An F^- strain of E. coli K 12 is unable to transfer its colicinogenic factor unless it has been transformed into F⁺. However, an F^- col⁺ can transmit its colicinogenic factor to F^- col^- when R factor (multiple resistance factor from Shigella flexneri 2b) is introduced into the F^- col⁺ cell. The frequency of co-transfer of the R factor and the colicinogenic factor is lower than that of F and the colicinogenic factors. The R factor produces “R substance” on the surface of a cell and the substance is inactivated by the treatment with sodium periodate. The production of male substance is suppressed when the R factor is introduced into F⁺ cell.

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1) A variety of wheat, “Shirahada”, showed an abnormal meiotic behavior, “chromosome-mosaics”. In every plant selected at random there were to be seen aneuploid PMC's such as “hypo-” or “hyper-” cells mixed together with euploid ones in the same anther-loculus. Especially the “hypo-” cells with less than 2n chromosome number were frequently noticed. Such aberrant PMC's are usually characterized by a relatively large number of unpaired chromosomes.
2) In euploid PMC's there were often observed one or two pairs of univalents while multivalent chromosomes such as trivalent or tetravalent were rarely discovered. On an average about 18% of aneuploid PMC's observed had such irregularities. Laggards and bridges were also frequently observed in both 1st and 2nd anaphase, especially so in 1st division.
3) An upset in mitosis which was induced by gene-controlled spindle abnormalities just before meiosis seems to be the probable cause of the origin of these hypo- and hyper-cells.
4) As a result of such irregularities in the meiotic division, there appeared frequently in the progenies various types of aneuploids, especially monosomics (2n=41). In the self-pollinated progenies of a plant with the lowest seed fertility, a series of aneuploids having 2n=39, 40 and 41 chromosome numbers were found together with euploids (2n=42).

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Copper resistant strains were obtained by training haploid strains of Saccharomyces cerevisiaethrough repeated subcultures in copper-containing media. Tetrad analysis made after mating one of those resistant strains by a sensitive haploid revealed that the resistance was controlled by a dominant gene which segregated independent of mating type, galactose fermentability and growth type.
From a copper culture of a sensitive diploid strain, resistant clones having a genotype Rr and those having a lower level of resistance were obtained. The genotype of the latter was such as representable by R'r. By genetical analyses of resistant cells isolated from a copper culture inoculated by R'r cells, it was conjectured that R, R' and r are multiple alleles, and that the mutation rate from R' to R is much higher than that from r to R' and from r to R.

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1. In the autumn of 1958, dormant seeds of a wheat variety, “Aoba-Komugi”, were immersed for 2 weeks in the solution of Na₂H³²PO₄ with the doses of 1.0, 2.5, 5.0, 7.5 and 10.0μc/seed, respectively.
2. The survival rate decreased with the increase of radioactivity, while the chromosomal aberration rate increased proportionally with the increase of radioactivity.
3. ³²P has different effects on different spikes in a plant as in X-ray. The main types of chromosomal aberrations observed at MI of PMC's were non-pairing, translocations, deficiencies, monosomics, iso-chromosomes and various combinations of these aberrations. Above all, non-pairing and translocations have occurred comparatively frequently.
4. The differences of chromosome numbers and of meiotic behaviors were found not only among spikelets of a spike but also among anthers of a floret.

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Crosses of four strains of synthesized 6x wheats with 20 varieties of Emmer wheats were made to test necrosis or growth abnormality in the resulting F₁ hybrids. These abnormalities are attributable to complementary genes, one of them belonging to A and/or B genome of Emmer wheat, and the other to D genome of Aegilops squarrosa. Crossability, on an average, was about twice or more effective in comparison with the Emmer wheat×autotetraploid squarrosa crosses. The viability spectra of ABD No. 1×Emmer wheat crosses (Group 1) was similar to that of Emmer wheat ×autotetraploid squarrosa crosses. The viability spectra, however, varied depending upon the synthesized 6x wheat used as the female parent, except that ABD No. 3× Emmer wheat crosses (Group 3) and ABD (Sears) ×Emmer wheat crosses (Group 4) showed similar spectra, resulting in three kinds of viability spectra. Thus, three strains of synthesized 6x wheats, ABD No. 1, ABD No. 2 and ABD (Sears) were found to be useful as test strains for hybrid necrosis or growth abnormality genes.
Two types of necrosis were found in some of synthesized 6x wheat×Emmer wheat crosses. The one designated as Type 1 occurred in crossing ABD No.1, ABD No. 3 or ABD (Sears) with T. dicoccum Khapli, T. dicoccoides kotschyanum and straussianum. The genotype for Type 1 necrosis was estimated to be ne₁ne₂Ne₃/Ne₁Ne₂ and Ne₁ne₂Ne₃/Ne₁Ne₂, which is in agreement with the three gene hypothesis presented by Hermsen (1959). The other, designated as Type 2, was a late appearing type of necrosis; it was found in the majority of crosses between ABD No.1 and dicoccum-and durum-varieties. The assumed genotype for Type 2 necrosis, Ne₁ne₂Ne₃/Ne₁n₂, requires further direct proofs.
Dwarfishness observed in the crosses between ABD No.1 and dicoccum Vernal, durum melanopus, pyramidale or persicum varieties are also attributable to complementary genes different from those for necrosis.
On the basis of viability spectra, 20 varieties of Emmer wheat can be divided into four groups as illustrated in Table 3.

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Cell wall preparations from various strains of E. coli and S. typhimurium were found to inhibit conjugation in E. coli K12. The inhibition seems to be caused by some specific interaction between a cell wall preparation and intact cells of an opposite mating type. Evidence suggests that not only male cells but also female cells are endowed with a specific substance or substances essential for conjugation.

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The number of nucleoli newly formed in telophasic cells of root tips was counted in rice species having the AA genome, namely, Oryza sativa, O. perennis, O. sativa f. spontanea, O. glaberrima and O. breviligulata, taking for each species about twenty strains from the stocks kept in the National Institute of Genetics, Japan. The root tips of germinating seeds were fixed in Lewitsky's solution (5% CrO₃3: Formalin 1), and after hydrolysis in warm N-HCl for about 20 minutes squashed with 1% aceto-carmine. The results obtained from the respective strains are given in Tables 1-4, and the distribution of the mean nucleolar number in each species is shown in Table 5. As shown in those tables, the variation in nucleolar number is continuous. If strains with more than 2.1 nucleoli per cell are considered to represent the quadri-nucleolar, and those with less than 2.1 the bi-nucleolar type, all the species investigated can be said to have both types. However, it is found that strains belonging to O. perennis and O. sativa f. spontanea, as well as those of the Indica type of O. sativa, are mostly of quadri-nucleolar type, while strains of O. breviligulata and O. glaberrima are of bi-nucleolar type. Another point of interest was that plants collected from adjacent sites, belonging actually to the same population, showed a marked difference. This indicates that the chromosomes of plants within the same population may differ in nucleolus-forming ability.

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Based on the data collected for 10 years (1951-1960) from the following three different crosses of the fox, silver × silver, platinum × platinum and silver × platinum, the litter-size, sex-ratio and the segregation of coat color in kits were observed. The results are summarized in Tables 1 to 4 and Figure 1.
Platinum character is dominant over the silver. The individuals homozygous for platinum gene are lethal. The crosses of platinum × platinum produce silver and platinum individuals at 1:2. The litter-size differs by the type of cross. In the cross of silver × platinum, the litter-size is very small and approximates that of the cross, platinum × platinum. This seems to be due to the fact that the foetuses from the silver × platinum cross die before parturition.
The sex-ratio is regular in every cross examined in this study; this shows that both silver and platinum are autosomal characters.

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The present article deals with some observations on hormone-induced polyovulation and pregnancy in mature and immature rats, with special reference to the number of ovulated eggs and pregnancy.
The rats used are of Wistar/Mk strain; they are 35 and 60 days in age, and females were all virgin. The average number of ovulated eggs from 10 females of this strain was found to be 8.4, and that of litter-size was 6.5 in the natural oestrus cycle.
The female rats in various stages of the oestrus cycle received an intramuscular injection of pregnant mare's serum (PMS) and 44hr. later an injection of human chorionic gonadotrophin (HCG).
1) Mature females: The following four doses, 20 i.u., 40 i.u., 80 i.u. and 100 i.u., of PMS and HCG, were applied. After treatment, they were mated by being placed with males at a rate of 1_??_: 2_??_. In the following morning, the females were inspected for presence of the copulatory plug in their vaginas, and some of them were sacrificed for examining induced ovulation.
The number of mated females showed no significant difference by doses here applied (Table 1). The number of eggs was significantly larger after injection with 40 i.u. PMS and HCG than after injection with other doses. The number of eggs extruded in the oviduct was 268 in total, being variable from 14 to 48 by individual and 20.6 on an average (Figs. 1, 2). The results are striking in showing a remarkable polyovulation, since the number of eggs extruded in natural ovulation was 8.4 on an average (Table 1).
Microscopical examinations revealed that fertilized eggs in induced ovulation were normal in process of development (Figs. 3_??_5).
Approximately fifteen out of ninety-seven females which mated in response to the injected gonadotrophins became pregnant. This number was less than that of pregnant females after the natural oestrus (Table 2). Most females failed to produce live young, but six females gave litters with a 7.3 averaged litter-size close to the control value.
2) Immature females: Injection of 20 i.u. PMS and HCG was made in immature females. Eight out of thirty-five females received injection showed vaginal opening 40 to 60 hours after the injection of PMS. But, there occurred no mating and no eggs were obtained from all treated immature females. Further investigations are needed to learn the optimum dosage of PMS in order to induce the ovulation and to produce live young, with special regard to the time-relation of the combined injection of two hormones in relation to the oestrous cycles of animals.

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1. In the present report, the external characteristics, the number of somatic chromosomes and meiosis in PMC's of trigeneric triple F₁ hybrids raised from Triticum vulgare × Haynaldia villosa F₁×Secale cereale (TvCHRF₁) were described.
2. The trigeneric hybridization was more successful when T. vulgare × H. villosa F₁ was crossed as the female to S. cereale than when the cross was made in the other direction. This situation is the same as that found in Emmer wheat-Haynaldia-Secale hybridization.
3. 55 grains of trigeneric triple F₁ were sown, of which 15 grains germinated and 4 mature plants were obtained. The percentage of the number of mature triple F₁ plants to the number of pollinated florets was 0.137.
4. The number of somatic chromosomes varied from 31 to 36 among 10 plants of TvCHRF₁ (Table 1). The somatic chromosome number of eu-trigeneric triple F₁ hybrids was 35. This number is the same as the sum of the gametic chromosome numbers of the three parents, T. vulgare (21), H. villosa (7) and S. cereale (7). In these trigeneric triple F₁'s, 7 out of the 31_??_36 somatic chromosomes were introduced from S. cereale (_??_) and the remaining 24-29 from TvCHF₁ (_??_, 2n=28).
5. The triple F₁ hybrids, whose meiosis in PMC's was studied, were classified into the following 3 groups according to their somatic chromosome numbers:
(a) A group having 2n=35 chromosomes; 6 individuals were included in this group, of which only one matured. At the MI of meiosis 1_??_7 bivalents were observed (Figs. 6_??_13). The frequency of the bivalents in PMC's is shown in Table 3. Almost all the bivalents consisted of 2 elements of equal size, but in a few cases heteromorphic pairs were observed. 4_II appeared to be the mode (Table 3). Most of the bivalents were stick-shaped, but some of them were ring-shaped. Trivalents of V-shape were observed in addition to bivalents at MI (75 trivalents in 1, 000 PMC's) and tetravalents of N-shape were observed only in 2 cases among 1, 000 PMC's.
(b) A group having 2n=31 chromosomes; 2 individuals were included in this group. At the MI of meiosis of PMC's 0_??_5 and 0_??_6 bivalents were observed with the mode of 0_II (Figs. 14_??_19). The frequency of bivalents is shown in Table 3. Stick-shaped bivalents were commonly observed in both individuals, while ring-shaped ones were only rarely found in No. 1 individual (9 ring-shaped among 621 bivalents). Heteromorphic bivalents were also observed only in a few cases. Trivalents of V-shape were observed in rare occasions, but no tetravalents were found.
(c) A group having 2n=32 chromosomes; only 1 individual was included in this group. At the MI of meiosis of PMC's 0_??_5 bivalents were observed (Figs. 20_??_24). Frequency of the bivalents is shown in Table 3, in which 0_II was the mode. Almost all the bivalents were stick-shaped. Trivalents of V-shape were rarely observed, but no tetravalents were found.
6. Although a few bivalents might have been consisting of chromosomes of R or V genomes, most of the bivalents observed in the triple F₁'s seem to have been formed by autosyndesis between the chromosomes of AB or ABD genomes of T. vulgare used as the grandparent, according to the results of cytological investigations in F₁'s between Triticum and Haynaldia by Kostoff (1937), between Haynaldia and Secale by Nakajima (1951, '59), between Triticum and Secale by Nakajima (1952, '54, '56, '57, '58, '60) and between Aegilops squarrosa and Haynaldia villosa by Zennyozi (1961).

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