It is well known that the density of a progeny population is determined by the density of the parent population and the so-called reproduction curve which represents the quantitative relation between these two successive populations has two classical types, as shown in Fig. 1. One is the saturation curve which has been experimentally obtained in the Tribolium population (CHAPMAN, 1928), and another is a mountain shaped curve obtained in the experimental population of Collosobruchus chinensis (UTIDA, 1941). Further, it has been theoretically assumed that these tww types and the intermediate one between them will appear when the duration of adult life is controlled(FUJITA & UTIDA, 1952,Ecol. 34,488). This assumption is now experimentally proved in the population of Calandra oryzae, changing the duration of adult life, such as 5,10,15,20 and 25 days, by taking the beetles from the culture populations at those dates. The results obtained are given in Fig. 2. It seems most probable that the change of the reproduction curve is produced not only by the adult duration but also by the different nature of the mechanism governing the density effect itself.
A knowledge of the seed population present in the soil beneath different types of vegetation is of great value in the consideration of some of the ecological problems with regard to agricultural practice. BLENCHLEY and WARINGTON investigated the seed content of arable soils in considerable detail and found an association between the seeds present and the treatment (by manures and cultivation) which the land had received. Such comprehensive studies of the buried seed population of arable soils in our country have not yet produced satisfying results. The present study closely follows the methods initiated by AKAZA, with some modification of which are given details of reexaminations. Numerical estimations were made of the number of seeds, as shown by the morphological features, in numerous soil samples of known area taken from the uncropped(a)and the cropped lands(forage crops land(b), soy bean land(c)). Further, the structural analysis of the buried seed population is reported by using the "occurrence probability method"and MOTOMURA's theory. From the results summarized in Tables 8,9,10 and Figures 1,2,3,it will be seen that the six types of seed population were divided into ; (a) Digitaria ascendens-Stellaria neglecta type, Persicaria nodosa-Rorippa atrovirens type, (b) Stellaria neglecta type, Portulaca oleracea-Euxolus ascendens type, (c) Digitaria ascendens type, Exolus ascendens-Stellaria neglecta type.
1. Girella punctata GRAY is one of the common inhabitants at the reefy shore near the Seto Marine Biological Laboratory of the Kyoto University. The young fishes, hatched out in the early spring, attain the size of ca. 3-7 cm in summer, usually make schools(composed of 10-200 individuals), swim about here and there near the sea-beaten reefy shore, and feed on algae or small invertebrates(Table 1). 2. Although no sign of social hierarchy are recognizable in the open sea, dominance and subordination relationship appears when they are confined to the tide pool at low tide. At first they swim about freely in these pools, making groups or solitarily, but after 10 to 20 minutes the pecking behaviors appear gradually, and the social dominance order is established. In the meanwhile, No.1 individual shows a tendency to stay at a particular place. which becomes its territory. Then other fishes occupy their territories successively according to the dominance order, i.e., the higher, the faster the establishment of the territory, and consequently occupy a more favorable place for feeding or hiding. These social organizations are exhibited most distinctly at about the time of low tide ; after that they become less and less conspicuous, and disappear at last when the open sea water begins to pour into the pool(Fig. 1,Table 2), The most dominant individuals usually wander freely in the pool, whereas subordinates are attacked when they approach the territory of the dominant or of individuals of higher rank. The fishes of low social rank sometimes fail to establish territories. 3. Many similar observations performed at tide pools as well as aquariums are described(such as shown in Figs. 3,4). The fishes demand a good place where food is available and where they can be hidden from enemies, and it will be natural that the most dominant individual occupies the most favorable place. 4. In conclusion, these facts seem to indicate, so far as young Girella punctata confined in the tide pool concerns, that the hierarchy organization and the territorial organization are not the antagonistic social principles, but the latter may be taken as a revelation of the former-an expression of the desire for the area which is satisfied according to the dominance order. 5. Considering with a number of works carried on some fishes, pigeons, horses, rabbits, deers, and monkeys, the writer became of the opinion that, in the animal world, there are many cases in which the above conclusion may fundamentally be applicable.
There occur three species of murids, Clethrionomys rufocanus ledfordiae, C. rutilus mikado and Rattus noroegicus, in the small tree stand near the farmstead of the Hokkaido University. These species do not intermingle spatially, but each of them has its own habitat. It seems probable that the natural condition of their habitat is not associated strictly with the occurence of each species. In 1951,from spring to summer, each species had approximately equal size of population and segregated spatially. In summer, as many as possible of the murid inhabitants of the area were removed and then about the same number of pairs of each C.r. mikado and C.r. bedfordiae were immigrated to the area from the peat-bog field of Nopporo, near Sapporo. Two immigrant populations occupied the area respectively, keeping the same spatial relation as the predecessors in spring. Furthermore they spread over the place which had formerly been occupied by R. norvegicus. In 1952,no observation was made. In 1953,from spring to autumn, C.r. bedfordiae was found abundantly and C.r. mikado was depressed spatially, while R. norvegicus occurred in small numbers at one part of the area, which in 1951 were inhabited by C.r. mikado. In 1954,C.r. bedfordiae became more abundant, occupying a larger area than in 1953,while C.r. mikado was much more depressed moving its habitat slightly. R. norvegicus recovered its population size slightly in the same place as in 1953. In 1955,C.r. bedfordiae decreased in number and rather concentrated at the center of the area, while R. norvegicus became very abundant and covered the whole area except the central portion. C.r. mikado hardly kept its population within the babitats of the others. In spite of the changes of the population sizes and the relative positions of the habitats, three species did not intermingle thoroughly, and even a small population concentrated spatially. During these process of changing spatial relation among the murids, the conditions of the tree stand showed no marked change. In short, from these observations we can conclude that the changes of the habitat is due to the fluctuation of the population, however the cause of which has not been acertained. The theory of "Sumiwake"(habitat segregation by IMANISHI 1941,or ecological segregation)is now being earnestly discussed by Japanese ecologists, As the mechanism of "Sumiwake", some authors emphasize the result of habitat selection according to the life form of the species, while others postulate the interaction between the species. The result of the present observations on the murids may support the latter view.
Numerous warm region plant species in Japan are found on the coast of Ise Bay. The writer investigated the distribution of these species in this area. While Lathyrus japonicus, Calystegia soldanella, Ischaemum anthephroides var. eriostachyum and Pittosporum tobira, etc. occur through the whole area of the coasts, Crinum asiaticum var. japonicum, Canavalia lineata, Euphorbia jolkini and E. esula are confined to the mouth of the bay. Such species as Dianthus japonicum, Crepidiastrum Keiskeawa, Arundo donax, Cirsium maritimum, Stephania japonica, Tetragonia expansa, Lysimachia mauritiana, Piper kadsura, Salsola komarovi, Vitex rotundifolia, Wadelia prostrata and Eurya emarginata, etc. are found far north along the eastern coast of the bay, but are present occasionally on the western coast, resulting in a peculiar distribution of the warm region plant species around the bay of Ise. The writer considered that the temperature is an important habitat factor, but the ocean current in the bay is more significant for the distribution of these species.
1. Only a few data have been reported on the periodit behavior of animal populations. The present paper records the daily periodic journey of the shore isopod populations observed under natural conditions. Observations were performed in 1954,on the intertidal rocky shore near the Seto Marine Biological Laboratory and at Fuji-Shima in Tanabe Bay, from late July to early August, and on the rocky shore at Karo, Tottori City, in August. 2. The shore isopods, that passed night among crevices of rocks above the tidal mark, commence the morning journey just before sunrise. They creep out from the resting places and march down towards the beach making several lines, getting over many stones, rocks or other obstacles, and at last reach their feeding places on the intertidal rock surfaces. They stay there in the daytime. In the late afternoon they begin to retire to their resting places, and the evening journey ends just before sunset. 3. Thus, they travel twice in a day, in the early morning and in the late afternoon. These periodic movements seem to be maintained by the combined action of daily changes of solar illumination and changes in the internal physiological conditions of animals (chiefly of conditions of alternative hunger and satiety). Such elements as air temperature, relative humidity or changes of tidal level may have not affected soundly these periodic movements. 4. It was observed that most individuals behave in aggregation throughout a day, whenever they are resting, migrating or eating. These aggregations are usually composed of several sub-groups, and the age of the members of each sub-group is nearly similar, i.e., animals have a tendency to make agers-assenblages. No sexual groups are recognizable. It is noticeable that the groups composed of younger individuals commence the journey always earlier than those composed of older individuals, regardless of morning or evening. 5. When migrating, the animals move from rock to rock, as it seeking an adequate pathway to the shore or to the resting place. It is thought that such pathways are characteristic to each populations of different habitats, so all members of the same population seem to march on the same way at the journey. 6. It is found that the aggregation has a sort of social organizations, namely, dominance order is recognizable ; the larger the individuals, the more they are dominant.
1. The typhoon No.13 attacked the east parts of Aichi Prefecture on September 25,1953,and about 5,000 acres of rice field was flooded with saline water(1-1.5 per cent C1') ; through the destroyed coastal bank. Some areas were submerged with saline water for a few days and other areas for 35-50 days, by which not only rice-plants themselves but also weeds in the rice-field and roadside vegetation were much injured or killed. 2. After draining the author studied the relationship among the duration of submergence, the contents of C1' left in soil and the degree of damage of the weed communities, and also pursued the process of revegetation in the field. 3. In the area under 35-50 days' submergence most kinds of chaemophytes and hemychryptphytes of roadside vegetation were killed ; but geophytes survived. As for therophytes, they were out of damage, because their seeds were not killed. 4. Most weeds of the rice-field belong to therophytes, and the seeds of these species were not injured even below 35-50 days' submergence of sea water. They appeared the next spring and summer in the rice-field, but their density was thin. 5. In the field, when the contents of C1' left in the soils were reduced to about 0.5 per cent Echinochola crus-galli and Brassica campestris germinated, when it became 0.3〜0.2 per cent Alopeculus aequalis and Bechmannia syzigachne germinated. The germination of these species serve as an indicator for the time when the soil is favorable to plant rice-plants.
Spawned larvae of the scallop, Pecten yessoensis JAY, in Mutsu Bay, grew to about 300 micra of shell length and were attached to the substratum in early June. These attached spats, which reached 6-10mm in shell length, turn to bottom life from late July. Meanwhile, a high mortality, which has not been explained, of these spats was ascertained, such phenomenon was often observed during summer and early autumn, and the mortality decreased in November when the spats attained from 30 to 40mm in shell length. In this paper the behaviors of the scallops in varlous stages of growth were observed under some environmental conditions which were of ecological importance. Gill pieces of 3×5mm were cut from the gill lamella of the scallops and immersed in sea water, then they crawled on the bottom of the containers, Petri dishes. The velocity of the crawl was measured and the relative velocity was estimated in comparlson with that of the control ones. The results are as follows : 1. Ciliary activity of gill pieces was decreased considerably by a small amount of suspended silt, especially in the young scallop(Fig. 1). 2. By low tension of soluble oxygen the ciliary activity of young scallops was slackened to 15-28 per cent after fifteen minutes and the gill piece crawling already stopped at about 20 minutes(Table 1). 3. Small pieces of the gill were appropriately stained with each of vital staining dyes, and then enclosed together with a small amount of sea water, in a small respiratory chamber on the slide glass and observed under the microsope. By this method the critical intracellular redoxpotential limiting ciliary activity could be determined(Table 2). Young scallop spats of 11-18mm in shell length remained in a high rH value and from these facts it was inferred that they have not yet developed a greater tolerance to anaerobic conditions. 4. Relative velocity of scallop gill pieces in varying sea water concentrations showed that the scallop was a stenohaline animal, especially it was so in the young, and a higher speed was observed in the concentrated sea water of 21.49 C1‰(38.819 S‰)than in normal sea water of 18.11 C1‰(32.719 S‰)(Fig.2). 5. Crawling velocity of gill pieces which were transferred suddenly from 5°or 20℃ to varying temperatures was decreased, especially in young acallops the crawling was stopped by the change of 15℃, i.e. from 20°to 5℃(Table 3). 6. From the facts obtained, the above-mentioned high mortality of the spats may be induced by the suspended silt and a low tension of soluble oxygen caused by the oxidation of organic matter in bottom mud, water stratification of summer calming, circulation in early autumn dredging of bottom fishery etc. In October and November the young scallop might have developed a greater tolerance to such environmental changes.
The seasonal fluctuation of the growth stage of weeds, the budding stage, the flowering stage and the fruiting stage, was observed(1952-1955)in Shiribeshi district, Hokkaido. Late in May, the kind and quantity of the budding weeds begin to increase suddenly, and reach the maximum period in June. But late in July they begin to decrease gradually and increase again in autumn. As the atomospheric and the underground temperatures here in June and September are almost the same, the temperature in these months is thought to be the most favorable for budding. The average temperature in June and September from 1952 till 1954 is as follows ; [figuie] The kind of the flowering weeds begins to increase early in July and reaches the maximum in the period from the middle of August to the early part of September. But, as the temperature descends, it begins to decrease in October, and early in November, only a few kinds of weeds remain as the remnants of late autumn. The kind of the fruiting weeds gradually increases late in August and most weeds bear seeds in the period between the latter part of August and the early part of October. But late in October, most seeds fall to the ground.
1. The term, "production, "used in ecology must properly be expressed as"biological production, "in order not to be confused with the production which man performs. 2. There are contradictions among the categories which name the green plants the producers, the animals the consumers, and bacteria the decomposers(THIENEMANN, 1926) ; among those which name the herbivorous animals the first consumers, the carnivorous animals the first consumers, the carnivorous animals the second consumers and so on(LINDEMAN, 1942). 3. These authors considered energy and material transfer in the biotic community or in the ecosystem from the viewpoint of the energetics, and treated the green plants simply as the catchers of the radiant energy. In this respect only the green plants are conceived as the producers of the organic substances. Such is an over-simplified and onesided treatment. 4. Such an attitude reminds one of a thought which confined the consumption in human society merely to the individual consumption and neglects the productive consumption. 5. The consumption of green plants by herbivorous animals represents the productive consumption on that level of the hiotic community, and so on. These animals are eventually the producer of the animal level. 6. Only from this point of view, we may properly recognize the ecological meaning of the organic"production"by animals, of animal proteins and the other organic substances, and of the whole body of the animal itself. 7. The method of approach used by THIBNBMANN, LINDEMAN and others, can only settle the "flame" of the inflow of the radiant energy into the biotic community and this flame is regulated by the organization of the community, the analysis of which forms the basic problem of synecology. Therefore, from the synecological viewpoint, these authors' systems seem to be unsuccessful for the solution of the fundamental problems of the"biological production."