1. An experimental study was made of the effects of high temperature applied to the excised anthers of Tradescantia paludosa, and in each experiment, the initial meiotic stage of the anther was tested. 2. Various abnormal figures previously reported by many workers were reinvestigated with special reference to the relationships between the treated meiotic stages and the chromosome aberrations. 3. Some characteristic behaviors of the meiotic chromosome were also discussed.
Division of the generative cell which occurs in the pollen tube was studied in seven species of angiosperms. Observations were made in vivo with use of the phase-contrast microscope, Fixed and stained preparations were also used to check the results from observations in vivo. The chromosomes are arranged in the equatorial plane in metaphase, The daughter chromosomes are regularly separated in anaphase towards the both poles. The spindle can be well observed in vivo as a transparent body, The phragmoplast and the cell plate are formed in the course of cytokinesis, the cell plate developing centrifugally. The phragmoplast and also the cell plate begin to degenerate after they have reached the maximum development. In fixed and stained preparations the spindle and the phragmoplast mani-fest to contain pentosenucleic acid. The cell plate region does not contain pentosenucleic acid and also does not show a positive staining reaction for polysaccharides. Division of the generative cell in the pollen tube is considered to occur essentially in the same manner as in other typical plant cells, although the cell plate is of a degenerating character.
1.) Transfer of durum genomes into ovata cytoplasm of Aegilotricum No. 2 was made in order to ascertain if male-sterility might always occur even if any lines of Aegilotrium No. 2 are used. All resulting offspring be-came completely male-sterile as in previous experiments. 2) Using pure ovata plants as a female parent, durum genomes were substituted into ovata cytoplasm. Resulting 14II-plants become male-sterile without exception. 3) Using the new synthesized amphidiploid (durum_??_+ovata _??_), restoration of durum genomes was made. All 14II-offspring showed normal pollenf ertility. 4) Ovata genomes were replaced again in the cytoplasm of male-sterile durum plants. All resulting 14II-individuals were normal with high pollenfertility. 5) Placing the ovata genomes into durum cytoplasm was carried out. Most of 14II-plants showed normal pollen-fertility. 6) It has been discussed that the male-sterile factor came from the ovata cytoplasm and that ovata plants contain a certain nuclear gene which makes the male-sterile factor inactive.
S. robustum as it is now known is basically a species of two cytological types, those with 2n=60 chromosomes, and those with 2n=80 chromosomes. Aneuploids, probable hybrids, and suspected hybrid derivatives also occur and exhibit a variety of chromosome numbers (2n=63-194) which have in the past suggested great cytological complexity in the species. The 60-chromosome types are known from Borneo, the Celebes, and Australian New Guinea. The 80-chromosome forms are found in Dutch and Australian New Guinea, on New Britain, and in the New Hebrides. The following observations are also recorded for related species found in the geographic range of S. robustum: From the Celebes 2n=96 in S. spontaneuna; and from New Guinea 2n=80 in S. spontaneum, 2n=60 in Erianthus arundinaceus, and 2n=38 in Miscanthus floridulus.
The commercial papain can be separated to many fractions by fractional saturation of their aqueous solution with ammonium sulphate. The different fractions thus obtained have different milk clotting and proteolytic properties. The fractions having great milk clotting property are not the highly proteolytic ones and thus the milk clotting and proteolytic fractions of papain can be separated.
The obtained data concerning the threadlike apparatus in the tissue of Mimosa pudica L. may be summarized as follows: 1) In the lacunal parenchyma of the petiole, the threadlike apparatus which is connected with the tannin vacuole can be observed in tap water immersion. 2) The threadlike apparatus are stained with neutral red, brilliant cresyl blue, Nile blue sulphate, rholamine B and chrysoidin. These dyes are all basic, and the positive reaction to them in vital staining indicates that the threads may contain a certain substances of a lipinous nature. 3) The threads gradually contract in lactic acid, and finally attenuate leaving only a trace. 4) From the data of these experiment, it is concluded that the threads are one of the cellular elements, and are not artificial figures.
Cytological abnormalities in the embryo-sac mother cell and endosperm tissue were observed in Allium and Lilium. The following points were made clear: 1. Nuclear divisions in the central part of endosperm are characterized by endomitosis, highly polyploidy and cytological abnormalities. These phenomena can be regarded as the indicators of the degenerating cell and also of chromosome decay in aging cells. Chromosome aberrations appear most frequently in highly polyploid cells. Polyploidy and mitotic abnormalities occur commonly in the endosperm of normal plants. 2. The abnormalities of embryo-sac and embryo development were described in Lilium. Some specimens had an abnormal embryo-sac, but in both immature and nearly mature embryos chromosome aberrations were not found. 3. It is unlikely that cytological abnormalities taking place in the early developmental stage of embryo-sac, endosperm and young embryo reappear in the seedling.
In Cephalotaxus drupacea var. pedunculata a case of partial failure of spindle during both divisions of meiosis in pollen mother cells has been re-corded. A wide variety of distribution has been observed at M.I, A.I, and AM. The chromosomes are scattered at all phases because of the lack of a directive influence of the spindle. Since there is no correlation between these arrangements at different stages it is concluded that many of these are supurious being caused by smearing per se. The chromosome division takes place normally in absence of a spindle and 48 chromatids are seen at the end of the meiosis. There are no other abnormalities. Inspite of this abnormality there is a tendency of forming two nuclei at telophase I and four at telophase II. Tetrads are produced upto 46.7% and the rest constitute monads, diads (equal or unequal) triads and polyads containing upto 10 microspores. As expected all the cell walls are not laid by cell plate but there is evidence that wall formation takes place by furrowing. Since normal and abnormal trees grow side by side it is concluded that the cause of the abnormality is genic rather than environmental. Furthermore, it may be said that such a genic control of spindle expresses itself under certain internal environmental conditions because both normal and abnormal cells are found within the same microsporangium. In this sense it appears that the genic control is not completely dominant.
The nature of the central body of the Cyanophyceae has been studied cytochemically. Enzyme treatments, followed by histo-chemical tests and also the effects of certain chemicals on the central body were used to elucidate the nature of the proteins in it. The central body and cytoplasm give an intense positive test for tyrosine and arginine but give negative test for tryptophane. After peptic digestion the cell does not give positive test for arginine or tyrosine whereas the central body takes deeper stain with leucobasic fuchsin, suggesting the presence of histone. The central body remains intact even after extraction of nucleic acids with 5% TCA at 90°C for 15 minutes, but if this treatment is followed by peptic digestion for 10-12 hrs. the integrity of the central body is lost indi-cating the presence of characteristics similar to those of chromosomes. The effect of trypsin on the central body also substantiates the above finding. It is however observed that the presence of an electrolyte is essen-tial for the digestion of the cells. 0.5M oxyquinoline solution is effective in scattering the chromatic threads in the central body. In Oscillatoria sp. the number of the chromatic threads can be counted. It is obvious from this study that at least the chromatic threads in the central body show characteristics, paralleled with those of chromosomes, so far as the protein-moiety is concerned,
1. The karyotypes were analysed in twenty-three collections, belonging to seventeen species, one subspecies and five varieties of Aster. 2. Cytological findings, presented here, corroborate Kitamura's system of classification in most cases. 3. Judging from their karyotypes, polyploid plants in Aster are possibly allopolyploids. 4. Sections of Aster have karyotypes quite characteristic of themselves. 5. Heterogeneity of the genus is evidenced in the wide range in chromosome length as well as morphology.