When fishes are instinctively aggregated in a water trough, it may be presumed that the some limited distance is always kept between them, although their relative positions vary every moment. In this paper, the average area occupied by aggregated individuals of the Japanese minnow is studied, and the results thus far obtained are summarized as follows. 1) When the fishes are arranged in a lengthwise series, the average distance between them is kept at about 3 cm. 2) When the fishes are arranged transversely, the distance between the axes of them is kept at about 2 cm.
1. In a volcanic district such as in Japan, there is a tendency of high moors developing on the upland of the mountain slopes. Genshi-ga-hara moor is considered to be such a case. This moor is located halfway up Mt. Furano, one of the Tokachi Volcanic mountains in the Taisetsu-zan National Park in Hokkaido. 2. The wood invasions into the moor region consist of Picea Glehnii-Sasa senanensis, community and P. Glehnii-Betula Ermani var. communis community. It is assumed that the succession of the plant community arising from the "Verlanding" in this moor will be follows : Fotamogeton subsessilifolius-P. nipponicus comm.→Carex Michauxiana-Rhynchospora alba comm.→Molinia japonica-C. Tsuishikarensis [table] 3. In this moor district there are 89 swamps of more than two meters in diameter, and most of these are the nourishing-type, thus suggesting that the whole process of "Verlanding" in the moor is rather fast. 4. The air, soil surface and the soil temperatures (at 10 cm and at 30 cm) are measured both inside the moor and in the wood invasions. The results are : a. The air temperature has no significant differences between the two places, showing that in the wood the temperature is 0.5℃ lower in the day-time, on the contrary at night it is 1.3℃ higher than that in the moor. b. The soil surface temperature in the moor is higher than in the wood, but the temperature in Sphagnum Girgensohnii and S. pulchrum growing places is lower than that in the wood. c. As to the soil temperature, the temperatures both at 10 cm and at 30 cm depth in the wood are lower than those in the moor. The temperature range at 10 cm depth is larger in the moor than in the wood, but at 30 cm depth in the moor the temperature is smaller.
The present paper states the results of some observations on the function of the biotic factor to daily infestation of A. femoralis. (1) During night they rest quietly on the under sides of leaves of various tall plants standing by the feeding place. Their nocturnal resting place seems to be selected by their negative geotaxis. Therefore, as the crops such as cucumber grow taller, the number of insects remaining throughout night at the diurnal feeding place become larger. The dietary crops such as pumpkin which are trained to creep on the ground seem to have no value for this insect as a nocturnal resting place. (2) The values of dietary crops as food varies by species and growing stages. (3) Because various dietary crops have different values as food or as nocturnal resting place for A. femoralis, the pattern of the daily rhythmic activity of infestation exhibited in some crop fields is easily modified when other species of crops are cultivated in the adjoining furrows.
The climatic climax forest vegetation in the eastern part of Kochi Prefecture was investigated. In this district the average annual temperature is 16.9℃, and the annual rainfall amounts to 3451.8 mm. Therefore the evergreen broad-leaved forest is found as a climatic climax. The results of the vegetational survey of seven residual stands shown in Fig. 1 are given in Table 2. Though the dominant species in the 1st tree layer is Shiia cuspidata and not Sh. sieboldii, it is considered that these evergreen forests should be included in the Rapanaeto-Shiietum sieboldii Suz.-Tok. which is distributed all over southwestern Honshu, Shikoku, and Kyushu. In this district this association is characterized by such plants as Shiia cuspidata, Meliosma rigida, Elaeocarpus japonicus, Distyrium racemosum, Randia cochinchinensis, Mephitidia satsumensis, M. japonica, Cleyera ochnacea, Rapanaea neriifolia, Ilex integra, Bobua theophrastaefolia, B. prunifolia, B. lancifolia, B. glauca, Alpinia japonica, Rumohra aristata var. pseudoaristata, Dryopteris erythrosora, D. fuscipes, etc.
The time of emerging of Antheraea Yamamai G. and Antheraea pernyi G. is different from that of Bombyx mori. The time of emerging of these wild silkworms as shown in Tables 1 and 2. The emergence of A. Yamamai commences from about 6 o'clock in the evening, with its maximum occurrence between 9-11 o'clock at night, whence it begins to decrease rapidly. Consequently the number of emergence just before dawn is very few. The emergence of A. pernyi, however, begins almost about 4 o'clock in the afternoon and is in full swing between 6-8 o'clock in the evening, whereas those emerging after midnight are extremely few. Therefore A. pernyi is earlier than A. Yamamai not only in the time of starting emergence but also in the maximum epoch, not to speak of the terminal stage. Moreover the female is later in emergence than the male at large. One of the main causes of this nocturnal cooling being supposed to be light, the authors divided the pupae into two groups, one of which were put under natural conditions regarding light, viz. bright in the daytime and dark at night, and the other under reversed conditions, viz. dark in the daytime and bright at night ; the temperature was Rept at ca 25℃ throughout. Although the emergence occurs throughout the day, it concentrates in the evening hours as regards the former group, whereas as in the latter group, in the hours starting from morning and continuing throughout the daytime. This inversion of the vigorous epoch of emergence obviously reveals the inhibitory action of light on the Imaginal differentiation, but the facts of the daylong emergence as is statisticaly shown in Table 4 indicates the significant role of temperature on the occurrence as well. Hence it is presumable that the composite effect of light and temperature chiefly determines the time of emerging of A. Yamamai and A. pernyi, though the authors desire to scrutinize this point later.
To investigate the interval between emergence and copulation, 191 pairs of A, pernyi, 117 of A. Yamamai ♀×A. pernyi ♂, 122 of A. pernyi ♀×A. Yamamai ♂ and 74 pairs of A. Yamamai were observed in July of 1953,with the result that the copulation ratio of those pairs with male A. pernyi moths (the former two groups) were as many as 100% and those of the pairs with the male A. Yamamai were meagre, that is 100%, 100%, 62% and 28% in A. pernyi ♀×A. pernyi ♂, A. Yamamai ♀×A. pernyi ♂, A. yernyi ♂×A. Yamamai ♂ and A. Yamamai ♀×A. Yamamai ♂ respectively. The items were as follows : -(1) As regards A. pernyi ♀×A. pernyi ♂, the account was 81% in the night emergence and 19% in the successive night. (2) In A. Yamamai ♀×A. pernyi♂, 90% and 10% were in the first and in the second nights respectively. (3) Concerning A. pernyi ♂×A. Yamamai ♂, it is a noteworthy phenomenon that no copulation occourred in the very night of emergence, but 77%, 19% and 4% of the total copulation were in the second, the third and the fourth nights respectively. (4) As to A.Yamamai ♀×A. Yamamai ♂ also, no copulation was seen in the first night of emergence. Although it must be added that one of the authors has once witnessed a pair copulating in the first night, such a case is extremely rare. Among the scanty total ratio of this species, 81% belongs to the second night and 19% to the third night, whence no copulation is usually seen. The impotent moths then, needless to say, were dead without copulation. In short, A. pernyi copulates almost exclusively in the very night of emergence and slightly in the successive night, where as A. Yamamai does not copulate in the first night but in the second and the third nights. The copulation between different species is determined by the male moth, that is, the copulation between A. pernyi ♀×A. Yamamai ♂ is similiar to the pattern of A. Yamamai and that of A. Yamamai ♀×A. pernyi ♂ to A. pernyi's one.
In the present paper the ranges of following two pecies of hepatics are treated. 12. Calobryum rotundifolium (MITT.) SCHIFFN., cf. HORIKAWA 1951,Jour Sci. Hiroshima Univ. Ser. B, 2-6,11 This species was established by MITTEN as Scalia rotundifolia based upon specimens collected by the "Challenger" Expedition in Japan. The 52 packets of specimens of Calobryum rotuudifolium in our herbarium, were examined by the writer. In this paper the species will be published for the first time from the six Prefectures, Yamagata (1), Fukui (1), Nara (3), Tokushima (1), Fukuoka (3), Oita (1) and Island Tokunoshima (1), and new localities will be added to the Prefectures of Wakayama (2) and Kochi (1). Map 12 has been prepared based on 67 localities (14 of which are new additions and 53 were previously known). As shown in the map, the northernmost limit of the species in question lies at Haguroyama (38°43' L.N.) in Yamagata Prefecture and its southernmost limit is on Mt. Chippon (22°45' L.N.) in Formosa. The values of macrofrequency of this species in each districts are shown in Table 13. As seen in this table, the values of macrofrequency in the region from Formosa to S.W. Honshiu are generally equal, but those of M. Honshiu and N.E. Honshiu become suddenly smaller, in other words the distribution-fall is distinct between S.W. Honshiu and M. Honshiu. [Table] According to our present knowledge, the highest elevation of this species is on Mt. Hikosan in Kiushiu where it was found at 760m above sealevel and it may be said that this species grows in the evergreen broad-leaved tree zone. Geographic distribution. Japan, Liukius & Formosa.
This experiment was conducted at the ponds of Yamada, Kanki and of the Kiyotaki Hatchery of the Hyogo-Ken Fisheries Experiment Station. The writer observed the nocturnal behaviour of 15 species of fishes in comparison with the behaviour during the daytime by the method of marking the fish at the front of dorsal fin with a badge, coated with self luminous greenish colour paint. The result of the research is as follows : [Table]
1. The structure of weed communities of cultivated fields of Solanum tuberosum in Shiribeshi district, Hokkaido was surveyed during 1952 and 1953. 2. As a result or the investigation about 40 kinds of weeds were found. Commelina communis continues to occupy a dominant position from spring to autumn. However, Digitaria violascens, D. adscendens, and Polygonum nepalense, whose area occupied is comparatively small in spring, attains a high position, being next to Commelina communis from summer to autumn. 3. Commelina communis, Digitaria violascens, D. adsccendens, Polygonum nepalense, Rumex Acetosella, and Sonchus brachyotis, are the most harmful weeds in this district. These weeds greatly hinder the growth of the crops, and also necessitate great efforts in weeding.
We have investigated the coaction between individuals of the sand-crab, Scopimera globosa DE HAAN, observing their behavior and the distribution of nest-holes, on the shore of the inner part of Tanabe Bay during July, 1953 and 1954,and the following results were obtained. 1) This crab lives in the sandy flat between the lines of the lower high tide and the higher low tide. 2) Tidal rhythmicity seems to be most prominent in the activities of this crab. Diel activity is of less importance. 3) There were observed two kinds of fighting between individuals : one is the sudden attacking without apparent reason and the other is in defence of the nest-hole when other crabs approach it. 4) The home-ranges coincide with the feeding areas, which do not overlap each other. They feed on fragments of small animals and sea-weeds, and plankton organisms attached to fine sand grains. They devour them together with the sand and the sand grains are disgorged forming "sand-pellets". Three types of the distribution of the sand-pellets are distinguished according to the variation of the population density of the sandcrabs. In the case of low density, the sand-pellets show uniform distribution except towards other nest-holes. In the case of fairly high density, the sand-pellets distribute in the shape of narrow sectors radiating from the nest-holes. In the case of very high density, which is not found under natural conditions but is made only experimentally, fighting happens frequently, the feeding area is overlapped, and the sand-pellets show a very irregular distribution making two or three layers on the ground. Another type of distribution of the sand-pellets is observed when they are made during night. 5) During the ebb tide, some crabs exchange their nest-holes and some of others make new ones. If the deserted nest-holes are not occupied again, they are destroyed by the rising tide. With these processes the distribution or nest-holes seems to tend to become uniform. In the field experiments, in which the population density is made about three times higher than the original density, some crabs are driven away to reduce the population to its original number. On the contrary, if the area is cleared off, new crabs invade the area and the population reaches the original number. 6) Statistically, the distribution of nest-holes is different according to the population density. In the case of low density, in spite of the fact that the distribution of the nest-holes is near-random, the coaction between individuals is clearly observed in fightings and nest-hole changes. In the case of fairly high density, the distribution is far from random, conforming to the mode of negatively contagious, and, of course, the coaction above mentioned is clearly observed. These observations teach us that the mere application of a statistical method on the distribution of the nest-holes does not necessarily clarify the existence of coaction between individuals. 7) All of the coactions mentioned above seem to be caused mainly with relation to their feeding behavior.
1. A permanent quadrat of 1 sq. m. was laid in the abandoned farmland in the grounds of the Chiba University where a field experiment concerning the competition between crops and weeds was perfomed. The surface soil was cultivated, mixed, and weeded in January, 1953. There, the developmental process of a weed community was examined. 2. There, at first, appeared a herbaceous community dominated by Ambrosia artemisiaefolia which is often a pioneer plant in the bare area. After the death of the hog weed, the rosettes of Erigeron were found in abundance (Table 1). The hog weed was stratified into the upper and lower layers because of the divergence of the germinating period. It will be a kind of social adaptation (Fig. 1). 3. The combination of dominated life-form and migrule type according to the number of species Is Th-D_4-R_5,which is a usual type of weed communities in the farmland (Table 2). That according to the density is Th-D_1-R_5,which coincides with the first rank of the actual combinations (Table 3). In the growth form spectra (Table 4). the erect form and tufted growth exceed the rosette and prostrate form where the habitat is spatially segregated and especially the rosette plants are to dominate in the following year. 4. Concerning the organizing process of the weed community, the law of geometrical progression can be applied in August when the Ambrosia community of the aestival type arrived at the maximum development (Fig. 2). Such a linear relationship was not recognized before and after August. This is a balance of power relations among species in the form of seasonal aspection or early development. Then it is shown that there is an undulatory process of establishment and breaking in the organisation of a community. 5. The mean area of the commonnest species (M) is related closely with P (dominant ratio)=(number of individuals of the commonnest species)/(total number of individuals) and the gradient of a straight line showing the number of individuals-rank relationship (Table 8,9). The suitability of 2M as a sampling unit should be, in general, determined by the individual structure of a community, which is indicated partly by P and the gradient. The distribution type of the weed community was considered as the POLYA-EGGENEERGER type (Table 10).
1) Concerning a quantitative character of an animal community, the equilibrium among the species constituting it is expressed by MOTOMURA's law of geometrical progression in an animal community, which is written as logy=b_1-a(x-1), where y is the population density of each constituent species, x its order in magnitude, a and b_1 constants ; accordingly a and b_1 are indices for measuring the condition of this equilibrium. Moreover, a expresses the intensity of competition among species in the community, and b_1 is the logarithm of population density of the dominant species. 2) When a habitat is divided into several layers or quadrats, a quantitative relation among the layers can, in connection with each layer, be measured by the communality, h^2,induced from the matrix of correlation coefficients among the population densities of the species constituting the community in each layer by means of the method of factorial analysis. 3) Number of species in each layer is mainly related to a and b_1,and a numeral relation of the common species between layers is measured by the coefficient of closeness, p. As it is empirically proved that p is in a simple functional relation connected with d, which is the distance between the points given by sets of coefficients of the common factors induced from the matrix of correlation coefficients among the population densities of the constituent species, then the factors concerning the number of total species and of common species are contained within the facts of the above 1) and 2). 4) From the above facts it is recognized that a great part or quantitative characters in a community is measurable by the three indices, a, b_1,and h. Putting K to one of these indices, K to its mean value, n to the number of layers, σ^2_K=Σ(K-K)^2/n, and t=(K-K^^-)/σ_K, from the values of t for a, b_1 and h, the community coefficient, R, has been defined as follows : [numerical formula] and it signifies an ecological value representing a community of each layer. 5) R has been tested in practice with the Ostrea spinosa-community observed by MOTOMURA and the plankton community in a small pond observed by HAMAI and OSAWA, and good results have been obtained.