In August 1965,the benthic communities at the four stations in the River Yoshino-gawa, were investigated by the quadrat (50×50cm) sampling method with the following results : 1. The aquatic insect larvae amounted to more than 99 per cent in number and 97 percent in standing crop of all the benthic animals. More than 95 per cent of the aquatic insects consisted of the members of the next four orders ; Ephemeroptera, Plecoptera, Trichoptera and Diptera. 2. Comparing with the results obtained in April and May in the same year, the standing crops of the benthos increased to some extent. And, the ratios of the standing crops of caddis-worms, especially those of the net-spinning type, increased at many stations. On the other hand, insects of the creeping type, mainly of ephemerid larvae, decreased. 3. The general trend that the standing crops were the largest at "Hayase" -rapids and the smallest at "Huchi" -pools, was observed to have recovered in August.
The breeding preparation, nest building, copulation, incubation, chick raising and fledging during the breeding season of the Red-cheeked Myna (Sturnis philippensis), based on the results of the outdoor observations, were investigated to know the life history of the birds on the campus of the College of Education of the Shinshu University in the central part of the Zenkoji basin, Nagano City in Nagano Prefecture from 1963 to 1964. Most of the life history during the breeding season of the bird was described based upon the observation of one nest in 1964.
In the azuki bean weevil, Callosobruchus chinensis collected from the field, the activity measured by photo-stimulated flying changed with the adult age in days. The mode of this change differed by the density of the larval stage (Fig. 9). Numbers of adults which flew to a light source, and which did not fly were counted every minute for 5 minutes. Flight-responsiveness to a light source differed by the larval density (Fig. 8). The active and sluggish types were in this way discriminated. But the intermediate individuals, that is the less active ones were found out. They did not fly to a light source, but walked about or stood still outside the dish. The number of eggs deposited by an active female was rather less than that by sluggish ones (Fig. 2). Little differences in the emergence date of these two types can be observed (Fig.3). Though the mechanism of the emergence of both types has still remained unsolved, it seems that temperature, larval density in a bean, and parent activity are in some way related to the activity of the female weevil. The results for male were rather obscure (Fig. 4,5,7,8). In both female and male, mating has no effect on the mode of the activity change (Fig. 6).
The reserved forest dominated by Cyclobalanopsis glauca and C. myrsinaefolia is developed on the immediately upper part of the slopes where the Akiyoshi-do, is situated ; this limestone cave is best known for its vast scale in Japan. This study is prompted by two ways of investigation on the present forest ; one is on the basis of the structural analysis and the other is of the analysis of floristic composition. Thirty one quadrats of 10m×10m in size were established according to the topographical conditions within the forest for sampling vascular plants. In order to get or select the typical and homogeneous stands for the C. glauca and C. myrsinaefolia forest, only the quadrats in which either of the two species concerned occupies at least 50 or more of Total Importance Value and one of the two is more than two times of the other in T.I.V. were picked up. The values of similarity index, C_λ (MORISITA 1959b), were computed among the quadrats with all their combinations by means of the number of individuals of the component tree species having more than 1cm in D.B.H. There were selected based on similarity index six quadrats representative of C. glauca and eight of C. myrsinaefolia. The former group falls undoubtedly into the category of Nandineto-Cyclobalanopsidetum glaucae by YAMANAKA (1955). The latter group suggests a lower unit of that association or another new association. The quadrats were classified into two groups according to the magnitude of the slope inclination ; one is more than 30° and the other is less than that value. There is statistically significant difference between the two groups concerned in the totol number of individuals of the two species of Cyclobalanopsis. Namely, C. glauca grows predominantly on the slope more than 30° in the inclination, while C. myrsinaefolia grows predominantly on the slope of less than 30°. The values of interspecific correlation, R_δ (MORISITA 1959b), between the two species of Cyclobalanopsis were calculated along the gradient of the slope inclination. R_δ-values near null, though they fluctuate somewhat along the gradient, suggest that difference in distributional behaviours of the two species under consideration may not result from the competition between them but from their specific preference for environmental factor or factor complex by which the slope inclination is represented.
Six hundred and fifty-two stumps of Pinus pumila were measured at Kuraigahara and the North Ridge of Mt. Norikura. The ages of these trees and their thickening growth are discussed in this paper in connection with their annual rings. 1) The Pinus pumila copse consists of the trees aged between 20 to 210 years, their average age is 80 to 100 years and the maximum age attained is 210 years. 2) In the Pinus pumila community, the average age of the trees becomes increases where the environmental conditions become better. 3) The mean value of the thickness of the annual ring (average of each longest radius and shortest radius) in all the samples studied was 0.241 mm, so that the annual rate of the growth is quite small. 4) In the Pinus pumila community, the thickness of the annual ring is determined by the environmental condition. 5) There is a close connection between the average thickness of the annual ring and the snowfall. If there is much snowfall, the thickening increases, and the snowfall can protect the trees in winter, so long as the snow coverage continues.
The vertical distribution of freshwater planarians in the Lake Doya-ko district, the south-western part of the Shikotsu-Doya National Park in South Hokkaido (Lat. 43°15′N. to Lat. 43°55′N. and Long. 140°35′E. to Long. 141°20′E.), is reported. The Lake Doya-ko district is characterized by volcanoes (Mt. Tarumae, Mt. Eniwa, Mt. Usu, Mt. Syowashinzan, Mt. Shiribeshi, Mt. Konbu, etc.) and three caldera lakes (Lake Doya-ko, Lake Kuttara-ko and Lake Shikotsu-ko). The highest peak, Mt. Shiribeshi (Mt. Makka'nupuri), is 1893 metres above sea level. There are many hot springs in this district. The Shiribetsu and the Osaru are main river systems of the area surveyed. The Shiribetsu River discharges into Iwanai Bay, the Sea of Japan. The Osaru River and the other many short rivers discharge into the Pacific Ocean. The surveys were made in August 4-5,1966. In the area surveyed, only two species of freshwater planarians, Polycelis sapporo (IJIMA et KABURAKI) and Polycelis auriculata IJIMA et KABURAKI, were found. Pol. sapporo was common in the stations both in the seashore and the mountainous districts. The altitude of the upper limit of distribution of this species is about 730 metres (inhabitable water temperature range, 6.4-16.5℃). Pol. auriculata was rather common in the cold-water stations in the altitude range from about 70 to 900 metres (inhabitable water temperature range, 5.9-13.2℃). The type of the vertical distribution in the area surveyed is shown as S-SA-A (S : Pol. sapporo ; A : Pol. auriculata).
In the previous paper (MAKI, 1966) it was stated that one of the life-cycle stages of this fish population which may be critically affected by certain factors for the yearly fluctuation is in winter, when the fish inhabit the bottom of the deepest part of the lake. Up to this season the fish are in the sub-adult or the adult stages. As the next step of this research the factors that regulate this fluctuation were investigated. Sample specimens of fry and juvenile were collected, using a small trap and a small beach seine from April to August in 1964,to examin their growth, condition factor and food. Sample specimens of the adults and sub-adults to examin the age, growth, condition factor, maturity and food were taken monthly from commercial landings between April 1964 and March 1966. Records of seasonal and vertical distributions of water temperature, pH, oxygen content and zooplankton from 1962 to 1964 by B.S.T. were used for the analysis of the factors of the population fluctuation. Records of the same environmental conditions measured by the Shiga Prefectural Fisheries Research Laboratory between 1949 and 1963 were also used for this analysis. Yearly changes of the environmental conditions such as water temperature, oxygen content and pH of the bottom layer of the lake in winter do not correlate to the abundance of the under-yearling population. The seasonal change of food organisms (planktonic crustaceans) in winter appear to have no correlation with that of the under-yearling population.