Supplementary observations on the cleaning behaviors of L. dimidiatus were studied in small tanks of the Suma Aquarium and in the open sea. 1) In this research also, as in the previous report, almost all the fishes having the same geographical and ecological distribution as L. dimidiatus displayed the requesting behavior to the wrasse. 2) Requesting behaviors were immediately shown by the fishes isolated from L. dimidiatus for more than two years and also by the young fishes which might not be encounter with the wrasse after hatching. 3) It may be concluded that requesting display of many rocky and coral reef fishes to L. dimidiatus has been now developed to a instinctive nature.
The marine algal communities along the coast of Izura, Kita-Ibaraki City, Ibaraki Prefecture, were studied from January 1961 to January 1962 and also from March 1967 to August 1969. As the result, the Hixikia fusiforme-Eisenia bicyclis association was bound to be distributed dominantly along the exposed shore of the coast. The Hizikia fusiforme-Eisenia bicyclis association is a typical community of Japan on the open sea coast of the Pacific Ocean. This fact was already found by TANIGUCHI (1965) on the coasts of Fukushima Prefecture, Boso, Miura, Izu, Atsumi, Shima and Kii Peninsulas, and the eastern and western coasts of Kyushu, etc. This association consists of two distinct belts : the Hizikia fusiforme upper belt and the Eisenia bicyclis lower belt. In the community of a sheltered shore, the Hizikia fusiforme-Eisenia bicyclis association is not separated distinctly into two belts and many other algal species are found in it. The difference found in the local communities is caused by wave action. The writer has newly observed that Gigartina intermedia and Sargassum sagamianum oum in the Hizikia fusiforme-Eisenia bicyclis association, and that the Ishige okamurai-and Ishige sinicola communities are not found along this coast.
The actions of a natural enemy on the equilibrium population of a pest insect, especially on the height of the population level and the shape of the population fluctuation, were studied experimentally using the almond moth, Cadra cautella WALKER, and its parasitic wasp, Exidechthis canescens GRAVENHORST. A serrated fluctuation of the host population was observed with an interval of about 37 days, which corresponds to an approximate length of a host generation, both in the single host system and the host-parasite interacting system. An average level of population density was stable in the single host system, while the population fluctuated with an interval of about 3 generations of the host in the interacting system. Food, rice bran, was less consumed by the host larvae in the interacting system than the single host system. Increased host finding ability of the wasp resulted in the increased amplitude of population fluctuation of the host and parasite and in the decreased food consumption by the host larvae. It was clarified, however, that the population in the host-parasite interacting system was regulated through the density effect of the host itself as well as through the effect of the interaction between the host and parasite. Through an analysis of UTIDA'S data on the system involving the azuki bean weevil, Callosobruchus chinensis, and its parasite, Anisopteromalus calandrae, it was demonstrated that the S-shaped functional response of the parasite to host density (B-type of HOLLING, 1961) was undetectable in his host-parasite interacting system. However, the possibility of the operation of the S-shaped functional response was noticed in the system of the almond moth and its parasite dealt with by the present writer. From this point of view the population regulation in the experimental system was considered as a model of natural insect populations.
To assess the amounts of light intercepted by leaves and stems separately, light profiles before and after artificial defoliation were observed in some pure communities of the weed, dwarf bamboo and shrub, and correlated with the vertical distributions of various leaf and stem dimensions such as leaf area index (LAI), stem surface area index (SAI), cross-sectional area of stems, etc. The total LAI and SAI in the communities were 3.1〜8.4m^2/m^2 and 1.6〜2.7m^2/m^2 respectively. Observed values of the relative light intensity at a given height z in a plant community before defoliation or I(z)/I_0 and that after defoliation or I_c(z)/I_0 led to the estimate of the relative amount of light intercepted by the leaves alone, I(z)/I_c. Both I(z)/I_0 and I(z)/I_c were found to depend upon the cumulative LAI above z-height or F(z), following the Beer-Lambert's law, viz. I/I_0=exp(-KF) and I/I_c=exp(-K_FF). On the other hand, stems alone intercepted 28〜69 per cent of the total incident light, and I_c(z)/I_0 was most closely correlated with the summed area of the stem cross sections at z-height, A(z), viz. I_c/I_0=exp (-K_cA). Based on these correlations, it was concluded that the three coefficients of light extinction, K, K_F and K_c were interrelated according to the formula, K=K_F+aK_c, which reasonably explained the role of the leaves and stems in the interception of light in terrestrial plant communities.
Der Gehalt an Kieselsaure und Kalzium in den Blattern der dominantartigen Laubbaume in allen Sehichten wurde aus einem immergrunen Eichenbestand, einem sommergrunen Eichenniederwald und einer Lespedexa-Arundinaria Weide wahrend der vegetativen Periode im Jahr 1968 viermal quantitiv analysiert. Die immergrunen Baume, Machilus thunbergii, Cyclobalanopsis glauca, Eurya japonica, die Waldbodenpflanzen, Ophiopogon japonicus und Lespedeza cyrtobotrya aus der Weide haben einen hoheren Gehalt an Kalzium als 2%. Aber die Wiesengramineen, Miscanthus sinensis und Arundinaria pygmaea mit Pteridium aqilinum, enthalten wenig Kalzium (minder als 1%) und viel Kieselsaure (mehr als 5%). Deswegen liefern immergrune Laubstreuen dem Boden mehr Kalzium als die anderen, so daB die Entbasung aus dem Bodenoberflachenhorizont vermindert werden kann. Die Wiesengraser und Adlerfarne konnen dagegen dem Boden wenig Kalzium zuruckgeben. Ob die Kieselsaure gleich als eine elementare unentbehrliche Nahrung fur Pflanzenwuchs nicht mitzuzahlen ist, mag jene doch wenigstens in einigen Pflanzen wie Gramineen an der Befestigung des oberirdischen Pflanzenkorpers teilnehmen. Es ist auch beachtenswert, daB die oft auf windigen Graten oder Felswanden bestehenden und mechanisch starkeren AuBenkraften ertra-genden Eichenarten mehr Kieselsaure als die Talbewohner wie die holzigen und krautigen Arten der untenliegenden Schichten, die nicht so groBer mechanischer Festigkeit bedarfen, enthalten.
The rate of litterfall in forests is usually estimated by means of litter trays, which are emptied at certain time intervals to measure the amount of accumulating litter. However, litter may be subject to considerable loss of its weight while remaining in the trays as the result of leaching, microbial decomposition and feeding by animals, so that the amount of litter accumulated at the end of an interval is likely to be an underestimate of the actual amount of litterfall during the period. To estimate the actual litterfall rate from the apparent litter accumulation rate, a correction factor based on a simple mathematical model was proposed, and appropriate time intervals for emptying the litter trays were suggested for different rates of leaf litter breakdown.
A hydrobiological survey was carried out in two lakelets in the Shimokita lake group, Lake Usori-ko and River Ohata in the Shimokita Peninsula at the northernmost part of Honshu, Japan. Lakelet Akagawa-numa, Tate-numa and Caldera Usori-ko are respectively eutrophic, dystrophic and acidotrophic. Their planktological characteristics correspond to their limnological designations. The phytoplankton are rich in Lakelet Akagawa-numa, on the other hand in Lakelet Tate-numa the phyto-and zooplankton are poor not only quantitatively, but qualitatively, and some species of Chlorophyceae are characteristic to the moor, Pediastrum or Hyalotheca are dominant. Lake Usori-ko contains strong acid water due to sulphuric acid ion and the phytoplankton is scanty but zooplankton is rather rich. The lake bottom is covered almost by the vegetation of the water moss Leptodictyum riparium, which plays an important role in basic biotic production. Only one fish species, Tribolodon hakonensis, inhabits the caldera lake ; it takes Asellus, insect larvae and Macrocyclops as food. River Ohata is one of the so-called natural rivers, it shows no pollution or human impact. Twenty-four species and 2 ecotypes of fish inhabit the river, especially"suginoko"an ecotype of the land-locked cherry salmon Onhorhyncus masou, is found throughout the year in the upper water area more than the habitat of Salvelinus pulvius.