A cytological investigation on the Triticum-Secale triple F1 hybrids (20 individuals), raised from (T. turgidum×S. cereale)×T. vulgare, was carried out in maturation division of P.M.C.-s. The number of somatic chromosomes has shown to vary from 39 to 42 according to the individuals. The triple F1 hybrids, having 39-42 chromosomes, were raised from T. turgidum× S. cereale F1, the chromosomes of which being n=21, with T. vulgare. 21 chromosomes in the 39-42 ones mentioned above seem to have come from T. vulgare, and the remaining 18-21 chromosomes from F1 plants of primary hybrid, T. turgidum×S. cereale, respectively. The number of bivalents in one P.M.C. at metaphase of first maturation division, has shown to vary from 10 to 17 in the individuals with 2n=39-42 chromosomes. Some gemini were seemed to be derived from allo-syndesis between the chromosomes of AB genoms of T. turgidum and T. vulgare, and one of the others, at least, to be resulted from auto-syndesis in R-genom of S. cereale, and the other ones to be from allo-syndesis between chromosomes of R-genom of S. cereale and D-genom of T. vulgare. Some of these gemini were observed as univalents early in maturation division. The number of univalents varied from 8 to 21 (Table 1, 2, 3 and 4). Trivalents and tetravalents were observed, and the number of them in a P.M.C. was only one in both cases. The constitution of genoms according to the results from the present investigation on the maturation division in P.M.C.-s of these 20 individuals of triple hybrids, is as shown in the following table: In maturation division the irregularity was observed generally at first and second divisions respectively, and consequently the cases, in which the tetrad consists of 2-9 cells instead of 4 cells, were sometimes observed. In many cases, in the cells consisting tetrad, those having some nuclei were found resulting from irregular divisions. The number of chromosomes at metaphase of second division of P.M.C.-s was counted as 22-24 in A-group, as 18-27 in C-group and as 22-23 in D-group respectively. At first metaphase of maturation division of Tri-F1-17, which ought have 2n=42 chromosomes in general, was observed a chromosome combination of 13II+30I=56. This case seems to be due to the duplication of chromosomes of both D-genom of T. vulgare and R-genom of S. cereale, i. e. 28 (14II=13II+2I)+14I(2D)+14I(2R)=56.
Karyotypes of the Chilopoda were observed in male germ cells of four species including two subspecies and they were classified after the fashion proposed by Oguma (1942), as shown in the following table
(1) The chromosome numbers of eight species of Rubus determined by the writer are as follows: R. Wrightii A. Gray 2n=14, R. palmatoides O. Kuntze 2n=14, R. Commersonii Poir. 2n=14, R. ribifolius Sieb. et Zucc. 2n=14, R. Fauriei Lev. et Vnt. 2n=14, R. trifidus Thunb. 2n=14, R. hakonensis Franch. et Sav. 2n=56 and R. pseudo- Sieboldii Makino 2n=56. (2) The somatic chromosomes of the species mentioned above are so small, that it is difficult to determine the karyotypes of each species. As far as my observation has reached, it is only possible to point out the following facts: In somatic cells, R. Fauriei has a pair of satellite chromosomes, R. ribifolius has a pair of chromosomes with the deep constriction on near its end and R. pseudo-Sieboldii has two V-shaped chromosomes, which are the longest among of its chromosomes. (3) R. pseudo-Sieboldii shows in morphological features almost the middle form between R. Buergeri Miq. (2n=56) and R. Sieboldii Blume (2n=28), but its chromosome number is 2n=56, the same number as that of R. Buergeri, and not equal to the sum of the gametic chromosome numbers of both species.
For the purpose of securing the inheritance of the frost resistance and maturity in potato, Solanum demissum L. and S. tuberosum L. were used. S. demissum has 72 somatic chromosomes with normal meiotic division, and S. tuerosubm is usual tetraploid form having 48 somatic chromosomes, but it belongs to the group 1 in which meiosis is very regular. They differ from each other in many characters (Table 1). S. tuberosum matured in late August and is very sensitive to frost, while S. demissum was still green duri g October and it was not injured by the frost or snow of the year on early November which killed S. tuberosum. Crosses between S. demissum and S. tuberosum were carried out. F1 plants were alike in general appearance and were intermediate in external characters as contrasted with their parents. The physiological characters of frost resistance and maturity in F1 plants were also intermediate. Most of the F1 plants did not set selfed seeds, although numerous hand pollinations were made both in the greenhouse and in the experimental field at Sapporo and Kucyan. In 1947 and 1948, however, 674 F2 plants were grown. The results were given in Table 2 and 3. Frost njury was recorded at November 1. As shown in Table 2, F2 plants showed a complete range from no injury to lethal. Maturity records were taken on September 1. At this time S. demissum was still green, while all plants of S. tuberosum were already mature, and F2 plants showed a complete range from mature to green as given in Table 3. It can be seen that the frost resistance and maturity in potato exhibit a incomplete monogenic difference, giving in F2 an approximate ratio of 1:2:1.
Zulueta (1925) reported that four elytral pattern-types were inherited under the mode of “sex-limited inheritance” in the Spanish leaf-beetle, Phytodecta variabilis. The Japanese species, P. rubripennis has no pattern (Fig. 1, A), but P. r. var. plagipennis has a considerable black stripe on each elytron (Fig. 1, B, C). So the writer has crossed between these two varieties with all combinations, to know the law of inheritance. The results obtained are listed in Table 1. From these data, it is no doubt that the stripe in P. r. var. plagipennis is due to a single autosomal dominant gene. Beside this fact, the variations of the elytral color and the width of the black pattern are discussed in this paper.
The present paper deals with the observations on the seasonal spermatogenetic cycle in the testis of a gecko, Hemidactylus flavoviridis, collected in India through the year. Evidence presented indicates that there is no remarkable seasonal variation in the spermatogenetic activity throughout the year. Active spermatogenesis uniformly occurs in every season of the year.
Um. die Geschlechtschromosomen zu erkennen, habe ich in dieser Arbeit 8 Arten von Frullania, einer Gattung von Lebermoos, untersucht. 1) Bei 7 diözischen Arten von Frullania konnte ich zum ersten Male die Geschlechtschromosomen entdecken. Ihre Chromosomenformeln sind wie Tabelle 1. 2) Bei einer sterilen Pflanze von Frullania nodulosa var. nipponica stelle ich die Chromosomenformel 9=7+X1+X2 fest.
The chromosomes of two teleost fishes, Sillago sihama Forskål (Sillaginidae) and Parasilurus asotus Linné (Siluridae), were investigated in male germ cells during the course of spermatogenesis. The results are summarized as follows: 1. The number of chromosomes in Sillago sihama was decided as 48 in diploid in spermatogonia and 24 in haploid in both primary and secondary spermatocytes (Figs. 1-7). 2. The spermatogonium of Parasilurus asotus shows 58 chromosomes at metaphase. The haploid numer is found to be 29 in the first and second divisions (Figs. 8-14). 3. In these two species, the diploid complement is composed of telomitic rodshaped chromosomes slightly varying in their length. 4. In the two cases described above, no particular chromosomes could be detected throughout the course of the meiotic divisions either in shape or behaviour.