. Morphology of gymnosperms. Gymnosperms; Plant morphology. 342 MORPHOLOGY OF GYMNOSPERMS (figs. 389-391). In Microcachrys (151, 163) the situation in Dacrydium is repeated, three (more frequent) or four prothallial cells appearing, depending upon the division of one or both of the two primary cells (fig. 393); and the prothaUial tissue of Saoce- gothaea (X49) is .exactly the same (figs. 394, 395). In these three genera, the second prothallial cell always divides and the first also may divide, and at pollination three or four free vegetative nuclei are found in the grain. Podocarpus is much mo
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 342 MORPHOLOGY OF GYMNOSPERMS (figs. 389-391). In Microcachrys (151, 163) the situation in Dacrydium is repeated, three (more frequent) or four prothallial cells appearing, depending upon the division of one or both of the two primary cells (fig. 393); and the prothaUial tissue of Saoce- gothaea (X49) is .exactly the same (figs. 394, 395). In these three genera, the second prothallial cell always divides and the first also may divide, and at pollination three or four free vegetative nuclei are found in the grain. Podocarpus is much more variable (69, 128, 139), the number of prothallial cells and free nuclei varying from one to eight (fig. 396). Only one prothallial cell may be cut off, and it may not divide; but usually there are two primary cells, the sec- ond of which always 'divides and both 9f which may, and in both cases there may be still another divi- sion. Therefore, there may be one, three, four, six, or eight prothallial cells, and subse- quently the same number of free vegetative nuclei that swarm into the pollen tube. This behavior of the male prothallial tissue among the podocarps is not only constant and striking, but it is the same in kind as that observed among the araucarians (p. 277), the only difference being that the vegetative cells and free nuclei in the latter group reach a. Fig. 397.—Phyllocladus alpina: the two unequal male cells, with the stalk and tube nuclei and one prothallial nucleus in advance; the archegonium shows a four-celled neck and a definite jacket; the egg is ready for fertilization; X440.—After Miss Young (174).. 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. Pa
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