The microscope : and its application to vegetable anatomy and physiology / by Dr. Hermann Schacht ; edited by Frederick Currey, M. A.

  • Hermann Schacht
Date:
1855
Catalogue details

Licence: Public Domain Mark

Credit: The microscope : and its application to vegetable anatomy and physiology / by Dr. Hermann Schacht ; edited by Frederick Currey, M. A. Source: Wellcome Collection.

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    buds, it is necessary to follow out acciirately tlie develo]ieinent of the stem. In order to render the investigation valuable, every impoidant individual part of the bud, and the changes which take place therein, must be accurately and progressively examined. Germination must be followed out in the same manner as bud-de velope ment. The formation of the stem and the origin of the root must be observed. In dicotyledonous plants the radicle itself becomes the first root, and forms the proper tap-root. In Monocotyle- dons, on the other hand, one or more adventitious roots oii- ginate in the tissue of the radicle. If a thin transverse section is now taken close under the Punctum vegetationis of a young branch, there will be foxind, in dicotyledonous plants, a number of dispersed vascular bundles, the ligneous cells of which are turned towards the pith, and the cambium towards the bark; these vascular bundles are sepax'ated by a mass of parenchyma, often of gi’eat Avidth, which unites the pith and the parenchyma of the bark. In a very young state of the plant, the wood-cells and vessels are scarcely distinguishable from the cambium, and the liber-cells are gene- rally not yet present. At a subsequent period the different parts are more dearly defined; the liber-cells appear on the out- side of the cambium, the vessels become extended, and the parenchyma, which at first separated the vascular bundles from one another, becomes reduced to a narrow remnant constituting the primary medullary rays. A closed ring of wood is now formed, increasing in circumference yearly by additions from the cambiimi-ring, which on its inner side forms new wood, and on its outer side new bai’k. In cryptogamoxis and monocotyle- donous plants, where the cambium of the vascular bundles does not coincide with the cambium-rin{r, the stem increases in thick- ness, but its vascular bundles do not become thickened, but ra- mify in the cambium-ring; the number of them, therefore, which is met with in a transverse section increases with the age and with the thickness of the stem, as may l)e seen in many Palms. When the activity of the cambium-ring ceases, the thickening of the stem, or of the root, also terminates. In order to trace N 2