Tetraploid in Lilium formosanum were obtained by colchicine treatment. Reciprocal crosses of diploids and tetraploids were made but only diploids were obtained from 2x×4x. Hypo-, hyper- and eu-tetraploids were obtained from 4x×4x and 4x×2x. Even some of the individuals having 48 chromosomes were not found to be eu-tetraploids because of the lack or excess of certain chromosomes. However, these hypo-, hyper- and eu-tetraploids could be of great use from the ornamental point of view because of their large, heavy-textured crowns and short stems.

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1. In 98.2% of the MI cells of a translocation heterozygote of Acrida lata, one chiasma was formed in one of the 'interstitial segment' and the distal unequal segments were separated equationally at AI in 96.1% of the cells. No chiasma was found at MI in the other interstitial segment and no equational AI separation of the distal unequal segments of this pair. The result indicates a close relationship between crossing-over and chiasma formation.
2. Frequencies of chiasmata at diplotene and MI were compared using a heteromorphic bivalent in which partner chromosomes were different for a block of heterochromatin and a special trivalent in a socalled centric fusion heterozygote, respectively, of Acrida lata. Chiasmata at these two stages were equally frequent, showing that in the present case no reduction in number of chiasmata was accompanied by the process of terminalisation from diplotene to MI.

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1. Eight kinds of double monosomics and five of triple monosomics were obtained by systematic procedures in a variety Chinese Spring of common wheat, Triticum aestivum ssp. vulgare.
2. Double monosomics (19_II+2_I) were obtained by crossing two different nullisomics (20_II). Triple monosomics (18_II+3_I) were produced by crossing these double monosomics to third nullisomics.
3. Plants of the double monosomics were hardly distinguishable from normal disomic plants in size, vigor and fertility. The triple monosomics had high fertility necessary for selfing and crossing, though they showed in general reduced size, vigor and fertility.
4. In progenies of the crosses, double monosomics (_??_)×nullisomics (_??_), plants with the least chromosome number in expectation, i.e. 2n=39, were obtained at the frequencies between 45 and 54 per cent. In the reciprocal cross, however, their frequency was only 4 per cent.
5. Apparently the double monosomics produced three kinds of gametes with 19, 20 or 21 chromosomes. The above results demonstrate that the eggs with 19 chromosomes were more frequently fertilized than those with 20 or 21 chromosomes.
6. For the maintenance of triple monosomic strains, crosses between triple monosomics (_??_) and normal plants (_??_) were made; F₁'s obtained had 39 to 42 chromosomes. The 39-chromosome plants appeared at a frequency of 25.5 per cent and showed the 18_II+3_I chromosome configuration at meiotic metaphase I, which indicated that they were triple monosomic.
7. It was concluded from the results of the present investigation that the 18-chromosome female gametes produced from triple monosomics were functional in fertilization.

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To make genetic analysis of the amylase gene (amy) of Bacillus subtilis, selective markers linked to amy were looked for. As the result, phe₉₆ (phenylalanine) and aro₁₁₆ (aromatic amino acids) were found to be linked to amy. The two mutations were closely linked each other.
By use of the linked markers, fine mapping of amylase negative mutations was carried out by transformation. Sixteen amylase negative mutations so far isolated were mapped in a single locus.

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1. In this paper the authors dealt with the heredity of a chlorophyll variant found in the progeny of X-rayed rice, which segregates habitually green and yellow seedlings at a ratio of 1:1, the yellows of which die soon. The genetic behaviour had already been explained by assuming two recessive lethal genes. Further survey of the selfed progeny was carried out as well as the examination of the mutant strain by testcrossing with other normal green rice and by γ-ray treatments.
2. Assumed were two recessive lethal genes, l₁ and l₂, which are unable to undergo normal chlorophyll formation, and the respective normal genes, L₁ and L₂. Coexistence of L₁ and L₂ produces normal greens, and loss of either of the dominant genes results in yellows. Also, both the loci are so closely linked to each other that recombination occurs scarcely between the loci, and L₁ and l₂ or l₁ and L₂ are locatcd on the same chromosome. That is, the green plants of the mutant strain has L₁l₂ l₁L₂ gene component, and the selfing gives L₁l₂ L₁l₂:L₁l₂ l₁L₂:l₁L₂ l₁L₂ in a ratio of 1:2:1, the two homozygous types either for l₁ or l₂ gene being yellow and the heterozygote green.
3. Rare occurrence of constant green line in this mutant strain seems to have been caused by mutable recurrence from l₁ and l₂ to L₁ and L₂ respectively. And it is proposed that the heredity due to such balanced lethal genes has a significance as a mechanism which protects permanent heterozygosity, having a relation to heterosis breeding.
4. The F₁ hybrids between this mutant strain and normal green rice were green, and the F₂ showed two different segregations; i.e., the one with 3 greens:1 somewhat greenish yellows, and the other with predominant greens: a few whitish yellows.
5. The latter segregation may be explicable by a competitive fertilization. Since the gene components of the F₁ plants are L₁l₂ L₁L₂ or l₁L₂ L₁L₂, if no competition occurred between the pollens with different components, a 3:1 segregation would be expected, while if the pollens underwent a competition, a distorted ratio would result. However, some inexplicable problems still remain to be solved.
6. Gamma-ray treatments of this mutant strain induced a new mutant strain which showed a segregation of greens, yellows and faint yellows in a ratio of 3:3:2. An explanation that a recessive mutation (A to a) was newly induced may be given. This locus is considered to be independent of above L₁ and L₂ loci but to be concerned in chlorophyll formation, and this gene seems to behave hypostatically to the balanced lethal genes.

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The question whether the degree of chromosome condensation of heterochromatic region differs from that of euchromatic region in the process of colchicine-induced supercontraction was studied using Vicia faba root-tips. The results obtained did not indicate the differential chromosome condensation between heterochromatin and euchromatin.

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