It is well known that the larvae of the cabbage armyworm, Mamestra brassicae take mass-migrations from their original habitat to other food plants when they outbreak. It is the main purpose of this experiment to ascertain whether there are any noticeable characteristics in the adaptability of larvae which were reared under solitary and crowded conditions encountering the food change in their developmental stages. 160 larvae were reared in solitary and 240 larvae in crowd of 10 individuals per vial under the condition controlled temperature at 25℃ and darkness. Young leaves of Chenopodium centrorubrum and Brassica oleracea, natural foods for the larvae, were used for their rearing. For the solitary and crowded larvae eight experimental cultures were prepared. In each culture the larvae were given Chenopodium or Brassica leaves at different larval instar, as shown in Fig. 1. Mortality of the solitary larvae depends almost entirely on the food plant given and the mortality caused by the food changes became higher as they received it in later developmental stages. Mortality of the crowded larvae, however, was not so strongly affected by the food plant in early iarval stages, and almost all of the final instar larvae survived on Chenopodium leaves after they had been reared on Brassica leaves in their preceding instars. Developmental velocity of the solitary larvae are affected by the kind of food plant at any time of their development. On the contrary, the developmental velocity of the crowded larvae was not so strongly affected in youngr stages and also in the final instar, when they were reared on Chenopodium after feeding on Brassica in the preceding instars. In this case it was also a notable result that the larval duration was shorter in the crowded cultures than in the solitary ones. The body colour of the final instar larvae was affected by the larval density and also by the food plant. The tendency of darkening colour in the crowded culture was slightly intensified by changing the food, even if the alternation of food was done just before the final instar.
Das innere Kurobe-Gebiet befindet sich am Nord des Hida-Gebirges, wo man aus dem Vegetationsgefuge nicht nur die Charakter vom inneren Japan, sondern auch die typischen vertikalen Stufen des mitteljapanischen Hochlands erfinden kann, denn der subalpine Koniferenwaldgurtel entwickelt sich hier zwischen dem montanen Buchenwald und dem alpinen Zwergkiefergurtel. Der Tannenwaldgurtel ist von dem Abietion Mariesii, das auch Abies Veitchii LINDL., Picea hondoensis MAYR, und Tsuga diversifolia MAST. begleitet, reprasentiert. Die Assoziation entspricht dem Abietum Mariesii, dessen Hauptteil sich mit der Subassoziation rubetosum SUZ.-Tok. et MABDA identifizieren kann, aber an den windigen Standorten nahe an der Waldgrenze werden die typische Zusammensetzung und Struktur etwas zerstort, sodaB es mit dem Sorbus Matsumurana-Variant ersetzt wird. Die Dauerschneemasse wirkt wohl ihren Vorkommnis begrenzend. Man kann infolgedessen ein streichenartiges Zerbrechen des Tannenwaldgurtels auf Bergsseiten fernsehen. Der Mischwald von Thuja Standishii CARR. ist eine azonale Pflanzengesellschaft, die, obgleich die Hohenlage seines Vorkommens erniedrigt ist, gerade an der Waldgrenze vorkommt. Das ist vielleicht identisch mit dem Rhodoreto-Thujetum USUI aus dem Yunisi-Fluβgebiet. Die Frage, ob sie zum Verband des Chamaecyparidion zugehort oder ins Abietion Mariesii umgefaβt sei, fordert noch weitere Betrachtung. Die Birkenbestande von Betula Ermani, die sich auch azonal gerade unterhalb der Waldgrenze befinden, bilden hier eine gute Assoziation mit Euonymus tricarpus KOIDZ., Polystichum microclamys MATSUM., u.s.w. als Kennarten. Sie bilden eine Dauergesellschaft unter dem machtigen Schneedruck und dem dauernden Schnee. Sie unterscheiden sich standortlich als auch floristisch klar von den anderen Birkenbestanden, die man in den Gassan-und dem Ontake-Berg finden kann.
Distribution of Pieris rapae crucivora on every leaf of cabbage plant was investigated by the censuses on the eggs and larvae. The eggs were distributed densely on mature leaves located in the middle part of a plant and sparsely on senescent leaves in lower part of it, The death rate of eggs was nearly the same with every leaf, but deaths were significantly less in densely laid plants than in sparsely laid plants on young or mature leaves. After hatching, the larvae became to be distributed more densely on young leaves in upper part of a plant with larval growth. Their inter-leaves movement may be due to their preference of young leaves as their food. The distribution of the number of eggs per plant was concentrating on young and mature leaves, and these of larvae were random on young leaves and concentrating on mature leaves, and these of larvae were random on young leaves and concentrating on mature leaves through all the stages. From these facts, it seems that the inter-leaves movement of larvae regulates their uneven distribution.
In the present paper, a description is given of the vertical distribution of freshwater planarians in the Ishizuchi mountain range (the main peak, Mt. Ishizuchi, is 1920m in height) in Shikoku in the southwest Japan. The area surveyed is situated from Lat. 33°42′ N. to 33°50′ N. and from Long. 133°03′ E. to 133°11′ E. The surveys were made in July and October 1958. In the district, the two species of freshwater planarians, Dugesia gonocephala (DUGES) and Phagocata vivida (IJIMA et KABURAKI), were found, D. gonocephala had been collected in relatively warm rivers, creeks, brooks and brooklets below the altitude of about 1230 metres. This species is the most common Japanese planarian ; it was also found in the streams running through the plains and lower mountain districts in Shikoku. Ph. vivida was rather common in the cold-water biotopes within the altitude range from about 1000 to 1850 metres. The inhabitable water temperature range of D. gonocephala and Ph. vivida found in the Ishizuchi mountain range is as follows : D. gonocephala (10.8〜22.5℃) ; Ph. vivida (2.3〜16.1℃). They were found together where their inhabitable water temperature overlapped. The type of vertical distribution of the district is G-GV-V (G : D. gonocephala ; V : Ph. vivida). The biotopes are described in detail. No planarian was found in the localities which were polluted with toxic discharge of the abandoned Omori Copper Min (Nagose Valley and Kawaguchi Valley). The distribution of Ph. vivida in the southwest Japan is also described. It has been recorded only on the northern side of the demarcation line drawn from the Suzuka mountain range, Mt. Odaigawara and Mt. Koya in the Kinki Region in Honshu to the Ishizuchi mountain range in Shikoku and Mt. Sobo in Kyushu.
The authors carried out some investigations on the population of soil invertebrates inhabiting in the litter and the soil under the fir (Abies firma), cryptomeria (Cryptomeria japonica), red pine (Pinus densiflora) and the mixed broad leaf (Carpinus and Quercus dominantly) forest in the vicinity of Kyoto, from December 1961 to October 1962. Five plots of square 20 cm were selected from each forest and these plots were divided into vertically litter (A_0) layer, soil surface layer (0〜5 cm in depth) and soil layer (5〜10 cm). The fauna was extracted from each sample by TULLGRBN funnel apparatus. Mollusca, Annelida and Arthropoda were extracted, but the major parts were occupied by Arthropoda, especially, the number of spring-tails (Collembola) and mites (Acarina) was enormous. The population number decreased as in the following order ; the red pine, fir, mixed broad leaf and the cryptomeria forest. The fluctuation in the whole population number was due mainly to that of Collembola and Acarina, and it was minimum in February, thereafter it came to a peak in June, decreased in August, and reached a peak again in October. 70〜85 per cent of the fauna was collected in the litter layer, the remaining decreased with depth of soil. In the macrofauna, Diplopoda, Araneina, Cheriferidae, Protura, Thysanoptera and Lepidoptera were mostly collected from litter layer, Oligochaeta, Chilopoda, Coleoptera, Formicidae and Diptera were collected from both litter and soil layer, but Thysanura was collected from soil layer alone.
From the examination on the specimens collected from three lakes and 20 ponds, it was considered that Tukugobius flumineus is not able to inhabit in lakes and ponds. This consideration was corroborated by the examination on the specimens collected in Sarutani Reservoir as well as in Lake Suwa-ko. In a river, as has previously been reported, this fish inhabits mainly in the tributaries or in the middle and upper courses of main streams, while in the middle and lower courses, Rhinogobius brunneus is generally abundant. It was newly added in this report that also in a tributary flowing into lakes of high altitude, above-mentioned situations were presented again. Only by way of reference, the author wishes to touch upon next matters which were previously reported by the same author. R. brunneus spawns a great number of small eggs, from which swimming larvae hatch, and send amphidromous or lacustrine life. On the contrary, T. flumineus spawns a small number of large eggs, in which their swimming stages are passed, and spend fluvial life. Though they are certainly distinguishable externally by the number of pectoral fin rays, they are considered to be closely related.
Two moors called "Oseyachi" (about 1200m above sea level) and "Oyachi" (900m) lie in the South Hakkoda Mountains. The peat samples obtained from the moors were studied pollen-analytically. From the pollen sequences in the profiles of the moors three stages were recognized for the profiles successively from the surface to the bottom. 1 A'ies-Fagus stage (the first peat layer) 2 Fagus stage (the middle peat layer) 3 Abies-Betula stage (the third peat layer) Abies-Fagus stage is characterized by the gradual increase of conifers and also by the decrease of Fagus. The Fagus stage is distinguished by the marked expansion of Fagus and the Abies-Betula stage by the dominance of Abies and Betula. The results of the present study are quite similar to those of Takadayachi moor in the North Hakkoda Mountains. Therefore, the first and second peat layers of Oseyachi and Oyachi may correspond to Nakamura's Period R III and R II respectively, and the third peat layer probably dates back to a cold age, Period R I-II or R I.