Archive image from page 228 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar Year: 1920 VII MEIOTIC PHASE IN PLANTS 213 At fertilization the two male gamete nuclei which are formed in each pollen grain are both introduced into the embryo-sac ; one fuses with the ovum nucleus to produce the zygote, while the other fuses Ns-ith the central fusion nucleus, forming thus a triploid nucleus. This afterwards gives rise to the endosperm, or reserve food material of the seed. For a more detailed account of the gametophytc and fert
Archive image from page 228 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar Year: 1920 VII MEIOTIC PHASE IN PLANTS 213 At fertilization the two male gamete nuclei which are formed in each pollen grain are both introduced into the embryo-sac ; one fuses with the ovum nucleus to produce the zygote, while the other fuses Ns-ith the central fusion nucleus, forming thus a triploid nucleus. This afterwards gives rise to the endosperm, or reserve food material of the seed. For a more detailed account of the gametophytc and fertihzalion in the flowering plants the reader is referred to any comprehensive work on botany, such as that of Bower (1919). Pollen Mother Cell Meioll Embryo sac MoOier Cell. Jieioli/c DKviswn Microspores m, (Pollen-ams)f\ Measporfs Fig. 90. Diagrams of the ceU generations involved in the haploid phase of the flowering plants. Mosses and liverworts present the reverse case to the flowering plants, for the dominant phase (the ordinary moss plant, etc.) is the haploid gametophyte. The zygote grows into a comparatively unplc sporophyte which is retained on and nourished by the gametoi)h>te, and produces spores with reduction of chromosomes. These are set free to produce the new generation of gametophytes. The relations of the haploid and diploid phases of the life cycle m animals and plants is summarized in Fig. qi ; the figures A-F forni a progressive series in the rise of the diploid and reduction of the haploid
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