The comparative studiets have been m, ade as to the tyrosinase activity, tyrosine, phenolic substances in the blood and integumenf. making use of sdm, e m, arking m, utants to ascertain the differences of melanin formation in the silkworm larvae. The investigation has been carried out from the 4-tn instar laryal stage to the pupal ones used the strains of Striped (p), Zebra (Ze), Moricaud(pM), Multilular (L), dilute black (bd) and lemon yellow (lem) comparing with ndrm, al (p or +P) segregated from the same batches. Warburg/s manom, eter was used for the measurement of tyrosinase activity making use of Brenzcatechin and p-Cresol as the substrates . The tyrosinase activities in the integum, ents of ps, p, i, Ze and bd were higher than normal . at before and during the m.o.ulting periods, and also ps showed higher level of tyrosinase concentration than norm, al at the 5 th age, but no sighificant difference was observed between L, Iem, and norm, al . On the other hand we could hardly recognize the differences of tyrosinase activity in the blood in all the strains at every stages. ' The tyrosinase activity of the integurri!, eht of black pigmental region was higher than that of nohe pi-g:nental one in Zebra m, arking during the rooultina period; but its. differe.nce was not clear at the 5 th age. Tyrosine and som, e phenolic substances were nea-sured making use of the above lrentioned strains by the reaction of Millon, 'xanthoprotei, n, am, m, oniacal silver nitrate, ferric chloride reactions. As for the aminoacids, the discrim, ination by paper partition chro-m, atography was adopted . No differences of the quantity of chromogen have been recognized between the norm, al and marking individuals in the blood and integunent. From these results we can conclude that one of the factor determ, ining the difference of the formation of marking pign), ent is the difference of tyrosinase activity in the integumnt befote and duririg the moulting period.

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An attem, pt has been m, ade to analyse the variance 'of grain yield on Fl plant and of endosperm-germ ratio in 24 inbred lines and its hybrids in maize. The following conclusions were obtained from the data obtained. 1 ) . The increase of endosperm-germ ratio through fertilization by forelgn pollen was recognized pnly in few special - inbred lines, and not signifieant in m, ost of them... 2). In the both cases, grain yield on Fl plant and endosderm-germ ratio, it may be assum., ed that the heterosis should be appeared as a result of the. cum, ulative action of any two giveh alleles among genes of a m, ultiple allelomorphic series as suggested already by East (1936). 3). There seems ta be a barely significant correlation (r=0. 3) between the increases of endosperrD.-gerrc' ratio and of tlle abili ?? y of grain-yieldihg in hybred strain, becuse of the existence of a com, mon regres-sion within all of inbred lines. 4-). A fact that any one of inbred lines differes si*anificantly from the another on the am, ount of re-gression in the grain yield on F, plant and the endo-sperm, *germ ratio may be demonstrated as a result of possible combination between two independent factors, one for the a*fain yield and another for the endosperm-germ, rati.o. 5). The cause that the prediction of grain yielding ability for each inbred line by meahs of the lri:easure-ment on F1 plant of specific grain characters such s endosperm, -gorm ratio is in difficulty, was discussed

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(1) Fertility of the 1st generation of the colchicine induced a, utotetrahaploid chinese dabbage was very low, ahd number of seeds per one pod in the case of 'selfing, mutual 'pollihation, and open pollination were in average 2. I, 5.3 and 6.3 respectively. . (2) In the 2nd generation, 55 of 677 plants was very poor in fertility and 3. 55 6 (24) was some good of which seeds numbers per pod were 13.94. The best stock No. 32 produced 48 cc seeds and found 16 seeds in their pod. (3) The next generation (1950) of best fertile stoc.k revealed much effect of selection in fertilities a.nd 14., 4 seeds per pod were obtained in every popul-ation. (4) In the 4 th generation seeds number per pbd inreased to 15.8, and reached to economic seed productipn. (5) The placeltal numbers of pod in the 2x and 4x plants were 31.74 and 30.68 respectively and their difference was quite insigniftcant. Sb the poor fertility of 4x plants means the :dec rease of seeds grovyn' ih ppd. (6) On the observation of fertility in self and open pollination of 30 plants, seeds numbers per pod were 15. 4 and 12. 3 respectively which presented only 3. I difference in numbers, (7) Fertility in self ollination and selfing without artificial pollination were also tested and seeds numbers were 13. and 11, 3 respeqtively which difference was quite insignificant. " (8) As the fertility was prdgressed in the progeni-es, was prov, ed that self fertile ability was improyed accordingly and self incompatibility became inactive

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1. To make clear ecologicai characteristics of auto-tetraploid in rice plant, diploid plants of six varieties and the auto-tetraploid ones induced artificially from each of them were used. They were exposed to various environmental conditions, i. e. natural conditions, short day, Ioilg day, high Lem-perature, early sowing, and iate sowing. Gtowth, date of heading, and fertility were investigated to corxipare the tetraploids with the diploids. 2. There was a tendency that tetraploids were. superior to diploids in the elongation of their heiaht from tillering stage to the booting stage. But as fbr the height of plant after he.ding.", the tetraploid were c, .earfy lower than diploids. The cause of this seems to lie in the fact that the d.iploids are very superior to the tetraploids in the length of the first interriode Sust Jender the ear. 3. In bomparison with diploids, the date of heading of the tetraploids was little later or nearly equal in the Japanese late varieties. This tehdency was more clear in Java N0.28. On the contrary Aikoku (middle variety) and P.hiiippine No. 5, were hastened. 4. Between the diploid and tetraploid of Philippine No. 5, there was a difference in photoperiodic resonse. The heading of the tetraploids was earlier than the diploids in aH the other treatments except short day treatment in which the former was later than the latter. Ear formatiori of diploids did not occur under the long day condition but in the tetra-plaids, it was perfectly indifferent to this condition. 5. These-facts will furnish same new valuable data on the problems of adaptation and geographical distribution of polyploid plants.

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I. A rice variety Rikuu-No. 132, which is cultivated today in Tanegashima Kytishu district, was introduced ab. out ten or m, ore years ago from Tohoku district, where it was bred and is commonly cultivated. The environm, ental conditions in Tanegashima are markedly differ froro, that in Tohoku district, and for thls reason, it is said that Rikuu-No. 132 in Ta-negashima seem.s to have some differetrt characteristics after the production of many gonerations., It is very im, portant and interesting problem, from genecological point of view that to ascertain whether any variation have been occured in charactefs of the produced in Tanegashima Rikuu-No. 132, and whether sclch variation is heritable one or hot, if it is so. 2. In order to make clear the question above mentioned, several investigations were undertaken and have been conducted at the Tohoku Agricultural Experiment Station in cooperation with the Tanegash-ip2a Agricultural Experiment Station. The report dealts with the studies in 1949 and 1950 at the Tohoku Agricultural Experiment Station. 3 . Although there is the variations of many characters between the variety, Rikuu-No. 32 in Tanega-shima and that in Tohoku district, it seem, s ta be the fractuation which is ;lot affect the next generation. 4. It seemed to be difiicult to distingfuish that the Tanegashim, a Rikuu-No: 132 from the Tohoku Rikuu-No. 132 as a differential ecotype.

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In order to clarify of tendehcy of the varietal resistance of riqe to the ' bakanae ' disease (Gibberella Fujikuroi (SAW.) WR.), the author studied the resistance of the different varieties with almost two hundreds. native in the different latitudinal r.egions in Asia. In the first time, some preliminary experi-ments Were undertaken on the reaction of rice varieties to the different strains of the fungus as well as different methods of inoculation . ' S0. far as the four strains of the causal fungus employed in the :present exptrirnents are con.cerned, the reactions of several different varieties ta these different strains were almost parallel . The varietal reactions to the different methods of inoculation were as follows. ( 1 ) When the sterilized seeds were immersed in the conidial suspension just before sowing for inspecting the resistance of the germinated seedlings to the ihvasion of the fungus, the varietal difference resulted as the different grades of abnormal elongation and blight of the seedlings. ( ) When the plants at the tillering stage were injected with the conidial ' slspension in the basal part bf stems in order ta insp6ct the resistance of the internal tissue of plants, the different varieties showed the different grades of abnormal elongation and blight followed by mouldiness due to sporodochia formation.' ( 3 ) In the case of spraying with conidial suspen-sion on the panicles at one day after blooming in ordef to know the difference of resistance of the yo -ung lernma and palea to the invasion of the fngus, varietal difference resulted as the grade of discolora -tion and mouldniess of the grains. B iochemical Jour. Imp.

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In this paper the author report the results of breeding process and observat.ions on the induced autotetraploid soybean by the dropping method with colchicine lanolin mixture: 4 varieties belonging to two ecdlogical types, that is surnmer and autumn types were tested. The reasaent of 0.2and 0.4% was dropiped on the ' growing p, aint of young soybcan plants just after the ovate leaves had opened by spait twice a day during one dr two days. Stopped their growth for a time, but soon after dark green irrogular shaped or teratol-ogical foliages appeared Although many of th' trea-ted plants died out, 5 seeds for surnmer type and 214 seeds for autumn type were harvested. In the next generation 19 tetraploid plants belong-ing to two autumn varieties were confrro, ed by the size of pollen grains and other morphological characters. This number of palyploid plants correspond to 30% for the reared lines and 13% for the sowed 'seeds. In the second generation, 18 Iines out of 19 were confirmed to be tetraploid by chromosome counting and other morphological characters. The chromosome number at diakinesis and first metaphase varied from 26 to 40 according ?? o the ' number of teiravalent chromosomes which ranged fron; O to 14, a.nd 40 chromosomes were counted witout exception in the figures of first anaphase atid second division . 80 chromosomes were obseived- in root tip cells from germinating seeds. Comparisons between diploid and tetraploid plants for tw.o autunn type varieties were tabulated in table 6 about the following characters, namly date of first fiower, time of maturity, total: plant height, number*of node, num, ber of pods per plant, nunl;ber of seeds per plant, fertility (no. of seeds per ovules), diameter of perfect pollen grain, Iength and width of stomatal cell, number of stolnata per unit area, Ieaf index bf 9 th and I O th foliage leaves, mean weight of one seeds, Iength and width of seed, seed shape index and, row protein content. Furthermore it was dscussed ftom the plant bree-ding standpoint about the method of colchicine treat-ment, and the necessity of selection to obtain the constant tetraploid line.

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1) The fertility of a tetraploid variety of rice was observed to be 70 per cent in pollen g'rains and 0-27 per cent in seed setting, showing lower fertility as compar.ed with the diploids where fertile pollen grains amout to 95 per cent and the percentage of, seed setting is 50-70 in number. 2) The tetraploid variety sets in many cases shrinked seeds which fail-to bring themselves to a successful development. 3) The tetraploid variety can be earlier in the ear han in that of the diploids when the short day treatment carried out. 4) Irs the tetraploid variety, uni-, bi-, tri- and quardri-valent chromosomes, are found in the rD:eiotic metaphase, the number of the quadrivalent chromo-somes being countd to be 10 in most ca, ses. Some irregularities aS to the behaviQr of chromosomes are fyequently observed . 5) As to the cause of sterility in the tetraploid variety, 'it may be pointed out the fact that, so far as these ' investigations go, 15-20 per cent of sterility is due to deformed garnete, 15 per ceint being du to env. ironmental disturbances ar;d 50 per cent ovyed to zygotic sterility. 6) The continuaus selection for three years for obtaining a teitraploid strain which hs high degree of fertility gives no effective results, and shows that the degree of fertility remarkably fluctuates year by year even in the individuals of the s'me strain.

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KAWAKAMI J, found diploid twins (2ni2 n) aruong F₂ generation of hybrids in wheat in 1933 and 1934. Genetical constitutions of tbese twins were studied experimentally and the numbers of twins which have different constitution were calculated. HATAMURA M. co-oiperated with:him explainihg statistically the mechanism of occurrence. of these twins: The authors postulate the following m:echanism : (1) In both of the male and female gametes of F₁ hybrids which will produce twins, domi hant genes studied are fundtional just like they have been' in the ratio of p, '(1-p) agaainst recessive ones by some reason or others. ( 2 ) In the embryo sac, three nuclei, an egg nucleus and probably two synergids, are able to be fertilized respectively by one nucleus o.f male ga.metes penetrated therein, producing at most three zygotes . These three zygotes combine' independently, resulting in 2n individua.Is, 2 n-2 n twins or 2 n-2 n-2 n triplets. ( 3 ) Two nuclei of the male gamete which may penetrate flrst into the embryo sac will fertilize two of the available femaie nuclei. One nucleus of another n), ale gamete follawing will fertiliz6 the remaining one available fem, ale nucleus . Probability, p that the gamete contains the func tional dominant ene was estimated by the maximum likelihood method . Applying this p, theoretical numbers of 2 n-2 n twins which have different genetical constitutions were calculaed . x2LTests did not provide eyidenc that the hypothesis above mentidned should be rejected .

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