. Elements of plant biology. Plant physiology. â Fig. 59.âThe ovule and fertilisation. A, cross-section of a single free carpel containing two rows of ovules; , midrib of car- pellary leaf; pi., placenta (thickened margin of carpellary leaf) bearing row of ovules. B, ripe ovule (megasporangium) in longitudinal section; , vascular bundle; nuc, nucellus (body of ovule = wall of megasporangium); , outer coat; , inner coat; micr., micropyle. The embryo sac (megaspore) contains in the centre the secondary nucleus {seen.) ; at the micropylar end the two synergidae (syn.) and the
. Elements of plant biology. Plant physiology. â Fig. 59.âThe ovule and fertilisation. A, cross-section of a single free carpel containing two rows of ovules; , midrib of car- pellary leaf; pi., placenta (thickened margin of carpellary leaf) bearing row of ovules. B, ripe ovule (megasporangium) in longitudinal section; , vascular bundle; nuc, nucellus (body of ovule = wall of megasporangium); , outer coat; , inner coat; micr., micropyle. The embryo sac (megaspore) contains in the centre the secondary nucleus {seen.) ; at the micropylar end the two synergidae (syn.) and the egg, and at the opposite end the three antipodal cells {ant.). C, development of embryo sac; a^d, division of primary nucleus to form eight nuclei, four at each end; e., formation of egg apparatus, group of antipodal cells and secondary nucleus. D, embryo sac at the time of fertilisation; , pollen tube, which has entered the upper end of the sac and evacuated the two male gametes, one of which is seen in contact with the nucleus of the egg (female gamete) and the other with the two polar nuclei, which in this case have not yet fused to form the secondary nucleus of the sac. Contact will be followed by fusion, in the former case giving the zygoU, in the latter the mother nucleus of the endosperm. I cell (Fig. 58, C). This independent cell later divides to form the two male gametes (E). Thus the male. 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 Tansley, Arthur George, 1871-. London, George Allen & Unwin Ltd. ; New York, Dodd, Mead & Co
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectplantph, bookyear1922
