. Botany of the living plant. Botany; Plants. 3" BOTANY OF THE LIVING PLANT surface (anticlinal). Their position is uniform, and the first is usually longitudinal (ii.), but their succession may vary. This suggests that no morphological value can be set on their order of appearance (iii. iv.). Later each octant divides into an outer and inner cell, by a wall parallel to the surface (periclinal); the superficial cells thereafter divide only by anticlinal walls, and the layer thus produced is called dermato- gen, because it forms the epidermis (). The inner cells divide again
. Botany of the living plant. Botany; Plants. 3" BOTANY OF THE LIVING PLANT surface (anticlinal). Their position is uniform, and the first is usually longitudinal (ii.), but their succession may vary. This suggests that no morphological value can be set on their order of appearance (iii. iv.). Later each octant divides into an outer and inner cell, by a wall parallel to the surface (periclinal); the superficial cells thereafter divide only by anticlinal walls, and the layer thus produced is called dermato- gen, because it forms the epidermis (). The inner cells divide again periclinally to form an inner and an outer series ; this is more regular in the lower tier of octants, which will form the hypocotyl and root. The inner series constitutes the plerome, which forms the stele ; the outer is the periblem, which forms the cortex (). Meanwhile the cell of the pro- embryo adjoining the lower tier of octants (the hypophysis, here shaded) has enlarged, and divided (vi. vii.), so as to form a group of cells which encroach into the spherical embryo. It provides the apex of the root, which is thus attached to the suspensor, and it is always directed towards the micropyle. The upper tier of octants soon gives rise to two pro- jecting lobes (cotyledons), which bear no constant orientation relative to the first segmenta- tions. Between them is a smooth groove, where the plumule will arise later. It is now possible to recognise the position of all the parts of the germ, viz. the radicle, the two cotyledons, and the plumule between them. In the Shepherd's Purse the seed is exalbuminous (p. 317), and the embryo develops fast in bulk, and in length (Fig. 231). But the ovule is of the type with a :urved embryo-sac. The embryo, as it grows, adapts itself by curving Iso, and soon fills the greater part of the sac. Meanwhile the plumule at last appears at the base of the groove between the cotyledons, position coincides with the intersection of the octant
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Keywords: ., bookcentury1900, bookpublis, booksubjectbotany, booksubjectplants
