Seeds stored in cold solvents retained the ability to germinate longer than in warm solvents. The seeds of Callistephus and Zea stored in cold solvents such as ethyl ether and benzene for I year germinated well like fresh seeds. Cold ethyl ether is seemed to be the most suitable solvent for long period storage of seeds.

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The time of expression of genes for blast resistance during the penetrati, Dn of Pyricularia oryzae into rice plants was examined using the leaf sheath inoculation method. It vras observed that the time of the expression varied from gene to gene.

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Parents, F₁ and F₂ of 605AXSweet Sudan were grown in both field and greenhouse and inoculated with the leaf blight organism, H. turciculee. Results of two tests agreed reasonably well. However, the field results were more useful than the greenhouse results, since field :resistance functioned in ccrtain genotypes. The field results suggest that resistance to leaf blight in sorghum-sudangrass hybrids is controlled by a single dorninant gene.

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The in vitro development from zygote to proembryo in ovules of Petunia hybrida Vilrn. was investigated. Zygote could grow to early globular ernbryo on a simple nutrient medium provided osmotic value of medium had been favourable. Attention is drawn to the initiation of abnormal structure in embryo sac.

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The contraction ratio (CR) of cocoons was genetically different among silkworm strains. Selection for the CR was carried out successively for three generations by the inbreeding of moths producing cocoons giving high, medium and low CR value. The rernarkable difference was observed in the selection effectiveness upon the CR among these three lines. Reelability of cocoons was also differed among three lines ; the line selected towards the low-CR showed the highest reelability.

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Marked varietal difference of the sensitivity wes observed when the dry seeds of rice (Oryza sativa L.) were treated by ethylene imine (EI). The sensitive varieties to EI took up more water during seed soaking and were rapid in the germinating speed than the resistant, ones, suggesting that the absorption amount of the chemicals into the seed and commencement of the germination metabolism may be the causal factors of the varietal difference. However, the varietal difference of EI sensitivity in the presoaked seeds was different from that in dry seeds ; EI sensiti-vity of each variety changed with soaking time. Pattern of this change was discussed with reference to metabolic change during seed germination.

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