. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. 26 SUPERFICIAL CUTICLE OE PELLICLE. skin) is a very thin continuous membrane, 'whicli is spread over all parts except the openings called stomata ; in some cases entering these openings, and lining the cavities beneath them. It is formed from the epidermal cells below it. Treviranus, Schleiden, and Payen, consider it as a secretion on the outside of the cells, ' while Mohl and Henfrey look upon it as com- posed of the altered primary walls of the cells. J Mitscherlich
. A Manual of botany : being an introduction to the study of the structure, physiology, and classification of plants . Botany. 26 SUPERFICIAL CUTICLE OE PELLICLE. skin) is a very thin continuous membrane, 'whicli is spread over all parts except the openings called stomata ; in some cases entering these openings, and lining the cavities beneath them. It is formed from the epidermal cells below it. Treviranus, Schleiden, and Payen, consider it as a secretion on the outside of the cells, ' while Mohl and Henfrey look upon it as com- posed of the altered primary walls of the cells. J Mitscherlich regards it as a corky substance, which preserves the humidity of the plant by '' preventing the evaporation of moisture. This substance is considered by him to be an im- portant constituent of the cell-wall. In many plants we meet with a corky epidermis com- posed of ceUs containing air. The cork cells are flat and thin-walled; and in some cases Fig. rs. *^^y ^^^ ^^ peeled off, as ui the cork oak. In fig. 73 the peUicle is represented as detached from the leaf of the cabbage, forming a sheath over the hairs, hhhh, and leaving slits, s s, corresponding to the openings of the stomata. The pellicle is perhaps similar to the intercellular substance sur- rounding cells, and to the definite mucus (collenchyma) which is seen in seaweeds (fig. 29 h). It is possible that this matter, in place of being produced on the outside of cells, may be formed within them, and ultimately deposited externally by passing through thek parietes. On the inner surface of the pellicle the impressions of the epidermal cells are sometimes observed. The pellicle is the only layer of in- tegument which is present in aquatic plants, and in some of the lower tribes. The Epidermis (!«', upon, and di^/ia, skin), (fig. 72 e e), is ex- tended over all the parts of plants exposed to the air, except the stigma. The internal cavities of seed-bearing organs are lined by a delicate membrane, termed Epithelium (It/, upo
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