. Elementary botany . Fig. 302. Podophyllum peltatum, ovule containing mature embryo sac ; two synergids and egg at left, endosperm nucleus in center, three antipodal cells at right. 455. Embryo sac is the young female prothallium.—In figures 303, 305 are shown the different stages in the develop- ment of the embryo sac in lilium. The embryo sac at this stage is the young female prothallium, and the egg is the only remnant of the female sexual organ, the arche- gonium, in this reduced gameto- phyte. 456. Fertilization. — Before /i fertilization can take place the ' pollen must be conveyed from
. Elementary botany . Fig. 302. Podophyllum peltatum, ovule containing mature embryo sac ; two synergids and egg at left, endosperm nucleus in center, three antipodal cells at right. 455. Embryo sac is the young female prothallium.—In figures 303, 305 are shown the different stages in the develop- ment of the embryo sac in lilium. The embryo sac at this stage is the young female prothallium, and the egg is the only remnant of the female sexual organ, the arche- gonium, in this reduced gameto- phyte. 456. Fertilization. — Before /i fertilization can take place the ' pollen must be conveyed from the anther tO the Stigma. (For Macrospore (one-celled stage) of lilium. the different methods of pollination see Part III.) When the pollen tube has reached the embryo sac, it opens and the sperm cell is emptied into the embryo sac near the egg. The sperm nucleus now enters the protoplasm surrounding the egg nucleus. The male nucleus is usually smaller than the female nucleus, and sometimes, as in the cotton plant, it grows to near or quite the
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisher, booksubjectbotany
