Similarly, the small amount of cuticular and of epidermal protection, and of lignification in succulent halophytes may also be related to the same circumstance.
The cell-membrane may become modified by the process of lignification, suberization, cuticularization or gelatinization.
As in other cell-walls, so here the older membranes may be altered by deposits of various substances, such as resin, calcium oxalate, colouring matters; or more profoundly altered throughout, or in definite layers, by lignification, suberization (Trametes, Daedalea), or swelling to a gelatinous mucilage (Tremella, Gymnosporangium), while cutinization of the outer layers is common.
In Ephedra helvetica, as described by Jaccard, no proembryo or suspensor is formed; but the most vigorous fertilized egg, after undergoing several divisions, becomes attached to a tissue, termed the columella, which serves the purpose of a primary suspensor; the columella appears to be formed by the lignification of certain cells in the central region of the embryo-sac. At a later stage some of the cells in the upper (micropylar) end of the embryo divide and undergo considerable elongation, serving the purpose of a secondary suspensor.
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