The elements of botany for The elements of botany for beginners and for schools elementsofbotany00gray Year: 1887 SECTION 16.] ANATOMICAL STRUCTURE. 135 have transversely elongated thin places, parallel with each other, giving a ladder-like appearance, whence the name. Annular ducts (Fig. 457) are marked with cross lines or rings, which arc thickened portions of the cell-wall. Spiral ducts or vessels (Fig. 453-455) have thin walls, strengthened by a spiral libre adherent within. This is as delicate and as strong as spider- web : when uncoiled by pulling apart, it tears up and annihilates t
The elements of botany for The elements of botany for beginners and for schools elementsofbotany00gray Year: 1887 SECTION 16.] ANATOMICAL STRUCTURE. 135 have transversely elongated thin places, parallel with each other, giving a ladder-like appearance, whence the name. Annular ducts (Fig. 457) are marked with cross lines or rings, which arc thickened portions of the cell-wall. Spiral ducts or vessels (Fig. 453-455) have thin walls, strengthened by a spiral libre adherent within. This is as delicate and as strong as spider- web : when uncoiled by pulling apart, it tears up and annihilates the cell- wall. The uncoiled threads are seen by gently pulling apart many leaves, such as those of Amaryllis, or the stalk, of a Strawberry leaflet. Laticiferou* ducts, Vessels of the Luffs, or MUk-vesseh are peculiar branching tubes which hold latex or milky juice in certain plants. It is very difficult to sec them, and more so to make out their nature. They arc peculiar in branching and inosculating tubes, running in among the cellular tissue; and they are very smal except when gorged and old (Fig. 1G0, 4G1).
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