Fertilization
During period of the fertilization the embryo-sac lies in a close proximity to the opening of micro Pyle, into which the pollen-tube has penetrated, the separating cell-wall becomes absorbed, and the male or sperm-cells are ejected into the embryo-sac. Guided by the synergetic one male-cell passes into the oosphere with which it fuses, the two nuclei uniting, while the other fuses with the definitive nucleus, or, as it is also called, the endosperm nucleus. This is remarkable double fertilization as it has been known, although only recently discovered, has been proved to take part place in widely-separated families, and both in Monocotyledons and of a prothallium after a cause following the reinvigorating union of the polar nuclei. This view is still maintained by those who are differentiate two acts of fertilization within the embryo-sac, and regard that of egg by the first male-cell, as the true or generative fertilization, and that of polar nuclei by the second male gamete as a vegetative fertilization which gives a stimulus to development in correlation with the other.