Sentence Examples


  • These spiracles, according to Hinds, are remarkable honeycomb-like structures, and perforations to the tracheal tubes have not been demonstrated.
  • In a second type they are situated at the ends of tracheal strands and consist of groups of richly protoplasmic cells belonging to the epidermis (as in the leaves of many ferns), or to the subjacent tissue (the commonest type in flowering plants); in this last case the cells in question are known as epithem.
  • In other cases the epithem may be absent altogether, the tracheal strand debouching directly on the lacunae of the mesophyll.
  • The tracheids or vessels, indifferently called tracheal elements, together with the immediately associated cells (usually amylom in Pteridophytes) constitute the xylem of the plant.
  • During the process the thin walls are stretched and the turns of the spiral become pulled apart without rupturing the wall of the tracheid or vessel, If the pitted type of tracheal element were similarly stretched its continuously thickened walls would resist the stretching and eventually break.

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