1. The seasonal variations of aquatic Phycomycetes were studied from October 1957 to September 1958 in Lake Nakanuma, Ibaraki Prefecture, Japan. The thermal stratification was established from May to December. 2. The number of the zoospore of aquatic Phycomycetes varied considerably through the year with one maximum and one minimum. The maximum appeared in early winter and the minimum in summer. The zoospore was counted 65/10cc and 0/10cc respectively. 3. The aquatic Phycomycetes consisted of seven species, in which Pythium sp. was the dominant one. The seasonal changes differed with each species. Saprolegnia monoica, S. ferax, Achlya flagellata and Dictyuchus sp. were found mostly in winter. Aphanomyces sp. and Pythium sp., however, were seen through the year with the maximum in winter. 4. There were two main types in the vertical distribution of the zoospore of aquatic Phycomycetes. The one was homogeneous distribution and the other was the stratum one. The former appeared during the circulation period and the latter was seen during the stagnation period. 5. The zoospore production of aquatic Phycomycetes was effected by the water temperature as well as by the lacustrine bacteria. The optimum temperature for the zoospore formation differed in each species.
1. In this paper, the author shows the results of a faunistic survey on stream bed animals in the Yada River System of Hyogo Prefecture. The field study was made during 1956 to 1959 and more than 81 species belonging to eight orders of insects were collected. 2. Whole River System was divided into four parts viz. spring, torrential parts, mid-stream, and lower part. The numbers of species of insects found in each part were shown in the order as 51,49,36 and 8. By the quantitative survey on standing crops of each parts, the torrential part and mid-stream has the largest standing crops than the others. The two species of netspinning caddisfly larvae belonging to Stenopsychidae were dominant in these parts. 3. The size distribution of Stenopsychidlarvae was examined at several stations. In the summer season, the body size of Stenopsyche griseipennis larvae was larger than that of Parastenopsyche sauteri in mid-stream but the body sizes of both species were similar in the torrential part. These facts seems to suggest the interesting and impertant problem of population dynamics in stream bed community.
Concerning the progressive change in the distribution pattern, the censuses on the eggs, larvae and pupae of Pieris rapae crucivora BOISDUVAL in a cabbage farm were made successively during the period from June to July of 1953 in every plant. The results are as follows : 1. The distribution pattern tends to change from concentrating to random with the hatching of eggs and larval growth and this change is remarkable between the eggs and the first instar larvae. 2. The hatching rate has no relation to the density. On the assumption that the hatching occurs at random with equal rate in every plant, a close agreement between the observed frequency distribution of the hatched eggs and the theoretical one is recognized in the comparison between them. 3. In the case where the distribution of the eggs on a plant conforms to the POLYAEGGENBERGER distribution and its contagious parameter is d, the coefficient of diversity, s^2/x^^- is given by(1+d), therefore, when the hatching of eggs occurs equally in each plant and its probability is p, the value of s^2/x^^- in the distribution of the hatched eggs is given by(1+pd). Namely, when the value of p decreases, the value of s^2/x^^- approaches to 1 and the distribution of the hatched eggs approaches to the POISSON distribution. 4. The movements of larvae among the plants are observed after the third instar but most of them are limited among the neighbouring plants. In the case of the last instar larvae, most of them emigrate from the observed farm for the pupation. 5. As the peak of the number of individuals in eggs and each instar larvae appears at intervals of two to four days, it seems that the time length required for the growth of each stage is almost the same in each individuals. The rate of molted larvae in each instar does not differ statistically among the plants of different density. 6. The mortality of larvae has no relation to the density but in some cases it has a tendency to be inverse density-dependent. Therefore, it is impossible to suppose that the approach of the distribution to the random pattern is caused by the mortality. The progressive change of the distribution pattern with larval growth may be based on the stochastic process as stated in the case of hatching.
Als drittes in der Reihe der internationalen Stolzenauer Symposien wurde vom 20〜22 April 1960 von Prof. Dr. Dr. h.c. R. TUXEN von der Internationalen Vereinigung fur Vegetationskunde in Verbindung mit der Bundesanstalt fur Vegetationskartierung eine organisierte Tagung unter dem Titel "Biosoziologie" abgehalten. Mehr als 80 Fachieute aus den Gebieten der Tier-und Pflanzensoziologie, der Hydrobiologie, der Mikrobiologie anverwandter Wissenschaften, der Pedologie und der Geographie aus zehn verschiedenen Landern waren in Stolzenau zusammen. Die 33 Vortrage waren in folgende Abteilungen gegliedert : 1. Allgemeine Grundlagen und Begriffe der Biozonose 2. Untersuchungsergebnisse bestimmter Biozonosen 3. Biosoziologie und Pedologie 4. Anwendung biosoziologischer Erkenntnisse in Wissenschaft, Wirtschaft und Naturschutz und wurden im einzelnen sehr eingehend diskutiert. Die Abende waren mit offentlichen Vortragen und der Besichtigung des Museums der Bundesanstalt "Die Schrift des Bodens"und mit einem vom Bundesministerium fur Ernahrung, Landwirtschaft und Forsten gegebenen Zusammenessen ausgefullt. Die Teilnehmer gewannen nicht nur einen Uberblick uber die einzelnen unabhangig voneinander erzielten Resultate der verschiedenen Fachgebiete, sondern daruber hinaus wurde in mancher fur die gesamte Biosoziologie entscheidend wichtigen Frage eine weitgehende Einigung erzielt. Der starkste Eindruck fur alle Teilnehmer war die einheitliche harmonische Synthese des gesamten Fragenkomplexes, die sich durch die zahlreichen Beitrage der Referenten zu aller Uberraschung dank der Organisation des Ganzen durch den Leiter der Bundesanstalt fur Vegetationskartierung unter Fuhrung des aus der Versammlung gewahlten Prasidenten sozusagen von selbst abrundete. Dieser Erfolg wird in den nachsten Jahren verschiedene Richtungen der Biosoziologie in der Grundlagenforschung sowie in der Anwendung einen groben Schritt weiterbringen. Durch diesen Bericht hoffe ich, fur die Weiterentwicklung der Biosoziologie auch in unserem Lande einen kleinen Beitrag zu leisten.