. Text-book of botany, morphological and physiological. Botany. MORPHOLOGY OF THE CELL. an example, large cells, the oogonia (Fig. 2, /, Og\ are formed in peculiar receptacles; the space enclosed by the cell-wall is densely filled with fine-grained protoplasm, which is at first homogeneous, but subsequently breaks up into eight portions (oospheres); these, completely filling up the cell-cavity of the oogonium-, press against one another and become polygonal. The wall of the oogonium consists of two layers; the outer one splits, and the inner one protrudes in the form of a sac, which becomes di
. Text-book of botany, morphological and physiological. Botany. MORPHOLOGY OF THE CELL. an example, large cells, the oogonia (Fig. 2, /, Og\ are formed in peculiar receptacles; the space enclosed by the cell-wall is densely filled with fine-grained protoplasm, which is at first homogeneous, but subsequently breaks up into eight portions (oospheres); these, completely filling up the cell-cavity of the oogonium-, press against one another and become polygonal. The wall of the oogonium consists of two layers; the outer one splits, and the inner one protrudes in the form of a sac, which becomes distended by absorption of water; in this enlarged sac •the oospheres become globular (Fig. 2, II); when this bursts, the oospheres, now completely spherical, escape. By the fertilis- ing action of other smaller proto- plasm-masses, the antherozoids, these balls of protoplasm or oo- spheres are excited to further development; on the exterior of each fertilised oosphere or oospore a colourless substance makes its appearance, which hardens into a continuous cell-wall. The newly- formed cell now grows in two different directions in different modes, and produces, after further transformations (Fig. 2, V and IV), a young Fucus-plant. Still more clearly does the inde- pendence of the protoplasm of a cell show itself in the formation of the swarm-cells1 (zoogonidia) of Algae and of some Fungi. In many cases, as in Stigeoclonium insigne (Fig. 3, B, a), the proto- plasm of a cell filled with cell-sap contracts, expels the cell-sap, and forms a roundish ball, which, escaping through an opening in the cell-wall, swims about in the water (C). While passing out, the protoplasm shows, by its motions and changes of form, that it is soft and extensible; but, once freed, it assumes a definite form. Usually after some hours, the swarm-cell comes to rest; if killed by proper means, the protoplasm contracts (27, F, p), and a delicate cell-wall may now be recognised, which it did not possess at the
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
