In the previous paper it was shown that the swimming nematodes migrated from hill to hill by mix-planting of the injured seedlings and normal ones, and thus the normal plants become remarkably contaminated. Therefore, from applied ecology, we have studied on the type of nursery bed which may protect the rice plants from contamination caused by the swimming nematodes. Two types of the nursery beds were used, i.e., the nursery bed covered with oil paper and the irrigated common nursery bed. The seeds treated with hot water or non treated ones were sown in each bed neighboring the injured bed. After the nursery stage the seedlings were transplanted in the experimental pots, then the plant growth and the population of the nematodes in unhulled rice grains were studied. The results obtained are : 1. Difference in total number of stems was insignificant between the two beds, but the number of injured stems was less in the protected nursery bed than in the normal one. 2. In unhulled grains of the rice plant grown in the protected bed the population density of the nematodes was very low or zero, while in the normal bed it was considerably high. 3. As for the plants grown in the normal bed, unhulled rice grains of almost all stems were contaminated by nematodes, even though the injured by nematodes in injured stems and non-injured ones in the same hill was insignificant. The population density of rice nematodes in the injured hill was higher than in non-injured ones. 4. When the seedlings were planted in the normal nursery bed, the population of the nematodes in unhulled rice grains was higher in the injured hills than in the normal ones without distinction of the treatment and non-treatment by hot water. But, when the seeds treated with hot water were sown, the population density in normal stems of injured hills was lower than in injured stems.
1. The lacustrine sediments in six ponds of the Suirennuma-group in Towada National Park were collected, and their colors and the structures of the diatomaceous floras were studied. 2. In measurement of colors of lacustrine sediments, the wet and dry sediments were compared with the standard color charts published by the Japan Color Company under the I.C.I. Standard illuminant C (6500°K). Table 1 shows the three values which were obtained by the C.I.E. color charts. 3. The color change from a wet sample to a dry one was discussed, using both the color difference and the tendency of change of chromaticity on the α-β diagram. As a result the lacustrine sediments of six ponds were classified into three types (cf. p. 6). 4. The triadic color differences (ΔE) between the wet and dry sediments were calculated from HUNTER's expression. The correlation between their values and the ignition losses of sediments is shown in Fig. 3,such a correlation agrees with the result obtained from the samples of lakes of the Tsutanuma-group published previously by the writer. 5. Fig. 3 shows the correlation between the water colors and the hue and chroma of the lacustrine sediments. From Fig. 3,it will be seen that the water color of a brown wet sample is darker than the water color of an olive wet sample Fig. 4 also shows the correlation between the water colors and the triadic color differences. From the above facts, it is clear that there is a tendency that the more humus is contained in the lacustrine sediments, the darker brown the water colors become. 6. All species of diatomaceous tests in the lacustrine sediments from the six ponds are shown in Table 2,27 species of them are common with those collected from Ozegahara by FUKUSHIMA. Also the similarity of the structures of the diatomaceous floras in the lacustrine sediments is discussed referring to the GLEASON's F.I.C.C. and the JACCARD's community coefficients (Table 3), and consequently the affinity of the diatomaceous floras was obtained as shown in Fig. 6. From Figs. 2 and 3,it is suggested that the two series of affinity shown in Fig. 6 show the series of a part of succession from non-dystrophic lakes to dystrophic lakes.
Experiments were carried out to examine the effect of different foods and densities on the growth rate of larvae of Dermestes maculatus at 30℃, 60〜70 per cent R.H. Egg laying habit and factors influencing it were studied. 1. Larvae reared on the dried pupae of silkworm were shorter in the duration of the larval period, fewer in the number of larval instar, lower in the larval mortality and heavier in the weight of pupae as well as newly emerged adults as compared with those reared on the fish meal (Tables 1〜3). 2. When larvae reared on a kind of diet, the isolated condition was more favourable for their growth than in a crowded condition. But the effect of diet was more evident than that of density (Tables 1〜3). 3. The pre-oviposition, oviposition and post-oviposition periods and the number of eggs laid by a female when fed on the dried pupae of silkworm were investigated(Table 4). 4. Egg laying usually occurred at the intervals of 1〜2 days and continued successively for 1〜3 days (Table 5). The mean number of eggs is 3 per day per female. When omit the resting period from oviposition, the net mean is 7.3 eggs per day. 5. Positive correlations were observed between the weight of newly emerged adults and their longevity, or fecundity. Adults accessed on food showed periodic changes in their body weight (Figs. 1〜2). 6. The number of ovalioles varies from 17 to 25,rarely exceeding 25. The commonest number was 24+24. 7. Female adults which were deprived of food did not deposit eggs and their longevity shortened as much as one-fourth as compared with those accessed with food (Tables 6〜7,Fig. 3). 8. Repeated matings are necessary for the attainment of potential fecundity (Table 8). The unfertilized female deposited eggs numbering one-tenth of the fertilized one. Fertilization could occur before the development of eggs.
The writer examined the stomach content of the Pacific mackerel, Pneumatophorus japonicus (HOUTTUYN), caught by purse seiners on its winter quarter off the southern districts of Niigata Prefecture in late February, 1958. The examination led to the finding that nearly half of the examined fish contained considerable quantities of sea bottom sediments such as gravels, sands, silts, shell fragments and tubes of annelid worms mixed with bait animals (Table 1). Taking into account the condition with which these sediments were included in the stomach as well as their size composition and sinking velocity through sea water (Figs. 1 and 2), it is supposed that the sediments were possibly taken by the fish skimming the sea bottom in search of food. The principal foods of the fish were composed of euphausiid, Exphausia pacifica HANSEN, pearlsides, Maurolicus japonicus ISHIKAWA, and a few species of copepods, in them the euphausiid was volumetrically dominant Finally, a short discussion was made concerning the aspect of the habit of this shrimp-like crustacean, suggesting that it may be an inhabitant of the sea floor, actually inhabiting on the bottom, during the daytime.
Salicornia europaea is found in Hokkaido, Honshu and Shikoku in Japan. In Hokkaido, it occurs in Lake Akkeshi, Lake Huren, Cape Notsuke, and the lagoons along the Okhotsk Side, namely Lakes Mokoto, Notoro, Saroma and Shibunaito. The writer investigated the Salicornia europaea community in the Lakes Notoro and Saroma, and divided it into 3 sociations ; 1) Salicornia europaea Sociation 2) Salicornia europaea-Spergularia var. asiatica Sociation and 3) Salicornia europaea-Juncus gracillimus Sociation. The community of Salicornia europaea can not keep the stable phase. In Lake Notoro, the floating ice renders great influence to the Salicornia vegetation. Sometimes the destructive action of the floating ice and the full extent of flooding due to its melting in spring cause quantitative or qualitative changes of the community over the whole salt marsh. The best development of Salicornia vegetation occurs near the mouth of the rivers emptying into the lagoons. Salicornia europaea forms often a pure community and sometimes it is accompanied by Spergularia salina var. asiatica. Glaux maritima var. obtusifolia is also found in the salt marsh but it also grows in drier places. Juncus gracillimus tends to be incresed by horse-grazing. The number of individuals of Salicornia europaea in one square metre amounts to 6,760 from 427 in 7 quadrats taken. Measurement of the salinity of the soil in contact with the plant roots shows that Salicor nia sp. has a preference for wider salt concer tration, 6‰-25‰. Spergularia sp. for medium, 9‰-12‰ and Juncus sp. for lower, 5‰. The salinity may be one of the factors which control the development of the communities mentioned above.
The relation between water and Oncomelania nosophora (ROBSON), an intermediate host of Schistosoma japonicum (KATSURADA), was observed experimentally from season to season (1956〜1957) in the laboratory, the rearing box was conditioned as naturally as possible. In all experiments 50 snails were used. After the snails were kept in water, the hourly changes in their numbers in each section (water, wateredge and grassy land) were recorded. The results are summarized in Text-figs. 3〜7. Under the optimum conditions for snail's activities, large numbers of adults crept out of the water in a short time. When the air temperature was lower than that of the water and the condition of low temperature was not suitable for the snail's activities almost all of them at the wateredge crept into the water. But large numbers of larval snails were remaining and living in the water, and some individuals on the waterside did not go away from the surface of water. Thus, it is a very interesting fact that the larval snails differ from the adults in their behaviour to water.
It has been shown that the true armyworm, Leucania unipuncta, exhibits a conspicuous variation dependent upon the population density in which the larvae grew up (IWAO 1956). In this paper, the author made an attempt to discover whether there are any differences in the mode of response to density change between L.unipuncta and its related species, L. loreyi and L. placida. L. loreyi is a pest of sugar-cane and other graminaceous crops in tropical and subtropical countries, though it is less injurious than L. unipuncta. L .placida occurs in Japan and adjacent areas but causes no damage to the crops. Parallel breeding experiments were carried out under the constant temperature of 25〜28℃ and natural daylight with Bromus or maize leaf as food. Larval density varied as 1,5,10 or 20 individuals per vessel. In L. unipuncta the larvae reared in crowds bear fine black coloration in contrast with greenish yellow or reddish brown color of the larvae in isolation. The crowded larvae of L. loreyi are also somewhat darker than the isolated ones but they never become blackish even at very high density. L. placida does not change its color in response to density conditions (Figs. 1,2). The rates of larval and pupal development are accerelated in the crowded culture of L. unipuncta but retarded in those of the other two species (Fig. 3 ; Tables 1,4). The weight of pupae decreases with increasing density in all three species (Fig. 4 ; Table 3). In L. unipuncta the crowded larvae are more irritable and consume more food than the isolated ones, while in L. loreyi and L. placida such clear-cut differences could not be found between the larvae reared in crowds and in isolation (Table 2). In any species the length of preovipositional and ovipositional periods, fecundity and coloration of adult moth are not affected significantly by the density during larval period (Table 5). Longevity of the adult is, however, considerably prolonged in high-density type of L. unipuncta, but rather shortened in that of L. loreyi (Fig. 5 ; Table 5). Thus the mode of density-dependent variation observed in Leucania unipuncta is quite different from those of its related species, L. loreyi and L. placida, while it resembles in many respects the phase variation of swarming locusts. It seems likely that "phase" dimorphism is characteristic in those species which fluctuate their population density extremely owing to their habits and/or habitat conditions.
In the previous report the author classified the sesame varieties into five groups according to their light sensitivity, but in this paper the author dealt with the relation between each group of different light and temperature sensitivity. The materials used in this experiment were 31 varieties introduced from nine countries including Japan. They were sown on the 26th of June, 1957. Then treatment was exercised from July 10th and continued through August 8th, and after treatment they were allowed to grow naturally. The treatment was as follows : Check plot : (N) Cultivation under natural conditions. Short-day treatment : (S) Exposure of eight hours per day. (9A.M.〜5P.M.) Long-day treatment : (L) In the day time, by natural exposure, at night illuminated allnight with two bulbs of 100w from the distance of 1.5m. Heat plot : (H) Cultivation in the Viyni house. (N), (S), (L) and (H) are days required from seeding to flowering. The days from seeding to flowering of each varieties were as follows in the relation to light sensitivity. (1) A group being highly sensitive to both Short-day and Long-day conditions : temperature sensitivity was high and showed the same tendency as the varieties treated under the Long-day conditions (African, Indonesian varieties and a Indian variety). (2) A group being more sensitive to Short-day, while low to Long-day conditions : temperature sensitivity was not recognized or seen (a part of Israel and Japanese varieties). (3) A group being less sensitive to Short-day but more to Long-day conditions : temperature sensitivity was low or flowering promoted under high temperature (Japanese, Korean and a part of Indian varieties). (4) A group being of low sensitive to both Short-day and Long-day conditions : the varieties flowering promoted under high temperature, in other varieties temperature sensitivity was not recognized or temperature sensitivity was low (Japanese, Korean and some of American varieties). (5) The variety in which flowering was promoted under Long-day conditions : flowering promoted under high temperature. By the results of the experiment, both temperature and light sensitivity differed according as the place of source difference in latitude. It was recognized that the higher the latitude of the place of source, the lower the temperature sensitivity becomes. With regard to the temperature sensitivity, which has a close relationship to light sensitivity;; both temperature and light sensitivity differed accordingly as the source of varieties differed according latitude. It was recognized that the higher the latitude of the place of source the lower the temperature sensitivity.
(1) The seasonal changes in phytoplankton productivity were investigated by means of both Winkler and chlorophyll methods at three fire pools (40m^2,2.5m in depth) in Tokyo from 1951 to 1953. (2) The gross production was large at the upper layers and small at the lower layers. The difference was small in winter and large in summer, and was comparatively small in pool A and large in pools B and C. At the surface layer, the production was small in winter ; and two maximum values were seen in spring and in autumn, or sometimes once in summer. The above phenomena were seen from the results obtanied by both methods. The values measured by the Winkler method showed different tend encies at 1m and 2m layers in pools B and C. (3) By the Winkler method, the respiration was large in summer and small in winter. It showed almost the same value at upper and lower layers in A, while in B and C it was markedly large at upper layers and small at lower layers. By the chlorophyll method, a marked parallel relationship between the seasonal changes in gross production and respiration were seen, and the value of respiration was much smaller than that measured by the Winkier method. (4) The net production measured by the Winkler method showed positive values at surface layer all the year round, and negative values at 2m layer of A and 1m layer of B and C in summer and winter. At 2m layer of B and C negative values were seen almost in every season. The values determined by the chlorophyll method showed that the positive net production was seen at 2m layer of B and C in spring and autumn. (5) The gross production per unit area measured by both methods showed mostly two maxima in spring and in autumn, and two minima in winter and in mid-summer. This was seen especially markedly when measured by the chlorophyll method. The respiration was found to be large in summer and small in winter when measured by the Winkler method, while by the chlorophyll method it was large in spring and autumn. As for the net production, the tendency was the same as in the case of gross production, It showed negative value in winter and summer by the Winkler method, while by the chlorophyll method it showed always the positive vaiue. (6) The production per unit area showed no remarkable difference among the three pools, increasing year by year. Mean value of the gross production measured by the Winkler method amounted to 1.25〜2.50O_2g/m^2/day, of which 70〜90 per cent was lost by respiration, consequently the net production was 5〜30O_2g/m^2/day. As for the values obtained by the chlorophyll method, the gross production was almost the same as the result by the Winkler method. In this case, however, the respiration amounted only 20 per cent of the gross production, and the net production was 40〜80O_2g/m^2/day. (7) The energy efficiency of the gross production (assimilation/solar energy) was low in summer and high in spring and autumn (especially high in autumn), and its annual average value of every pool was 0.26〜0.45 per cent. Respiration was 0.25〜0.27 per cent by the Winkler method, being 3〜8 times as much as the value by the chlorophyll method. The net production measured by the chlorophyll method was 3〜6 times as much as the values by the Winkler method. (8) As the range of photosynthetic activity under field conditions, 2.0〜100.0O_2mg/Chl. mg/day in Lake Suwa were measured. In general these large values were seen in eutrophic lakes. (9) The advantages of both methods were comparatively examined. Also the comparison with the C^<14> method was made. It was concluded that the method must be chosen in accordance with the trophic state of the waters.
1. The writer examined the species composition of the schools of the tunas caught by the live-bait fishery basing on the data collected in 1955 and 1956,and also investigated the size composition of each single school of skipjack using the data of 1951 to 1957. 2. The species composition becomes complicated in the following order : Free School…Birds-School…Whale-School…Shark-School…Drifter-School. 3. The coefficient of variation becomes larger in the following manner : Free School…Birds-School……Whale-School……Shark- and Drifter-School. 4. The facts mentioned above suggest that the structure of the fish school depends on the media of the schools.
1. The pine forest of low elevations on serpentine was studied in the vicinity of Kochi City from the standpoint of phytosociology. 2. The vegetation on serpentine in this district is characterized by open and stunted stands of Pinus densiflora accompanied by deciduous shrubs. 3. The floristic composition of this pine forest is very characteristic and is remarkably different from the pine forests on other rocks. Accordingly, this pine forest should be treated as the Pinus densiflora-Abelia serrata association (Abelieto-Pinetum densiflorae) characterized by Abelia serrata, Pourthiaea villosa var. zollingeri, Diplomorpha sikokiana, Pertya glabrescens, Ilex serrata, Smilax sieboldi, Dioscorea gracillima, Berberis thunbergii, Corylopsis spicata, Enkianthus perulatus var. japonicus, Carex multifolia, C. subdita, Epimedium trifoliatobinatum, Heteropappus hispidus ssp. leptocladus, Bupleurum falcatum, Saussurea nipponica ssp. yoshinagae, Gymnaster pygmaeus, etc. 4. Though the pine forest on serpentine appears in general to be characterized by apparent initial stages from its physiognomical features, it can be regarded as an edaphic cllmax within the area of warm-temperate forest region.
Utilizing the mouth opening reaction of On comelania, its food taking activity was examined with feeding by various artificial materials. From the results of experiments it was revealed that the frequency of the food taking activity of Oncomelania depended upon the size of the particles of the feeding materials. When the size of the feeding materials was decreased the food taking activity appeared to be more accelerated. Generally speaking when fed with feeding materials of carbohydrate nature such as boiled rice, rice powder (glutinate and non glutinate) and wheat powder the food taking activity of snails became more vigorous. Chlorophyceae, diatomes and the soil of the habitat were also taken by them relatively good. The shell of the egg, dried small sardines and beancard refuses, however, were taken in high frequency when they were previously prepared as a fine powder. The food taking activity on liquid substances appeared to be closely related with their concentration.
Nach meiner pflanzensoziologischen Forschung Uber die Algen in Kagoshima habe ich in der Algengesellschaft Monostroma nitidum-Scytosiphon lomentarius Assoziationen entdeckt, In ihnen, wie sie die Tabelle 1 zeigt, sind Monostroma nitidum und Scytosiphon lomentarius die Vorzugsarten und wachsen teilweise auch Enteromorpha compressa, Petrospongiumg rugosum, Colpomenia sinuosa, Gymnogongrus flabe lliformis, Grateloupia filicina und Gloiopeltis furcata. Die abnlichen Assoziationen habe ichauch in Misumi in Provinz Kumamoto, Toyooka in Provinz Oita, Toba in Provinz Mie und Takeshima in Provinz Aichi gefunden.