The floating habit of 10 strains belonging to Oryza sativa, O. perennis or O. glaberrima was studied by sinking them up to 3m deep in water at 6 different rates, namely, 0 (control), 1.5, 3.1, 4.6, 6.2 and 9.3cm per day. Number of days of floating, plant height, leaf length, total internode length, number of internodes and average internode length were observed.
From this experiment the following results were obtained.
(1) The 10 examined strains can be classified into 3 groups regarding thefloating habit. Strains 1 and 2 of O. sativa and strain 5 of O. perennis were pronouncedly floating, strains 6 and 7 of O. perennis and strain 8 of O. glaberrima were weakly floating, and strains 3 and 4 of O. sativa and strains 9 and 10 of O. glaberrima were non-floating.
(2) In the pronounced floaters the increase in plant height under flood conditions is almost entirely dependent upon the increase of the total internode length but little upon length of a floating leaf. Effect of the latter is, however, rather important in the weak floaters.
(3) The increase in total internode length is almost equally dependent upon the increase in the number of internodes and their elongation.
(4) Internode length of floating rice types collected in their native places was extremely variable, while that of the experimentally raised plants was uniform. Length of almost all internodes of the collected plants falls within the range of the average internode lengths of the experimental plants raised in the control and a high sinking rate-plot.
(5) Rate of internode elongation increases, within a limit, proportionally with sinking rates. Floating habit of individual strains can be characterized by 3 factors, a, b and c, which determine a regression of the rate of internode elongation on the sinking rate. Factor a, indicating the rate of internode elongation achieved under normal conditions, can be used as an index of resistance against a sudden flood. Factor b represents the slope of the regression line and indicates the capacity of a strain to elongate the internodes in correspondence to water raise. The third factor c represents the maximum rate of elongation.
(6) Analysis of those 3 factors is a useful means to characterize the floating habit of individual strains. Among the 3 pronounced floaters, strain 1 has an extremely large a and the smallest b, being most resistant against a rapid sinking for a short period. Strain 2 is characterized by the smallest a and c and a much larger b than that of strain 1. Strain 5 has the largest b and c and is most resistant to a chronic flood condition. All 3 weak floaters have only small a and c but their b's are almost comparable to those of the pronounced floaters.

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Fifty amylase deficient mutants have been obtained independently from the wild strain of Aspergillus oryzae by using the filtration-concentration technique (eliminating conidia in the minimal solution supplemented with starch or amylopectin as a carb on source) after UV irradiation. These mutants do not grow on the medium containing starch but grow on glucose. Genetic study for amylase production was carried out through the parasexual cycle by using twenty-five mutants.
All twenty-five mutant genes are recessive to normal ones. Amylase production is controlled by genes at two loci; one locus (ae) contains twenty-four alleles (these mutant genes show negative or diminutive in both their dextrinizing power-DP and Saccharifying power-SP) and another locus (ae') includes one allele (the mutant gene shows normal in its DP but not in its SP).

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The gametic-development gene hypothesis, formerly put forward by the senior writer, could convincingly explain the sterility of F₁ hybrids and related phenomena in cultivated rice, but could not account for the occurrence of sterility in F₂ and later hybrid derivatives. It was found that among many intervarietal crosses, F₁ fertility and mean F₂ fertility were not correlated. Experiments were then conducted to throw a light on the genetic basis of sterility of the latter type, using cross combinations which showed a high fertility of F₁ hybrids. Their fertility in F₂ segregated in a wide range, and from a few partially sterile F₂ plants, partially sterile lines which bred true for sterility have been established. Embryological observations showed that both male and female gametes partly degenerate after normal meiosis.
The partially sterile lines were then back-crossed to the parental strains, and the F₁, F₂ and F₃ generations were investigated regarding fertility variation. The results led to the conclusion that duplicate factors might be involved sustaining the development of gametes on the condition that at least two dominants are present in the plant, and that this diplontic sterility might be due to certain recessive combinations of those factors. The parental strains were considered to have different combinations, A₁A₁a₂a₂ and a₁a₁A₂A₂. A linkage relation was found between such a fertility factor and the apiculus pigmentation gene C. In the sense that those factors behave as genes, they were called Duplicate-fertility genes. The genetic basis of this sterility thus postulated is similar to that formerly shown for the segregation of weak plants in F₂. Both phenomena, which spell a breakdown of hybrids, seems to be the isolating barriers frequently found in rice.

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1. Lethal chromosome frequencies, the allelic rates of lethal genes and homozygous viabilities of quasi-normal chromosomes were estimated in the second chromosomes extracted from four natural populations of D. melanogaster distributed in the western and central parts of Japan.
2. The combined frequencies of lethal and semi-lethal chromosomes in each population were 15.1, 15.7, 7.3 and 20.1 per cent respectively. The mean viabilities of quasi-normal chromosomes in three populations were about 32 per cent. The allelic rates within population in the three populations were 5.3, 4.1 and 7.0 per cent respectively. Based upon these data, the Japanese natural populations were regarded to besmall in their sizes.

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Twenty isoleucine and valine requiring mutants including a temperature mutant were found to be separable into three groups genetically, I, II and III. The mutants are located at sites distal to lysine-1 and proximal to spray in linkage group V in the order III, II and I. This arrangement of the groups is of particular interest when considered in conjunction with the biochemical characteristics of the mutants.
Certain unexpected ratios of recombinants with respect to outside markers are noted and discussed. In addition selfing crosses are described some of which resulted in a high frequency of progeny with a wild phenotype.

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The chromosomes of five species of beetles have been studied in male germ cellswith particular reference to the number, morphology, behaviors of chromosomes and the sex-determining mechanism. The results of observations are summarized in Table 2. The X-chromosome in H. macroderus is always found lying off the plate at the first metaphase.

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Pregnant mice of B72 strain from crosses with Swiss albino males received X-irradiation at a dose of 200r through a whole body exposure, at various days ranging from 0.5 to 15.5 days of gestation. The effects of X-rays on embryos were examined at varying days of gestation. The results are summarized as follows:
1. A number of malformations was observed in embryos irradiated at 8.5 to 12.5 days of gestation. A frequency in total of abnormal embryos was found to be 27.7%. The abnormalities here observed were anophthalmia, exencephalia, short snout, syndactylia, polydactylia, deformed tail, short tail and malformed arms.
2. An average number of litters was observed to be 5.1 for 32 irradiated mothers, and 6.0 for 5 non-irradiated ones. No remarkable difference of litter size occurs between irradiated and non-irradiated mothers.
3. In total of 166 embryos derived from irradiated mice, 88 were male and the remaining were female. There is no marked deviation of sex-ratio in embryos derived from irradiated embryos.
4. An average weight of embryos derived from mothers which received irradiation at 8.5 to 12.5 days of gestation was considerably lower than that of control embryos. The minimum weight was found in the embryos irradiated on the 11.5th to 12.5th day.
5. Body-length/tail ratio was between 2.1 and 2.5 in control embryos, while that of embryos from mothers irradiated at 8.5 to 12.5 days of gestation was generally over 2.5, due to short tail.

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Chromosome numbers of the genus Chenopodium observed by the authors during 1960 areshown in Table 1, and it has been confirmed that its basic numbers are 8 and 9, as reportedin the previous papers.

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The reduction division in PMC's was studied in 5 interspecific hybrids: N. suaveolens× N. plumbaginifolia, N. suaveolens×N. longiflora, N. gossei×N. plumbaginifolia, N. gossei×N. longiflora and N. gossei×N. alata. N. suaveolens and N. gossei are Australasian species and N. alata, N. plumbaginifolia and N. longiflora are American species. These five plants are low chromosome number species and have a similar external morphology.

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1. Capsaicin content in dry matter (%) and the total capsaicin per fruit (mg) produced in the course of development of fruits of Capsicum annuum L., C. frutescens L., C. pendulum Willd., C. chacoense Hunz. and C. pubescens Ruis et Pavóm. have been determined (Table. 1 and Fig. 1).
2. The secretion of capsaicin started from a remarkably early stage, namely 1 week after flowering in C. chacoense, and in 2 weeks in the remaining species.
3. The maximum capsaicin content in dry matter appeared 2 weeks after flowering in C. chacoense, 1 week later in C. annuum, 2 weeks later in C. pendulum and C. frutescens, while it was markedly delayed until 10th week in C. pubescens. This agrees with the order of optimum growth temperatures required by those species (Smith 1958, 1959), i.e. the actual temperatures of the greenhouse were too high for the first species, optimal for the second and too low for the rest (cf. Ohta 1960b).
4. The total capsaicin per fruit reached a plateau 4 weeks after flowering in all species, except C. pubescens. This indicates that immature fruits about one month after flowering should be used for the extraction of pungent substance.
5. From the view-point of breeding utilizing related and/or wild species, C. frutescens is considered to be the most promising material in hybridization for more pungent peppers in the temperate regions.

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