No seeds were exposed to the acid for longer than an hour, but at the end of this period the light line was still intact. As compared with other portions of the Malpighian layer, it is extremely resistant to concentrated sulphuric acid. Since all cell walls below the light line are mainly cellulose, the resistance of the light line prevents the acid from destroying the entire seed coat and reaching the embryo. LITERATURE CITED. (1) Beck, Gunther. 1878. Vergleichende Anatomie der Samen von Vicia und Ervum. _In_ Sitzber. K. Akad. Wiss. [Vienna], Math. Naturw. Kl., Bd. 77, Abt. 1, p. 545-579, 2 pl. (2) Bergtheil, C, and Day, D. L. 1907. On the cause of "hardness" in the seeds of Indigofera arrecta. _In_ Ann. Bot., v. 21, no. 81, p. 57-60, pl. 7. (3) Crocker, William. 1906. Role of seed coats in delayed germination. _In_ Bot. Gaz., v. 42, no. 4, p. 265-291, 4 fig. Literature cited, p. 290-291. (4) Darwin, Charles. 1885. The effects of cross and self fertilisation in the vegetable kingdom. 482 p. New York. (5) Ewart, Alfred J. 1908. On the longevity of seeds. _In_ Proc. Roy. Soc. Victoria, v. 21, pt. 1, p. 1-203. Literature, p. 3-4. (6) Gola, Guiseppe. 1905. Ricerche sulla biologia e sulla fisiologia dei semi a tegumento impermeabile. _In_ Mem. R. Accad. Sci. Torino, s. 2, t. 55, p. 237-270, 1 pl. (7) Haberlandt, G. 1877. Ueber die Entwickelungsgeschichte und den Bau der Samenschale bei der Gattung Phaseolus. _In_ Sitzber. K. Akad. Wiss. [Vienna], Math. Naturw. Kl., Bd. 75, Abt. 1, p. 33-47, 2 pl. Hanstein, [Johannes]. (8) 1863. Erläuterung des Nardoo genannten Nahrungsmittels der Urbewohner Australiens, einer Marsilea-Frucht, nebst Bemerkungen zur Entwicklung dieser Gattung. _In_ Monatsber. K. Preuss. Akad. Wiss. Berlin, 1862, p. 103-119, 1 pl. (9) 1866. Pilulariae globuliferae generatio cum Marsilia comparata. 16 p. Bonnae. Dissertation. Harrington, George T. (10) 1915. Hard clover seed and its treatment in hulling. U. S. Dept. Agr., Farmers' Bul. 676, 8 p. (11) 1916. Agricultural value of impermeable seeds. _In_ Jour. Agr. Research, v. 6, no. 20, p. 761-796, 6 fig., pl. 106. Literature cited, p. 796. (12) Harz, C. D. 1885. Landwirtschaftliche Samenkunde. 1362 p., 201 fig. Berlin. (13) Hiltner, L. 1902. Die Keimungsverhältnisse der Leguminosensamen und ihre Beeinflussung durch Organismenwirkung. _In_ Arb. K. Gesundheitsamte, Biol. Abt., Bd. 3, Heft 1, p. 1-102, 4 fig. (14) Hughes, H. D. 1915. Making legumes grow. _In_ Farm and Fireside, v. 38, no. 19, p. 7, illus. (15) Huss, Mathias. 1890. Über Quellungsunfähigkeit von Leguminosensamen und Mittel zu deren Abhilfe. 73 p. Halle. Dissertation. (16) Junowicz, R.