. A textbook of botany for colleges and universities ... Botany. Fig. 581. — Development of an anatropous ovule, the series beginning at the left; the two integuments appear successively and gradually overtop the nucellus as the ovule becomes curved; last figure a section showing relation of the two integuments and the nucellus at maturity of ovule. — After Gray. later a second ring may arise outside of the first, which develops into a second integument (fig. 581). Soon the integument (or integuments) overtops the nucellus, and where it closes in over the nucellus there is left a narrow, more
. A textbook of botany for colleges and universities ... Botany. Fig. 581. — Development of an anatropous ovule, the series beginning at the left; the two integuments appear successively and gradually overtop the nucellus as the ovule becomes curved; last figure a section showing relation of the two integuments and the nucellus at maturity of ovule. — After Gray. later a second ring may arise outside of the first, which develops into a second integument (fig. 581). Soon the integument (or integuments) overtops the nucellus, and where it closes in over the nucellus there is left a narrow, more or less elongated passageway, the micropyle (fig. 582). Among the Archichlamydeae and monocotyledons there are m em-,. Figs. 582-584. — Directions of ovules; 582, orthotropous; 583, campylotropous; 584, anatropous; also showing outer {p%) and inner {ii) integuments, micropyle (m), nucellus («), and embryo sac {em). — After Coulter. usually two integuments; while among the Sympetalae there is almost invariably a single massive integument. Direction. — Important differences are shown in the directions as- sumed by mature ovules. Some grow straight outward from their place of origin, the axis being straight and the micropyle directed away from the point of origin; such ovules are called orthotropous (fig. 582), and this condition is regarded as the most primitive. In other ovules the axis. 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 Coulter, John Merle, 1851-1928; Barnes, Charles Reid, 1858-1910, joint author; Cowles, Henry Chandler, 1869- joint author. New York, Cincinnati [etc] American book company
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