Identifier: textbookofstruct00thom (
find matches)Title:
Text-book of structural and physiological botanyYear:
1877 (
1870s)Authors:
Thomé, Otto Wilhelm, 1840- Bennett, Alfred William, 1833-1902Subjects:
Plant physiologyPublisher:
New York : J. Wiley & sonsContributing Library:
Smithsonian LibrariesDigitizing Sponsor:
Biodiversity Heritage LibraryView Book Page:
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view book online to see this illustration in context in a browseable online version of this book.Text Appearing Before Image:ortion of the stem of Equiseta, and the acicular leavesoi Pinus pinaster, or of collenchymatous tissue which tends to increasethe difference of tension between the epidermal and the subjacenttissues (see Chap, V.). In plants with a long term of life, and whichincrease greatly in girth, cork is subsequently formed in the epidermalcells themselves or the subjacent layers of tissue, replacing the trueepidermis, which has generally in the meantime perished. The true epidermis consists, when young, of similar cellswhich are everywhere closely contiguous. In the course ofgrowth some of these separate from one another, the deri-vative cells that result from one or more divisions leaving acrevice or pore between them which is called a sto7na (Fig.85). These are always^ enclosed by two or four cells, thegua7d-cells^ which are crescent-shaped, and also smaller andwith thinner walls than the rest of the cells of the epi- Exceptions, however, occur in the case of the Marchantiese andRhizocarpeae.Text Appearing After Image:Fig. 85.—I. Horizontal section through the epidermis of the under-side of the leaf ofEuonyimis japomc7iS, looked at from below ; sp stomata (x 370) ; II. Course ofdevelopment of the stoma oi Arthropcduivt cirrhaUivi s pin mother-cellready for division ; sp^, sp^^, sp^^^ successive stages of division : III. Maturestoma, (x 370.) 6o Structural and Physiological Botany, dermis, and are in addition distinguished from them bycontaming chlorophyll. This last circumstance gave rise tothe earlier view that these cells belong to the subjacentparenchyma of the leaf rather than to the epidermisNote About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.