Introduction to structural and systematic botany, and vegetable physiology, : being a 5th and revedof the Botanical text-book, illustrated with over thirteen hundred woodcuts . in contact throughout. Of the same char-acter are the larger and irregular spaces in the lower stratum ofthe tissue of most leaves (Fig. 7 and Fig. 221), and which formirregular winding passages through which the air, admitted throughthe stomates (70), freely circulates. 66. Air-PassagCS, however, are not always so irregular. The stalks,and often the foliage also, of aquatic and marsh plants generallyabound with regular
Introduction to structural and systematic botany, and vegetable physiology, : being a 5th and revedof the Botanical text-book, illustrated with over thirteen hundred woodcuts . in contact throughout. Of the same char-acter are the larger and irregular spaces in the lower stratum ofthe tissue of most leaves (Fig. 7 and Fig. 221), and which formirregular winding passages through which the air, admitted throughthe stomates (70), freely circulates. 66. Air-PassagCS, however, are not always so irregular. The stalks,and often the foliage also, of aquatic and marsh plants generallyabound with regular air-channels, of much greater diameter thanthe cells of the tissue. These air-passages are symmetrically ar- INTERCELLULAR AND EPIDERMAL SYSTEMS. 51 ranged, and are as elaborately constructed as any proper organ canbe. They are built up of cells in a manner wliich may be comparedto a stack of flues or chimneys built of brick: they are constructedupon a uniform plan in each species, and are evidently essentialparts; plants which grow in water requiring a full supply of airin their interior. Fig. G8 shows some of these air-passages in theflower-stalk of Calla 67. Receptacles Of Special Secretions. These arise from the exuda-tion of the proper juices of the cells into intercellular passages,which are distended by the accumulation; or from the obliterationof contiguous cells, so as to form cavities of considerable size. Suchare the turpentine-canals of the Pines, &c.; the oil-cells of thefruit of the Urubelliferre, and those in the rind of the orange andlemon; the latex-canals in Sumach, &c. Internal Glands, such asthose which form the translucent dots in the leaves of the Orangeand Myrtle, are little clusters of cells, filled with essential oil. 68. Epidermal System. In most plants, except of the lowest grades,and those which grow under water, the superficial layer of cells isdifferent from the rest, and forms 69. The Epidermis, or skin of the plant. This consists of
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Keywords: ., bookauthorgra, bookcentury1800, bookdecade1860, booksubjectbotany
