The intertidal zonation of the marine algae along the coast of Tsuruga Bay, Fukui Prefecture which faces the Sea of Japan, was studied. The field work which forms the basis of this paper was carried out during April to May 1963. As the results of the investigations, two inland-sea communities were ascertained. Namely, the Ulva pertusa-Grateloupia filicina association was found only at the innermost part of the bay, where it is influenced by the fresh water from the rivers. The same community is also distributed along the Japanese coasts in such bays as Kasumi, Tokyo, Osaka, etc. The Enteromorpha compressa-Scytosiphon lomentarius association was found almost all over the bay. It consists of two belts from above downward, that of Enteromorpha compressa and of Scytosiphon lomentarius. The community is also distributed along the coasts of Toyama Bay, Atsumi, Fukaura and Setouchi, etc. The distribution reference between the two communities on this coast goes parallel with that of the Pacific Ocean side.
The catches of flshes in number by the gill net in the Sarutani Reservoir which was filled in 1956,and the population densities of the fishes in its tributary, the Tenno-kawa River, were investigated in 1961 and 1962. The following results were obtained. 1) The remarkable inarease in catches of two species of stagnant waters, Biwia zezera and Pseudoxasbora parva and of two species, Zacco platypus and Rhinogobius brunneus, which require a wide water body in their larval stages, and the decrease of Tribolodon hakonensis in 1962 were observed (Tables 2 and 3 ; Fig. 2). These indicated that the composition in number of fish fauna in the reservoir changed considerably to that of the stagnant water type from that of running water type which is seen in the tributary at present. 2) This change seen in the reservoir has markedly affected the abundance of Z. platypus and T. hakonensis near the backwater in the tributary as shown in Table 1. 3) Tukugobius flumineus, which is very abundant in the tributary, has not been collected in the reservoin. It seems to be difficult for them to inhabit there.
In the previous paper, the authors reported on the occurrence of organic acid fermentation coupled with sulfate reduction in the polluted river-water under anaerobic condition and explained the mechanism of the phenomenon on the basis of the assumption that the carbohydrates discharged into the river-water undergo successive metabolism of lactic acid fermentation and sulfate reduction with the ultimate production of acetate. To justify the above assumption, an experiment in which sulfate reduction was blocked by lowering the supply of sulfate and increasing that of carbohydrate was carried out, and as the result heterolactic acid fermentation was found where lactate and acetate were produced predominantly. Furthermore, two coliform bacteria, i. e. Escherichia coli and Aerobacter aerogenes were isolated as the heterolactic spccies from the culture. As the fermentation types of the single-species populations of these two bacteria were almost the same as that of the mixed-species population of the polluted river-water, it was suggested that the coliform bacteria might play a decisive role in the first step-breakdown of carbohydrates within the polluted river-water.
There are two rivers (Torii River and Kusu River) in the Togakushi Highland (Nagano Prefecture), in central Japan. Aquatic insects of those rivers were studied in August 1963. The results are summarized as follows : Torii River had more standing crops of aquatic insects than Kusu River, for. example the standing crop of station 3 (in Torii River) was 5.2g per 0.25m^2 in a wet sample. The net-spinners were dominant in Torii River, the communities of the river being in climax in the succession of aquatic insect communities of the rapids. In Kusu River, more creepers were found and standing crops were less than those of Torii River, the aquatic insect communities being far from the climax in the succession. Distribution of the net-spinning species of the two rivers are shown in Table 3.
Some analyses were made on the variation of the stem-height, and the dry-weight of the whole and those of the flowers, leaves, stems, roots and overground parts in two species of plants, Campanula hondoensis and Solidago virgaurea subsp. leiocarpa. The specimens were collected at every 100 m of altitude along the line attending from the Okoya Ridge to the Kengai Ridge of Mt. Yatsugatake. 1) In both species, the size and the weight of the body decreased with the increase of altitude of the station. 2) The relative weights of the overground parts, flowers and stems against the whole decreased, and that of the root increased, but that of the leaves was constant with the increase of altitude in both species. 3) The relation of the dry-weights of the whole and the stem-heights at every altitude conform to the equation, w=kf^α where w is the mean weight or mean stem-height, and f is the altitude. 4) Double logarithmic plots of the overground part weights against the root-weights at every altitude form the straight line. Therefore the relation of the two parts along the altitude conform to the allometry formula, y=bxα where y is overground part weight, and x is the root-weight. As α>1.0 was shown, the altitudinal variation of the overground part was larger than that of the root. In Solidago virgaurea subsp. leiocarpa, the relation of two parts shows diphasic allometries with the critical point at the forest line (alt. 2500m). As the value of α above the forest line was larger, the cline of the variation of the overground part above the forest line was larger. 5) The relation of each part of the overground parts along the altitude conform to the allometry formula, too. In this case, the discontinuity at the forest line was not shown.
It was proved that the phenomenon of "cannibalism" participated in the cause of the loss in number of rainbow trout in their early rearing stages. This phenomenon was studied in datail, and the results obtained are as follows : 1. The fingerlings were reared under the ungraded conditions for four months after the initial feeding. Approximately 20 per cent of them were recognized as dead fish but other 30 per cent disappeared during this period. The main cause of the loss may be "cannibalism". 2. In the experiment, the frequency distribution of body length in the fourth month was obtained as a curve inclined to the smaller fish, its skewness being +1.90. 3. It was observed that the smaller the predators were, the smaller the ratio of their body length to the upper limit length of the prey's was, and the smaller the range of the prey's size was. The body length ratio to prevent "cannibalism" at the first stage of the initial feeding is thought to be 1.3. 4. "Cannibalism" in rainbow trout fingerlings in pond culture is observed since approximately ten days after the initial feeding. 5. The predators' preference to the prey is thought to be considerably strong in view of their satiation rate. But the food efficiency in cannibalistic feeding could not be thought to be especially excellent compared with other natural diets. 6. "Cannibalism" does not always happen. In the population in which it does not take place, the dead fish recognized are relatively few and the health of the fish and rearing circumstances are found to be favorable.