File:Text-book of structural and physiological botany (1877) (14753296266).jpg

Identifier: textbookofstruct00thom (find matches)
Title: Text-book of structural and physiological botany
Year: 1877 (1870s)
Authors: Thomé, Otto Wilhelm, 1840- Bennett, Alfred William, 1833-1902
Subjects: Plant physiology
Publisher: New York : J. Wiley & sons
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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Fig. 64,—Transverse section throug;h the collenchyma of the sowthistleSonchus asper. « epidermis ; <; collenchymatous cells, (x 670.) formative or generating tissue and meristcm have been given.In contrast to this, a tissue in which the cells are not as arule capable of dividing, is called 2,permanent tissue) andthe separate cells which no longer serve for the formationof new cells, permanent cells. The generating tissue of the punctum vegetationis offlowering plants is parenchymatous, and is called primaryparenchyma ox primary 7neristem^ because every kind of celland every part of the plant may or actually does develope,directly or indirectly, from it. Independently of growth by theactual increase in size of the individual cells, the apical 42 Striicttiral and Physiological Botany, growth of plants depends mainly on the constant fresh forma-tion of this tissue. The increase of thickness in plants, on the contrary,
Text Appearing After Image:
Fig. 65—Tela contexla from the medullary layer of the pileus of aFungus, Amanita 7miscaria; h ordinary cells; in laticiferous cells,(x 360.) occurs especially in those parts where there are permanentstructures which increase in diameter during the whole The Cell as a Member of a Group. 43 period of their existence, chiefly or even exclusively fromthe formation of a special generating tissue, the cambium.The cambium is usually a prosenchymatous tissue, not foundin the ^ punctum vegetationis,^ but distributed elsewhere invery various parts of the plant. To it is due the final deve-lopment of the fibrovascular bundles, which however originatein its forerunner, the procambiiim. The cambium forms,according to its arrangement, a central cambium-cylinder,or isolated dispersed cambium-bundles, or a cambium-ring. A thickening-ring of this character occurs, forexample, in the layer formed between the wood and the barkof those trees which are characterised by the formation ofannual rings. In t

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