The authors have elucidated the biochemical characteristics of each stage of the life cycle of oat plants which were treated under different photoperiodic conditions. As the 1 st report of the series the result of observations of morphological changes will be discussed 1) During the vegetative period, the speed of leaf sprouting was caused to become lower in accord with duration of vegetative period under short day treatment, and when the plant was put under long day treatment from under short day treatment, the speed of leaf sprouting became quicker in accord with passage of time under short day treatment. 2) Number of leaves on the main stem which sprouted during reproductive phase was six, in spite of the length of vegetative period, but number of leaves on the main stem sprouted during vegetative phase increased in response to the length of vegetative period. 3) The internodes which belonged to the six leaves during reproductive phase, mainly elongated during reproductive poriod. These facts suggest that each different sort of leaves of two phases has its own characteristic physiological function relative to growth of oat plant. 4) a) Number of tillerings increased even in reproductive phase when preceding vegetative period was shorter than S_4-teatment . b) The ratio , weight of ears to that of leaves which sprouted during repoductive phase, was smaller as vegetative period was shorter. These above facts show that there occurred an overlapping of the reproductive phase on the vegetative phase. 5) Both of the weight of ears and percentage of weight of ears to that of whole plant; were maximum in two plants of which one was grown under the natural photoperiodic conditions and other was put under long day treatment from the six leaf stage Vegatative and reproductive phases in these plants did not overlap or separate from each other.

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The object of paper is to examine the chemical composition of mud taken from the bottom of river in Kojima polder, and the effects of iron sulfides in the mud on the change of reaction and soluble salts after they are applied to the field. The content of FeS in the fresh mud lies botween 0.025 and 1.491 per cent, and that of FeS_2 lies between 0.197 and 1.089 per cent as S0_3. In most of muds, the original pH values of fresh samples become extremely acid, ranging from pH 2.6 to pH 5.0,after the incubation at 30° under the condition of the moisture content of field capacity for four weeks. Total solids and water soluble sulfates are increased greatly in the incubated samples. It is concluded that the polder mud must be weathered for so sufficient a time as the oxidized products of iron sulfides are washed out by rain water, before it is applied to the field.

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According to the results on the nitrogen fixation studies which have been reported, the following points must be noted. (1) Since the effectiveness of rhizobial strains may be changed according to the kind of host, it must be stressed that any strain of rhizobia should not be called effective or ineffective apart from host. And, therefore, whether or not the classification of rhizobia in artificial media contributes to the grouping of them on the basis of the degree of effectiveness must be discussed in the relation to each host, respectively. (2) The classification of rhizobia in part I is generally accepted from the view of nitrogen fixation, though not without some modifications. The modification does not mean to combine one type with another, but to divide further one type into subtypes. The behavior of strain to nitrate or nitrite seems to be used as a basis for chachterization in some cases. It is desirable to examine which type of strain is effective to each host, respectively. (3) Concerning the finding that the strains of different type are equally effective to some hosts, it is necessary to determine whether similar relation is found even under different conditions. Under the experimental condition some strains (or hosts) are able to symbiose well with wide range of hosts (or strains) . (4) The results on size, number, and distribution of nodules do not always agree with the descriptions which have hitherto been made by some investigators. Numerous small nodules are found over the entire root system in some ineffective associations, while few, but large, nodules are produced in others. The difference in type of nodulation is sometimes evident among the types of rhizobial strains, even when they are all ineff ective. (5) It must be added that there are a few cases in which the rhizobial strains are hardly divided each other in artificial media, despite that they are markedly different in relation to host. But such difficulty is inevitable to a certain extent, because the mechanism of nitrogen fixation, especially the part played by each symbiont, has not yet been clarified.

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Nitorogen fixations of Yellow and Ando soils at Iwatahara, Shizuoka prefecture, were studied, and the results obtained were as follows : A. symbiotic nitrogen fixation of Vigna sesquipedalis 1) Nodules are increased, plant growth is favored, and nitrogen in the plant is increased, by the applications of phosphorus and potassium to these soils. 2) Small application of ammonium sulphate resulted in decrease in nodules and nitrogen, but increase in the yield and the total nitrogen content of the plant. 3) Soil inoculations have remarkable effect on the fixation of nitrogen, but no effect on the nitrogen of the plant. B. Non-Symbiotic nitrogen fixation 1) the nitrogen fixing powers of these soils examined by ASHBY'S medium are poor, especially those of Ando soils are so poor as negligible. 2) The nitrogen fixing powers are increased by the application of CaO to correct soil acidity and the inoculation with germ-carrier soil.

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Elementary analyses of various humic acids were conducted. Humic acids were extractecd by hot dilute alkali from soils and peats which were pretreated by 5%hydrochloric acid or not (of these humic acids the one which was extracted after acid pretreatment was provisionally designated as SrL humic acids and the others, not pretreated, as L humic acids). Humic acids extracted after SIMON'S method were also used (these humic acids were designated as Si humic acids). Elementary composition of humic acids was different with the sources and also changed according to the extraction practices (Table 1,2 and 3). In general, carbon and nitrogen contents of Si hnmic acids were considerably lower than those of L and SrL humic acids. SrL humic acids showed higher carbon and nitrogen contents than those of L humic acids. It was found that elementary composition of L or SrL humic acids varied regularly with their degree of humification. It may be reasonable to suppose that the forming process of humic acid consists of two stages; during the first stage, accumulation of nitrogen in the nitrogen-free basic materials (which might be lignin) takes place, accompanied with the decrease of its carbon and increase of its nitrogen contents. During the second stage, humic acids thus formed are transformed to the deeply colored substances, losing its nitrogen and methoxyl group (Fig. 1 and 2).

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The distribution of radiophosphorus in the various parts of the wheat and sesame plant fertilized with P^<32> at each stages of the growth was investigated. The crops used in this experiments were grown by sand culture. For the measurement of the radioactivity, GEIGER-MULLER counter was used. On comparing the P^<32> content of various parts of the plant, it was found that difference existed according to the time of supply and maximum content was coincident with leaves, tops and grain, whilst in the case of root, the later the supply of P^<32> , the greater the accumulation, as shown in Tables 2,3 and Fig. 1〜4.

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