. Fossil plants : for students of botany and geology . Paleobotany. 394 BENNETTITALES [CH. distally as a slender cylindrical column or micropylar tube at the base of which it becomes broader owing to the increase in breadth of the middle or paUsade layer. A nucellar beak projects as a cone into the base of the micro- pylar tube. No pollen-chamber has been found. It is noteworthy that the micropyle is closed in the ripe seeds. Internal to the testa there is a crushed membrane separated from the embryo by a space (fig. 521, D, sp): this is the remains of the nuceUus and, as Solms-Laubach points
. Fossil plants : for students of botany and geology . Paleobotany. 394 BENNETTITALES [CH. distally as a slender cylindrical column or micropylar tube at the base of which it becomes broader owing to the increase in breadth of the middle or paUsade layer. A nucellar beak projects as a cone into the base of the micro- pylar tube. No pollen-chamber has been found. It is noteworthy that the micropyle is closed in the ripe seeds. Internal to the testa there is a crushed membrane separated from the embryo by a space (fig. 521, D, sp): this is the remains of the nuceUus and, as Solms-Laubach points out, there is no proof that any endosperm was present in the ripe seeds i. The embryo con- sists of a short axis, the conical radicle and the very short apex of the epicotyl, also two equal coty- ledons each with a few vascular bundles (fig. 521, D). The long interseminal scales, as seen in transverse section in the lower part of a flower between the sporophylls, appear as compressed polygonal organs (fig. 521, B, i) with an axial vascular strand surroimded by parenchyma and limited by a strong epidermis; they pass up between the seed-stalks, m, and in the distal end become con- siderably enlarged (figs. 514, 515), gradually expanding to form a truncate or slightly pyramidal apex (figs. 553, 563). The swollen peltate apices of adjacent scales form a continuous covering to the flower interrupted, except in the lower sterile part of the flower, by symmetrically disposed cylindrical micropylar tubes (fig. 515). The peripheral interseminal scales form a homogeneous parenchymatous tissue which springs from below the edge of the receptacle (fig. 521, A, B, pr) and the individuaUty of the scales composing this ' pericarp' is indicated by occasional invaginations 1 It is possible that, as Scott suggests, a small patch of endosperm is repre- sented in a seed of this species figured by him. Scott (09) B. p. 569, fig. 203, D, Fig. 523. Cycadeoidea Gibsoniana. Seed with embryo. (Britis
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
