A few theoretfcal considerations on the efiiciency of seleccion in hybrid populations of sutogamous plants are given in the present paper. l. The proportion of homozygotes in subseqlient hybrid generations, under assumption of twb linked alleles on each chromosome with the recombination value ot, will be computed by the formula (1.04). The dg in that forniula stands for proportion of homozygotes in g segregating generations, and R is the number of chromosome pairs.

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. The experiment on the synthetic variety by short time inbreeding suggsted by JENKlNS M. T. was conducted. 2. Com, biuing ability was tested in So generation by topl and, sib-crosse(combination with original variety). 3. So Plants were divided into four groups : A, B, C, D, throuh the performances of topand sib-crosses. The performances were as follows ; Top-cross Sib-cross A high high B high low C low fow D low high 4. So Plants were selfpollinated and in S0 generation they were crossed within groups, and designated as synthetic varieties A. B, C, and D. respectively. 5. Synthetic variety A, B, C, D and original variety were compared on the yielding ability.In 1949, synthetic D. and in 1950, aynthetic A had significantly high yield, but in 1949, it was dry, and therefore, synthetic D with lesser titllers had high yield. 6. On the basis of performance in 1950, if the two tester"varieties were used, testing the combining ability in So generation was efiicient. but otherwise, Iines with lower combining ability were contained in high class. 7. This phenemenon may be recognized as the action of specific combining ability.

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About the breedirig of self-fertilized: plants, the pedigree culture method by simple crass now has been carried out mainly in Japan, but in foreign countries various plant breeding methods has been practiced. Amomg these methods the bulk method has been especially discussed recently in a colleague of Jap anese plant breeders.. The bulk method that have been prevalent in foreign countries is such a method that almostly any artificial selections are never praceiced except some natural selections untill F₅ oir F₆ generation. When this method will be applied in our rice or wheat breeding, it is supposed that there are many matters to be discussed from the stand point of riews of the recent aspect about the varieties of rice or wheat and the objects of breeding in our country. In the cace of our rice dr wheat breed-ings, when a cetairi ideal type will be immgied to be bred coricerhirg man imcortant characters such disease resistance, grass habit, maturity, quality of grains and yield etc.; mariy allelomorphs more than 10 should be usually concidered everi in carefully chosen matings. In such a case it is almostly impossible to obtain the ideal object by the bulk method withotlt any selections. There-fore, we must carry out a bulk method with selections as strict as possible on individual plants, the majority of which are consisted of heterozygG'Lls plants, as an object in every generations. And when a certain breeding with such a lilraited object will be ceiried out, the bulk method with strict selec-tions in every generations will be strpposed to bc more simple in treatment and more effective than the pedigree culture method.

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The sclerotial diseases d.ue to Corticium Sasaki (SHIRAI) MA, TS. et YA, M. (sclerotiosis or orientai sheath and leaf pot) and Hel, eeintJ."ospor, ium sigmoideum CA.V. var. irregulare CRALEY et TULLIS (sclerotial diseage or irregular stem rpt) are of scrh e second. importance to blast in distribution as well as damage for the rice cul-ture in Japan and Fonnosa. During his stay in Formosa (1944-f48 at Taiwan Agr. Res. Inst., Taipeh), the author studied the resistance of the variety groups native to the different latitudinal regions and the inheritance of resistance to the above-named two diseases in order to get the fundamental knOwledge on the breeding of the resistant rice. The experiments on the varietal resist.ance to Corticium Sasakii wete conducted under glass-house as well as field conditions by means of inoculating the cultured fungus on the rice vari-eties amounting t, o almost two hundreds. The difference of resistance among the variety-groups. was more distincf. when inoculation was made with the adult plants at the booting-heading stage than when with the seedlings. In general, the variety group of the Japanese lowland type was more liable to infection, whereas many of the tropical varieties, especially the native Formosan, were rather resistant notwithstanding their less digestive ability of fertilizers in corilparison to the former. Certain native Formosans are there-fore considered to be suitable for the materials of breeding of the resistant rice.

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The present paper deals with a ecological studies on the soy-bean varieties, collected from Japan, Manchuria, Korea, America and especially on the leading varieties of Japan. The experiments were carried out on the field of the Kqnosti Ekperimental Farm, Agricultural Experiment Station, Ministry of Agriculture and Forestry, during three successive seasons irom 1946 to 1948. The results dbtained are summariied a follows : ( 1 ) In soy-bean varieties, there is a wide variation on the days from germination to blooming. It was found from the experiment of r94:6, in which the varieties were sown at the different planting times that the days from . germination to blooming became shortef when sown late than sown early, although the blooming date was, late, and this shortening due to the late sowing appears to be more remarkable with early varieties than with late varieties. ( 2 ) On the basis of the varietal responses. observed from the late sowing experiment : in 1946 sown at the 8thof May and in 1947 at 10 th of Imay soybean varieties were classfied into five groups from the s'tandpo.int of the days from germination to blooming. ( 3 ) In soy-bean varieties, there is a wide v.ariation: on the days from blooming to ripening, too. On the basis of the result of the experiment a above mean.tiond, soy-bean varieties were further classified into three groups from the standpoint of the days from blooming to ripening. ( 4 ) In soy-bean varieties, there is in soine degree, a correlatiop! between the days from germination to blooming and the days from blooming to ripening. ( 5 ) Taking into consideration the both variete.l responses ; days from germination to blooming and that from blooming to ripening, we attempted to classify soy-bean varieties including 4-92 used as material in past three years into nine ecological types. Those varieties which require short period to reach blooming are 'found in Hokkaido and with the lowering . of the latitude those which require a long pericd make their appearences, while in Kytrhu, they are both of short and long period. ' And, in Hokkaido ' and K;nto distr, icts, those varieties of short ripening period are 'distributing. A vride var-iation in the ripening period was found in varieties grown in Tohoku., Hokuriku and Tosan distric.+s. Thosd varieties from the other districts were of lbng"ripening, period, while the varieties of Kyushu were of short and long ripening period! We discus-sed a reason why these tvpes distribute in respe-ctive districts of Japan.

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1.Observations on artificial 4x-Bellis perennis L. and 4x-Centaurea cyanus L. obtaind through colchicine treatment were described in view of breeding. 2.The chromosome numbers of B.perennis and C.cyanus were confirmed by the auther to be 2n=18 and n=9 for the former and n=12 for the latter, whichi did not accord with the results of Saito(1950) who had reported n=10 for both of them.

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1) In 195d, four tetraploids of Sugi (Cryptomeria; japonica D. DoN) were discovered among l- and 2-year seedlings at forest nursery. 2) In comparison with the diploid, the tetraploids have the fdllowing charactristics : (a) The arrangement oi the tetrapioid stomata band tend to be disordered. (b) The tetraploid needles tend to be thick, twisted and bend at the topend. (c) The tetraplpid stomata size increases about. 30% and the teraploid stomata numbers decrease abaut 40% The tetraploid chromosome number seems to be doubled at the stage Of embryo development or, growing.

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In order to discriminate femalenness and maleness of the silkworm even in early egg stage, an experiment was planned with X-ray treatment to join a fernale deter, mining gene and a normai aliele to white egg color (white-2, 2) by mutuai trans-location between the Wand the tenth chtomosomes. Such translocat:ion night bepected by X-rayin the heterozygols w, females (w./-F, Z/W) in early or mid pupal stage, when the erly prophse of the maturation division of the oocyte is going on. The irradiated females were back crossed to w. males, and all the fenale offspring from such crassing. were tested by crossing them to white and translucent males (w/w2' Z"d/Z"d) of their genetic construction. Among 6523 batches yielded from the same numbers of ferilale parents of BF2 of which genotype-analyses were carried on, only one batch showed an expected type of translocation and it was confirmed by her progeny test. This is the type of translocation that we have expected for this experiment. The frequency and the proba-bility of its appearance were discussed. The high rateo, apearance beyond our expectation muse be noticed.

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The authors had previously published that they could classify the horse blood corpuscules by cattle serum. Thereafter, we have obtained results by heterobaemagglutination of. rabbit blood corpusclues with sheep blood serum. The ro;ain results obtained here may be summarised as follo. w : 1. Sheep blood serum has agglutinins which reat with all rabbit blood corpuscules ( x64-18) and moreover, the authors classiried 4 blood types by absorption-test which were named lo, Loi, L02 and Lol L02' . The group-specifiq substan, ccs which were cl. assfied fonlerly by heterohaemagglutination were made sure with immunization of cocks. 3. Anti-Loi and Anti-LO2 in normal serum exist in the horse, ass and pig sera besides the s. heep serum, but not in other animals. 4. The distributiop; of appearance of each type is similar. and there in no racial tendency, and moreover, we surmised from some tamily-group, of parents and child that Lf0, 1 and L02 were allelo-morph. 5. The agglutinin is not affect, ed at 45'C. 3C mm and becomes weak at 56'C 30 1lin., and mpreover, is entirly destroyd at 60'C.30 inin.. 6. The influence of the preservative upon ag-glutinin is remarkable when. added in greater quan. tity (1/1 /2) consisting of I physiological solution. of salt with phenol of of 1 6 form lin solution of which phenol has a stronger effect. 7. The reaction of this group-specific h.etero-haemagglutination in our research were niost re-markable at more or less 20"C. 8. The nature of the heterohamagglutinogeng in our research is ther mostabil. 9. The group-specefic haemagglutinin in our resarch is different frotn pen, haem-agglutinine. 10. ' The group-specific haemagglutinin in our research is different from coldhaemag lutinin.

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The anthocyanin coloration in the stem node of rice is d, eveloped by the action of the complementary effeof of the three genes C, Sp and pn, that is : C : the gene responsible for the formation of chromogenic substance ; 'Sp : the gene which converts the chromogenic substance to anthocyanin ; Pn : the gene responsible for spreading the anthocyanin pigments to the sterp node. The co-existence of the genes C and. Sp gives anthocyanin coloration at the apiculus as well as empty glumes in the spikelet. Each af, these genes comprises respectively of the following multiple alleles, the dorpinance runing in the given order, namely : CB > CBp > Cn >, c and Sp > Spd > sp The expression of anthocyanin color characters of apiculus is determined .according to the mode of combinations between the above trienti ?? ned ge-nes. Thtis the stem node color is found in plants which have spikelets with some arithocyanin co-loration, no plants with green zipiculus but colored, stem node being able to find. Put it into other words the Pn is effective only when it acts toge-ther with both genes of C arie Sp. In the crossing ekperiments of ours, the gehe Pn was found to be linked to the gene Sp, the recombination value being counted roughly to be 18 per cent. Saying as to the segregation of 1055 F₂ plan, ts, the total of the three crosses, 721 had purple apiculus and colored node (C Sp Pn):, 89 had purD. Ie apiculus and green node (C Sp pn), 82 had red apiculus and colored node (C Spd 'pn) and 163 had red apiculus and green nod (C Spd pn). These ntimbere aree well with the calcula-ted ratio of 323 : 40 : 40:81 which is based on the gametic ratio of 4. 5 : I : I : 4.5, showing the existence of linkage relation between the genes Pn and Sp.

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Since 1937, breeding works on wrater-melon have been carried out at the Nara Agricultural Ex periment Station. One of the most significant results obtained was the ascertainment in the practical use of F1 hybrid vigor between commercial varieties. The Sin-asahi, as this new melon was called in 1940, is. an F1 hybrid between Asahiyamato and Miyako No. 1. Owing to the world war, however, this new variety was not put into practical cultivation. In, 1950, the authors recognized again that +, his water-melon shows such super.ior qualities of first hybyid generation as incr6ased in yield, vigor, earliness, ld resistance to diseases. The fruit is round and has refined green stripes on a light green baqkground. The flesh is bright scarlet and very sweet. The skin of fruit is comparatively hard as a cohsequence it can stand well transportation and storing.

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