Flyways of the black swallowtail, Papilio maackii tutanus FENTON, are generally formed on the ridges or summits of hills. The spring flight activities of the black swallowtail were quantitatively observed at a flyway in Maruyama, Sapporo. The seasonal and diurnal trends of flight activities at the flyway coincided well with the phenological experience on this species. Among the main weather factors, insolation and wind velocity seem to be quite important. But it was suggested that the diurnal activities could not satisfactorily be explained by weather conditions alone. The directional nature of the flyway was quantitatively confirmed. The flyway under observation was a small one, with the highly concentrated portion of the traffic about 130m long. The behavior difference between P. maackii tutanus FENTON and P. bianor dehaanii C. and R. FELDER was briefly referred to. Finally, some comments on the butterfly flyway are given in the concluding remarks.
The present paper deals with the ecological studies of the aquatic insect communities of Echi River, Hino River and Yasu River which flow into the southeastern part of the Lake Biwa. The biotic index of same rivers was determined based on the BECK-TSUDA method. The field study was made in early September in 1963. The results are summarized as follows : 1. Aquatic insect fauna was poor in the three rivers. Especially the middle and lower parts of those rivers had far smaller standing crop of aquatic insects than the rivers flowing into the northwestern part and the northeastern part of the Lake Biwa. The causes are probably due to the water pollution by wastes from a pulp plant, digging out the sand of the river bed for construction purposes and drying up of the river bed in some seasons. 2. The larger part of the standing crop of each station of the three rivers was occupied by the net-spinners and creepers with only a few exceptions. 3. The biotic index of the three rivers are shown in Fig. 4. The biotic index of the middle and lower parts of the same rivers is small for various reasons.
The social behaviors of Prionurus micralepidotus, one of the most common tangs or surgeon fishes along the southern coast of Japan, were studied both in the sea (Tanabe Bay, Wakayama Prefecture) and in a large tank (in the Suma Aquarium) in 1955,1956 and 1961. In the open sea, relatively large schools (average number of one school is about 20 individuals) were found on the large and deep offshore reefs, while schools on the small and shallow inshore reefs were small (average : about three individuals) and there were found even solitary and resided, or territorial individuals. In the large tank, ten individuals of this fish were brought to the tank one by one. The first to fifth specimens resided under the rock or rock shade and showed territorial behavior, whereas the next five specimens did not resided anywhere, but made schools and hovered. Moreover, three specimens out of five territorial fish joined these schooling individuals resolving their territories. From these facts, it seems that the social behavior type of P. microlepidotus is apparently effected by its population density as well as by the habitat condition, whether it is large or limited.
The important environmental factor influencing the types of vegetations of a sandy coast is the sand movement caused by wave and wind. Two shore types are thereby discriminated : strand and dune. The wave strongly influences a strand, while the wind is the most influential factor for a dune. These two vegetations should be regarded as the types belonging to wander desert formation.
Until recently, the interspecific competition between the species occupying the similar ecological niche has been fully studied in an experimental way, based upon the theoretical postulate of LOTKA or VOLTERRA. Among these, such works as CROMBIE's (1947) or PARK's (1954) seem to be most extensive and classical. In this paper, the interspecific competition was studied experimentally using two species of parasitic wasp Trichogrammatidae with 170 replications under the constant condition of temperature and relative humidity. Two species of parasitic wasps, Trichogramma japonicum ASHMEAD and T. minutum RILEY, were reared on the eggs of the almond moth, Cadra cautella WALKER, propagated on rice bran. And they competed changing the initial number of wasps, the ratio of the initial number of wasps, the area of rearing space and the number of hosts. Counts of wasps were made in every generation at regular intervals(10 days). The population of each single species grew and attained a steady state under the given experimental condition where 100 eggs of the host species were supplied in each parasite generation (Fig.1). The amplitude of population fluctuation of T. minutum was greater than T. japonicum. It may be caused by the difference of the ecological charactors between the two species. When each species competed with one another, one species was depressed and became completely extinct or both became extinct after several generations. As GAUSE's principle, the coexistence of these two competing species should not occur. However, the results were not always uni-directional and adverse results were obtained, even under the same environmental conditions. These results are nearly the same as that of PARK et al.(1955) in Tribolium. Thus the treatment from the probability theory seems to be adequate to analyze these results. But, generally speaking, the following definite tendency was found. T. japonicum had much opportunities to become the victor, when the two species competed with each other under the condition of narrow area of rearing space and high density of initialy introduced wasps. While the results were vice versa under the condition of wide area and low density of wasps. So, it is possible to consider that the competition process became different by varying the density of parasitic wasp. And these suggest that the difference of ecological characters between two species affected the competition processes and outcomes. Therefore, it is important to clarify the difference of ecological characters between the two species in order to analyze the mechanism of competition.
The senior author and his collaborators have made experimental studies on the plant succession, especially its earlier stages (NUMATA and YAMAI 1955,NUMATA 1956,NUMATA and SUZUKI 1958,NUMATA 1961), where the sociological structure and succession were analysed in detail. However, there have been published very few informations on the buried-seed population which is the mother's womb of plant communities. Concerning the studies on seeds, there are many reports on the agricultural and silvicultural seeds in applied fields, and physiological studies in pure fields. But there are very few reports on the "ecology of seeds" ("Okologische Samenkunde") where they must be studied related to the structure and succession of the plant communities. For this reason the purpose of the present project is to obtain precis knowledge on the seeds. In this paper, the Erigeron stage (I), the Imperata stage (II), and the Pinus stage (III) in the campus of the Chiba University were studied and compared with each other concerning their floristic composition (Table 2), biological spectra (Table 3), and the degree of succession (Table 4). The buried-seed populations in the same stands were examined. Ten units (sampling unit : 40 cc) of soil were sampled based on the species-volume curve (Fig. 1) according to the stratification of 0〜1,1〜2,2〜5,5〜10,10〜20,and 20〜30cm in depth. Buried-seeds in the soil were separated by 50 per cent K_2CO_3 solution. The buried-seed populations in the three seral stages does not exactly correspond with the floristic composition of the actual plant communities, and that in a seral stage contains seed-grains of the former stages as well as some of the later stages. The number of seed-grains and the number of species decrease as the succession proceeds. The number of seed-grains the rank of species relationship (Fig. 3) satisfies the law of geometrical progression as in the terrestrial parts of the plant communities. The decrease of the number of seed-grains with increasing soil depth frequently shows a certain tendency (Fig. 4).