. Fundamentals of botany. Botany. SEED-BEARING PLANTS 429 filling, the venter of the archegonium. The pollen-tube passes between the neck-ceUs of the archegonium, but does not ordinarily enter the venter. The apex of the tube is ruptured, probably by internal osmotic pressure, and its entire contents are emptied into the cytoplasm of the egg. One of the sperm-nuclei luiites with the egg-nucleus (June of the second season), and fertilization is accomplished (Fig. 319).. Fig. 319. -White pine (Pintis Slrohus). Longitudinal section through an archegonium at the time of fertilization. Above the fu
. Fundamentals of botany. Botany. SEED-BEARING PLANTS 429 filling, the venter of the archegonium. The pollen-tube passes between the neck-ceUs of the archegonium, but does not ordinarily enter the venter. The apex of the tube is ruptured, probably by internal osmotic pressure, and its entire contents are emptied into the cytoplasm of the egg. One of the sperm-nuclei luiites with the egg-nucleus (June of the second season), and fertilization is accomplished (Fig. 319).. Fig. 319. -White pine (Pintis Slrohus). Longitudinal section through an archegonium at the time of fertilization. Above the fusing nuclei are various other elements emptied iato the egg from the pollen-tube. Col- lected June 21, 1898. X about 62. , starch grains; , prothallium; , cytoplasm from poUen-tube; , stalk-cell; , tube-nucleus; , sperm-nucleus; , egg-nucleus; , nutritive spheres. (After Margaret C. Ferguson.) f 382. Formation of the Seed.—After fertilization the oosperm begins at once to develop, giving rise to three distinct structures; the pro-embryo, the suspensor, and the embryo-sporophyte. During the early divisions of the 'fertilized egg the male and female chromatins can be clearly distinguished (Fig. 320). At the same time the adjacent tissues of the ovule become transformed. A portion of the prothallus or gametophyte nourishes the developing embryo, but the large bulk of it becomes. 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 Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's son & co.
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Keywords: ., bookauthorgag, bookcentury1900, bookdecade1910, booksubjectbotany
