A new case of incompatibility observed in, a variety of cabbage, "Summer". Brassica oJeracea L., is reported in this paper. Self and mutual crosses in every direction among 5 plants were made. These 5 plants numbered as l, 2, 3, 4 and 5, were obviously self incompatible giving only very few seeds on selfing. They proved to form 3 intrasterile groups, A (1), B (2 and 4) and C (3 and 5), whose relationships 'are shown: in the upper left part of Table I and Fig. 1 The incdmpatibility behaviors of the progenies obtained from selfing can be reviewed also in Table 1. Those of the progenies originated from mutual crosses are shown in Table 2. Discussions were made to the effect that. none of the hypotheses posturated hitherto by several workers could explain the results here obtained. Only GERSTEL.'s hypothesis, which in one hand assumes epistacy among 'oppositional factors and sporophytic reaction in the other, seems to be partly applicable. It can explain therelationships amang the 3 groups, but it fails to make out the behaviors of the progenies. From the obvious secondary polyploid nature of the cabbage genome the authors have deviced a new scheme of tetraploid o, ppositional factor constitutions (see Fig. 2). This not only allows the existence of the 3 groups, but alsa can explain the incompatibility phenomena displayed by the prqgenies fairly well. However, it fails also to give full explanation of the facts.

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The aulthor compared several quantitative chairacters of the silkworhl between parrents and F₁ hybrids which were reared in Autumn, in order to analyse a real effect of heterosis. The following signs are used to simplyfy the mention, for the work; D is representing the, <lifference of quantitative values of the parents, M the mean value of the parents, so called mid parents value, and 8 the effect of heterosis e, i, F₁ -M . Heterosis of several characters is similariy with each other, so at present the author describes some typical characters for example the percentage of hatching eggs total cdcoon weight, Iength of fibre and size of fibre. In general, the results, of comparison are as follows:

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l) Four varieties of tobacco plants, "Nambu" (early flowering type), "Slate s Gold Dollar" (rather early), "Brrght Yellow" (medrum) and "T.1.-448A"(late) were compared in the grovJtll and development under combined conditions of ternperature and day-length. 2) Four plots were prepared i. Low temperature (20'-10'C), Sh.ort day (8hr. ) ?? ?? S ii. Low temperature ( // ), Long day (1ighting through night) ?? ?? 1 iii. High temperature (30'-20C) Short day (8 hr. ) ?? ?? ?? ?? ?? s rv Hrgh temperature ( // ) Long day (lighting throuh night ?? ?? 1 3) At the early stage the growth were generally vigorous in the plot H1, but plot Hs were lately superior to the plot H1.

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On the use of advanced generation hybrides as parents of double cross seed corn, a few investigators found that double crosses between F₁, F₂ or F₃ generations of single crosses produced essentially similar yields. The authbrs have inve-stigated this problem from the standpoint of seed production. The materials used in the experiment were single crosses, B 8XA 151, WF9 XM 14 and these parent inbred lines. In 1951, seeds of four inbred lines, two F₁ hybrids, two F₂ hybrids and four back-crosses were harvested.In 1952, these seeds were planted on field with three replications. Each replicati6n contained four groups and each group consisted. of inbred lines, F₁ hybrids, F₂ hybrids and back-crosses, respectively. Groups were arranged at random in replications.The results obtained as follows :-

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The luffa (Luffa cylindrica ROEMER.) is a wellknown sponge gourd grown in oriental regions.The young fruits pickled are eaten rarely for food and the dried pulp fibre of matured fruits is widely used for industriatl materials. In 1949 new tetraploid plants were created by colchicine treatment and then triploid ones were obtained by crossing between this induced tetraploid and the original diploid. Tetraploid luffa has merits of distinctly thicker lea.ves and stems, Iarger flowers and seeds, and, especially, strbnger pulp fibre of matured fruits than the common diploid. Regard to purity of the strain, however, the tetraploid is much inferior to diploid due to, extreme segregation of genetic characters among individual plants. And a most of them are endowed with too late rTiaturing habit and much lowered seed productability to thrive in our mild temperate regions. Triploid plants bear generally srnaller fruits and have a smail amount of fertile seeds which are ascertained afterwards to be "tetraploid" throug'h progeny testixig of' the next year. At any rate, we may be able toget, in future, the earliest useful tetraploid strain selected which will have larger flowers and stronger pulp fibre than the common luffa ones

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1. The fertility of the Edgeworthia fJapyrffera, which had been considered as selfsterile, was tested in the fQllowing way. a) Self pollinatiation was conducted with 2 different varieties, namely, "Kochl shu" and "Shizuoka-shu. " b) Both cross pollihation among the same variety and intra-specific, pollination bctween 2 different varieties, were darried out. Thus the relative fertility of each of the above mentioned groups was tested. 2. As the result of the test, it was found out that both of the above 2 varieties are sterile due to their self incompatibilities. 3. It may be ascribable to the cross pollination among the same variety that "Shizuokashu" has a good fruitsetting in the plantation. 4. "Kochi-shu" seldom bears fruit though itblooms. This is probably due to the fact that this is a variety of asexual propagation by suckers. Therfore, though cros pollination is made, the tre-es belong to the same clone and the result is sterility as in the case of self po1lination. 5. Intra-specifc pollination such as ("Kochishu" x "Smzuoka hu " "Shl'uoka shu" x "Kochi-shu") always results in good fr'ditsetting. But as "Kochi shu" blooms earlier than" Shl u oka-shu", there is little c'nance of a crossing comirg out though their plantations may be closs to each other. As a matter of course, therfore, their fertility is very low.

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These experiments have been carried out to clarify the mechanism of the variation of flower colour in Dahlia, applying qualitative and quantitative analysis of their pigments with paper chlomatography. The results obtained after examination of 101 strains are summerized as foilows : 1). Two anthocyanins and two flavonoids are detected and each of them is decided as pelargonin, cyanin, apiin and butein respectively. Pale red strains generally contain pelargonin, but dark red strains and blue strains have pelargonin and complex-salt of cyanin. Yellow pigment in Dahlia are not apigenin or butein, and it is probablly due to carotene, so that the effect of flavon()ids to flower colour may be thought to be neglected in this case. In general, increasiTrg the content of pigment makes flower colour darker . 2). All the strains are divided in nine ciasses from theirc onstitution of pigments and four genes P, C, A and B, each corresponds to the presence of pelargonin, cyanin, apiinf and butein, are considered genetically. Name of classes, constitution of their pigments, genotype and:i number of strains belong to each class are given in the following table.

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1. This experiment is one of the studies in which the authors intended to make clear the occurrence and mechanism of competition among genotypicaliy different plants. Five barley varieties (Table 1) were sown separately and mixed together in a randomized bfock design with three replications in the field experiment. Additionally, each variety was grown in pots to find. intervarietal difference of root development. The young plants of the varieties were measured in respect to their assimilative activity by the weighing method or the electroconductivity method (Fig.3), The intervarietal difference of top weight and number of tillers or heads was significant in the mixed 'plot, though not in the separate plot, while in other characters the difference was little in degree between the two sowing methods (Table 2 and 3). Such warp of normal pheno types of the variable characters, which seemed to be caused by the comp.etition among the varietie, s, occurred in the early growth stage and the variation became enlarged as the plants gew (Table 4). At the young stage the varieties were clearly different in their physiological and morphological characteristics such as assimilative activity, plant height, root growth and recumbence-habit. These genotypical differences seemed to act as an ihternal factor upon the occilrrence of competition (Table 6-11).

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With the aim of transferring the leaf rust resistance of Triticum Timopheevi to common wheat, a cross was made between them by using the former species as female parent, and from 2 cross combinations 9 mature F₁ plants were obtairied. In the root-tip cells of all F₁ plants, the number of somatic chromosomes was confirmed to be 35, which cor.responds to the sum of reduc, ed numbers of their parents (T. Timopheevi (n= l 4) +T.vulgare(n = 21 ) = 35) . At MI in meiosis of PMC's of these F₁ plants, far more univalents were observed than in the usual wheat pentaploid hybrids with Emmer, group, and correspondingly the number of bivalents to be inet with has been decreased. Some multivalents were often observed up to quinquivalent, above all, trivalent being frequently met with. The results obtained are given in Table 2 and 3.Laggards and bridges were frequently observed in anaphase of both 1st and 2nd divisions. Dyads or polyads were not observed, but pollen tetrads normal in shape with many micronuclei were formed considerably frequent. The highest number of micronuclei contained in the monospore of a pollen tetrad is 5, the mode being in I in F₁-a. O in F₁-b.

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1. In the present reseach were studied the fertility and germination of the seeds of F2 piants, and the external characters, fertility and somatic chromosomes of F₃ plants raised from T. turgidum (n=14) and S. cerea!e (n=7). 2. 17 individuals of 42 F₂ plants were fertile, 5 individuals of them having 2n=41 chromosomes and the remaining 12 individuals having 2n=42 chromosomes (Table 1). 3. The fertility for the number of spikelets of the F2 plants having 2n=41 chromosomes appears to vary from 0.54 to 20.88 percent, and that for the case of those having 2n=42 chr.omosomes from 3.0 to 50.56 percent. In other words, in the former case 92 grains of seed were obtained from 690 spikelets and in the latter 555 grains from 1725 spikelets, and the fertility for the number Of spikelets corresponds to 13. 33 and 32..12 percent respectively, the latter value being 2.4 times than the former one. 4. That the fertility is low as mentioned above seems due to the fact that these hybrids are intergeneric and that the generations they passed are very few. As a consequence, the hybrids show irregularity in meiosis, generally resulting poor fertile power in the gametes. 5. 76 of 92 grains of seed obtained from F₂ plants having 2n=41 chromosomes and 345 of 555 grains of seed obtained from those of having 2n =42 chromosomes were sown in pots and in the former case 30 F8 plants, in the latter one 137 of them were obtained, the percentage of the number of germinated plants fer the number of seed sown being 39. 5 and 39. 7 percent respectively.

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