The influences of mouths upon the velocity distribution of a lake or a paddle field assumed to be rectangular are treated. They are remarkable in apaddle field put not in a lake.

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It is shown that the theoretical result of the velocity distribution on the assumption of two-dimensional motion can not account for many observations of salinity off an estuary, even though the effects of Coriolis forces and the eddy viscosity supposed to increase with the distance off the shore are taken into account; but the specification of the vertical variation in density gives a considerably different result which may explain actual distributions of salinity.

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In the present treatise the chief characteristics of the oceanographical conditions of the Antarctic Ocean are founded on the observations taken on board the Japanese whaling fleet during the years 1946 to 1952. Among many interesting facts found by the Japanese fleet, we may mention these significant points.
1) In the Antarctic Ocean, the temperature and chlorinity graph of the sea surface increases in the shape of a parabola as the distance from the pack-ice line increase.
2) Ocean currents computed from dynamic calculation near the Scott Island in 1949 show eastward flow to the north of 67° S, and southward flow along the 180° line to the south of 67° S.
3) The insignificancy of the Antarctic circumpolar water is due to bottom topography and to small clockwise circulations.
4) The boundary of two currents is a good whaling ground, even in the Antarctic Ocean, and in the homogeneous area good whaling is not expected.

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The analytical method for phosphate in sea water has been studied by using Beckman's Quarz spectrophotometer. Some knowledge concerning the maximum absorption of phosphate coloration, the condition of color development, the salt effect and the standing time for color comparison after the addition of reagents has been obtained. On the basis of the results of the experiments, brief descriptions of analytical procedures have been given.

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Any attempt to discuss theoretically the distribution of nonconservative concentrations like nutrient substances in sea water has scarcely been made, on account of difficulty that biological processes are introduced into the theoretical computation. In this note, the author has attempted to calculate the biological term, R, based on a sinking remains model, where it is assumed that the supply of inorganic nutrient substances is due to the dissolution of decomposed plankton organisms and that their consumption is determined by biological activity.
Although at present we must be satisfied with rough correspondence between observed and calculated results, we shall be able to develop this treatment to a more precise theory in future.

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There are problems of potential marine resources, potential fishing conditions and fishing conditions in situ in studying marine ecosystem.
Studies of the marine ecosystem in a ocean current may be fundamental for the purpose to analyse those problems. In the marine ecosystem, its dynamic conditions are followed by dynamics of the spacial and the nonspacial structures of the ecosystem. Owing to the author's consideration on ecological grounds, structure of the marine ecosystem may be recognizable by means of investigations of the oceanographic structure of the current system which is a factor for the spacial structure of the system. Since such structural elements as vortex movements, upwelling, horizontal advection of the coastal water are physical conditions in structure of the ecosystem, especially in the view point of marine biochemical cycle, it is reasonable that these conditions are dynamic component of the ecosystem and restrict not only spacial structure but also nonspacial structure of the ecosystem in the sea.

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The Tsushima Current is the warm current that branches off on the left-hand side of the Kuroshio over the mud line neighbouring in Lat. 28°30´-29°00´ N, Long. 127°30´ E on the sea area north-west of Amami Oshima in the Eastern Sea, and runs against the Tsushima Islands : from the south-west to the north-east in the waters between Kyushu and Quelpart, and goes through the Straits of Tsushima on to the Japan Sea. Then, on the continental shelf between the Eastern Sea and the Japan Sea, there is the Straits of Tsushima about 100 metres deep. The Tsushima Islands consists of two long principal islands, the upper and the lower islands including some small islands, and divides the strait into two channels; one of these is the eastern channel on the side of Japan, the other the western channel on the side of Korea. Passing the Straits of Tsushima, the current forms fishing grounds of such migratory fishes as the sardine, Sardinia melanosticta, the mackerel, Scomber japonicus, and the horse mackerel, Trachurus japonicus on the lee side of the Tsushima Islands.
Depth of the fishing grounds round this islands is shallower than about 130 metres. Almost all areas of the grounds are 80-120 metres in depth and presented morphologically as comparatively flattened sea bottom. While the Tsushima Current runs over this area, vortex movements are formed in the water sheltered by the Tsushima Islands; a significant vortex in economic meaning is found in the waters of the Eastern Channel off the upper principal island.
The presence of the circulation is explained schematically as if the liquid ran against the elongated ellipsoid body from the oblique side. Therefore topographical positioning of some vortices, current rips and stratified waters may be able in the waters of the Tsushima fishing grounds. The author and his collaborators held two oceanographic observations in winter of 1949 andspring of 1953 for the purpose of examining the oceanographic structure of the Tsushima fishing grounds. As a result of these observations, it is recognizable that the observed oceanographic structure is composed of such physical factors as vortex, current rip and stratified water as shown in text figures.
Owing to author's conception on this observed oceanographic structure from the ecological point of view, those factors form the partially spacial structure of the ecosystem of the warm Tsushima Current System, and they form the bounding verticals and coastal fronts which are ocean spaces of the maximum gradients of such scalar quantity as water temperature, chlorinity, dissolved oxygen and other ecological factors. Therefore, after author's theoretical consideration, the fishing ground is the ocean space that the change of the scalar (s) on the distance of the three space coordinates, ∂s/∂xdx, ∂s/∂ydy, and ∂s/∂zdz are maximum and the time rate of energy change ∂E/∂t is also maximum in the view point of trophic dynamics. It is likely that the oceanographic structure of the Tsushima fishing grounds represents such ecologically spacial structure as mentioned above.
The author wishes to express his grateful thanks to Prof. Dr. Uda of the Tokyo Fisheries University.

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