This part of the light line stained slightly blue with aniline blue and was easily dissolved with sulphuric acid. In cutting free-hand sections of fresh material the Malpighian layer sometimes broke along this line. The greater part of the light line reacted to none of the tests, and its chemical nature was not determined. When microtome sections of seeds in different stages of development were treated with various stains, the results were in accord with those obtained with free-hand sections. Thus with safranin the periphery and cones of the Malpighian cells were slightly stained, while haematoxylin and methyl blue stained all the seed coat except the light line. The cones and cuticle stained more readily than the cuticularized layer, but neither stained as deeply as the cell walls below the light line. Methylene blue, methyl violet B, and mauvein stained all above the light line, indicating the presence of pectic substances; however, the staining was more prominent in the cones and cuticle. The difference in reaction of the cones and cuticularized layer to the cellulose and pectose tests probably indicates a difference in density rather than a difference in chemical composition. Since the cuticularized layer separates readily from the cones, there may be a difference in physical properties. With Congo red the upper part of the light line was only very slightly stained, but aniline blue had a more pronounced effect. The microchemical tests applied to the seed coat show that in the region above the light line there is only a slight trace of cutin or suberin, but a considerable amount of cellulose and pectose. All cell walls below the light line are mainly cellulose but contain some pectose. The upper portion of the light line contains callose, but the remainder of the light line appears to be chemically different from all other parts of the seed coat or else so dense as to resist the attack of the reagents. THE SEED COAT IN RELATION TO THE ABSORPTION OF WATER.