The large twenty-eight spotted lady beetle, Epilachna vigintioctomaculata MOTSCHULSKY, was released in a small experimental potato field and their dispersion and movement were observed for several days. The results can be summarized as follows. (1) Those beetles which were released at the centre of a field of 50 square meters decreased in number day by day. Five days were needed to complete diffusive dispersion, and they scarcely emigrated to neighbouring potato fields. Two parts of this field were planted with one stem potato hills, two others were left without removal of weeds, one was shaded from sunlight, and the other parts were planted with potato hills of more than two stems. The beetles showed no significant difference in number though they were less in parts of the potato hill with one stem. (2) Some of the beetles were marked and released on the potato plants which were selected in different parts of the field. There beetles remained on the plants as long as four days. (3) Four batches of beetles painted with different colours were released into a field of about 50 square meters divided into four parts. They were found to mingle with each other, but their decrease was different in different parts as well as in different batches. Batches of the beetles which showed remarkable decrease in a certain part of the field, showed a similar decrease over the whole field. Luxiriously grown plants were found to harbour more beetles than poorly grown plants and the beetles were remarkably less in parts of poor growth. (4) When the air temperature attains about 20℃, beetles were observed to fly actively over the field, but the distance covered by single flight was short, generally being to the nearest plant. The direction of flight seems not to be affected by wind. The role of these behaviours was discussed with regard to the heterogenous distribution of the beetle in the field (IWATA, 1953). This beetle is rather lazy in movement and this seems to be explain heterogenous distribution. In the open field, the population of this beetle is high near the hibernating place, while it is low in more remote places.
Although it has been considered that the ground temperature and soil moisture are the most important elements among those which cause the change of living features of plants, the mutual relations between those elements and the life of the plant have not been clarified yet, because the problem is attended with such difficulties as follows : 1) There has been no accurate method to measure the state of soil moisture under natural conditions. 2) No one has hitherto succeeded to clarify the mutual relations between the changes of soil moisture and ground temperature under natural conditions. To solve the problem, the authors have devised an apparatus to record the soil moisture and ground temperature simultaneously (Figs. 1,2). Such an apparatus will play an important role to analyse the plant-environment relationships.
Comparative studies have been made on the pondsmelt, H pomesus olidus, in Lake Sinji and on certain other groups of fishes of the same species, which were transplanted from Lake Sinji to Lake Koyama (Tottori Pref.), Lake Senkari (Hyogo Pref.), Lake Miike (Miyazaki Pref.) and Lake Unagiike (Kagoshima Pref.). In the mentioned lakes the transplanted fishes have been subjected to various environments for twenty generations. The water temperature differed in lake during the early stage of development of the fishes. The salinity in Lake Koyama during that period is slightly higher than in the other lakes. For such reasons it was first presumed that the vertebral number of the fish may vary in each group, as in the cases studied so far by many investigators. However, the result of our studies revealed almost no difference in the vertebral number. Also no difference was found in the morphology, as reported by Dr. FUJITA (1926) who made a comparative study on the fishes in Lakes Kasumigaura and Suwa.
In this paper first are given an introduction and critical discussions to Cole's Index (COLE 1949), Goodall's Indicator Value (GOODALL 1953) and Goodall's objective method of grouping plant communities (GOODALL 1953), all of which are based on 2×2 table treatments of Statistics. The Index of Goodall's Indicator Value is modified by the writer so as to indicate it in a form of coefficient values (Equation 10 and 12,Table 18) between +1.00 and -1.00. However, when b (Table 2) is O and a (Table 2) is O, in spite of the figures of c and d (both in Table 2), the indices become +1.00 and -1.00. Therefore, to correct this point the writer gives other equations (Equation 13 and 14). The structure of the beech forests on Mt. Hiko is studied by means of those 2×2 table methods mentioned above. Fifty-four sample plot areas, 15m×15m in size, are obtained at almost random from the beech forest area at altitudes of 840-1150m on Mt. Hiko, considering significantly such a relief factor of environmental complex as peak, slope, ridge and ravine. More than 100 species are recorded in 54 quadrats, from which are selected 24 major species having frequency values of more than 20% and mean values of cover of more than 0.3 by means of Braun-Blanquet's total estimation method, and moreover including some species which locally predominate over the others within each orographical area. X^2 values of those major component species are shown in Table 3,with their values of Cole's Index in Fig. 1,and in Table 4 (Index of the degree of Habitat Segregation) and Table 5 (Index of the degree of Joint Occurrence). Following Goodall's method (GOODALL 1953), four different procedures of grouping plant communities are performed, which are shown in Tables 6,8,10,and 12. In consequence, four different kinds of plant communities are distinguished from each other in the stand of Sasamorpheto-Fagetum crenatae of Mt. Hiko ; the Sasa nipponica group, Rhododendron Metternichii group, Fagus crenata group and Fraxinus Spaethiana group, and it seems to the writer that each group corresponds to "Facies" in the concept of BRAUNBLANQUET. The Sasa nipponica facies is developed on ridges near peaks (1030-1150m alt.), Rhododendron Metternichii facies on and near ridges (960-1140m alt.), Fraxinus Spaethiana facies in and near ravines (880-1040m alt.), and Fagus crenata genuine-facies almost everywhere in the area (840-1110m alt.) regardless of such a relief condition (Table 19).
1. The midge, Telmatogeton japonicus TOKUNAGA, inhabits on the rocky sea-shore near Karo, Tottori City. We studied the daily rhythmic activity of this midge, with special reference to its swarming in the early morning and evening. 2. Observations were made in the early spring of 1952. In the early morning, after sunrise they creep out from their resting place of the night in the crevices of rocks. On the rock surfaces they walk at first slowly; then, as the day progresses and the solar illumination increases to about 500 Lux, begin to fly in mass, and move towards the island, getting on the "sea wind" blowing at that time, where they pass through the daytime feeding on various microorganisms. In the evening activities of midges decrease with the lowering of solar illumination, and as soon as the "land wind" begins to blow, they get on it and begin their evening mass flight to the nocturnal resting place. 3. The daily rhythmic activities seem to be controlled chiefly by the solar illumination, and other climatic elements in the morning or evening may have only secondary meanings. 4. As mentioned above, the animals utilize the sea or land wind only when they attempt to take the morning or evening journey, whereas these winds are blowing from time to time throughout the day. This fact seems to reveal that the wind is taken as the effective factor by the animals through their subjective response, not through the mere objective action of the wind, as stated by MORI ('52).
To study the drought resistance of the mulberry trees, an investigation was made on the specific gravity of the mesophyll tissue powder and the results were as follows. (1) The changes of the specific gravity of the mesophyll tissue powder according to the leaf position on the shoot and also on the one-year-old stem were studied. The value was at the highest on top, getting smaller at the middle while it tended gradually to get higher at the lowest again. When comparison was made at the same leaf order between the races of strong drought resistance it was found as in all cases that the strong ones show more remarkable values than the weak ones, at the various leaf order. (2) A comparison was made between the mulberry leaves on the one-year-old stem of seven races of Morus bombycis (KOIDZ) and those of ten races of Morus al'a (LINN) and those of eight races of Morus latifolia (POIRAT). Sampling of the leaves were made according the morphological basis, that is coloring of lenticels of petioler base and color and shape of their axillary buds. In all cases with few exceptions, the drought hardier races had always greater specific gravity of the mesophyll tissue powder than less hard races. (3) The same relationship between the specific gravity of the mesophyll tissue powder and the drought resistance were obtained in case of the comparison of mulberry trees cultured under different manuring conditions, if the sampling was made according to the same basis mentioned above. (4) Summarizing the above mentioned results. We can conclude that the more drought resistance races of mulberry trees have higher specific gravity of the mesophyll tissue powder than the less drought resistance ones, accordingly the increased dry matter content in the mesophyll of the leaves is supposed to correlate with the higher water holding capacity of the leaves. Sampling the leaves of mulberry trees which are different in growth condition, is found to be done under morphological basis, utilizing the coloring condition of the lenticels of petioler base and axillary buds of leaves.
The breeding season of the green frog (Rhacophorous schlegelii var. arborea OKADA et KAWANO) begins at the end of May and terminates at the begining of July in the Kanazawa district. In this season, the frogs are found on trees and under stones near ponds. The following observations were performed at four ponds which are situated on the campus of the Kanazawa University. The frogs were tagged with vinyl string of various colours or wire ring to facilitate the individual difference. Observation reveals (1) that the frogs did not migrate from pond to pond during the breeding season, (2) that each frog remained near the pond no longer than several hours each day, and then retired under stones or decayed woods, and (3) that the same male came out several times within 8 to 18 days after its first arrival. The shortest distance between the ponds is about 70 metres. The pattern of emergence of the frogs was observed mainly at the fourth pond. The number of frogs appearing during the breeding season showed three peaks, the first peak occurred from the 8th to the 10th of June, the second from the 13th to the 18th, the third from the 24th to the 27th of the same month. As shown in Fig. 3,this roughly corresponds to the meteorological conditions. In cloudy or rainy days some of the frogs were found throughout the daytime. When the weather was fine, the frogs were seen very rarely, while they come out abundantly in the cloudy or rainy day; on these days the humidity was very high (90-100%). The illumination intensity, therefore, seems to be related to this behaviour. This is also shown from the fact that the frogs were more abundant in the morning and the evening than in other times of the day even in the cloudy or rainy day. To reveal the fluctuation of the frogs which come into sight newly again during the season, the season was divided into five periods, each of 7 days, and the total number of frogs during each period were divided by the number of observations. The average obtained is shown in Fig. 5. The frequency of new individual appearance was higher in the second one fifth of the breeding season, but then it decreased as the season advanced. As stated above, the frogs remained for 8 to 18 days near the pond, but the population was found to decrease day by day in the later half of the season.
It has been shown that soaking injury to seeds of the kidney bean, soy-bean, pea, rice, wheat, rye, and barley causes a change in the amount of water the seeds contained before soaking in water. The seeds which absorbed various amounts of water by placing in desiccators or moist chambers were soaked in tap water filtrated through the ion-exchange resin and kept at 25℃. for two to ten hours. At the termination of the soaking period the water was drained off and the seeds were placed for germination tests on moist filter papers in room temperature or in soil under greenhouse conditions. Dry-seeds showed a decrease in germination capacity as a result of soaking in water for several hours, but by increasing their water contents in the moist chamber, they showed normal germination after the soaking process. Therefore, the harmful effect to dry-seeds is not by dry treatment but by soaking in water. Seeds of the kidney bean and soy-bean having the water content less than 9.5-10.5 per cent showed a decrease in germination and in those with less than 4.5-5.5 per cent water could not perfectly tolerate for more than two hours of submergence in water at 25℃. There was no difference between the effect of soaking in water for two hours than that for four to ten hours. Soaking injury to dry-seeds commences at an early period of soaking in water. Dry-seeds showed cotyledonal-cracking as a result of soaking in water, but by increasing their water contents in the moist chamber, they showed no cracking after the soaking process. Dry-seed cracked during soaking in water for two hours. The rate of water absorption during soaking in water by dry-seeds was faster than that by the other seeds. From these experiments it seems likely that the soaking injury of dry-seeds occurs as a result of cracking of the seeds by rapid absorption of water during the soaking period.
1. The water-tunnels, which conduct the water from the dam to the power plant, are very often inhabited by a number of the net-spinning caddis-fly larvae, the nets and cases of which resist the water flow, so that the efficiency of the power plant is reduced more or less, sometimes by 10 to 20 per cent. 2. Herein is reported the case of the Kinbara Water Power Plant, Gifu Prefecture, where we found 4 species of net-spinning caddis-larvae : Hydropsyche ulmeri, Hydropsyche nakaharai, Stenopsyche griseipennis and Parastenopsyche sauteri, the first two being the principal inhabitants. 3. Besides, in the tunnel were found such water insects as : Rhyacophila yamanakensis, Paragnetina tinctipennis, Ephemerella trispina, Ephemerella nigra, Epeorus latifolium, Epeorus curvatulus, Protohermes grandis and Antocha sp. 4. Hydropsyche-larvae are devoured by Paragnetina tinctipennis, Rhyacophila yamanakensis and Prothohermes grandis. 5. The food relations in the community are shown in fig. 4. 6. In this tunnel the Hydropsyche cases were made mostly of plant fragments (fragments of leaves, stalks, halms, tendrils etc.). It is advisable not to let these fragments flow into the tunnel. 7. The most promising way to prevent the attaching of the Hydropsyche larvae to the tunnel wall is to apply paints containing some insecticides.
The emigration of the larvae of the almond moth, Ephestia cautella from their food (rice bran) to the food which is renewed each day was observed in relation to their population densities under the experimentally controlled condition of 30℃ and 70 per cent R.H. The emigration in the larval stage of this moth can be divided into two separate parts. The first one arose in the immature larval stage (Fig. 1A), and it may be due to the shortage of the food and to the interaction between larval individuals. The rate of it at this stage, relatively as well as absolutely, increased with the increase of the initial density. However, the emigrants were rarely found in sparse population below a certain point of density (Fig. 2). Another sort of emigration arose in the full grown larvae (Fig. 1B) which walks about in searching a site for pupation. The rate of it was also low in the sparse population corresponding to the number of the remainders. It increases remarkably with the increase of density and then above a certain point of density it diminishes (Fig. 2). With increasing density the number of individuals which remained in the ruined food decreases in its percent in all stages of larvae (Fig. 4) but in absolute value it reaches to a maximum at an intermediate density (Table 1). With the increase of initial density (x) the head width of the adult (y) becomes small. In a relatively sparse population this decreasing trend can be followed by the auther's previous paper^<6)> where a and b are specific constants. Beyond a certain point of density the decreasing trend of the head width is relieved and it should approach to a certain level of value (Fig. 3). This shows that the density effect is operated by food in each density even though the larvae are able to emigrate. The availability of food which is measured by the number of emerged moths is remarkably high in this case comparing to the case when the larvae can not emigrate (Fig. 5). This is caused by the fact that some individuals in a population emigrate to the outside to reduce the larval mortality of the remainder.