The natural population of the Bedford's redbacked vole on the same plot (5-6 acres), in the peat-bog grassland in southern Hokkaido has been studied from the view of its yearly change in size and structure. Field work with concern to the problem was conducted three times under the same trapping design. The first field work (F.W.I) was done at the end of July, 1952,the second (F.W.II) at the end of september, 1952 and the third (F.W.III) at the end of July, 1953. The actual number (M) of marked and the estimated (L) of the unmarked members of the first population may change into the corresponding unknown numbers M' and L', respectively, of the second population. The values of M' and L', as well as of the probability of capture (π, p), in the time of F.W.II can be estimated by the formulae (1) and (2) shown in the text (refer to the literature^(10)). The results of mark-and-release operations are given in Table 1,and the list of actual or estimated numbers of marked and unmarked groups of the population in each of the field works is cited in Table 2,which includes in addition the estimated values of π and p. The histogram summing up the yearly change of the population is indicated in Figure 3. Within two months the population diminished in size to 80% of the original level and replacement in about 70% of the animals occurred. Most of the animals which survived in the plot are recognized as showing their cruising ranges in the localities separated from those of the apparent home ranges or territories which they kept the previous time (Figure 2). In one year the population was reduced to 30% of the original level and a complete replacement of the animals took place. Only three males remained on the plot for ten months from September to July. Thus we may say that the population may undergo a considerable change in size and structure and that the degree of retention of the same home range by an individual seems to be unimportant. The character and cause of the population shift are unknown to us, but it might be a local phenomenon on the plot and its vicinity.

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1) The distribution and the role of hormones in the long term dormant axillary buds of Nandina domestica were investigated by the methods of MOLISCH's warm-bath and WENT's Avena-test and also by the application of paper-chromatography to the separation and identification of hormone substances. 2) Until five years, the germination-and growthpower of the dormant axillary buds of Nandina, gradually reduce in proportion with the elapse of years, but after five years, their powers of germination and growth will be remarkably reduced. 3) All dormant axillary buds of Nandina contain the growth promoting substances, the younger bud containing more than the older one. 4) It may be concluded from the Avena-test, and by the application of paper-chromatography to the separation of hormone substances, that the growth promoting substances contained in the dormant bud of Nandina that localize in the zones of Rf 0.8-0.9,0.4-0.5 and 0.0-0.1 of the paper-chromatgram, and the growth inhibiting substances are the substances localizing in the zones of Rf 0.5-0.7 and 0.1-0.2. Among these substances the chief growth promoting substances are the substances that localize in the zones of Rf 0.8-0.9 and 0.4-0.5,and the growth inhibiting substances are the substances localizing in the zone of Rf 0.5-0.7.

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The vertical distribution of each animal found on the leaf and stem of soy bean in the soy bean field A and in the fields B and C cultivated with different ratio of soy bean and corn in the same ridge was compared with each other by the correlation coefficients of vector that consists of two components of the individual number and the rank in individual number. The results obtained by the above-mentioned treatment, are : Aphis glicines showed characteristic vertical distribution in each of A, B and C. Thrips setosus and Collembola sp. showed respectively a similar distribution in A, B and C. In the case of Acarina sp. the vertical ditribution in A was different from those in B and C.

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Obuchi-numa and Takahoko-numa are small brackish water lakes situated at the neck of Shimokita Peninsula, Aomori Prefecture (Fig. 1). The benthos of these lakes were collected by means of a modified EKMAN-BIRGE's bottom sampler with an opening of 1/25 sq. meters. Sampling was repeated for six or more times and the benthos in the area of about 1/4 sq. meters were obtained at each station. Individual numbers of each species composing the benthos were counted and represented by the percentage of individual numbers of each species to the total number in each station (Fig. 2). Based upon whether there is overlapping of each two 90 per cent confidence limits of the said percentage in each species, three and four different communities were distinguished in Obuchi-numa and Takahoko-numa respectively. The distribution of these communities in both brackish lakes runs parallel in some degrees with the distribution of chlorinity of bottom water. Here the sectioning of chlorinity correlated with the distribution of the bottom communities corresponds to the one used by REDBKE in his study of evaluation of brackish water lakes in the Netherlands. The bottom communities of the above-mentioned two brackish water lakes and the other two previously studied by the present writer and his associates were arranged according to the chlorinity contents of bottom water. These communities were traced serially by two joint species of two or more communities in different lakes with the result that they seem to form a series with some branches.

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1. Differences in high temperature torelance and growth among five races of the striated spinous loach, Cobitis taenia striata are described. These fishes were reared at 20°, 25°, 30°, 33°, 34°, 35° and 36℃ during developmental stages. 2. The five races differ from each other in high temperature torelance, as in the following order : Large race<Middle race<Biwa-small race<Spotted-small race≒Small race. 3. The five races differ from each other in total length of young fishes, reared at the same temperature, as in the following order : Small race≒Spotted-small race<Biwa-small race<Middle race<Large race. This order is completely parallel with that in body length of adult fishes or in egg diameter, and reverse to that in high temperature torelance. 4. In the same race, the total lengths of young fishes vary with differences in temperature. They become larger at lower temperature and smaller at higher temperature. This phenomenon is considered as an expression of physiological responses of individuals to thermal conditions.

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In this paper the range of the following species of hepatics is treated. 10. Microlejeunea punctiformls (TAYL) SPRUCE Microlejeunea punctiformis belongs to one of the smallest hepatics and is usually found in corticolous or epiphyllous conditions in Asia. There are 89 psecimens of this species from various sources in our herbarium at present. In this paper it will be reported for the first time from Tochigi (1), Ibaraki (2), Nagano (1), Shizuoka (2), Yamaguchi (1), Kagawa (1), Tokushima (1), Kochi (4), Fukuoka (2), Saga (1), Nagasaki (2), Oita (2), Kumamoto (2), the Bonins and the Liukius. Additional new localities of the species are in municipitabity of Tokyo (1), the prefectures Hiroshima (9), Ehime (4), Miyazaki (3), Kagoshims (10), and Formosa (3). Map 10 in the text is based on 57 localities, among which 54 are new additions and 23 were previously known. From the it may be noticed that the northernmost limit of distribution of the specier is at Nikko (36°45' L.N.) in Tochigi Pref. With regard to the nature of the substrata, the results given in Table 9 were obtained from an examination of the habitats of 65 specimens. 95 (95%) specimens were collected on tree-trunks, [Table] and 3 (5%) on the living leaves of vascular plants. The macrofrequency of this species in each district is shown in Table 10,and the distribution-fall is distinct between S.W. Honshiu and M. Honshiu. [Table]

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1. The relations between the population densities and the rates of dispersion in the experimental populations of the ant-lion and some other insects were examined. 2. For the observation of dispersion of the ant-lion, soil was spread uniformly on the floor, covering the area of 120cm×120cm with the thickness of 2cm on which the individuals were liberated. 3. Two types of behavior of the ant-lion on the experimental field were seen ; one is the normal type, the individuals of which usually make their pits at short distances from the released point when the population density is low, and the other the "unstable" type, in which the individual pit-formation takes place after migration over long distances even in low density. A remarkable increase in the number of unstable individuals was seen when food was not supplied for two or more weeks. 4. When the normal individuals are released in the centre of the field, the rate of dispersion increases with the increase of initial number of individuals. The following equation which relation agrees well with the empirical data : [numerical formula] where y is the number of individuals found in the area S, and N the individuals introduced initially, while b and c are constants. 5. To indicate the degree of population pressure which accelerates the dispersion, an index P was proposed, which is calculated by [numerical formula] 6. Using the data obtained by KONO (1952) with the rice-weevil (Calandra oryzae) and by WATANABE et al. (1952) with the azuki-bean weevil (Callosobruchus chinensis), the change of the dispersion rate with the elapse of time was examined. As the result, it was found that this change is related to the change of the value of c in the equation (1), the relation being as : [numerical formula] where t is the time, and u, v are constants. Thus, the equation of the "density-time-area dispersion curve" is given as : [numerical formula] 7. The change of dispersion rate when the dispersion is disturbed by a barrier was also studied experimentally using the ant-lion. The result showed that the decrease of dispersion rate caused by the barrier is expressed by the increase of the value of c when t→∞. Thus, the degree of barrier effect to the spatial distribution can be represented by the index α, the value of which is given by [numerical formula] where u_1 is the value of u when the barrier exists, and u_0 is the value when no barrier exists. Similarly, the degree of barrier effect to the velocity of dispersion may be represented by the index β, the value of which is given by [numerical formula] 8. By comparing the values of P of three species of insect, it was shown that, the population pressure in unit area is largest in the ant-lion, and smallest in the rice-weevil, while it is intermediate in the azuki-bean weevil, when the population densities are equal to one another.

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1. Plants which are recognized as weeds constitute a group which are ecologically specialized as they flourish on such unstable lands as cultivated fields, foad-sides, etc. To dynamically analyze of weed communities which are adapted to habitats under various artificial factors, we attach a great importance to the growth form as constituting a part of the life form of weeds and we have accordingly set up a new system of the growth form. 2. Classification of the growth form of weeds is based upon the external, morphological features of vegetative-body of the plants of those species and individuals of weeds which are well-adapted to the life-environments of the cultivated land, in a broad sense including road-sides, fallows and other secondary weed communities possessing extremely artificial factors. 3. Two forms of weed growth are recognized : shoot form and root form. Each of the two forms is classified into 5 divisions, and furthermore into 10 subdivisions as a convenience for actual use (Table 1). 4. Our first examinations of weed communities, utilizing our system of growth form were conducted in the following two regions, which are widely separated and thus afford an excellent comparison. (1) Takasu in Hiroshima City (0.5m and 50m above sea level). This locality was chosen because of its being on the coastal region of the Inland Sea of Seto. (2) Fukiya in Okayama Prefecture (550m above sea lavel). This locality was chosen because it is a rather cool plateau in the Chugoku district. In both regions we studied the cultivated and the abandoned fields for seasonal fluctuation of weed communities with respect to growth form, growth stage, floristic features, weed dominance and the RAUNKIAER's system of life form. The investigations were conducted once or more times during each month from March 1951 to January 1952. 5. The following shows the number of species observed growing in the cultivated land by locality. (The area of each investigation was 20 sq. m.) [table] The number of species observed growing in the abandoned cultivated fields were : [table] Fukiya 48 species abandoned for three years after cultivation (4 were tree seedlings) 6. In our observations of the seasonal aspects of weeds, it was found that the ephemeral plants such as Stellaria media CYR., Stellaria uliginosa MURR., etc. decrease in quantity in summer at Fukiya, but they continue to grow throughout a year, whereas, in comparison, at Takasu they grow as distinct winter annual weeds and are never found in summer. 7. The growing period of summer annual weeds as Digitaria ascendens HENRY, Cyperus microiria STUD., etc. is much shorter in Fukiya than in Takasu. 8. Generally speaking, on the cultivated fields, E of the shoot form is at its maximum in summer, while in winter it is replaced by P, the value of which is the greatest. Moreover, in winter, R, Ca and sometimes T are recognized. Spring is the shifting period of the maximum value from P to E and autumn is that from E to P, and this shift is most likely due to the change of local environmental factors on habitats and to the degree of artificial factors. Some variations in the values are always recognized in each of the types. In the root form, Re shows a particularly great value in winter and spring, but in summer and autumn S and Fb become more abundant than during the periods of spring and winter, and accordingly Re shows a smaller relative value than in the periods of spring and winter. 9. Throughout a year, in the shoot form the value of P is always great and in the root form Re is the greatest, which indicates the distinguished feature of the cultivated fields. 10. In the field which had been abandoned for one year, E of the shoot form covers 64 per cent in summer when it attains the maximum value. In winter R takes the same place as P on the cultivated fields and attains its maximum, and T also shows an increase. In root form, Re, which always

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The structure of the natural population, especially the growth of the population a food infesting Acarid mite, Carpoglyphus lactis L., which lives in the "miso"(salted bean-paste) brewing tank, was studied. Acarnia species found in the tank observed in the present work, were C. lactis L., Tyrophagus dimidiatus HERMANN, some of Tarsonemus and a species of Gamasides. Here, C. lactis was dominant in the population density and its distribution was characteristic comparing with other species. Concerned to C. lactis, the following facts was recognized by the statistical treatment : 1. When the brewing materials are put in a tank, the animals which are scattered on the wall of the tank begin to migrate and the new young population is formed which is recognized by the active oviposition. 2. If the environmental conditions are favourable to the animals, the population continues to grow and thus becomes to have a simple gradient structure, namely, in the central zone of the population the eggs are most numerous, being surrounded by the zone, where the eggs, larvae, nymphs and adults are almost equally found. In the marginal zone the adult mites distributes more density than the younger ones. 3. When the enwironmental conditions become to be unfavourable, the simple structure of the population splits into some small populations, each of which has respectively characteristic constitution, and finally these small populations become to converge to two types. One is the population, where the eggs are most numerous, and the other is one where the adult mites are more numerous than the others.

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