Adopting the notations as follow: φ_i (x), the distribution function of i-age class; N_i, the number of individuals of i-age class; f_m(x), the selection curve of m-meshed cod end; C_m, the number of individuals caught by m-meshed cod end; n, the number of age class: the formula (4) is set, which is a linear equation.
Using more than n-1 gears with combinated cod ends of various meshes more than n, we can get homogeneous equations more than n-1. Solving these homogeneous equations we can estimate the age composition representing the natural shoals without bias caused by the selective action of net.

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The purpose of this paper is to explain usefulness of the mode which appears in a length distribution of fish for separating a mixed group into homogeneous subgroups, e. g., by age.
A mixture of two subgroups each of which distributes normaly with difference of means d, the ratio of standard deviations Ó and mixing ratio A are considered. When d becomes larger than a certain limit d₀, two modes would appear very close to the respective means (Fig. 2). Ratio of the modal values are also near to A/Ó (Table 1). Sometimes, though d is less than d₀, existence of heterogeneous group is indicated through a bump in the skirt of the distribution curve. These facts show that the mode can be made use of in isolating a mixed group into subgroups. An effort has been made to obtain the conditions of parameters which enable to separate the mode and have the bump appear (Fig. 3, Fig. 4).
Furthermore, means and areas which were calculated for parts of the distribution curve separated at the point of minimum value, have been compared with the locations of modes and the ratio of modal values, respectively (Table 2, Table 3). As regard to the biases of estimations for the mean values of respective subgroups and the mixing ratio, the modes excel means and areas for the parts. However, it is necessary to discuss the varidity of the mode from the standpoint of sampling error, the problem which should be studied in future.

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Starfish (Asterias amurensis) made a sudden attack in large number on the coast of Tokyo Bay from October 1953 to March 1954 and devoured large quantities of clams (Meretrix, Venerupis, Mactra etc.)
The experiment was desiged to find out the optimum temperature for the larvae (Bipinnaria) and the young of the starfish and the optimum specific gravity for the larvae. The larvae used in the experiment were obtained by artificial fertilization and reared in Tauchi's thermostat for 22 days from March to April 1954. Similary, the young of the starfishes (arm length 4-9mm), collected from sea bottom by dredge were reared in the same thermostat for 30 days form April to May. The larvae used in the exeriment dealing with the optimum specific gravity were reared in Petri dishes for 22 days from March to April. The results obtained were as follows:
1) The optimum temperature for Bipinnaria and young starfish is 5-20°C and 5-26°C respectivly (see Table 1 & 2).
2) The optimum specific gravity for the Bipinnaria is 1.011-1.026 (δ₁₅) (see Table 3 & 4).
During the seaon of high summer temperature, both young and adult starfish died in great numbers. This fact seems to prove that the range of temperature tolerance for both adult and young is similar. The upper limit of tolerance in the young starfish was found experimentally to be 26°C. It seems probable that the appearance of starfish in vast number in Tokyo Bay during the peried from October 1953 to March 1954, was related to the unusually low temperatures which prevailed during the summer of 1953, which in turn, permitted the survival of the unusually large number of individuals.

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Crucian carp hooked at upper jaw was drawn by gus line at constant speed, and the tension of gut line was recorded by means of the apparatus illustrated in Fig. 1. Fig. 2 shows two examples of the records. Fig. 3 shows the magnitude of primary peak of pulling force in relation to the time interval between the primary and the succeeding secondary peaks, and we see that the speed of drawing and magnitude of primary peak have no influence on the time interval. Fig. 4 shows the magnitude of primary peak related to the body weight of fish, and we see that the magnitud of primary peak have influenced by the body weight of fish and the speed of drawing. This, it is concluded that both the primary and succeeding secondary peak are resulted by the action of fish.

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A study has been made of purifying the alkali pulp waste liquor by treatment with chemicals. It has been shown that aluminium sulfate can remove effectively the oxidizable matters with the increase of its concentration. The removal of oxidizable matters can also be achieved without aluminium sulfate by the addition of enough hydrochloric acid as to bring pH of the waste liquor to 4-5 (Fig. 1.). The extent of removal was increased with lowering pH value and raising temperature of the waste liquor (Figs. 3 and 4). In order to estimate the amount of acid required for purification of the waste, the titration curve has been made (Fig. 2). The determination has also been made of the change in color intensity during the titration with hydrochloric acid (Fig 5).

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Using a barrel of 70 liters capacity, the acid treatment of the waste liquor has been carried out with promising results. It has been observed that passing live steam into the waste was effective to both sedimentation and filtration of the flocculum formed. It is to be noted that the thick washing waste (Bé. 7-5) was found to be able to reuse with good advantage for digesting straw and the used paper. In this way the amount of hydroochloric acid was as much reduced as by 60 per cent. It has also been noticed that the original waste can be used for conglomerating briquet and that the precipitate obtained on the acid treatment can safely be used as boiler-fuel since its sulfur content amounts to less than 1 per cent on dry basis.

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Authors determined the titrable acid in the pyloric coeca extract, and also confirmed the existence of organic acid by using the method of paper partition chromatography with the following results.
1. In 100g of the pyloric coeca extract the total amount of acid was found to be 0.30g calculated as oxalic acid.
2. Four acids were ascertained to be present by paper the partition chromatographic method in the precipitates by lead acetate, Na₂CO₃ and CaCO₃. But among these, oxalic acid and citric acid were detected together with two other unknown spots.
3. The existence of ether-soluble organic acid was not evidenced by this experiment.
4. Hydrazons obtained on adding 2, 4 dinitrophenyl hydrazine was examined by the paper partition chromatography. It was presumed that the following ketonic acids might be present, viz., a-keto glutaric acid, oxaloacetic acid, pyruvic acid and two unknown ketonic acids.

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1. By using the method of paper partition chromatography, the existence of arginine and octopine in fresh pyloric coeca-extract was ascertained.
2. But, in the extract of the pyloric coeca stored for one month at -4°C, the following six guanidine compound were found; methyl guanidinc, arcaine, agmatine, arginine, octopine and glycocyamine.

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In the present investigation, we have found that in the course of the putrefaction at the free state of the yellow-tail, mackerel, and bonito, there have been little difference in the putrefactive products except the histidine and histamine contents in them; and in the yellow-tail, the production of the histamine has been proved to be the least, in spite of the largest amount of the histidine contained.
Even if these fishes were softened through any pressing or crushing, no difference has been found in the processes of putrefaction between the yellow-tail and the others seems to us, therefore, to be independent on the tenderness of their flesh.

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From the facts that the extractive nitrogen and the amino nitrogen, especially the monoamino fraction nitrogen and the monoamino nitrogen are contained very abundantly in the muscle of the shirmps, and the better the taste of these muscles, the larger these amounts are found, moreover, a tendency shows that these nitrogens are reduced in amount in proportion to the deterioration of the flavour in the course of storage, we have suggested in the previous report³⁾ that the palatability of the muscle of shrimps was largely attributed to the amount of the amino nitogen, especially to the monoamino acids in their extractives.
To make sure of this assumption, we have estimated the gly cine content in thier extractives. As the result of this examination, the monoamino nitrogen was proved to be contained with the glycine nitrogen in more than a half of it. And yet the tendency to be larger in its amount in the species having the more intense flavour, and to be decreased in the course of storage was shown. By these reasons, the glycine in the meat extractive of the shrimps seems to be one of the most effective tast stuffs in their muscle.

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The distribution of the extractive nitrogens and the free glycine content in the muscle of the various kinds of squids have been investigated with special reference to their taste.
The amino nitrogen, especially the monoamino nitrogen was found to be contained in rich amount in all species, and so in larger amount in the kinds having the better taste. It seems to be a property common to the shrimps and the Mollusca.
The glycine content in their extractives showed a tendency containing less amount in the unsa-voury kinds, and larger amount in some of the palatable kinds contained over half of the monoamino nitrogen by way of the nitrogen. It is very probable therefore that the glycine is one of the essen-tial taste stuffs in the squid muscles. However, as even in such squids having the best flavour, some of them contain the glycine in small quantity, we are to inquire into the reason why it was so occurred.

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The concentration of liver oils by the solvent extraction was already studied by Dombrow, Buxton, Gloyer, Passino and Abe etc., but they have little studied on the method for selecting the solvent.
To find the suitable solvent in the concentration of liver oils, chromatography method was proposed by the authors, and the results are summerizedas follows:
(1) The chromatography method is useful for selecting the solvent of liver oils.
(2) Aniline and picoline have the possibility as the new solvent in the concentration of liver oils, if it is possible to separate out the solvents from the liver oils in any way.
(3) It is considered that the solvent actions of furfural and of isopropanol are due to not only Van der Waals force but also mutual action of π-electrons in the unsaturated bond.

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In succession to the first report, the distribution and the characteristics of liver oils on chromatogram in the cases of furfural and isopropanol were pursued by the so-called chromatopile method.
The measured values are given in Table 1, 2 and Fig. 2, and it has been proved that the nature of oil-portion developed by furfural is differ from by isopropanol.
With the results obtained, some considerations were given on the mechanism of solvent extraction.

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In the previous work when the authors studied the vitamin A content in fish meat by the anatomical locality, all the samples were taken from one side of the bodies.
The present paper deals with the difference in vitamin A content of the meat sampled from the left and right sides of fish body.
In the sardine, a filefish Cantherines modestus, Promethichthys prometheus and harvest fish Pampus argenteus, the vitamin A content in meat is not always equal to each other side of the body (Tables 1-5, Figs. 1, 2).
In flatfishes, the vitamin A content in meat of the eyed sides are higher than that in the blind sides. In the case of meat of flounder, Paralichthys olivaceus, the difference in vitamin A content between both sides is remarkable on the surface layer but very small on the inner layers (Tables 6-8, Figs. 3, 4).

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Two fillets which had similar properties to each other as shown in Table 1 were prepared from several samples of Mackerel for the present study. One fillet of the sample was protected from rusting by treating with Butyl-hydroxyanisol (B. H. A.) as antioxidant and with NaCl before drying and the other, control, salted without antioxydant, then dried. When standing for 6-23 days after drying, each fillet was separated to three layers: inner surface, skin layer and interior layer between them, of which to examine lipids.
From the results represented in Tables 3-8, the following facts have been revealed.
1) When salted dried fish is disolored, the lipids transfer from the skin layer to the inner surface (Fig. 1, Tables 7, 8).
2) Lipids of the inner surface of dried fish which has been discolored is remarkably deteriorated, whereas lipids of the interior layer or the skin layer do not suffer so much variation (Tables 3-6).
3) It seems that during the discoloration of dried fish various conjugated double bonds are formed in fatty acids of the surface lipids due to the transition of their proper double bonds (Figs. 2, 3).

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