In the seedling of Lilium and Allium, mitotic disturbances of various patterns have been described previously (Kato 1954a (Kato , 1955a. It has been suggested that the substance(s) formed by the metabolic activities specific to the early stage of seedling lead to the cytological abnormalities. This as sumption was partially supported by the finding of a radiomimetic action of water extract obtained from seeds. However, the abnormalities of embryo sac formation, and of embryo and endosperm

more »

... pment can not neglect as other cause responsible for the chromosome aberration, although these pheno mena themselves reduce the fertility as measured by seed setting. The pre sent report deals with the investigation of cytological abnormalities observed in the endosperm tissue of Lilium and Allium, and found incidentally in the embryo-sac mother cell of Lilium. Observations with Allium The following problems are treated in this material; 1) endomitotic cycle, 2) highly polyploid division and 3) abnormal mitoses in the endosperm tissue of Allium fistulosunt. At 14 and 21 days after selfing, immature seeds were separated into embryo, endosperm and ovular coat by the manipulation with a sharp needle under the binocular microscope. Thus isolated endo sperm tissues were fixed in absolute alcohol-glacial acetic acid, and then squashed in aceto-orcein. In order to know the mutual position of endosperm, the materials were embedded in paraffin, sectioned and stained with thionine or tholuidine blue. The cytological observations were much more readily fol lowed by the use of squashes than sections. The three localized areas in the endosperm were selected for study; the adgerminal part lying between the embryo and the adjacent enveloping tissues, the peripheral part on the abger minal side and the central part of endosperm. I. Endomitotie cycle and highly polyploid mitosis In the material of 14-day-old, the mitosis in the peripheral part of endos perm is normal, as usual 24 chromosomes (triploid number) were counted (Fig. la) . In addition to the normal mitoses, all the stages of an endomito tic cycle were found, Each of 24 chromosomes appeared paired, and united at a single kinetochore in prometaphase. The following stage is a diplo