1. F₁ hydrids between Aegilops Heldreichii Holzm. (n=7) and Ae. comosa Sibth. et Sm. (n=7) have in most cases 1_IV+5_II at the 1st meiotic metaphase in PMC. The tetravalent complex is arranged in an N- or U- configuration (90.20%). Metaphase plates with 7_II or 1_III+5_II+1_I are also observed (9.78%).
2. In diakinesis and in early metaphase the N- and U-configurations could not be recognized (fig. 1, 3, _{I, II}). The arrangement of chromosomes are determined during the stages from early metaphase to metaphase.
In F₂ two chromosome types, the one with 7_II and the other with 1_IV+5_II were observed in a ratio of 1:1. F₃ offsprings from F₂ with 1_IV+5_II gave also these two types in the same ratio.
3. Two types of tetravalent chromosome configuration (N and U) were counted most extensively with F₃-heterozygotes (Table 1).
4. In such tetrapartite chromosomes regular disjunction of chromosomes occur when adjacent chromosomes separate at metaphase. This type of separation is expected from N-configuration.
Deficiency and duplication of chromosomes segments occur simultaneously, when adjacent chromosomes pass to the same pole (U-configuration).
The average of regular disjunction of tetravalents in F₁, F₂ and F₃ was about 75.8% and the amount of good pollen was 75.1% (see fig. 5, I). In F₂- and F₃-Plants having only 7 bivalents regular disjunction was observed and showed more than 90% good pollen grains. The percentage of regular disjunction in this material is therefore closely related to the degree of pollen fertility.
5. The percentage of ovule fertility observed in F₁- and F₃-plants having one tetravalent was 82.58 and 82.27 respectively. This fertility is a little higher than that of good pollen grains and that calculated from chromosome arrangement. However germination test showed that such difference between ovule fertility and percentage of regular disjunction is due to the vitality of a part of female gametes having incomplete genom resulted from irregular disjunction.
The percentage of ovule fertility in plants having 7 bivalents in F₂ and F₃ was more than 90%.
6. From these cytological results it can be said that this tetravalent complex is resulted from a simple translocation.
7. From our observations it was assumed that the types of chromosome disjunction are in the main attributed to the repulsion between the homologous chromosome segments. Position of the kinetochore, number and position of chiasmata and environmental conditions affect also the chromosome arrangement.

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1) An ovary of the silkworm larva with genotype WPR(1) or wPR(2) was transplanted into the larva with genotype WPr.(3) It was found that the presence of a well developed transplanted ovary in the body cavity of the moth did not bring about any modification in the color of serosa, formed in the eggs laid by the host from its own ovary.
In a reciprocal experiment, an ovary of the silkworm larva with genotypic constitution WPr was transplanted into the unilaterally ovariotomized larva having genotype WPR or wPR. When the transplanted ovary successfully connected to the oviduct of the host moth the serosa formed in the eggs produced from the transplanted ovary developed red pigment as expected from the genotypic constitution of the donor and was not at all influenced by the host.
From these results, it seems highly probable that if there is a production of “R substance” originating in gene R from ovary or other tissues of the moth with this gene it is not a diffusible substance or a gene-hormone.
2) The conclusion that gene R does not liberate a diffusible gene-hormone in the body fluid is well substantiated by the results of crossing of various silkworm races reported by Uda in 1932. The analysis of Uda's results from hormonal point of view also shows that there is no production of a gene-hormone originating in gene P.
3 ) If an ovary of the silkworm larva with genotype WPR or WPr was transplanted into the larva with genotype wPR the color of serosa formed in the eggs produced from the ovary of the host moth was modified, although the degree of modification was not same in individual eggs. The eggs developed a pigmentation phenotypically identical with that of the eggs of the moth having genotypic constitution WPR.
In a reciprocal experiment, an ovary of the silkworm larva with genotypic constitution wPR was transplanted into the unilaterally ovariotomized larva with genotype WPR. When the connection of the transplanted ovary to the host's oviduct had been established all the eggs coming from the transplanted ovary developed a dense pigmentation in serosa as in the eggs of the moth with genotype WPR.
The pigment formation in serosa in these cases seems to take place under the effect of a diffusible “W substance” originating in gene W. Uda's results of crossing experiments also show that gene W can produce a deffusible substance or a gene-hormone.
4) It is highly probable that the “W substance” is produced not only in the ovary but also in various tissues of the body. When the eggs of the moth having gene W are laid they may have the “W substance” already in their cytoplasm. On the contrary, the “P substance” or the “R substance” may be produced in the eggs only after they have been laid or perhaps in the cells of serosa and the substances are not diffusible from the cells in which they have been produced. Tazima (1939) subjected newly laid silkworm eggs to a high temperature and found that the color mosaics were produced in serosa due to the mixture of the cells with phenotypes WPR and WPr. This result supports the conclusion that the substances originating in genes P and R are not diffusible.
5) If the eggs laid b y the moth which has not gene W are fertilized by spermatozoa of the moth having this gene, an incomplete pigmentation takes place in serosa. In this case the “W substance” may be produced by the cells derived from the fertilized eggs.

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Although the distribution of sex ratio in each family, as obtained by the writer from the complete permanent domicile registers of Usigome ward, Tokyo, gave the same result as Koya's, that is, the frequency of families in which only male or female children are born, is much larger than that which may be expected from the probablity law, the writer is of opinion that the births of male and female children do not follow any particular law, but occur at random, the reason for the statistics pointing otherwise being due to the arbitrary ways in which births are at present registered by the authorities.

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