巨態花粉粒の生成に關する研究補遺 (第六及第七圖版附屬)
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1. The material used in the present study is Sutton's New Blue Bedding (2_n=14) and Sutton's Leviathan (2_n=28). Some branches with young buds were put in flasks filled with water and kept in ovens at 40℃, 42℃, 45℃ and 47℃ respectively. After differing lengths of time buds were examined in Belling's acetocarmine. Irregularities were observed in regard to both karyokinesis and cytokinesis; only the latter will be reported here. 2. At higher temperature tetrads formation proceeds in a manner different from the normal furrowing process (Fig.2-Fig.3). A narrow hyaline area appears at the middle of cells which gradually becomes clearer and bisects the cytoplasm (Fig.5). A wall is then formed around each daughter cell (Fig.6). The sister cells thus formed remain sticking to each other by the division plane and often fail to separate. The secondary division sometimes takes place in one or each of the daughter cells (Fig.8). As a result there are formed three or four daughter cells, all of which also remain sticking together very often, although a slight indication of separation is sometimes seen between the sister cells. Some pollen mother cells, on the other hand, are divided simultaneously into four parts which also remain stuck together (fig.9). Possibly the giant pollen grains are. derived from those cases in which sticking cells have fused together and have been enclosed within one and the same wall (Fig.10). 3. The fusion of cells can occur at later stages among microspores (Fig.11-Fig.17). When cells more than four in number or corresponding to more than four fuse together a super giant pollen grain larger than the tetraploid grain reported in my previous paper must naturally result (Fig.14). This fact also clearly accounts for the irregular shape of super giant pollen grains. 4. Fusion also takes place at earlier stages while the meiosis is still proceeding (Fig.19-Fig21). This must result in giant pollen grains or if any cytokinesis fails to occur, a super giant pollen grain. This sort of fusion is as rarely observed in the heated material as in the greenhouse material. Abnormal temperature (at least high temperature), therefore, may not be the important factor for its occurrence 5. A uninucleate interkinesis is found with at least fourty nine chromosomes (Fig.18). Cell dimension in this case is normal. This has probably been caused by cytomixis occurring at a certain stage of meiosis and has no relation with the formation of giant grains. 6. In the giant pollen grain formed by means of cell fusion the nuclei possibly do not fuse into one, so that in fertilisation only one haploid nucleus will join the egg nucleus. This, to some extents, accounts for the fact we reported at the previous meeting, namely that artificial pollination exclusively with giant pollen grains resulted only F_1 progenies with a diploid number of chromosomes, although we have some reason to believe that the chromosome elimination must take place at a certain stage during the progress from pollen division to fertilisation, or much later.
- 日本作物学会の論文
- 1930-07-25
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- 巨態花粉粒の生成に關する研究補遺 (第六及第七圖版附屬)