. Elementary botany. Botany. GAMErOPHYTE AXD SPOROPBYTE. 243 â When fertilization takes place the number of chromosomes is doubled in the embryo.âIn the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) oi lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve;
. Elementary botany. Botany. GAMErOPHYTE AXD SPOROPBYTE. 243 â When fertilization takes place the number of chromosomes is doubled in the embryo.âIn the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) oi lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; the number is doubled. The fertilized egg is the beginning of the sporophyte, as A\'e have seen. Curiously throughout all the divisions of the nucleus in the em- bryonic tissues of the sporophyte, so far as has been determined, up to the formation of the mother cells of the spores, the number of chromosomes is usually the same 475. Reduction of the number of chromosomes in the nu- cleus.âIf there were no reduction in the number of chromosomes. Fig. 322. Karyokinesis in sporopliyte cells of podophyllum (twice the number of chromosomes here that are found in the dividmg spore mother cells). at any point in the life cycle of plants, the number would thus become infinitely large. A reduction, however, does take 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 Atkinson, George Francis, 1854-1918. New York, H. Holt
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