The island of Kunashiri is situated at the southernmost part of the Kurile Islands and is faced to the Shiretoko Peninsula by the Nemuro strait. The limnological surveys of the island were carried out by Viscount A. Tanaka and Prof. D. Miyadi and others during the summer of 1933 and 1934. The results of the explorations have already appeared in many papers chiefly in the Japanese Journal of Limnology, vol.3, 1934 and Internationale Revue der gesamten Hydrobiologie, vol.37, 1938. The materials of the present contribution were collected by Prof. D. Miyadi in the lakes of the island under consideration and their general aspects were reported by him from the limno-zoological standpoint, but the algae of those lakes are not reported as yet. The lakes of the island are divided chiefly into two parts geographically, one being situated at the side of the Nemuro strait (the Okhotsk Sea) and the other at the side of the Pacific. Most of them lie on the sea coast and are barried lakes formed by sand-dune.
There are some interesting species of phytoplankton in the lakes of the southwestern part of the island (south of 44° N. lat.). Staurastrum cingulum was the important constituent of the phytoplankton in the Lakes Tôhutu-ko and Nihon'iwaonneto, and Staurastrum dorsidentiferum var. ornatum was a remarkable planktont of Lake Tôhutu-ponto. These two species are not found as yet in large lakes of Hokkaido and the Tôhoku district except Lake Akan. These three lakes mentioned above and Lake Nikishoro-ko (all lie at the south of 44° n. latitude) are deeper among the lakes of Kunashiri and are fairly eutrophicated, showing a water-bloom by Anabaena flos-aquae, Microcystis aeruginosa, Coelosphaerium Kützingianum. Most of the small lakes in the northeastern part of the island are shallow in general, marshy-like, and are rich in desmids. The desmid-flora in the marshy lakes resembles that of Hokkaido, and not that of the island of Shinshiru. Only ten species are common to both the islands, 56 species of Kunashiri and 43 species of Shinshiru, but the survey of desmids in both the islands is not complete as yet. All the species of algae found each lake were listed in the present contribution.

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An antagonistic relationship between large rooted aquatic plants and phytoplankton has been long recognized intuitively and empirically according to the facts that even in eutrophic lakes the smaller the amount of rooted aquatic plants is, the larger the amount of phytoplankton or transparency of lake water becomes, and vice versa. This relationship must be an important factor in the course of hydrarch succession of lakes. In the present paper, the authors are going to clarify the antagonistic relationship objectively, and then to analyse the relationship experimentally. The main results obtained are as follows.
1. In some eutrophic lakes, the standing crop of rooted aquatic plants and phytoplankton were determined in the summer season when the maximum values were attained. The standing crop of phytoplankton was remarkably larger in Lake Suwako than in Lakes Tega-numa or Inba-numa, while the amount of rooted aquatic plants per unit surface in the former lake was smaller than in the latter lakes. Transparency was smaller in the former lake than in the latter lakes.
2. In a series of pot cultures with or without rooted aquatic plants of several kinds, such as Hydrilla verticillata var. Roxburghii, Vallisneria spiralis and Nymphoides indicum, the same phenonmena as seen in the lakes were also observed regardless of the difference in species.
3. The concentration of nutrient salts in the water of lakes and pot cultures was lower than that of minimum requirement of phytoplankton for normal growth. The fact that the growth of phytoplankton is inhibited by rooted aquatic plants in the initial stage of culture even under sufficient supply of nutrient salts, indicates that the antagonistic relationship mentioned above is not always resulted by the lowering of the nutrient factor. It was confirmed that the changes in underwater illumination and water temperature by rooted aquatic plants are not the main reason why the antagonistic relationship occurs.
4. A series of culture experiments of Chlorella sp. in the water of Lake Teganuma was carried out under the conditions of enriched or non-enriched nutrient salts and with or without heat-treatments at 125°C for 20 minutes. The results indicate that the lake water containes a substance inhibiting the growth of Chlorella, and moreover that the inhibition is lost easily by heat-treatment. The concentration of this substance seemed to decrease with the march of season, and no inhibiting effect was observed no longer in early winter.

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In the present paper are reported the following 12 groundwater species belonging to the Cyclopoid Copepoda which were collected in 16 localities, 9 driven wells and 2 limestone caves, “Akiyoshi-dô” and “Taisho-dô”, in various districts in the western part of Japan, such as Hyôgo, Wakayama, Yamaguchi and Kôchi Prefectures.

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“Okama” is the crater lake of the Zao Volcano. In this lake, the volcanic activity has often taken place in the historic time. The most recent one took place in 1939. The present investigation has been carried out with the aim at elucidating the geochemical and morphometrical features of the lake after the cessation of the last volcanic activity. The results are summarized as follows.
(1) This lake has a circular form as is shown by the bathymetric map (Fig. 2) in the text. Having been buried by the volcanic ash crumbling down from Mt. Goshiki-dake and the suspensions transported by the Goshiki-gawa River, the lake is now 27 meters in depth.
(2) The vertical stratification of temperature and chemical ingredients was investigated in summer, 1955. As the result, the development of two hypolimnions (B, D layers in Fig. 4) was found. As for the deeper hypolimnion (D layer), the relation between water temperature θ (°C) and depth z (m) is shown by the equation :
θ=1.81×10³exp (-0.164z).
The formation of the upper hypolimnion (B layer) is mainly due to the influx of cold water of the Goshiki-gawa.
(3) Judging from the seasonal change of the chemical composition of surface water, the lake water seems to be influenced by the incoming melt water during May and June.
(4) Recently the symptom of volcanic activity has not been recognized in this lake, but the water seems to be supplied with the matter intimately related with magma.

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1. Observations of plankton in Lake Nukabira in eastern Hokkaido, which was impounded as a reservoir in September 1955, were carried out five times during the period from 1957 to 1960.
2. Plankton species identified were nine both on October 26, 1957 and on July 25, 1958, twenty one on November 11, 1959 and twenty four on July 15, 1960.
3. The succession of the predominant species of plankton from year to year was as follows :
Synedra ulna→Asterionella formosa→Daphnia longispina→Asterionella formosa→Daphnia longispina→Dinobryon divergens→Mougeotia viridis8 months one year two years three years four years five years five years afterimpounding
4. The total number of plankton in the present lake is larger than that in other reservoirs, such as Lake Fusen (UÉNO, 1941, 1951; YAMAMOTO, 1941) and Lake Miure (YAMAGUTI & YAMAMOTO, 1958), and it is smaller than that of Lake Sagami (SHIRAISHI et al., 1953) and of Lake Arasawa (ABE et al., 1960).
5. Asterionella formosa and Daphnia longispina predominated by turns in the present lake for four years after being filled with water, instead of Dinobryon which usually occurs in artificial lakes.
6. The appearing of Polyphemus pediculus in 1960, which is a typical lake plankton, suggests that this lake is becoming similar in type to that of a large lake.
7. From general plankton association, this lake seems to be mesotrophy, but a vigorous thiving of Mougeotia viridis in monotonous composition in 1960 gave it an impression of oligotrophic nature.

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Having examined the precipitating process of plankton in the reservoir, there are found distinguished 2 types in summer, when it dies naturally or is killed by algicide.The first type has always the bulk of plankton at the depth of the thermocline during the decreasing process continues, as shown in fig. 1; and the second type has the considerable numbers of plankton, which descend slowly holding that condition until it reaches the bottom, as shown in fig. 3.
The first type is seen when the plankton of the epilimnion decreases, while the second type is seen when the plankton of the hypolimnion dies or when the plankton falls in the hypolimnion from the upper layers. The quantities of plankton sedimented in the beakers, which were set for experiments at various depths of the reservoir, were counted.
After the first type decreases, a considerable amount of plankton was counted in the uppermost beaker, suspended at a depth of 2.5m. Smaller and nearly the same numbers of plankton were counted in the beakers below the thermocline (fig. 2). It shows, therfore, that most of the plankton disappear in the epilimnion without precipitating toward the bottom.
On the other hand, the beakers contained more quantity of plankton as the depth for the test increased, after the second type decreases. And it shows, in this case, that the plankton actually precipitates itself toward the bottom.
Concerning the mechanisms of two types of the precipitation of plankton, I presume as follows :
The plankton in the epilimnion is transported to the shore of the reservoir due to the horizontal current which is caused by the wind over and over again, while it is prevented to fall down by the thermocline so far it precipitates itself toward the bottom there. Below the thermocline, however, the horizontal current is so weak that the plankton precipitates as if it does in the standing water.
The precipitation types mentioned above seem to be influenced by the constituent species of the plankton, because most of the second type consist mainly of Melosira or Cyclotella. They are characterized by the area/volume ratio smaller than the other diatoms (Table 1).

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The currents of lake water are very important in limnology, but the investigation for such problems had scarcely been carried out in this country.
About thirty-five years ago in Lake Biwa-ko, Shiga Prefecture, the greatest lake in Japan, measurements by EKMAN current meter had been obtained by the staff of Kobe Marine Observatory for the first time and a series of three swirls, anti-clockwise, clockwise and anti-clockwise were observed from north to southward.For generation of such a current system, they had pointed out the three local wind directions, south to southeast, depending on the topographical condition around the lake basin, but the existence of these swirls have not yet been ascertained.
In the summer season of 1960, we tried the drift-bottle experiments in Lake Biwa-ko to observe the surface current. On Aug. 12, we released 300 bottles from 6 stations, 5 of which stood on the cross line over the lake, and next time, on Sept. 2, 500 bottles from 14 stations on the longitudinal axis of the lake. The percentage of recovery was about 33% for the first time and 57% for the second. The distribution of drift-bottles recovered around the lake are tabulated in locality number and the frequency of recovery in each location as well as the drift time deduced from the time of recovery for the first bottle ashored are also described in the table.
In the first experiment, the bottles released from STs. I and II were recovered in various positions along the coast in the northern part of the lake, and the bottles from the Stations III to VI are recovered only at the west coast. In the second experiment, some of the bottles released from the Stations I-1 to II were recovered only at the southwest coast. Such drift current may be assumed to set up due to the lake water effluent to the Seta River in the southwest end of the lake. Some of the bottles released from the Stations III to VI were recovered only at the southeast coast in narrow range and the tendency appears contrary to the first experiment. Although the bottles released from the Stations VII to X were recovered at the southeast coast in comparatively wide range, none was recovered at the north or northwest coast, where many bottles had been recovered in the first experiment.
With reference to the wind direction at Hikone Meteorological Observatory, Locality No.9, on the east coast of the lake, it may be able to understand the difference between the both experimental results. In the first experiment, as the southeast wind was predominant, the drift-bottles had been flown nothward, but in the second time northwest wind was so predominant that the bottles could not easily flow northward.
Though such a wind drift may apparently be considered, the lapsed time from release to recovery of the bottles are enormously divergent, as in Figs. 4 and 5, which may deduce the counter-clockwise circulating currents in the northern part of the lake. Velocity of the currents may be estimated 510cm sec^-1 from these experiments.

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The Ishikari-gawa in Hokkaido is one of the big ten rivers in Japan. At the lower course of this river, there is a large area covered by confining stratum zone. In this report, the author gives classification of piestic water and its distributional area, as well as the relationship between piestic water and geology of that area.

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In this paper the author has discussed the scientific validity of B.W. SKVORTZOW'S paper “Diatoms from Biwa Lake” (1936), and has summarized the results hitherto obtained from his analytical studies of diatom shells found in the bottom deposits of Lake Biwa-ko and its neighbouring lakelets.

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Waku-ike is a striking salt-water lake which was formed during the landslides caused by the great Zenkôji Earthquake on May 8, 1847, in the northern part of Nagano Prefecture. The writer, having visited the lake three times in 1954 and 1956 respectively and once in 1960, investigated chemical and physical characters and plankton of that lake. The results obtained are as follows :
1) The maximum temperature and the pH values of surface water increased in summer and decreased in autumn, of both 1954 and 1956.
2) The metalimnion developed in the layers 12 meters deep in August 1960; the water temperature varied from 22.8°C in the upper layer to 10.3°C in the lower layer; the pH values ranged from 8.2 to 7.2; the dissolved oxygen of the surface layer was 154%, but the layer below the depth of metalimnion was anaerobic.
The surface water contained only a trace of hydrogen sulphide, but the water from the depth of 2m to the bottom contained as much as 13.614.8mg/l H₂S, where a sulphur bacteria, Chromatium sp. abounded in large amount.
3) The plankton consisted of 24 species, of which 17 were the phytoplankters and 7 were the zooplankters. The dominant species of plankton were as follows :
Anabaenopsis Raciborskii
Nitzschia sp.
Brachionus calyciflorus var. amphiceros
4) In this lake we have seen a phenomenon called “Mizukawari”, which means the suden change of water colour from dark green to yellowish brown, with the death of a large number of freshwater fish inhabiting there. It is considered that this phenomenon of “Mizukawari”is caused by some sudden changer of circumstances in autumn circulation period.

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A linear correlation among temperature and chemical elements of hot spring group suggests that two water systems mix with each other, one being normal cold ground water and the other hot spring water. But the chemical element is not always the character of hot spring water itself, as Cl ion of Atami hot springs, and that of Ibusuki hot springs. When the graph distributes areally, some two hot spring water systems are suggested to exist, but in a hot spring district, the systems more than one hot spring origin are not to be expected, except connate water. Some different types of chemical elements will appear by fractional distilation from the only one hot spring origin.

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Ground water temperature has no relation to the depth, where the water flow speed is so rapid that the water can not be heated with the normal earth temperature gradient and the thermal conductivity. Such a case is seen in the ground water in the northern part of Shimabara City alluvial fan. Where there is hot spring water in the deep formation, the upper layer has a sharp temperature gradient. The temperature gradient in the hot spring layer is almost gentle, which claims there the vertual conductivity, from heat balance rule. Where the deeper layer has constant temperature, it can be explained by the hot water flowing upwards vertically. The negative temperature gradient suggests the constant seepage of lower temperature water. The relation of depth and temperature being not linear, suggests that there is some heat generation or sink. But there can not be expected such facts, so it may be caused by the upwards leakage of hot water through crevices, and flowing horizontally.

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While echo-sounder has been used in finding fish-school as well as in the sounding of depth of water, this instrument will also be able to use for other various fields of scientific study in water. For example, in limnological works, not only measurements of lake basin and thickness of lake deposits but also the judgement for the nature of deposits, sandy or muddy, will be able by an echo-sounder. Especially in hydrobiology, distribution and vertical migration of plankton as well as the distribution of water weeds can be examined. Moreover, in relation to hydrology, it will be effectively used for researches of the state of contact of two water-masses and thermocline as well as other physical phenomena such as current and wave in lakes and reservoirs. Finally, it will also be used to examine the distribution of methane and turbidity in water.
In conclusion, the present author believes that echo-sounder will increasingly be applied to the all features of limnological researches.

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We have made a geological survey and the investigation of the quality of water in the limonite bed area and its neighborhood that lie near the Inago mineral spring at the town of Komi, Minami-saku county, at the eastern foot of Mt. Yatsugatake, in Nagano prefecture.
1. This limonite bed at Inago lies in the hillside where the Ôtsuki River has dissected the slope of the Yatugatake Volcano. Its bed-rock consists of tuff-breccia, on which basalic andesite, two-pyroxene-andesite and dasite lie one upon another.
2. The constituents of the mineral bed was derived from the two-pyroxene-andesite, iron of which was dissolved by underground water and springed up as mineral spring, and was consequently piled up on the surface of the earth. The mineral bed is only a small scale, 300m long, 5m wide, and 20cm200cm thick.
3. The standing water as well as the spring water in the mineral bed area show the pH values lower than the head water of the Ôtsuki River, but are more abundant in the amount of sulphuric acid. There are, however, only a little influence upon the main course of river, because the quantity of water run off from this mineral bed is so little.
4. The pH value is not always proportional to the amount of sulphuric acid, the former being often higher when the latter increases. The pH of water in this area becomes lower when left as it is.
5. The water in this area contains Ca²+ and Mg²+ greater in quantity than that of other rivers and springs.

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The Mogami River, which rises from Mt. Azuma, receives at Terazu of Tendo City a strong acid water river the Sukawa rising from Zao Spa. (the Mogami pH 7.1, the Sukawa pH 3.8). As the consequence, the ample water of the Mogami River is polluted into an acid water. I examind the mixing mechanism of different waters after the conflux of both the rivers. The results obtained are shown in the tables and diagrams.
1) The waters of both the rivers do not mix easily before they come to the Murayama Bridge 3.4km down from the junction of two rivers.
2) The distribution of pH (fig. 5) shows that it is closely related to the topography of the course of the river as shown in Fig. 1.
3) From the results of analysis, it is able to find the pumping places of water suitable for industrial and irrigation purposes.

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1. The seasonal variations of the zoospores of aquatic fungi were studied from July 1955 to June 1956 in Senshun-ike Pond, Tokyo, Japan.
2. The amounts of the zoospores of aquatic fungi varied seasonally with two maxima and two minima. The maxima appeared in spring and autumn, and the minima appeared in summer and winter. The zoospores were counted 911/10cc in the maximum peridos and 32/10cc in the minimum periods. The water temperature of both maximum periods were 1520°C and 912°C respectively.
3. Ten species were isolated from Senshun-ike. They showed different seasonal changes. Achlya flagellata and Pythium sp. were seen throughout a year, while Achlya racemosa and Apodachlya brachynema were obtained only in winter. Aphanomyces laevis and Saprolegnia sp. prefered to the high temperature season.
4. The production of the zoospores of aquatic fungi was much influenced by the water temperature as well as by the prosperity and decay of lacustrine bacteria.The temperature curve was drown from the data obtained at Senshun-ike Pond. The curve showed that the production of the zoospores took place by the step wise with the rise of the water temperature.
5. The optimum temperature for the formation of the zoospores in some species was as follows:
Saprolegnia monoica 318°C
Achlya racemosa 312°C
Achlya flagellata 921°C
Aphanomyces laevis 1518°C
Apodachlya brachynema 45°C

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We studied the exuviae of aquatic insects flowing down the stream at some stations of the two rivers, Yuragawa and Yoshinogawa.
The exuviae of Ephemeroptera and Chironomidae showed a considerably high percentage.
We found only a few exuviae of Trichoptera, although there lived a large number of larvae of this group in the stream. The reason may be : (1) The larval exuviae of Trichoptera seem to become to pieces easily. (2) Most species of Trichoptera live in their cases in which they cast their skins, so that they have less chances to be washed down in the water.
Nevertheless, the stations of the stream, where many insects inhabit, we can find many flowing exuviae. Therefore, we can probably use the quantities of flowing exuviae as rough indicators of the productivity of aquatic insects in the stream.

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Reviews on the cyclic fluctuation of land water level due to drought, transport of dissolved chemical substances, sedimentation in river and estuary &c with some discussions were presented. Boundary problems linked to limnology and oceanography are stressed.

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The small daphnid inhabiting the two alpine lakes, Mikuri-ga-iké and Midoriga-iké, which lie at an elevation of 2405m. and 2430m. respectively on Mt. Tatéyama, is identical with Daphnia ambigua SCOURFIELD, by the characteristics of the post-abdominal claws and the male antennules as well as in having a short shellspine. When the writers visited those lakes on October 6th, 1960, both the populations of that species yielded a great number of the males and the females carrying ephippial eggs. In Mikuri-ga-iké, the deeper one of the two lakes and having 14.5m. in greatest depth, most individuals were seen at the layer 4m. deep, where the temperature of water was 10.3°C. Dinobryon was found in the digestive truct of Daphnia in both the lakes, although it was uncertain whether Daphnia was able to use this alga as food or not. It is noticeable that both the populations of Daphnia were markedly red-coloured, probably due to the increase of haemoglobin. Red colour was remarkable in the population of Lake Midori-ga-iké, a. shallow body of humose water east of Lake Mikuri-ga-iké. Some limnological characteristics of these two alpine lakes are discussed in showing the nature of the habitats of Daphnia ambigua.

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The water colors of goldfish ponds consist almost of vegetable color derived from phytoplankton or phytoneuston. As almost these colors are derived from the lights reflected by algal cells occurring in the pond waters, they may be said to be certain surface color chromatologically.
To measure the vegetable color, there are only two methods, the one being YAMAZAKI-WATANABE'S method which uses the MAXWELL'S principle of color mixture and the other NAKAMURA'S method using the MUNSELL Book of Color.
The author improved the previous method as the following manner.
(1) In the YAMAZAKI-WATANABE'S method, if we want to change the proportion of the three color disks, we must stop the rotation of disks before changing. It will however be better that if possible, we change the proportion without stopping the rotation. The author then devised an improved apparatus (Fig. 2), in which the disks do not move and the color mixture may be obtained by the rotation of a prism instead of the disks. With this apparatus we can change the proportion of the exposed areas of disks, looking at the mixed color at the same time.
(2) In the YAMAZAKI-WATANABE'S method, the values of chromaticity coordinate (x, y) and brighteness (Y) based on the C.I.E. color language will be computed by applying the percentage of exposed area in the standard color disks to the equations 1 and 2. To save time and labor, the author want to give for water color measrement the computed values of Y, x and y (Table 2, 3 and 4) in obtaining them immediately from the percentage of the exposed area of the standard yellowish green and orange color disks.
This apparatus will be widely useful in limnology for various kinds of surface colors, for example the seston colors including the vegetable colors derived from phytoplankton or phytoneuston as stated above, the algal colors on the stones in streams, and the color of lucustrine sediments. The author has used this apparatus for such objects.

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びわ湖は代表的な貧栄湖であるので,他の貧栄養湖と同じく,プランクトンは量的には少ない.
植物性プランクトンについてもCyanophytaはほとんど見られず,また,ChlorophytaもEudorina,Volvox aureus,Pediastrumを除いては,量的には甚だ少ない.しかし,Chlorophyta中のDesmidiaceaeは種類も多く,特にClosterium aciculare,Staurastrum dorsidentiferum var.ornatum,St.limneticum var.Burmense,St.paradoxum,Cosmocladium等は量的にも多く,他の貧栄養の湖と比較すると,特異な性状を示している.この特異性を持つ原因の一つには,びわ湖の歴史の古さが考えられる.
Pyrrophyta中のCeratium hirundinellaも夏期には量的にも多く,しかもこの湖特有の型を示すのも,上記の原因と関連しているものと考えられる.
なお,しらべたプランクトン材料の大部分は,筆者が副湖盆で採集したもので,採集時期は1933年以後である.

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Lake Biwa-ko is well known by the occurrence of a large number of endemic species among the various groups of animals, while, so far as the rotifer fauna is concerned, the special faunal characters are not observed. The numbers of rotifer species which are extraordinarily ubiquitous, are not so large in this lake, but the unusual species are seldom seen as well. Most of the rotifers recorded belong to the vulgar ones. Some of the rotifers found in the plankton samples are often to be the dominants or subdominants of the zooplankton, when the individual numbers are taken up.
As Lake Biwa-ko is situated near the centre of our country, both the boreal and the austral rotifers are collected there. The plankton rotifers of Lake Biwa-ko is said to be represented by the typical members in the oligo- or mesotrophic lakes of the temperate region.

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