1. In this work, the writers intend to make clear the modes of quantitative inheritance in main crops from the view point of breeding.For this object, ' a part of the hybrids of " NA BESHIMA" x "KAlRYO-AIKOKUHEN-DAIKO-KUGATA" was used namely-the F₅-F₇ generations from the F4No. 70 and F4No. 106 of the hlybrid. The total numbers of lines and individuals are 27.2 and 15244 respectively. 2. The conditions of cultivation are the same as those already described in the previous reports (SYAKUDO, 1948), excepting the dates of sowing and transplantation. The date of heading indicates the first day when the top of one ear emerged from the leaf-sheath. And the heading duration indicates the nunrber of days from sowing to.heading. 3. As the result of the progeny test, the genes E₁, E₂ and the dwarfish gene D₁ determine the heading duration accumulatively. Ptobably the effect of E₁ may be of perfect dominance, while that of E₂ of inperfect dorrLinance. The gene-interactions are recognized b.etween E₁ and E₂, though their qualifying effects are neither additive nor multiplicative. 4. The qualifying values of the genes which indicate the medium type of heading duration are the same in the two years, but those of th.e genes which indicate the early and the late typ, es are not the same respectively. These differences seeni to be due to the difference of the daily mean temperature during the heading of each type. 5. The gene El for the heading duration seems to be the same as the gerne H₂ for the culm height (SYAKUDO, et.all. 1952-b), while the gene E₂ for the heading duration has no effect to the culm height.

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The possibility of prediction of dairy performance in virgin goats by means of the induced lactation by the injection with the synthetic estrogen was studied by examining the relation between induced lactation and normal lactation. Sixteen virgin goatlings adopted randomly were injected subcutaneously with 0.25mg. diethylstilbestrol ("Euvestin")in oil once daily for 20 days in spring, aird the induced lactation was examined. Then, the nornal lactation following to pregnancy and parturition in the next year was also examined. Further, the relation of dairy characters between these two lactations vyas investigated. The examined dairy characters were as such, maximum daily yield (in average 5 of days), maximum period, duration of lactation, total milk yield, average milk yield, coefficient of regression line at rapid increase and average butter fat percentage. To regret, the survived goats at the terminal of the ekamination fell to six by the disasterous death and accidents, so the obtained figures were examined on the significance in scarce cases. Further, the comparison of mammary gland between these two lactations at the height of milk secretion was carried out histologically by removing the small block of the giand. Results obtained here are briefly summarized as follows.

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1. In all possible combinations of single cross between n parent lines as shown in Table 1, the mathematical model of F₁ hybrid is as follows ;

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In order to testing the varietal resistance of the paddy-rice to the bacterial leaf-blights, 142 varieties contained the inlanided typical varieties were examined during three years from 1950 in the ever-occurring areas of those disease. The upper three leaves in each variety were researched and its bacterial resistance was resumed. In result, all examinated varieties took bacterial leaf-blight and the complete resistant varieties were not iound and a slight difference of resistance appeared in the varieties testod in the early stage which become evidently by and by in the progress of growth. When water was poured over the plant's head to be took bacterial leaf-blight in the seedling stage on the bed, the treatment was not effectively, sothat the degree of bacterial leaf-blights in the ever-occurring areas may be resulted by storm in autumn. It is very difficult make to get ill similarily in these areas in the test, it seems a good idea to directly confounded the degree of bacterial resistance in every variety. The strong 8 varieties, sub-strong 12 ones, sub-weak ll ones and weakest 7 ones were found in this experiment. A Iarge number of varieties were examined, but: the superior resistant varieties were very few, therefore it is important to breed the superior resistant varieties.

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1. The aim of the present study is to gain informations as to how the varieties of rice plant are to be divided into groups. More than one hundred and twenty varieties were taken out nearly randomly from numerous varieties collected from various districts of Eastern Asia, and were observed with respect to various characters. On the ground of those results, discontinuity of varietal variation, intervarietal correlations and tendencies in character combination wete investigated. 2. Besides phenol reaction which is known to be determined by a single genic change, several characters as follows which would be effected by a number of genes, i.e. potassium chlorate resistance, Iow temperature resistance, drought resistance and the length of awn, showed discontinuous intervarietal variations, and in regard to each of these characters the used varieties seemd to be divisible into two groups. The number of days of germination and the weight of grain shedding seemed to some extent to be discontinuous. The degree of destruction of endosperm by caustic potash solution (alkali-test), the number of days of endosperm maturation, the length-width ratio of unhulled grain, the length of first and second internodes grown in a dark place, showed continuous appearences of varietal variation. 3. In a gre;ater part of these characters, except the lerigth-width tatio of unhulled rice and the length of frst and second internodes, the varieties positive in phenol reaction and the negative ones showed characteristics contrary to each other. And intimate intervarietal correlations were found between these characters.

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Pedigrea and plant numbers of the artificially indnced napus plants, which have been bred by selfing since 1946 in the progenies of COO (cf. the previous paper I, 1950), are shown in Table 1. The fertility of C-type (chinese cabbage type) plants may be disturbed by the irregular meiosis. That is to say, the fruit setting of 2n=38 plants among them are fairly good and the leaves of the plants are just like those of O-type (forage rape type) or N-type (oil rape type) . On the contrary, the 2n=40, 41 etc. plants have low fertility and their leaves are like those C-type(cf.Table 5). The fertility of O- and N-type plants may be disturbed by an interaction of self, -incompatible genes rather than the irregular meiosis. The O-type plants have already been utilized as a new type of forage rape, but the N-type plant will be worth of consideration as crops when the complete self-compatible plant is found in the progenies.

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The transmlssion of the effect of vernalization in Japanese radish plants (Raphanus sativeis L. var. raphanistroides Makino, Race "Minowase ") was studied by grafting the vernalized cion on the untreated stock and vice versa. The treatment of about 5 days in 5'C was enough for vernalization of this plant, yet usually the material was treated 15-20 days in 5"C in this ex periment. Several variations in methods grafting together the vernalized and untreated young seedlings were used, but it was not succeeded to induce an untreated part to produce bolters and flowers, however, sometimes "preudo-bolting " was seen in an untreated part. On the other hand, when an untreated young: plant was grafted on a mature plant (naturally or artificially vernalized, and already flowering), the former was adcelerated to flower. From these experiments, it will be assumed that the stimulus of vernalization in the young plant is different quantitatively or qualitatively fronl that in the mature plant ; seemingiy the latter (the transmissible stimulus) must be belonged in the category of "fiongen "

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The present report deals with theoretical considerations on a possible loss of vigor in an improved allogamous plant variety during a period of seve. ral generations of breeding for seed production. For instance, the seed growers of leaf- or root-vegetables in Japan usually select only a very small number of mother-plants for propagation, the selection being based on a few char.a.cteristics of commercial value, without paying any attention to the heterotic vigor. concerning either the productivity or some injury -resi, stance of the variety. Under such circumstances, it should be expected that a random drift of allelic genes or chromosomes will soon occur, resulting in a loss of heterotic vigor.

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Seedlings of 37 varieties or strains of 9 species of Hordeum, 50 varieties or strains of 16 species of Triticum, 34 varieties or strains of 17 species of Aegilops., 4 species of Elymus, 9 species of Agropyron, Haynaldia villosa, Lolium remotum, Avena sativa, 5 selections of Aegilotricum and 2 selections of Agrotticum were tested for susceptibility to Puccinia Hordei OTTH. The experimental results are sulnmarized as follows : -1. A-mong the 9 = species of Hordeum, (37 varieties or strains) Hordeum agrlocrithon. H. distichum var. tridax, H. sponianeum and H. vulgare were susceptible ; while Hordeum murinum. H. nodosum, H. pusillum, H. Gussoneanum and H. jubatum were highly resistant or immune. 2. A11 of the tested -16 species of Triticum, 17 species of Aegilops, 9 species of Agropyron, 4 species of Elymus, Havnaldia villosa, Lolium remotum, Aveud sativa, 5 selections of Aegilotricunl and 2 selections of Agrotricum were highly resistant or immune.

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