Using the almond moth, Ephestia cautella W., it was examined under the experimentally controlled condition of temperature (30℃) and relative humidity (70 per cent), how the initial egg density influences the number of moths emerged and the average head width of them when the number of eggs and the times of their introduction to the rice bran are changed. The mountain shaped relation between the egg density and the number of moths emerged was seen in the case of simultaneous introduction of eggs. But, when the eggs were put into the food in two or three times half by half or t third by a third respectively at given intervals, the relation was changed in its shape to the saturation type in consequence of the increase of number of moths in the higher densities and their decrease in the intermediate densities. In these latter cases the average head width of moths increased in the higher egg densities. The curvilinear relation between the initial egg density and the total number of eggs deposited in the next generation, which are expected to be deposited by the female moths emerged was obtained as shown in Fig. 5. This relation changes from a mountain shape to the saturation type by these experimental procedures in both cases of the representation (the reproduction curve) when the relation is calculated by their number and their average head width.
This paper deals with the spawning time of the Teleostean fishes based on various published data. From the viewpoint of the spawning time, fishes can be generally classified into four types as follows. A) Species spawning at night, especially during the period from evening twilight to midnight. B) Species spawning in the daytime, especially from the dawn to the early morning. C) Species spawning in relation to the tides, i.e., spawning mostly at the high tide in the highest flood-tide. D) Species without any specific spawning time. Clupeida-fishes mostly belong to the first type, while many fresh-water species of Cyprinida belong to the second. Some inshore fishes may fall into the third. Only a few species are included in the fourth type (Table 1). The light seems to be an important factor affecting the impulse of fish-spawning, the time of which is more or less fixed by each species. But it is hard to say that each species had obtained such habit of the regular-time-spawning by the influence of the present environment as there are several facts which can be considered only by the phylogenetical viewpoint of these fishes.
Rice nematodes distribute widely in the rice planting regions of Japan, but there is almost no knowledge or estimation if any of the damage caused by them. Therefore the writers have studied on the growth of the rice plant attacked by nematodes and the decrease in yields caused by them to obtain some data for the estimation of the damages. Experimental pots, except for the germination test of injured seeds, were used. The non-injured seeds harvested in the past year from a non-injured field, were sowed on pots, and after about two weeks the liquid with the swimming nematodes was injected into the said pots. About 50 nematodes were found living in 5 cc of the liquid. At the growing stage the number of injured stems of each hill, the height of the plant and the number of stems were observed, and after the harvest the yield was estimated. In this paper, the estimation of damage was. done by the correlation between the ratio of injured stems and the plant growth or the yield characters The results obtained are as follows ; 1. In injured seeds the ratio of germinated seeds and its germinating vitality were recognized to be somewhat lower than those of non-injured seeds, and the maximum germination in injured seeds was rather delayed compared with non-injured seeds (Fig. 1). 2. The height of the plant originated from the injured seedling was considered to be about one half of those from non-injured ones (Fig. 2). 3. The ration of injured stems in early August (x) had positive correlation with the ratio of the injured stems (y) on September 1st and 24th. There was negative correlation between the ratio of the injured stems (x) and the two growth factors, the height of the plant and the number of the stems. The correlation with height of the plant reached the maximum in late August and with the number of stems in early August. There was negative correlation between the ratio of the injured panicles and the ratio of the injured stems, the correlation coeficient being about 0.9. 4. There was negative correlations between the ratio of the injured stems and such yield characters as the length and weight of the panicles, and the weight of rice grains. But these correlations were higher in "Ginchu", a susceptible variety, than in "Norin 43", a resistant variety. 5. According to the regression equation, when all stems of a hill were injured the decrease in yields of the hill could be estimated to be about 60 per cent in Ginchu, and about 20 per cent in Norin 43.
1. The spine of the shells of Ostrea echinata obtained from one habitat is very variable in number, and some spineless individuals were found. 2. The primary factors of this variation are considered to be : a) Population density of the oysters. b) Inclination of the rock surface to which the oysters adhere. 3. The increase of the population density tends to check the development of the spines. 4. A decrease in the inclination angle tends to show decrease in the spine number. 5. The collaborated effect of these two factors to the spine number is recognized to some extant.
1. To analyse the heterogeneity of any vegetation to establish some homogeneous plant communities, as GOODALL suggested in 1953,it may be possible by stochastical estimation of the correlation between any two species in the vegetation, which is drawn from 2×2 table treatments of the statistics. Modifying GOODALL's method. the writer tried to judge the degree of correlation between any two quadrats among those diffused in the plant community to be examined, which is drawn also from 2×2 table like Table 3. Thus, the community may be grouped into some more homogenous one. 2. The slope of Mt. Ibuki, 1377 m above sealevel in central Japan ; consists of two geologically different fields, limestone and sandstone, contacting with each other at about 900m alt. Here there were selected ten quadrats, 7×7m in size, on a line separated by a distance of ten meters, five in the limestone area and the rest in the sandstone one. In September 1957,the components of the vascular plants in each quadrat (Tables 1 and 2) were investigated. 3. As the result of comparison by x^2-test of floristic components of any two quadrats, it was found that five quadrats in the limestone area and the rest in the sandstone area positively correlated with one another, while the negative or no significant correlation was found between those two groups of quadrats (Table 4). In such case, the writer considers that the community should be subdivided. This is an objective evidence that the flora of calcareous areas and that of siliceous ones are quite distinguishable from one another. 4. On the other hand, the values of ELLENBERG's "Prasenz-Gemeinschafts-Koeffizienten" indicate that the quadrat No. 5 which is richest in flora may be taken as the standard one. They attain over 50 per cent in the calcareous area, and 25 per cent to 50 per cent (Fig. 2) in the siliceous area. The fact shows that the two communities (L- and S-) do not possibly belong to different associations, but form two "Variante" in the sense of BRAUN-BLANQUBT (1951) in the same association, probably "Fraxinus commemo-ralis-Dryopteris polylepis association". 5. L-community in the calcareous area is characterized by such species as Kerria japonica, Orixa japonica, Zabelia integrifolia, etc., which should be called calciphilous plants. The vegetation concerned may be attributable to one of the edaphic climax. S-community in the siliceous area is characterized by such species as Clethra barbinerbis, Rhododendron Kaempferi, R. semibarbatum, etc., which should be called calciphobous plants (Table 6). 6. To test the homogeneity of the L-community by means of the same procedure, it was subdivided into two groups including two and three quadrats respectively, depending on the positive correlation among them (Table 5). The former is in the field poor in gravels and the other rich in them. S-community may be divided into two groups though it is not apparent what they are derived from. 7. The pH values of the soil samples in each quadrat indicate that the L-community is favorable on alkaline or neutral soils and the other on acid soils. Other factors causing the distinction of the two communities could not be determined.
We studied the fauna hygropetrica of a mountain stream, Miyatani (Fig. 1), Ooto-mura, Yoshino-gun, Nara Prefecture, quantitatively. Table 1 shows the constitution of four quadrate samples, the size of the quadrate being 50cm×25cm. The results are summarized as follows : 1. All members of this community are small in size. 2. Standing crop of the community is little. 3. There are true hygropetric forms, such as Osmylus sp. and Nogiperla sp., almost true hygropetric forms such as Stactobia japonica and Psychomyia sp., and indifferent forms such as Mystrophora sp., Micrasema sp., etc. 4. When the wet rock is covered with mosses, as quadrate No. 4,its community is more or less different from that of the bare rock.
1) Tripogon japonicus OHWI is an endemic species of Japan occuring only in the northern part of the Kanto district, namely in Ibaraki and Tochigi Prefectures. It is always found on the almost vertical cliffs of andesitic agglomerate or andesite (Fig. 2). 2) The already-known, about 20 localities of Tripogon japonicus OHWI are shown in the geological map. (Compare with Fig. 1). 3) In the community of Tripogon japonicus OHWI, we can usually find Sedum Makinoi MAXIM., Hosta longipes MATSUM., Conandron ramondioides SIEB. et ZUCC., Lespedeza Buergri MIQ., Fraxinus Sieboldina BLUM. and Clethra barbinervis SIEB. et ZUCC. The floristic composition and the community structure are presented in Table 1.