On the Nuclear Divisions and Partial Sterility in Oenothera Lamarckiana, SER (A Preliminary Note)

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1. The number of the pollen mother-cells with the homologous chromosomes paired in the heterotypic metaphase, or with those showing the regular nuclear plates are found as much as ca.50 per cent, a result which widely differs from that of the' previous investigators.
2. Ten different cases of the irregular phenomena in the behavior of chromosomes on the spindles of the pollen mother-cells and the embryosac mother-cells were observed.
3. In the nucella nuclei of this plant it was not infrequently observed that the thickened long spireme first segmented into seven shorter spiremes, and subsequently by the further segmentation of the latter the diploid number of chromosomes were formed.
4. The chromomeres observed in the spiremes and the chromosomes of the meiotic and somatic nuclei have no individuality. In a somatic chromosome at metaphase three or four chromomeres are seen, so that the total number in a nucleus varies from forty-two to fifty-six, as this plant in diploid has fourteen chromosomes.
5. The counting of the pollen grains in the five anthers and seeds in one hundred and fifteen capsules was made.The abortive spores amounted to ca.50 per cent.which agrees with the percentage of abnormal mitosis in the pollen formation.The germination experiment made with each of the seventeen capsules showed that the percentage of the normal seeds was about 35 per cent.
6. The seedlings of this plant produced some mutants; the seven O. mut. nanella-like plantlets were found in one hundred and seven seedlings raised from one and the same capsule.