. The evolution of plant life, lower forms. Cryptogams; Plants. 97 to move with great rapidity. The sixteen cells constituting the first colonies formed in the spring, originate from the repeated division of a single cell, that had passed the winter. Fig. i8.—Pandorina morum (x 400). A, a motile colony (ccenobium). The individual cells have their cilia protruding through the gelatinous envelope of the colony. B, two zoogonidia, formed by the division of the cells oi A, in process of conjugation. (From Prantl.) as a resting-spore. But during the summer, the coenobia, after remaining
. The evolution of plant life, lower forms. Cryptogams; Plants. 97 to move with great rapidity. The sixteen cells constituting the first colonies formed in the spring, originate from the repeated division of a single cell, that had passed the winter. Fig. i8.—Pandorina morum (x 400). A, a motile colony (ccenobium). The individual cells have their cilia protruding through the gelatinous envelope of the colony. B, two zoogonidia, formed by the division of the cells oi A, in process of conjugation. (From Prantl.) as a resting-spore. But during the summer, the coenobia, after remaining in a motile state for some time, become quiescent, owing to the retraction of the cilia ; each of the sixteen cells then divides into sixteen smaller cells; the mucilaginous envelope of the ccenobium disappears at this stage and the 256 daughter-cells are liberated, each of which secretes a mucilaginous sheath, and forms the starting-point of a new ccenobium. Sexual reproduction by conjugation of zoogametes takes place as follows. The sixteen cells of a ccenobium each divide into sixteen daughter-cells, which escape from the colony as motile pear-shaped zoogametes, having bright H. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Massee, George, 1850-1917. London, Methuen & Co.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectplants, bookyear1891
