. Morphology of gymnosperms. Gymnosperms; Plant morphology. 272 MORPHOLOGY OF GYMNOSPERMS THE MALE GAMETOPHYTE The male gametophyte of Pinaceae has long been known in a general way, but the present knowledge of the functions of the cells dates from Belajeff's work in 1891 on Juniperus (33), and Stras- bxirger's work in 1892 on a wider range of forms, notably Larix and Cupressus (38). Every year since has increased the number of forms observed, until now a fairly complete knowledge of the principal features of the male gametophyte is available. The onto-. FiG. 301.—Pinus Laricio: part of micros
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 272 MORPHOLOGY OF GYMNOSPERMS THE MALE GAMETOPHYTE The male gametophyte of Pinaceae has long been known in a general way, but the present knowledge of the functions of the cells dates from Belajeff's work in 1891 on Juniperus (33), and Stras- bxirger's work in 1892 on a wider range of forms, notably Larix and Cupressus (38). Every year since has increased the number of forms observed, until now a fairly complete knowledge of the principal features of the male gametophyte is available. The onto-. FiG. 301.—Pinus Laricio: part of microsporangium showing mitosis in pollen mother cells, May 3; X500. geny is comparatively uniform, so that a single account will include a general outline for all forms. For this purpose, the development of the male gametophyte of Pinus Laricio will be used. About May 9 (in Chicago) the nucleus of the microspore of P Laricio enlarges for the first division (fig. 305), a spindle is formed rapidly (fig. 306), and an equal division follows. Before the cell plate is organized, the nucleus nearer to the wall of the spore begins to disorganize, and the other begins to enlarge (fig. 307). In this way a lenticular and disorganizing cell is cut off against the spore wall (fig. 308). A second division follows immediately, the spindle being observed about May 25 (fig. 309). This division is a repetition. 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; Coulter, John Merle, 1851-1928. Morphology of spermatophytes. Part I. Gymnosperms. Chicago, University of Chicago Press
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