As a method to measure freshness of fish, the determination of volatile basic nitrogen in flesh is adapted in many cases.
The author examined a method usually employed in preparing the sample for the determination to see if it is really efficient for the purpose. The following results were obtained.
The sample solution to be used for the determination has been prepared by adding acidic protein precipitants to a fish flesh. When the sample was kept in store under certain conditions, the amount of volatile basic nitrogen increased in it.
The increase of volatile basic nitrogen may be attributed to the presence of precipitated substances. Because no increase are observed in the sample solutions which have been filtered and stored in a cold place.

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The scale of pond smelt, Hypomesus olidus (P_ALLAS), shows no definite annual-ring in such a manner as the scale of salmon or herring. Two different zones, one of which grows in summer and the other in winter, are recognized on the scale of the fish in Lake Kasumigaura by F. M_ATSUZAKI (1916), while, according to H. K_OBAYASHI (1936), the fish of Lake Shironuma shows the spawning mark which may probably be formed by the spawning. The present study aims to find the local difference of scale structures of pond smelts. The fishes of three localities of Hokkaido, the anadromous type of the river Ishikari, the land-locked-form Lake Junsai and the fishes of Lake Abashiri connecting with the sea, were taken up as the materials under three different ecological conditions.
The marks on the scales of pond smelt from Lake Abashiri (Fig. 3) ought to be thought as the spawning mark, but those of the fishes of Lake Junsai (Fig. 5) are the interstitial mark bet-ween the winter and summer zones, and the material from the River Ishikari (Fig. 1) lacks these marks. There, the scales of pond smelts differ with their localities and appear the different cha-racteristic structure.

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The pond smelt, Hypormesus olidus (PALLAS), migrates inherently into the sea and ascends for spawning to streams, but the land-locked form also occurs commonly in lakes and pond in Japan.
The studies on the land locked-form of Main Land of Japan have been carried out by F. MATSUZAKI, ('36) and T. FUJITA, & S. KOKUBO, ('26), I AMEMITA & Y. HIYAMA, ('31), H. KOBAYASHI ('36) and K. MATSUBARA, ('46). However, nothing has been studied on the fish which ascends in fresh water from the sea.
Of the fishes of the River Ishikari, the school of the present waterway which ascends from the sea differs from the fish of the old waterway in the morphological characters such as the body length, the scale structure and the number of vertebrae.
Consequently, each school of both waterways is independent ecologically with each other, The fish of the present waterway migrates into the sea, while the school of the old waterway stays through the life in fresh water, in spite of the presence of passage to the sea.

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The mode of cellulose-degradation by the marine a robic cellulose-decomposing bacteria (Vibrio purpureus, Vibrio purpureus var. albus and Cellvibrio flavescens var. marinus) was studied by observing the changes in weight, copper number and index (R) of residtuai cellulose.
The results obtained indicate that there are distinct differences among the modes of cellulose-decomposition by the organisms employed. It is thought that the mode of attack of cellulose by Vibrio purpureus and Vibrio purpureus var. albus is “weathering” type and that of Cellvibrio flavescens var. marinus “liquefying” type.

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O_RTON and I_SAHAYA set forth that bivalves make a concentric circular resting zone on the surface of shell as a sign of their growth.
In order to know the time in which the resting zone is formed and the rate of growth of the animal in question, the author has measured the distance between the umbo and each resting zone as shown in the table 1 (h₁-h₇).
The results drawn from the present scrutiny are as follows. The resting zone appers to be formed twice in a year irrespective of size of the shell. One is formed in June, and the other one dring the season from December to February. The shells reach to a length ef 9mm in height in the first year, 17, 22, 25mm in the subsquent years.

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The results taken in the present investigation may be condensed as given in the following lines.
1. In the natural conditions, reproductive substances of Corbicula sandai are emitted in a smoky manner from exhalent siphon. The fertilization takes place in water.
2. The egg is about 129 μ in diameter, with coating about 43 μ thick, which is scarcely cohesive, and has a nature of sinking.
3. The spermatozoa survive from 30-40 minutes to an hour after ejected in water.
4. At the water temperatures of 20-25°C, the larva forms the umbo about 90 hours after fertilization. At about 70 hours, prodissochonch-shelled larva 180 μ long hatches out from coating and immediately becomes to take benthic life, having no free-living stage.
5. The process of development suggests that Corbicula sandai may belong to an intermediate type between the groups of C. leana and C. Japonica

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We dissolved the vitamin A concentrate into the olefin, linolein & linolenin, and examined the relation between vitamin A destruction and peroxide formation in those synthetic glycerides by the use of storage test.
The increase of peroxide was lesst in olefin, and largest in linolenin, but the difference between linolein and linolenin was small.
The velocity of vitamin A destruction was similar in all glycerides.

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In order to ascertain the action of cupric salts in producing the antibiotic action of shark liver oils by their addition, further investigations on the action of metallic salts and compounds were carried out. Results obtained were as follows:
Copper and iron salts are effective, and the former more so than the latter. Potassium permanganate has a remarkable effect. Potassium bichromate, chromic acid and hydrogen peroxide are scarecely effective when they are employed alone, while hydrogen peroxide becomes effective when its oxidative action has been accelerated by the addition of a certain heavy metal.

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F_RIEDEMANN s method for estimating the amount of volatile acids was adopted for the judge ments of the freshness of several kinds of fish.
At high temperature, 20°C-30°C, the increasing curves of volatile acids were sharper than those of volatile basic nitrogen which were usually taken as an index of spoilage.
For fish, stored above 0°C, the determination of volatile acids was a reliable test for quality.
By using B_EHRENS' method, it was disclosed that formic acid was found in the distillate of fresh fish (plate 1, 2), while butylic, iso-valeric and acetic acid was found in the distillate of spoiled fish. (Plate 3, 4, 6)

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In the previous paper, the author reported that the volatile acids, such as, formic, acetic, iso-valeric and butylic acid increased during the descendence in freshness of fish.
So it was tried to estimate the freshness of fish by detecting volatile acid, especially acetic acid.
The results obtained could be summarized as follows,
1) It was proved by paper chromatography that acetic acid was not detected in newly caught fish muscle, while it was found in the period of descending in freshness. (Table 2)
2) It was found that the detective reaction of acetic acid, socalled lanthanblue reaction by Krüger, was inhibited by fish muscle extract. (Table 4)
3) A remarkable relation between the degree of the inhibittion of the reaction and the fresh-ness of fish was noticed. (Table 6)

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The weight and composition of the food of the “Hokke” Pleurogrammus azonus JORDAN et METS, taken during 1947-1949 along the western coast of Hokkaido were examined They were taken by trawls in summer and by bottom trap-net in spawning season (autumn).
The amount of the food of the trawl-caught “Hokke” was in most cases small. The “Hokke” taken at night contained less food trawl-caught than those taken in the day time.
Of the 300 stomachs of the trawl-caught “Hokke” examined, 82%, 44%, 44%, and 33% contained small shrimps of the genera Crago and Spirontocaris, Themisto, Mlysidacea and the young of fishes of the families Pleuonectidae, Cottidae and Blenniidae, respectively ; and 20%, 9%, and 8% contained small bivalves, squids and Sagitta, respectively.
The food contained in the stomachs mostly included two or three animals, and small shrimps were almost invariably found in the food.
More than half of the stomachs of the “Hokke” taken during the spawning season were empty, and few contained much food. The food were mostly the anchovy and eggs of the “Hokke”.

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In the determination of freshness of Tuna, the author found that “Distillation ratio”-% by acidity of the 2_ad fraction (50cc.) to the l_st fraction (50cc.) at the steam distillation with sample solution in H₂SO₄ acidic condition-was changed proportionaly by the freshness of the fish flesh (cf. from Table 1 toTable 3).
In this results the author is studying a new method of estimating freshness of fish flesh.

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In order to determine the dist. ratio, an apparatus was designated as Fig. 1. Its original plan was showed on A. 0. A. C. Fig. 32, p. 298 (1951), but details were varied as follows.
1. C0₂-free boiling water in the steamer must be used from 2 l.
2. The round bottomed dist. flask is non side arm flask, and fit a trap up the top of it.
3. Tube length of the condenser is 25-30cm.
Some examinations showed that the dist. ratio is influenced by the dirt. speed, the dirt. volume and the amount of H₂S0₄ vol. and sampling wt., so their conditions were determined as follows.
1. The dist. speed influences the dist. ratio in inverse proportionaly, therefore it must be adjusted to 50cc./8 min. by the variable resistance.
2. Total volume of the content in the dist. flask influences the dirt. ratio in direct propor-tionaly, therefore 5% H₂SO₄ and sample must be taken 100cc., 20g.
3. concentration of the additional H₂SO₄ influences the dist. ratio slightly, and the sampling wt. not influences the ratio. But it is desired to keep constantly the total volume of the content in the dist. flask, H₂SO₄ must be 100cc. 5% solution and the minced-meat is sampled 20g. usualy.

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