. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. 198 MORPHOLOGY OF ANGIOSPERMS bryo. In the octant stage the dermatogen begins to be differ- entiated, the perielinal divisions appearing first in the terminal octants and proceeding toward the root end of the embryo. The differentiation, however, is almost simultaneous, so that the dermatogen is soon completed except that of the root-tip, which is derived from the adjacent cell of the suspensor, and appears comparatively late. The periblem and plerome are differen- tiated early from the tissue w
. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. 198 MORPHOLOGY OF ANGIOSPERMS bryo. In the octant stage the dermatogen begins to be differ- entiated, the perielinal divisions appearing first in the terminal octants and proceeding toward the root end of the embryo. The differentiation, however, is almost simultaneous, so that the dermatogen is soon completed except that of the root-tip, which is derived from the adjacent cell of the suspensor, and appears comparatively late. The periblem and plerome are differen- tiated early from the tissue within the dermatogen. The stem- tip and cotyledons are derived from the four apical octants, and the bulk of the hypoeotyl from the four basal octants. The root-tip, however, is completed by the adjacent cell of the sus-. Fig. 90.— Capsella Burm-pastoris. Scries showing contribution of upper cell of suspen- sor to embryo (plerome and dermatogen shaded): s, upper cell of suspensor; //, hypophysis; d, dermatogen; </', portion of dermatogen derived from hypophysis; pi, plerome; p, periblem ; p\ portion of periblem derived from hypophysis ; x 400. pensor (Fig. 90, s). This cell divides transversely, the basal daughter-cell taking no part in the formation of the embryo, but the other daughter-cell (hypophysis of Hanstein) filling out the periblem and dermatogen of the root-tip. The hypophy- sis divides transversely, the daughter-cell next the embryo com- pleting the periblem of the root. The other daughter-cell by two longitudinal divisions gives rise to a plate of four cells, each of which divides transversely, the plate of four cells toward the embryo completing the dermatogen of the root-tip, and the other plate constituting the first layer of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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