. Elementary biology; an introduction to the science of life . Fig. 134. Fertilization in a flower When a pollen grain,/, alights on the moist surface of a stigma, s, it absorbs water and puts forth a thread of proto- plasm, or a pollen tube,//, which grows down the style into the ovary. The tip of the pollen tube finds its way to the inside of the ovule, 0, through a small passageway, the micropyle, m. The large cell in the middle of the ovule, called the embryo sac, es, undergoes a number of changes which result in pro- ducing several nuclei. One of these nuclei at the end nearest the microp
. Elementary biology; an introduction to the science of life . Fig. 134. Fertilization in a flower When a pollen grain,/, alights on the moist surface of a stigma, s, it absorbs water and puts forth a thread of proto- plasm, or a pollen tube,//, which grows down the style into the ovary. The tip of the pollen tube finds its way to the inside of the ovule, 0, through a small passageway, the micropyle, m. The large cell in the middle of the ovule, called the embryo sac, es, undergoes a number of changes which result in pro- ducing several nuclei. One of these nuclei at the end nearest the micropyle corresponds to an egg cell. Similar divisions take place in the nucleus of the pollen grain, and one of the result- ing nuclei corresponds to a sperm cell. The cell walls separating the pollen tube and the embryo sac dissolve, and the pollen nucleus unites with the egg nucleus. The newly formed joint nu- cleus, or fertilized egg, begins to divide. Thus it develops into a new plant, or embryo; the ovule becomes a seed; the ovary becomes a fruit
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishe, booksubjectbiology
