. Morphology of gymnosperms. Gymnosperms; Plant morphology. ii8 MORPHOLOGY OF GYMNOSPERMS ened, and the layers between the epidermis and the spores disorganize, as in the sporangia of ferns. Two rows of elongated thin-walled cells bordered by cells with thick walls give the de- hiscence much the appear- ance of that of Angiopteris. The formation of micro- spores from the mother cell has been described by JtiRANYi (5) and by Miss F. Grace Smith (56) for Ceratozamia, and by Teetjb (11) for Zamia muricata. With the appearance of the cell plate in the first divi- sion, a ringlike thickening of cel
. Morphology of gymnosperms. Gymnosperms; Plant morphology. ii8 MORPHOLOGY OF GYMNOSPERMS ened, and the layers between the epidermis and the spores disorganize, as in the sporangia of ferns. Two rows of elongated thin-walled cells bordered by cells with thick walls give the de- hiscence much the appear- ance of that of Angiopteris. The formation of micro- spores from the mother cell has been described by JtiRANYi (5) and by Miss F. Grace Smith (56) for Ceratozamia, and by Teetjb (11) for Zamia muricata. With the appearance of the cell plate in the first divi- sion, a ringlike thickening of cellulose appears on the wall of the mother cell, and proceeding from this ring a thick wall develops between the two daughter cells. Each of these two cells divides and heavy walls are formed again, and within this heavy four-celled and often lobed case the micro- spores are organized. The number of chromosomes in the pollen mother cells of Ceratozamia and Zamia is 12; other numbers (7, 17) have been reported for Ceratozamia, but technic at that time was hardly adequate to meet the trying demands of such difficult nuclei. Miss F. Grace Smith counted 50 cases in Ceratozamia, and in forty-six found 12 chromosomes, in three. Figs, i 01-104.—Zamia floridana: early stages in the development of the microsporan- gium; fig. loi, single hypodermal archesporial cell; fig. 102, first periclinal division; fig. 103, usual divisions following stage shown in previous figure; fig. 104, longitudinal section of a sporangium in a more advanced stage; all figures X920.—After F. Grace Smith (56).. 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 P
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