. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. C Fm. 55.—Podophyllumpeltatum. Mitosis in pollen mother-cell. A, telophase of first division; £, late anaphase of second division; C, telophase of second division; the nuclei of the four microspores are formed, but the cell walls, as is characteristic of simultaneous division, have not yet appeared.—After ; besides, the enlargement and consequent readjustment of the spores soon break up the row (Fig. 58). The first record of the occurrence of a tetrad in Asclepias seems to have bee
. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. C Fm. 55.—Podophyllumpeltatum. Mitosis in pollen mother-cell. A, telophase of first division; £, late anaphase of second division; C, telophase of second division; the nuclei of the four microspores are formed, but the cell walls, as is characteristic of simultaneous division, have not yet appeared.—After ; besides, the enlargement and consequent readjustment of the spores soon break up the row (Fig. 58). The first record of the occurrence of a tetrad in Asclepias seems to have been made by Stevens41 in 1898; and the fourth independent discovery of it was by Gager 58 in 1002. Elving,7 Wille,15 and Stras- burger 12 showed that in various species of the Cyperaeeae a tetrad is formed although only one microspore becomes func- tional, the other soon disorganizing. Juel 50 has recently made a thorough study of Carex acuta (Fig. 59). He finds that the two characteristic nuclear divisions take place, and that a cell-plate is formed at each division. The cell-plates are soon resorbed, however, so that the four nuclei lie free within the wall of the mother-cell. Three of the nuclei then disintegrate, while the fourth becomes the nucleus of the single functional microspore; and the wall of the mother-cell, inclosing the four nuclei, becomes the wall of the microspore. In Zostcra manna Rosenberg r'7 has described the tetrad division of the remarkably elongated mother-cell (Fig. 11). The divisions are longitudinal and in parallel planes, resulting in four remarkable filiform. 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 Coulter, John Merle, 1851-1928; Chamberlain, Charles Joseph, b. 1863. New York, D. Appleton
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