Abstract
ON SOME NEW LOWER GREEN ALGÆ.—George Klebs publishes some very interesting facts about a number of forms of green Algæ found living within the cell-tissues of some flowering-plants. The painstaking way in which the life-history of these have been worked cannot be too sufficiently admired. For full details the student should refer to the numbers of the Botanische Zeitung for April and May, where also will be found excellent coloured illustrations of all the species. In order to call attention to these curious species we give the specific diagnosis in detail:—Family Protococaceæ. Genus Chlorochytrium.—Through continued division into two parts each cell becomes resolved into spherical zoospores, which upon leaving the mother-cell conjugate within the gelatinous envelope. The zygozoospores before becoming surrounded with a membrane make their way by means of processes into the intercellular spaces of living plants. During the time favourable for vegetation many generations follow one another in a single year; that nearest to the winter falls into a resting stage. Chlorochytrium lemnæ.—This species lives in the widened intercellular spaces of the parenchyma of the Lemna trisulca: cells chiefly spherical or elliptical; the part of the growing zygospore which remains in connection with the epidermis becomes a spherical cellulose plug. In the next genus, Endosphæra, through continued division into two, each cell falls into a number of daughter-cells surrounded with a membrane, from which, by further division, the spherical zoospores result; those, taking their origin from the same mother-cell, immediately upon leaving it conjugate; they make their way into living tissues like those of the Chlorochytrium. The formation of zoospores only takes place in the spring; the new generation requires a full year to reach maturity. The species Endosphæra biennis lives in the intercellular spaces of the sub-epidermal parenchyma of leaves of Potamogeton lucens: its cells are mostly spherical; the part of the germinating zoospore which remains in connection with the epidermis soon dies off. In the genus Phyllobium at the time of maturity, the protoplasm of every cell containing chlorophyll is differentiated into cylindrical or spherical portions, through the changing of some of these into smaller ones, zoospores—both macro and micro are formed—these conjugate. The zygozoospores make their way into the stomates of partly living, partly dead leaves of phanerogams. The development of every cell takes a year. The species Phyllobium dimorphum lives in the leaves of Lysimachia nummularia, Ajuga, Chlora, &c.; the zygozoospores develop processes which grow into branched green tubes among the vascular bundles belonging to the veins of the leaves. The protoplasm of those zygospores which develop a process forms into either a spherical or longish resting cell, which lasts during the winter, and in the next summer again develops zoospores. According to the surrounding circumstances the processes are well developed or not. They may be quite rudimentary, in which case small tubeless resting cells become formed, which form asexual zoospores. In the genus Scotinosphæra every cell shows at the time of maturity a differentiation of its green protoplasm into cylindrical or spherical bodies; by their conjugating, during which a reddish granular substance is secreted, a single mass is formed, through whose repeated division, during which division the granular substance is gradually again taken up, the zoospores are formed. These are asexual, and make their way into decaying vegetable tissues. Their development lasts a year. Scotinosphæra paradoxa lives in the dead or dying tissues of Lemna trisulca, and also in species of Hypnum. Its cells are mostly spherical, and the zoospores are spindle-shaped. (Botanische Zeitung, May 27, 1881.)
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Biological Notes . Nature 24, 292–293 (1881). https://doi.org/10.1038/024292a0
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DOI: https://doi.org/10.1038/024292a0