1. From 120 rice varieties of various districts of Eastern Asia (same to those used in the preceding work), seven varieties were chosen as analysing varieties, and were crossed with each of the 120 to examine which of the analysing varieties would produce fertile hybrids with it. 2. The percentage of good pollen, by which the degree of sterility was measured, was different with the combination of parental varieties and ranged from nearly 100% to 0%. It was not affected so greatly by outer conditions. 3. No difference was found between reciprocal cfosses . 4. Among three varieties A. B and C there were often found such cases where A x B and B x C were fertile and A xC was semi-sterile. 5. By denoting a cross-combination higher or lower than 87. 5 % in good pollen percentage by a plus or minus sign, the reaction type of each variety was represented by a combination of seven signs. Arnong 128 (27) kinds of possible reaction types, 31 kinds were fcund actualiy. Having arranged them according to the number' and position of plus sings, they were dividable into two groups, and in each again into two minor groups (Fig.1). 6. Group I was nearly equivalent to "Continental"l variety group, which had been established inthe preceding work on the ground of a definite tendency in character combination. Groups II a and 11 b seemed to bc comparable to "Tropicai Insular" and "Temperate Insular" variety groups, respectively . 7. Formosan wild rice (Oryza sativa sponetanea var. formosana) was largest in the number of fertile analysing varieties. It was pointed out, after some considerations on the genetical mechanism of the intervarietai hybrid sterility, (refer to OKA 1953) that the above-mentioned classification of reactiol types of hybrid sterility would serve as, a model of the pattern of differentiation of rice varieties .

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Cytological investigation on genus Mentha has ever been imconrpletely carried .out by a few authors (Schilrhoff 1927, Ruttle 1931, Wolf 1938, etc). The present author intends to advance it comprehensivly, and this paper is an initiate report. I. Mlentha rou, sdifolia, (L.) Huds. As material M. roundifolia, subspecies rotuudifolia Briq. was used. which is identified with morphological characters, (Briquet 1895). It has somatic chronosome nunrber oi 24 (Nagao 1941). At Diakinesis, 12 chromosonres as bivalent are observed (Fig. Ia), and simultaneoully occurrence of 1 - 5 quadrivalents are observed (Fig. I b - g) wherein the frequency follows the Polssons' distribution (x=1.530) (Table 1. Fig. 3). At I-M. 12 chromosomes as bivalent are regularly dispersed (Fig. 4-A) and l-6 secondary association's figures of two bivaients are also observed (Fig. 4 B-M), showing frequency of binomial distribution: (0.468+0.532)G (Tabie 2. Fig. 5).

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The authors reported previously that the inheritance of a variegated strain in rice plays due to mutable plastids. Further investigations of some lines were continued after generations, with the results mentioned below. ( 1 ) The reciprocal crosses were made among common green rice, variegated strain in question, ajo:d green, and yellow lines from the var.iegated one. Thus F₁ and F₂ genefations were investigated, and all of those behaved as maternal inheritance (Tab. 1). Then( 2 ) three special variegated lines from the original variegated strain were tested (Tab. 2) and they were idehtifiod on the basis of the occurrence of albinotic and mosaic seedlings as well as the degree of variegation and developmental feature of it. M )reover ( 3 ) a mutated line showing yellowseedlings was obtained (Tab. 3) and this line denoted somewhat lower growth than the usual one (Tab. 4). Gradually the yellow seedlings became green from near the vein of leaf on 5 - 6, days after germination. Thus after 8-9 days they beca-me almost usual green leaves. The feature of yellow seedlings was indistinct in some year. and it seemed to be clear when sowed in a season of low temperature. Therefore ( 4 ) a preliminary test for temperature was done at the stage of gen:nination. In late July, matterials treated for 2 days with water were maintained 3 - 5 days at temperatures 5, lO, 15, 18, 21, 25 and 40 'C respectively. Then they were removed to the usual room (ca. 30'C) and the colour of seedling leaves was obsereved. From this result (Tab. 5) the 2nd leaf of seedlings maintained at 15'C showed yellow clearly, but no reaction around 30'C (room temperature). Moreover, at a temperature as low as 5 'C the change of colour was indistinct, perhaps depending upon almost stoppage of growth. At a high temperature as 40'C, the leaf also became somewhat yellow due to inhibition of chlorophyil formation.

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1) The plant appeared as a bud-mutation in the . taro variety "Yoshihama" has remarkable anthocyan colouring in leaf-stalks, somewhat larger piant growth and later maturity than original. The mutant of "Yamagata-taimo" has much anthocyan colouring in leaf-stalks, somewhat wider leaf-blades and opener plant-form like "Toimo. " These charactere.s are, however, in the limit of variations presented in the group classified by the author. 2) The old varieties of taro ili Japan and China indicate almost same variations except a variety "Ishikawa-wase", and no mutation appeared beyond the limit of group. 3) It is recognized by the s'ystematical study of taro varieties that some quar.Ltitative variations in size of plant and leaf, maturity, quantity of anthocyan and chlorophyil, and shape of tuber are found in the group, but these variations in many cases, might be as occured bud-mutations.

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188 varieties of foreign rice plants and 25 varieties of Japanese upland rice were examined during 3 years from 1940 to 1942 on their response of heading time for day-length and temperature. Most of upland rice seemed to be low sensitive for day-length and temperature. Foreign rice, however, showed wide variability for the degree of basic vegetative growth and sensitibity for daylength and temperature, and it seemed to be closely connected with their geographical distribution. These results tell us that the cultivated riceplants in every region in the world have been selected by the day-length, temperature and agronomical technics in their locatiori during a long: historical time.

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1) A great number of rice varieties were exa-mined in order to clear up how heading time and growth period before heading be changed by delayed seeding. 2) In general, the heading time becomes later in accordance with delayed seeding, but the growth period before heading is shortened. 3) Owing to the extents and types that the growth period before heading is shortened, many varieties were classified finto two groups which correspond to the two groups described in the previous repor, ts, e. g. the Ist group, which is more sensible to higher temperature and less to short day-length, and the 2 nd group, which is less sensitive to higher temperature and more to short day-length concerning ear emergence. 4) Because the heading time is determined by the length of the basic vegetative growth period. and also by the responsibility for temperature and, , dayilength, the relation of heading time between earlier variety and later one in usual cultivation is expected to be reversed sometimes when seeding is delayed so far. 5) On the geographical and local distribution of rice varieties it may be seen that in Japan, varieties belonging to Ist group are mainly cultivated in Hokuriku area and more northern parts, and varieties involved in 2rid group in Kanto area and more southern parts of Japan ; in China, there are two types of varieties, although they are not so clearly distinguished as the case in Japan ; and in South-East-Asia, only varieties of Ist group are dlstributed . 6) The results obtained in this experiment lead to the conclusion that the changes of heading time by delayed seeding and the distribution of varietiein all parts of the world should mainly be determined by the responsipility of rice for temperature and day-length

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Cross pollinations were reciprocally tried between diploid and tetraploid plants of Capsiculee annuum L . var takaleotsume, the latter having been artificially induced 12 years ago (Nlshiyama 1940) . In the cross, 2x( ) x4x( ), 42% of pollinated flowers set normally developed fruits. The reciprocal cross gave a somewhat higher percentage (60 f of 204 pollinated flowers) of fruit setting, but the fruits were usually more or less poorly developed .

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1. In order to increase the efficiency in Cucurbita-cross work, the pollinations in the evening should be considered in comparison with those in the early morning. The author attempted to investigate the ability of pistils and polJen in different ages to effect fruit and seed set, and furthermore to study the physiological changes in pollen and pistils during the time from the evening to the flqwering tiine in the next morning. 2. The ages of flowers, which can be crossed in the evening and in the early morning, are as follows : (a) The ages in the evening : B(the bud stage in the eveni'ng prior to anthesis) ; B , f (the mature condition, that have been artifically kept in the cold condition of about 10'C from the evening to the next fiowerning morning) . (b) The ages in the early morning : b(the early bud stage in the morning of the previous day of, anthesis) . F (the flowering stage) . L (the late stage in the following morning of anthesis) ; F 3. The fruit and seed set in the cross-combinations could be accepted as reliable measure of the fertilizing power of pollen and the receptivity of styles at different ages. 4. In 1951 the percentages of fruit-setting and seed numbers were worse in the cross-combinations of B XB than in those of F xF . The decrease of fruit and seed set in the bud combinations varies with species and varieties. 5. According to fruit setting and seed numbers, the cross-combinations in 1952 are arranged as follows :

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1. In t.he present report, some results of cyto10gical studies on the maturation divison of PMCs of F₂ plants raised between T. compactunm and S. cereale (TCSF2) w.hose chromosomes are 2 n=47, 48, 54 and 55 were described. These TcSF2 plants were obtained in 1943. 2. The group having 2 n=47 chomosomes : At the heterotypic tnetaphase in PMC-s of one plant (TcSF₂-9) of this group, were observed 15-23 bivalents, or l-17 univalents. The frequency of bivalents in the PMC-s was shown in Table I and the case of 19 appeared to be the mode. The nuclear plate showing 43JI +81 = 94 chromosomes was observed at the heterotypic metaphase of PMC (Fig. 6). This case ought to be due to the duplication of the chromosomes of ABD genomes of, T. compactum and R genome of S. cereale. 3. The group having 2 n=48 chromosomes : At the heterotypic metaphase in PMC-s of one plant (TcSFa-8) of this group were observed 17-20 bivalents or 2-14 univalents. The frequency of bivalents in the PMC-s was shown in Table 2 aiid the case of 19 appeared to be the mode. The tetravalents were sometimes obsetved in addition .to bivalents at the heterotypic metaphase but no trivalents was found.

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1. In the present report, some results of cytological studies on the meiosis of PMC' s of F₂ plants raised between T. compactum and S. cereale (TCSF2) whose chromosomes are 2n=56 and 58 were descibed. These TcSF₂ plants were obtained 1943. 2. The group having 2n=56 chromosomes : At the heterotypic metaphase in PMC' s of every plant of this group were observed 22-28 bivalents, or 0-12 univalents (Figs. 4-lO). The frequency of bivalents in the PMC' s was shown in Table 1 and the case of 26II and 27IIappeared to be the mode accarding to individuals at the hetero-typic metaphase but no trivalents was found. Haploldic nuclear plates having 7II+14I or 8II +12I chromosomes, were observed (Figs. 18-20). Moreover, a nuclear plate with 14II +14I chromosomes (what may be ca, 1led hyper-haploidic) was sometimes observed in additijon to the haploidic plate (Fig. 21). The distribution of chromosomes to opposite poles at the anaphase in heterotypic division proceeded nearly normally in most cases, viz., a nuclear plate having 28 chromosomes at the homLotypic metaphase was frequently observed. Among TcSF₂ plants, five individuals having 2n= 56 cllromosomes showed fertility, and the fertility for the spikelet has shown to vary from 12. 90-95.55 percent according to the individuals.

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(1) Studies were made on the germination and storage of the pollen of "Nori-Asa" (Abelmoschus glutino-terdilis), an amphidiploid crop raised between Abel. esculentus and Abel. Manihot, in compariscn with those of its parents. (2) The optimum amounts of agar-agar and succharose in artificial germination were 3-4% and 30-35% tespectively in " Nori-Asa ", 0.5-3%' and 5-30% in esculentus and 7% and 25% in Manihot. The germination % was ca. 90% or more in escelentus and "Nori-Asa ", but only 50-60% in Manihot, so far as the present experirnents are concerned. (3) The optimum temperature for the pollen germ;.nation was 28'-31'C in escgilentus and "Non Asa" and 25'C in Manihol. The relative humidity good for the same was 50-100% in esculentus and 75 100% m Mamhot and " Norl Asa ". The optimum pH valu of the medium for the germination was 4.0-7.0 in esculenllis and 5.6-7.0 in Manthol and "Nori-Asa". Light and darkness showed no effect on the germination of the pollen in the three crops . (4) The elongation of the pollen tube occurred most speedily and its length attained was the longest in esculentus. Manihot was rapider in the tube elongation at the early stage th.an "Nori-Asa "but the le<ngth attained was the shortest of all thle three crops. In " Nori-Asa " the tube elongated slowly at the early stage and quite rapidly later, but the length attained was intermediate of its; parents . ( 5 ) The germination % of the pollen was superior when it was gathered in the following periods : in esculenteis from 6 hours 'previous to and to 10 hours after the flower opening, in Mardhot from the fiower opening to 14 hours after it and in " Nori-Asa " from 2 hours previous to, and to 12 hours after the flower opening. ( 6 ) The best conditions of temperature and relative humidity for the storage of the; pollen were 15'C-22'C and 80% respectively in the three crops. Escelerdus showed the longest period in which the pollen vitality was kept and M22:nihot the next, "Norl Asa" being about the same as in Manthot.

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(1) Studies weie made on the relation between the peroxidase content and germination of seeds in "Nori-Asa", an aro.phidiploid crop raised between Abeleeeoschus esculeletus and Abel. Maleihot, as weil as in the two parent crops of the amphidiploid . (2) In each crop the seeds proclticed in 194-7, 1948, 1949, 1950 and 1951 were stored in the ordinary condition and the seeds produced in 1947 were stored in tlle dry state. The germination tests and the measurement of peroxidase content were made in 1952. (3) The percentage of germination and the amount of peroxidase in the seeds of the three crops clecreased with the lapse of time. The percentage of germination was ca. 0 in the seeds of Manihot prrJduced in 1948, and also in those of esculeletus and "Norl Asa" produced in 1947, while the decrease of the amoun. t of peroxidase does not proc eed in parallel with that of the percentage of germination. Namely in esculentus the amount of peroxidase is kept quite high even in the seeds produced in 1947, and in Maecihot and "Nori-Asa" the decrease of peroxidase content was not foundin the seeds produced before 1949 and 1948 respectively (Fig, 1). (4) The decrease of the amount of peroxidasein the seeds was the lowest in esculeletus, and that of Manihot was the same as that of "Nori-Asa" in the seeds produced in 1949 and later, but in those produced earlier the decrease became lower in Maeeihot than in "Nori-Asa", (5) As for the seeds stored in dry state of the three crops which were produced ih 1947, the gemination was good and the amount of peroxidasewas very high than that, of the seeds stored inthe ordinary condition. Especially tthe amount.1was quite abundant in "Nori-Asa".

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Four highly fertile tetraploid rice plant were sent to the autlllor in the spring of 1951 from Dr. Luong Dirih Cua. Which were produced by colchicine treatment of the highly sterile inter-subspecific hybrid Sekitori (Japonica) xKonanto (Indica). In the same year 341 F₂ plants were reared from these F₁ plants in our experimental farm by the ustial transplanting method. Such important practical characters as date of heading, culm height. panicle length, number of ears per plant, number of spikelet per ear, and percentage of sterillity were recorded about all F₂ plants. Wide variations were observed among these characters as shown in tables 2-7. 100 F₂ piants selected for their larg.e panicle and high fertility were treated in next generation and 360 F₃ plants were selected am-ong 82 Iines. Number of spikelet per ear and percentage of sterility were measured about 3-5 ears perplant of the selected F₃ plants. These results were compared as in table.s 8, 9, 10 and fig. 1, 2 with those of F₂ and autotetraploid plants which were consisted of 30 Iines decended from 5 original stocks discovered by Dr. T. MORlNAGA and E. FUKUSHIMA about 20 years ago. The author discussed briefly from the data obtained that we may be able to hope to use such intersubspecific tetraploid ricefor future breeding materials.

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These experiments were practised during four years from 1949 on the two different "akiochi"paddy-field, about 116 varieties, so as to test the varietal difference of the resistance to the brown spot of paddy-rice, which fall evidently ill in the "akiochi" one. In the result of examination of numbers of brown spot, those size and leaf-wilting degree on the upper three leaves in every variety ; the clear diffeirences fetween those were recognized. Brown spot has a high correlation between years, if those were classified early or late, and there are +0.85090. 0397 correlation in the early group, +0. 6222 0. 0849 correlation in the late one. The correlation between two experimental plots 'aried the climate and the soil condition is +0. 5310 0.0856 and the clear differences to resistance were recognized in the varieties. The sizes of brown spot differ remarkablly from the varieties and have to the very great spot from the smallest one. There are a slight correlation between the spot types and numbers. Also the excellent differences on the leaf-wilting degrees were recognized in the varieties, and a low correlation between those leaf-wilting degrees and spot numbers and the correlation between ones and spot types was not almost recognized, that is the leaf-wilting phenomena on the "akiochi" paddy-field don't occur especialy in relation to the numbers and types of brown spot, but the many sided and secondary phenomena. A few number of blown spots, tne small spot types, and a low degree o. f the leaf-wilting are the desirable varieties ; these low correlation indicafes a possibility of breeding good varieties.

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