Using Hamach, young yellow-tail, body weight 450-1200g, Seriola quinqueradiat TEMMINCK et SCHLEGEL, experiments were carried out in an outdoor tank (L. 8×W. 6×D. 1.5m or L. 4×W. 4×D. 1.5m) with pooled water, in order to obtain the foundamental knowledges about the model fish reefs (Fig. 2 and 3), to reaction of fish schools.
Method of experiment: In this experiment, two occasions were compared with each other, the one the distributions of fish schools when model fish reefs were not set in the tank and the other those when they were set.
Observations were made 50 time in total at every one minute, recording the positions of the fish.
The results of experiments are as follows:
1. Young yellow-tail was most frequently distributed on the more bright, area in the experimental tank on both conditions, when model fish reefs were not set and when those were comparatively small, even if they were set.
2. Young yellow-tail was more attracted to the increase of hight than that of area of model fish reefs.
3. Young yellow-tail was the more attracted to the increase of area, when the model fish reefs were of the same height.
4. The sense of “sight” has the important role for the attracted movements of young yellow-tail to the model fish reefs.

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Masu-ami is a small but very popular net among trap nets in Japan. The construction of the net is divided into three parts; a lead net, a fence net and bag nets which are attached at three or more places of corners or sides of the fence (Fig. 1).
In the present paper the catching efficiency of the bags was studied from the point of view of their colors. Each bag of the aimed net was made from saran twine and their colors were red, yellow, blue, green and light brown of the natural color of the twine. The effect of the position of the bags on the catch was considered by changing the place of them in every 10 to 15 operations. The experimental data were taken from a masu-ami setting on coastal water of Kanazawa Hakkei, Yokohama, during the periods of April to November in 1956.
The results obtained are as follows.
1) The species of fishes entered the net are divided into two groups, judging from the catch in each bag; the one has a tendency to select the colors of the bags and the other has no tendency to it. The species belonging to the former are sea bass, Lateolabrax japonicus, black porgy, Sparus awinhonic, flat fishes, conger-eel, Lumpenus anguillaris, hock trout, Hexagrammos actogrammus, squid, Sepiella maindroni, and the species of the latter are gray rock cod, Sebastodes inermis, surf perch, Ditrema temmincki, prawn, Penaeus japonicus, blue crab, Neptunus trituber.
2) Gray rock cod and surf perch which are liable to enter the bag in the daytime have no tendency to select the colored net, on the other hand, the fishes such as squid, flat fishes and black porgy which are liable to enter the bag in the time from dusk till dawn have a tendency to select the colored net. This phenomenon suggests the motion of the fish toward colored net are different by the species.
3) The catches seems to be effected not only by the difference of light intensity in the bags but also the difference of the other factors which are resulted by the colors of the bags, for example, spectral distribution in the bags and so on.

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A series of experiments on the rice powder as the diet of the pearl oyster were made with special reference to the sedimenting velocity and the frequency distribution of size of the particles of rice powder, their distribution and sedimenting rate in culture vessels, and the feeding rate and growth of the oyster.
1. In the rice powder which was made by soaking grains of rice for one day in distilled water and pulverizing them with a homogenizer, about 85% (in weight) of the raw material was available as the diet of oyster. The 15% loss may be a total of the embryos which are not easily broken, the moisture lost during powdering and drying and a part of the soluble components (Table 1 and 2).
2. From the velocity of sedimentation, the size of most (about 90% in weight) of the particles prepared as stated above was calculated to be under 10μ in diameter. These particles took one hour or more to sediment 10cm in sea water (σ₁₅ 1.025). Particles less than 5-6μ (about 4 hours to settle) account for 60% of the total (Table 2, 3 and Fig. 1).
3. Particles suspended from the surface to a depth of 10cm were removed by filteration and dried. The actual size of these particles measured 2-10μ in diameter, averaging 5.3μ immediately after preparation of suspension and 4.5μ after 5 hours (Fig. 2 and Table 4). These observations show that the rice powder may be suitable in respect of size as a diet for the pearl oyster.
4. The distribution of rice powder particles in two vessels, CV and FOV in a re-circulating rearing system shown in Fig. 3, became approximately similar (51.5:46.0% in weight of the total particles added) 20 minutes after the beginning of circulation and almost the same (49.0:48.5%) after 40 minutes. The diminution of the amount of suspended particles due to sedimentation in this rearing system amounted to only 11.5% after 4 hours (Table 5 and Fig. 4). These results suggest the possibility that almost all of the rice powder particles supplied may be utilized by pearl oysters in this type of culture equipment.
5. Additional experiments using 7 culture equipments of the same type and 56 full 1-year-old pearl oysters (7 groups of 8 animals each) which had been reared on diets of various quantities of rice powder for 56 days before experiments were conducted as follows: Each group of oysters was supplied with rice powder of the same quantities as in the rearing period (20-200mg/time; twice a day, a. m. and p. m.) and the amount of the rice powder suspended in the water of the culture vessels were determined at an interval of 1 hour for 5 hours. Starch content was taken as a measure of the amount of rice powder. The diminution rate of rice powder varied depending on the quantity of diet given. When 120mg was supplied, the rice powder was diminished more rapidly than in case of other quantities (Table 6, Fig. 6 and Table 7, Fig. 7).
6. The starch content of the substances sedimented on the bottom of the culture vessels was measured after 4 hours. By deducting the amounts of rice powder remaining suspended in the water and sedimented one from the quantity supplied at the beginning, the feeding rate of the oyster was calculated, on the assumption that the rice powder fed by the oyster was digested and no starch was paesent in the faeces. The results showed that the amount of rice powder remaining suspended in the water 4 hours after supplying was negligible as compared with that fed by the oysters, while the starch content of the sediments was in direct proportion to the amount of rice powder supplied (Table 8 and Fig. 8). The calculated feeding quantities were in direct proportion to and the feeding rates in inverse proportion to the amount supplied.
7. A relationship between the amount of rice powder ingested and the growth (increase in under-water weight) in the last week of the rearing period (Fig. 5) was shown to be a linear regression (Fig. 9).

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The Carotenoid component of corb shell, Corbicula japonica, was studied. The absorption spectra of the crude oils and unsaponifiable matters of the samples differed markedly with each other (Fig. 1), and this phenomenon was never encountered in the cases of both short-neck clam and hard clam.
Among fractionated six carotenoids, lutein, lutein ester and β-carotene were identified, and taraxanthin like pigment, though remain unsettled, was found in four samples.
The lutein content of corb shell is ten to twenty times more than hard clam.

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The blue-green pigment of eel was analyzed for amino acid composition and constituent sugars. It contained relatively large amounts of aspartic acid, glutamic acid, lysine, leucine, and histidine. Small amounts of both N-acetylneuraminic acid and glucosamine were detected as constituent sugars. The composition, as a whole, resembled those of β1-lipoprotein of human blood serum.

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It was previously shown in our laboratory that certain lipids in visceral lipid of fin whale (Balaenoptera physalus), which were eluted chromatographically with methanol-chloroform after being eluted most of neutral lipid with ethyl ether, have infrared absorption at 5.96 and 6.28μ due to amide linkage. Judging from chemical tests, thin layer chromatography and infrared absorption spectroscopy, they seem not to be phospholipids, glycolipids nor sphingolipids.
The amide lipids were separated by the procedure as shown in Fig. 1, and their components were analyzed after 2N-HCl hydrolysis in 80% methanol (8 hrs, 110°C). Ether soluble moiety of the lipids consisted of fatty acid methyl esters and small amounts of unmethylated fatty acids (Fig. 3). After remethylation with BF₃ methanol, fatty acid methyl esters were analyzed by gas liquid chromatography. Twelve kinds (C₁₂-C₂₀) of fatty acids were detected and the composition was generally similar to that of original visceral lipid of fin whale (Table 1). On the other hand, water soluble moiety of the lipids was analyzed by paper chromatography and amino acid autoanalyzer, and ammonia and trace amounts of amino acids (0.07%/weight of the amide lipid) were detected. From a comparison between the amide lipids in visceral lipid and synthesized palmitoyl amide in infrared spectra and thin layer chromatogram (Fig. 2), it was concluded that the former are fatty acid amides.

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