1. Some peculiar unstable caryonides, all individuals of which change their mating type during vegetative reproduction, were isolated from crosses of types XXIV and XXIII and from selfings of type XXIV in syngen 12 of Paramecium caudatum. 2. The change of mating type was reversible and affected by fission rate. The low fission rate favors the change to and the maintenance of type XXIII whereas the high fission rate favors the expression of type XXIV. 3. In ordinary selfing caryonides, the occurrence of selfing is due to the change of mating type during vegetative reproduction, which is also affected by fission rate. But in this case the change occurs only in a part of members of a caryonide. 4. The difference in the ratios of the changing individuals was clonal, though some slight differences were also observed in sister caryonides. 5. As to the patterns of inactivation of mating type substance by formalin, the unstable caryonide mentioned above was intermediate between types XXIV and XXIII. 6. In the light of these results, some considerations on the differentiation of mating types were presented.
It is well known that the wing phenotype of vestigial and its alleles in Drosophilamelanogaster varies under different environmental conditions, among which the effect of temperature is most remarkable. The differences of temperature-responses among vestigial alleles have been studied by many investigators, but those among different stocks of vestigial have not yet been well known. Recently Ogaki ('56) and Tanaka ('58) reported that the several Bar-eyed strains have shown marked differences in response to the facet-forming substances. The present paper deals with the differences of temperature-responses among the five vestigial stocks of vg, vg (coiso), vg; e11 (coiso), B; vg; e11 (coiso) and vg; se. These strains vary in their sensitivity to temperature, that is, vg; se strain is most sensitive to high temperature (from 28°C to 30°C), thus the wing phenotype of this strain has reverted nearly to the wild type at 30°C in both sexes, however the remaining strains show only a slight response to the same temperature range. Cross experiments seemed to reveal that some modifiers contained in the vg; se stock would accelerate the responses of wing expression at high temperature.
Information was obtained on the chromosome number and morphology in somatic cells which originated from a variety of organs of 41 different Japanese individuals. The greater part of the observation were carried out with cells in primary cultures established from various organs of 39 aborted embryos aged 2 to 7 months, which include 4 males, 3 females and 32 foetuses whose sex could not be determined by gross examination. Cells squashed directly from several organs of 6 fresh foetuses of unknown sex were also studied. The results, as shown in Table 1, indicate that regardless of sex, age, organ and culture medium, in almost all cases the somatic number of chromosomes was 46 with a small incidence of polyploidy. In a total of 433 cells in which exact counts were made, 428 cells (98.85%) showed the consistent value of 46. Rough counts were performed on 3048 cells of which 98.33 per cent had nearly 46 chromosomes. Individual chromosomes were characterized by morphological analyses on the basis of their size and position of their centromeres. The autosomes showed no significant difference among cells from various organs of the same or of different individuals of both sexes. Also, there was no morphological difference among the X or Y chromosomes from various Organs of different individuals. No evidence for chromosomal polymorphism was found in the Japanese population here under consideration. The X chromosome was recognized as one of the larger medium sized elements which approximately ranks between the 6th and 7th autosomal pairs in the descending order of size. The Y chromosome was recognized to be one of five smallest acrocentrics in the male complement. The recognition of the Y in somatic cells served to identify the sex of somatic cells of foetuses whose sex had not been determined by external features.
In clasping the hands, some persons place their right thumbs on their left ones (R-situation) and the others have the opposite habit (L-situation). Statistics of family studies by Lutz (1908), Yamaura (1940), Kawabe (1949, 1953) and Freire-Maia et al (1958) have confirmed that this trait is hereditary. The author has analyzed these data by a mathematical method of population genetics established by Goto (1954, 1957) to determine the mode of inheritance, the gene frequency and the manifestation rate. The trait of R-situation is inherited by one dominant gene and not only all of homozygous dominants and heterozygotes but also a part of homozygous recessives (the genotype of L-situation) manifest the R-situation by a phenocopy. The frequency of this gene has a racial difference, which is higher in Japanese than in Europeans. The manifestation rate i.e. the rate of phenocopy is higher in adults than in children.