The aquatic oligochaete, Aeolosoma hemprichi, was inoculated into two continuous culture media containing constant numbers of bacteria and bacteria and a protozoa, Cyclidium sp.. The oligochaete was established successfully, and its population density maintained a steady state in both cultures even though the maximum specific growth rate was considerably lower than the dilution rate of the culture media. In both cultures a large number or bacteria formed flocs. Many oligochaetes attached to the larger flocs. Since the larger flocs were rarely washed out, they prevented the oligochaete from being washed out from the culture vessels. The larger flocs were broken up by the shear stress of aeration as well as by the feeding action of the oligochaete. Thus due to the balance of formation and degradation, the floc mass maintained a steady state. We suggested that the establishment and the maintenance of a steady state in the population density of the oligochaete depended on the formation and maintenance of the bacterial flocs. Additionally, it was proved that the population density or the oligochaete increased when protozoa were present as the protozoa accelerated the enlargement of the flocs to which the oligochaete attached.
Based upon ecological aspects, Myrmica ruginodis Nylander from Sapporo and its vicinitv is divided into two forms, one occurring in riverside areas and the other in woodland. The riverside form is polygynous and produces fewer new queens, which suggests colony reproduction by fission and the internest movement of workers. The woodland form is generally monogynous, produces many queens, and conducts colony reproduction by solitary queens.
Surveys were made for stored-product insects in a barley mill in Saitama prefecture once or twice a month during March 1975-June 1976. At each survey, 200 g samples of barley dust were collected from 15 sampling areas in the mill and the insects were extracted using modified Tullgren funnels. Out of the 24 species obtained, the most abundant species were Tribolium confusum, Sitophilus oryzae, Ephestia kuhniella and Rhyzopertha dominica in this order of decreasing abundance. The insect fauna of the barley mill was compared with those from flour mills, a feed mill, and farm granaries using MORISITA's index of similarity, and it was found that the fauna from the barley mill was very similar to those of the flour mills but different from those of the farm granaries. The erratic seasonal change of species diversity (BRILLOUIN's index) in the mill was caused mainly by T.confusum.
The growth process during the growing season of 1-year-old Q.acutissima and 2-year-old F.crenata seedlings was analyzed. Based on seasonal changes in the distribution of dry weight increment and of the "soluble" carbohydrate increment to the photosynthetic and non-photosynthetic systems, the growing season of Q.acutissima was divided into the following five periods : (1) the first period of constructing new organs with consumption mainly of "soluble" carbohydrate reserved in old organs ; (2) the second period of the expanding photosynthetic system due to photosynthetic activity ; (3) the third period of the expanding non-photosynthetic system due to photosynthetic activity ; (4) the fourth period of accumulation of "soluble" carbohydrate ; and (5) the fifth period of leaf fall during which the soluble substances in the leaves were withdrawn and/or consumed by respiration before leaf fall. Of these periods, th second and third periods could not be observed in the F.crenata seedlings. In bath species, the major part or the "soluble" carbohydrate consisted of crude starch fraction. Both species, appeared to use about 80% of the net production for net growth, and the remaining 20% were shed as leaf fall.
In order to investigate the life cycle of Ch.yoshimatsui, the egg masses of chironomids were sampled at the water's edge along the wall in the Zempukuji River, on every fourth or fifth day from September 1976 to December 1977. The peaks of ovipositions in Ch.yoshimatsui seemed to occur at intervals of 28-54 days from March to November in 1977. The development of a generation required 540-620 and 500-550 day-degrees respectively, under the critical water temperature (threshold of development) of 2.5 and 4℃. From the above facts Ch.yoshimatsui seemed to produce eight generations per year in the river.
In winter, brown dippers are mainly solitary and exclusive in relationship with adjacent conspecific individuals. They drive other individuals out of their surrounding spaces along stream by threat (warning call, confronting) or aggressive behavior (chasing flight). The area along the stream, where a dipper can find others approaching is limited, and this area is defended as a territory. Some individuals are observed within narrow ranges (Sedentary type), and they held stable territorial ranges. On the other hand, others (Nomadic type) live within more extensive ranges, and change their territorial ranges day by day. Roosting individuals in upstream areas must be nomadic ones and they come downstream for feeding during the daytime.
The investigation on the migration of Form III was conducted in a small deciduous broad-leaved forest at the center of Sapporo. Form III is a univoltine species, overwintering mainly within the forest. They migrate from the inside of the forest to the forest edge between May and June. This tendency is especially conspicuous in females It is possible that the dense distribution of females in the forest edge where the temperature is higher than within the forest, resulting from the temperature preference by females. Possibly this migration is an adapation to shorten the egg period and to increase the number of times of ovipositions (total number of eggs).
This paper is dealt with the factors affecting the annual fluctuations of litter fall rates in Chamaecyparis forest mentioned in the previous papers. Leaffall rate over 10 years ranged from 1.966 to 5.070 t ha^<-1> y^<-1>. It suggests that leaffall rate or death rate of older leaves is related to the leaf production rate, considering the high correlation between leaffall rate and daily accumulative temperature. However, there are no clear relations between leaffall rate and the accumulative temperature of the year in which dead leaves were produced. High production rates of reproductive organs are found in the year of the high accumulative temperature during flower bud differentiation. Concerning dryness and high temperature in rainy season or in summer, it is shown that the production rates of reproductive organs varies greatly for precipitation or its daily pattern. The number of years necessary for the accurate estimation of mean fall rate in the studied forest is 5 for the total litter, 6 for the leaf, 13-17 for the branch and bark, 51 for the cone and seed, and 119 for the male flower.
To understand the adaptation to the low temperatures in the life history of Pteridophyta, the freezing resistance was evaluated with the overwintering sporophytes of fifty-five species native to Hokkaido. Most fern species increased their hardiness from September to December and reached the maximum in December. Evergreen ferns had their maximum leaf hardiness ranging from -12.5℃ to -40℃, and the increase was much earlier and greater than that of the rhizome. Most summer-green ferns could not survive freezing in the leaf during October. The hardiness of the rhizome of the summer-green fern ranged from -5℃ to -40℃ in Hokkaido. Almost all fern species growing on the trunks of deciduous hardwoods and cliffs resisted freezing at -40℃. Many species growing on the floor of deciduous forest and in the humid and humus-rich dale had the hardiness ranging from -5℃ to -17.5℃. It is known that gametophytes of soem ferns tolerated freezing even at -40℃, while the sporophytes growing in the deciduous forest floor in Hokkaido survived freezing at the temperatures ranging from -5℃ to -17.5℃. Thus, the present evidence foresees the possibilities of wintering by means of gametophytes on the cliffs and the trunks, where it is extremely severe to winter in the state of sporophytes.
The late-glacial period, characterized by plentiful pines and/or birches, contains two distinct pollen zones, i.e., LI (ca. 15,000-12,000 years B.P., with abundant boreal conifers) and LII (ca. 12,000-10,000 years B.P., with a rapid rise of beech and other cool-temperate species). This is especially clear south of about 37°N latitude. The Holocene consists of five pollen zones, RIa, RIb, RII, RIIIa and RIIIb. RI, generally including RIa and RIb, is a transitional zone from late-glacial to mid-postglacial RII vegetation. The RIa/RIb zonal boundary (about 8,500 years B.P.) is defined by a slight increase of plants which develop fully in RII. RII (ca. 7,000-4,000 years B.P.) shows the maximum development of the laurilignosa in southwestern Japan and the deciduilignosa in northestern Japan. RIIIa (the maximum Neoglacial period) is distinguished by a small expansion of the cool-temeprate forest in southwestern Japan, and by downward and southward migration of the boreal forest in central and northeastern Japan. RIIIb (after ca. 1,500 years B.P.) is the pine period. The high correlation coefficient (0.938) between the first continuous occurrence of buckwheat pollen and the beginning of RIIIb's pine increase suggests that Pinus densiflora forest was established as a result of intensified prehistoric shifting agriculture.