This paper deals with the bio-economy of the larval populations of pleurostict Scarabaeidae. The field surveys were carried out to see the population dynamics during the periods from July 1956 to July 1957 and from Nov. 1957 to Nov. 1958 on the flood plain of the River Tamagawa near Tokyo. On the other hand, several representative species were reared on quartz sand and soils in the laboratory, and fed on dried leaves of Shiia sieboldi and Miscanthus geniculatus to determine the amounts of such bioeconomic items as ingestion, defecation, assimilation, respiration and growth. Computations of population metabolism were made based on the above two series of data. The quantitative relations obtained for population metabolism of the main species Anomala orientalis are as follows. The amount of matters ingested per square meter per year was equivalent to 1700 Cal or about 300g in dry weight of plant leaves and that defecated was 832 Cal or 164g in dry weight, and the body materials of the larvae produced (growth or net production) was 65 Cal or 52g in live weight. The larvae were reared at constant 20℃, 25℃, 30℃ and at room temperature. At 30℃ the growth rate was the largest and the length of the larval stage was the least of the above four. The larvae fed on the dried leaves of the grass, M. geniculatus, grew faster than those fed on the leaves of the evergreen forest tree S. sieboldi. The meaning of the difference of food substance and that of habitat are discussed. Comparisons were made on the metabolism of the larval population of Scarabaeidae and that of Pieris rapae with reference to the difference of the habitat and the life type.
When some reservoirs are constructed in the same river, the autochthonous environmental conditions of each lake and allochthonous limnological conditions caused by the inflow give remarkable effects on the aquatic communities of each reservoir. In this study, the Asahigawa Daiichi and Daini reservoirs among the four reservoirs constructed in Asahi River, were compared with the other two reservoirs from the limnological point of view. The results obtained from this study are as follows : 1. The environmental conditions of the Asahigawa Daiichi reservoir are similar to those of the Yuhara reservoir which is situated 30 kilometers above the Asahigawa Daiichi reservoir, and the plankton fauna of the former is about the same as that of the latter. As for the phytoplanktons, the pollution torelant species were found only in the former. From this result it can be said that the Asahigawa Daiichi reservoir is more eutrophic than the Yuhara reservoir. 2. In the Asahigawa Daiichi reservoir, some aquatic animals and plants were found in the shore zone. This phoenomenon is not generally found in other reservoirs constructed at about the same time. This phoenomenon seems to be caused by the following two circumstances. (1) Much organic matters or polluted water flow into this lake, making the lake eutrophic comparatively in a short time. (2) The shore of this zone is not too steep, therefore it has a comparatively wide shore zone, forming good habitats of the aquatic animals and plants. Furthermore the change of water level is so slight that the shore zone is not exposed in the cases of the low water levels. 3. The Asahigawa Daini reservoir receives the outflow of the Asahigawa Daiichi reservoir. The Asahigawa Daini reservoir is small in its volume, so the current velocity is fairly rapid compared with the other reservoir. The plankton flora and fauna of this lake is similar to that of the Asahigawa Daiichi reservoir.
Among the components studied in the present work, Shiia cuspidata and Cyclobalanopsis gilva, one subtree, Camellia japunica, and one shrub, Aucuba japonica were measured monthly for their water, ash, calcium contents of the leaves and the fallen leaves in fixed plots from Dec. 1962 to Nov. 1963. 1) The lower a tree or a shrub is in height in a forest, the higher the water content of the Ieaf is. (Fig. 1) 2) The foliage is renewed every year after the juvenilation, and the annual amount of fallen leaves attained 4.55tons/ha in dry weight (Table 1). 3) The foliage is renewed every year. The yearly curve of the ash and calcium contents in the leaves show two minima in winter and in summer. (Fig. 2) 4) The ash and calcium contents are higher for the subtree and the shrub than for the dominants. 5) For an area of one hectar, nearly 300kg of ash containing 100kg of calcium are estimated to be returned from the foliage to the ground each year.
"Chojaga-mori"is a grove developed on the Akiyoshi limestone plateau which is an extensive one of the Karst areas in Japan. There were set up two different series of transect belts of 2m in width in the present study. To make a distribution map of the forest trees (more than 3cm in diameter), one is set up successively across the grove in E-W, and the other is in N-S directions. The authors attempted to analyse in detail the vegetational structure of the forest community on the basis of this map. The authors found a total 26 tree species, of which 11 are included into the evergreens and 15 in to the deciduous, however, the total of importance value of the former is about three times as much as the latter. The distribution pattern of the value of D. B. H. in this grove does not indicate the L-type, that is, it is considerably different from those reported from many primeval forest. This, together with the fact that the dispersion type of all the individuals in the forest is contagious, may suggest that the human agency such as firing or deforesting in the past had influenced the structure of this forest. The value of the standing crop or LAI (leaf area index) of the grove as well as the value of α (index of diversity) reveals the magnitude comparable with those of many other evergreen forests in Japan. Camellia japonica and Machilus thunbergii, the most important species, are distributed repulsively to each other in the forest.
To investigate the change in oviposition site of Pieris rapae crucivora with the increase of its parental density, the eggs laid by the 3rd generation were censused in the cabbage field and the net house in which the female adults were released at different densities. The following results were obtained : 1) At a low parental density, the butterflies laid more eggs on the peripheral plants than the inside plants, and the spatial distribution of the eggs was rather heterogeneous in the field or the net house. This heterogeneity of the egg distribution was decreased with the increasing parental density. 2) As the parental density increased, the oviposition site on the plant was extended to the senescent from the mature leaves, and more eggs were laid on the upper surface of the leaves. 3) Such trend to homogenize or extend the oviposition site with the increase of the parental density was considered from the mutual interference among the butterflies in the oviposition behaviour.