Meiotic Mitosis in Hordeum Sativum

[摘要] 1. The material used in this investigation is the pollen mother cells of Hordeum sativum of two rowed and six rowed varieties. These were fixed in BOUIN's solution and stained in HEIDENHAIN'S iron-alumhaematoxylin. 2. With the beginning of the nuclear division, the nuclear contents contracts and separates from the nuclear membrane to form the synizesis stage (Fig. 2). Perhaps this contraction of the nuclear contents is due to the concentration of the spireme at the pole of the nucleolus. 3. At the end of the synizesis stage the contracted threads begin to expand again in the nuclear cavity (Fig. 3) and gradually become arranged in the pairs which are characteristic of the zygotene stage (Fig. 4). During this stage, however, the pairing threads draw closer together until they seem to have united and enters the pachytene stage (Fig. 5). 4. At the late pachytene stage the spireme seems gradually to lose its chromatin, until all the spireme becomes nearly colourless and enters the achromatene stage (Fig. 6). 5. After the achromatene stage, chromatin gradually begins to reappear on the achromatic spireme. At about the same time, however, the spireme begins to split into two threads and enters the diplotene stage (Figs. 7 and 8). From these facts it appears that the achromatene stage is a necessary preliminary to the resolution of the spireme in to two threads. 6. During the first telophase, the nucleolus is formed from the chromatin of the chromosomes, which concentrates gradually to form a mass of spherical shape, while the chromosomes which have thus lost most of their chromatin become the spireme of the interkinesis (Figs. 16 and 17). But, during the second prophase, the spireme seems to reform the chromosomes, gradually receiving chromatin from the nucleolus (Figs. 18 and 19). Again in the second telophase, the opposite movements takes place, as the chromatin of the chromosomes apparently concentrates to form the nucleolus (Figs. 24 and 25). These facts indicate that the nucleolus contains the material of the chromosomes.

[学科分类] 农业科学（综合）