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

  • Hermann Schacht
Date:
1855
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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.

    200/230 (page 176)
    period, shewdng the commencement of the formation of the two lateral excrescences. Fig. IIG shews a young pollen-grain of Picea vulgaris, somewhat further develojied, seen i;iider watei'; {x) is the place of egress of the pollen- tube. A large nucleus, surrounded by granular matter, lies api>arently free in the middle of each j:>ollen-graiu. From this time the lateral protuberances con- tinue to increase in size, the cuticle, i.e., the outer membrane of the pollen-grain, which does not consist of cellulose, becomes stronger and stronger, and delicate markings, streaks and lines appear upon it, especially upon the protuberances. Figs. 117 and 118 represent respectively ripe pollen-grains of Abies pectinata and Picea vulgaris which liave been soaked Fig. 116. Fig. 117. Fig. 118. for half an hour in oil of lemons; in each figure (a) Ls the terminal cell of the cellular body; [h) and (c) the ])cdicel-cells; in both (c) has the appearance of a fissure, as is the case in Larix; (x) is the place of egress for the ])ollen-tube. The processes going on in the interior of the pollen-grain are at this time concealed, more or less, by the granular contents ; never- theless, I believe that in Abies I have seen the formation of a cell-membrane, that is the origin of a cell, around the central ■ nucleus. When the anther of the above-mentioned Conifers o})ens, which takes place about the end of May or the be- ginning of June, eveiy perfect pollen-grain of Larix Europa'a^ Abies pectinata, Picea vulgaris, and Pinus sylvestri.s, exhibits the cellular body mentioned by Meyer; there may also be seen the fissure between the outer and tlie inner membrane, be- tween the pollen-cell and the cuticle; the latter seems to consist of