In order to obtain an objective measure of evaluating the surface color of fish sausage, reflactance spectra of fish sausage surfaces after various treatments (Fig. 1) and extinction ratios of them at 570/650m_μ (Table 1) were measured. It was confirmed that the ratio is useful to evaluate the surface color of fish sausage.
The effects of erythorbic acid on the formation of cured color and on the discoloration of fish sausage were compared with those of L-ascorbic acid, using E₅₇₀/E₆₅₀ as an index in evaluating them. As shown in Table 1 and Fig. 2-4, the intensity of erythorbic acid in accelerating the color formation and protecting the discoloration was about the same as that of L-ascorbic acid.

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Acquisition of resistance against chlortetracycline (CTC) by Pseudomonas fluorescens, which is closely associated with putrefaction of fish and shellfish, was studied. The results may be summarized as follows:
1. Three starins of P₈. fluorescens were exposed to CTC of either a constant dose at the maximal tolerance level (M. T. L.) of each strain or 0.1 ppm, or an increasing dose at M. T. L. at each stage.
After 60 successive subculturings in nutrient broth (Difco) containing a constant dose of CTC, the organisms acquired 4 to 16-fold higher resistance at the M. T. L. and 2 to 8-fold at 0.1 ppm, while the corresponding values obtained at the increasing dose were 16 to 64-fold that of the original culture (Figs. 1 and 2). The resistance acquired in vitro seemed to be comparatively stable since 25 successive subculturings of the in vitro resistant organisms in plain nutrient broth held almost the same level of their resistance.
2. A complete cross-resistance against CTC and oxytetracycline was observed. A slight cross-resistance against chloramphenycol was recorded with the CTC-resistant organisms, while that against streptomycine was not appreciable (Table 1).
3. No marked difference in the biochemical characters, especially those relating to putrefaction, was observed between the resistant and sensitive strains (Fig. 3).
4. The distribution curve of resistance of individual cells of a sensitive strain obtained by plotting the numbers of the colonies counted in agar plates added with various levels of CTC appears to be a S shape (Fig. 4), which indicates heterologous sensitivity to CTC by individual cells. While, the curves for the resistant descendants are composed of two linear lines crossing at nearly right angle, which means the majority of the individuals has the same level of resistance. Neither the sensitive nor resistant strain showed CTC-dependence because the largest number of colonies was counted in the plates without CTC.

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The characteristics of the acetone-soluble lipid and lecithin contained in the pyloric appendages of yellowtail, Seriola quinqueradiata, were studied from the view point of lipid metabolism of fish.
The acetone-soluble lipid was obtained in the yeild of 5.46% from the fresh pyloric appendages. The characteristics of this lipid are given in Table 1.
Lecithin purified from the lecithin fraction was obtained in the yield of 0.20% from the fresh samples. The properties of the purified lecithin are shown in Table 2.
Spectrum of the alkali-isomerized liquid acids separated from the lecithin indicated the presence of conjugated tri-to pentaenoic acids in the lecithin. According to rough calculation, the composition of the conjugated fatty acids of the lecithin seems to consist of 37.44% saturated and 62.56% unsaturated acids.
The paper chromatography indicated the presence of myristic, palmitic, stearic, zoomaric, oleic, linolic and linolenic acids in the lecithin.

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The purified cephalin fraction was obtained in the yield of 0.70% from the fresh pyloric appendages of Yellowtail, Seriola quinqueradiata.
The purified cephalin was precipitated fractionally after the way of FOLCH into five fractions, and the presence of phosphatidyl ethanolamine, phosphatidyl serine and a small amount of inositol phosphatide was confirmed from the analytical data on each fraction.
The characteristics of the fractionated cephalins are given in Table 1.
After the analysis, the rest of each fraction was mixed together following the proportion by which yielded from original cephalin, the fatty acid component was analyzed by alkaliisomerization which showed no presence of polyenoic fatty acids. According to simple calculation, the conjugated fatty acids of the cephalin consist of 29.22% saturated acids and 70.78% unsaturated acids.
The paper chromatography indicated the presence of myristic, palmitic, stearic, zoomaric, oleic, erucic, linolic and linolenic acids in the cephalin.
Sphingomyelin and cerebroside separated from the sphingolipid fraction by washing method of FOLCH et al., were obtained in the yield of 0.02% and 0.03% respectively, from the fresh samples.

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Succeeding to the previous experiment with phosphates and other inorganic salts, there were examined in the present work the effects of tri-sodium citrate, di-ammonium citrate and potassium sodium tartarate on jelly-strength of Kamaboko. The results obtained were as follows:
1) Similarly to the salts already examined, the citrates and the tartarate respectively added to a fish paste as raw material produced Kamaboko specimens with minimal jelly-strengths at the salt concentrations satisfying the previously presented equation.
1/2•;^∑_iV_iZ_t²×1/2•^∑_i|Z_t'|=0.1
2) Addition of the citrates more or less strongly enhanced the jelly-strength of Kamaboko. This effect seems to be referred to chemical specificity rather than pH elevating power of these salts.
3) Considering from practical appricability to Kamaboko manufacture, citrates promise to be used as additive at concentrations of M/306-5M/180 for jelly-strength enhancement, while tartarate seems to be little available for the same purpose. So far as disclosed in the present study, di-ammonium citrate is more convenient to be used than tri-sodium citrate because of to delicate dependency on concentration of the effect of the latter.

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Using a fish paste added or not added with pyrophosphate, jelly-formation advancing at a relatively low temperature and Kamaboko-formation effected by two-step-heating, namely, by subjecting the jelly to after-heating were examined.
1) When batches of raw fish paste added in the one series and not added with pyrophosphate in the other were heated each for 30 minutes at temperatures of 35°, 40°, 45°, …… and 70°C, respectively, a jelly of largest jelly-strength was attained in either series with a sample heated at 45°C, and a smallest jelly-strength was shown by a sample heated at 60°C.
2) When batches of raw fish paste were heated at a definite low temperature of 40°C, for 20, 40, 60, …… and 320 minutes, respectively, raw fish paste not added with pyrophosphate showed a largest jelly-strength when heating time was 60 minutes, while that added with pyrophosphate showed a greatest jelly-strength when heating time was 40 minutes. With both the batches added and not added with pyrophosphate, when heating was prolonged over said times, respectively, the smaller jelly-strength was arrived at, the longer the heating time.
3) So far as heating temperature was lower than 70°C, addition of pyrophosphate to raw fish paste had an impeditive effect on jelly-formation, irrespective of heating time and temperature.
4) When specimens of Kamaboko were prepared by the process of two-step-heating, a maximal jelly-strength was attained under a condition of preheating of 40°C and 40 minutes. For Kamaboko specimens finished by two-step-heating, addition of pyrophosphate to raw fish paste had an impeditive effect on Kamaboko-jelly formation.

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The jelly-strength and pH value of jelly-specimen attained by heating for 60 minutes at various temperatures of 30°-100°C were examined with raw fish pastes prepared from five kinds of fishes, Makaira mazara (a kind of tuna), Nibea argentata, Muraenosox sinerus (sea-eel), Trachurus japonicus (horse mackerel) and Isuropsis glauca (a kind of shark), respectively.
1) Faculty of jelly formation of raw fish paste varied broadly between different kinds of fish used as material. When the raw fish pastes were heated for 60 minutes at relatively low temperatures, 30°-60°C, they underwent the phenomenon of setting into flesh-colored and lucid jellies^***. Raw fish paste of Makaira mazara acquired a largest jelly-strength when heated at 60°C and that of Isuropsis glauca, Nibea or horsemackerel did so when heated at 45°-50°C and 30°C, respectively.
2) When raw fish paste is heated at a temperature higher by 10°-20°C than that at which setting jelly displays a maximum jelly-strength, the paste produces flesh-colored very weak jelly with rough surface and deprived of lucidity. This phenomenon is called “Modori”, collapse of jelly.
With raw paste of sea-eel or Makaira mazara, the phenomenon of “Modori” is very reserved and barely becomes apparent when heated at 65°-70°C. Raw Nibea paste, on the other hand, has such a great inclination to “Modori” that the jelly-strength produced by heating at 65°-70°C proves to be very low. In the case of raw shark paste, “Modori” is hard to occur but appears at 55°-65°C as a faint depression of jelly-strength. Raw paste of horse-mackerel is very different from others and quite liable to suffer “Modori” even at a low temperature as low as 50°C, giving rise to only a specimen very small in jelly-strength.
3) When raw fish paste is heated at a temperature higher by 5°-10°C than the temperature where a largest degree of “Modori” appears, a spcimen with a jelly-strength rather higher than that shown by a specimen subjected to “Modori”. The jelly-strength effected by heating at a temperature above that at which “Modori” occurs is called Kamaboko formation.
The jelly-strength which raw fish paste acquires on heating under a definite condition is so diverse between different kinds of fish manufactured into the raw paste that the difference in faculty of jelly formation has been considered to originate from some specialities entirely inherent to fish species. In the present work, however, it was clarified that the change in jelly-strength of produced jelly with heating temperature consists of three phenomena which take place in sequence as setting-jelly formation, collapse of jelly and Kamaboko-jelly formation, respectively, according to elevation of heating temperature. The author is now of opinion, therefore, that, insofar as the faculty of jelly formation of fish paste is concerned, difference in fish species can be dealt with in a rather general or simplified aspect of the problem, viz., as the difference of said three phenomena in relative speed of progress.

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Assuming that the diminution of tags which involves the extra natural mortality of the tagged fish and the loss of tags, occurs at a constant rate throughout the period of experimentation, the extent of overestimation in the PETERSEN-type estimate, caused by the above factors was analysed. The calculation showed that the bias of estimate increases as time passes and tends to approach the maximum limit which is determined by the ratio of the tag diminution coefficient to the total mortality coefficient (Eqns. 4, Table 1 and Fig. 1).
In order to eliminate this bias, a method based on the series of sample tag ratios obtained for regular intervals after liberation, was deduced (Eqns. 7 and 14).
The validity of this method was ascertained by the bead drawing experiment and comparing the results obtained by this method with those of simple PETERSEN method and the BEVERTON method, the advantages and disadvantages were discussed. It was also shown that the size of natural mortality coefficient may roughly be estimated by using the Author's method and the BEVERTON method together (Table 4).

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Previously it was suggested from salting-out analysis that intermolecular interaction between actin and myosin might be weaker in myosins (=muscle proteins which are extractable with 0.6 M KCl and precipitate on dilution) from carp killed after struggle than in those from carp put to an instant death. Variation in mutual reactivity of actin and myosin would necessarily have any influence on shape of myosins particles. Thus in the present work, viscosity was examined, expecting to obtain some knowledge about the variation in particle shape of fish myosins as a reflection of difference in lethal conditions.
Material and Method As test animals carp, red sea bream, and flatfish (for scientific names, see Table 2) were used. With each species, two methods of killing fish have been compared in respect of their effect on the viscosity behavior of extracted myosins: a group of fish was put to an instant death by beheading, and the other was allowed for several hours in air and then beheaded. Red sea bream died 30min. after it was taken from water.
Viscosity was measured under varying concentrations (c) and mean velocity gradients ( ?? ), and η_sp/c (η_sp: specific viscosity) were plotted against ?? +kc, k being an arbitary constant and here put to 1000. From viscosity patterns thus obtained (Figs. 1-3), intrinsic viscosity [η]=(η_sp/c)_{^c→0 ?? →0} was determined and relations between η_sp/c and ?? as well as between η_sp/c and c were examined for each sample. In viscosity patterns (Figs. 1-3), slopes of lines parallel to XZ denote velocity gradient dependence of η_sp/c at respective concentrations, and slopes of lines parallel to XY denote concentration dependence at respective velocity gradients.
Results
1. As seen in Table 1, values of [η] fell roughly between 2 and 3 for all tested species of fish. No significant difference in [η] was observed between instant death group and deathafter-struggle group with the same species. Therefore, the same would be true with avarage particle asymmetry in resting solution at infinite dilution.
2. Velocity gradient dependence of η_sp/c which is a function of both asymmetry and length of particle, was obviously greater in instant death group than in the other with each species, as seen from slopes of XZ curves in Figs. 1-3. This might lead to conclusion that whether myosins particles are rigid or not, average length of molecules of myosins should be greater in instant death group, at least in the field of flow.
3. Effect of concentration upon η_sp/c varied considerably with species of fish, as seen from slopes of XY curves in Figs. 1-3. The effect was marked in carp (Fig. 1) and flatfish (Fig. 3), being slightly greater in the former. Difference was hardly observed with these fishes between instant death and death-after-struggle groups. In these respects red sea bream (Fig. 2) proved to be unique. Thus, in instant death group, concentration effect was so small as η_sp/c seemed nearly constant independent of c. In death-after-struggle group the effect of concentration was appreciable, but obviously smaller compared with that in carp or flatfish. As concentration effect is considered due to mutual interference of solute particles, the effect might be a function of accessible active groups on the particles as well as asymmetry and length of solute particles.

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Recently a possible function of vitamin B₁₂ in the environment of aquatic organisms was discussed in relation to such phenomena as abrupt bloom of “red tide”. In connection with this significant role of the vitamin, more information should be needed about the source from which the organisms can uptake this vitamin.
Existence of the vitamin found by several authors in the alimentary system of aquatic invertebrates as well as phytoplankton has made it inferable that it may be derived either from food for the animals (mainly phytoplankton) or produced by their intestinal microorganisms. With a view to elucidating these points, the little neck clam, Tapes japonica, has been cultivated in artificial sea water in the presence of vitamin B₁₂ labeled with ⁶⁰Co at various concentrations. The experiments proved that the clam absorbs the vitamin from the environmental water. The measurement of the radioactivity absorbed into different parts of the clam revealed the following.
1) The radioactive vitamin B₁₂ was transferred from the artificial sea water to the clam within six days (Table 1).
2) The level of radioactive vitamin B₁₂ absorbed in the tissues of the clam was higher in the liver and gill than in the foot and gonad. While almost no radioactivity was detected in the intestinal tract (Table 2).
3) Fairly active absorption ability of the clam for this vitamin was suggested from high concentration factor for radioactive vitamin B₁₂ in the tissues of the clam, especially in the liver (Fig. 2).

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In the preceding paper, radioactive B₁₂ absprbed in tissues of the little neck clam (Tapes japonica) was calculated directly from measured radioactivity. This calculation, however, cannot be established if radioactive B₁₂ is decomposed and the labeled part loses B₁₂ activity. Therefore, the stability of radioactive B₁₂ in tissues of the clam and in artificial sea water has been examined in the present work.
1) Extracts from body tissue of the clam which absorbed radioactive B₁₂ were prepared and spotted on the paper for chromatography using sec. butanol-H₂O solution as developer. The paper was cut into ten pieces or so, each 1cm wide, in parallel with the original line. Radioactivity and B₁₂ activity on Euglena gracialis were measured for these pieces (Fig. 1).
The results showed that ⁶⁰Co detected in the chromatogram existed as a constituent of certain substance which had a biological activity similar to that of vitamin B₁₂. The fact suggests that radioactive B₁₂ absorbed by the clam was not decomposed or, at least, maintained the activity for Euglena gracialis (Table 1).
2) When radioactive B₁₂ was added to artificial sea water and was kept at 15°-20°C under the shelter from the daylight for 15 days, the radioactivity and the B₁₂ activity on Euglena gracialis were found maintaining the initial levels (Table 2).

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The tagged ratio method already introduced by the Author, was applied to the tag-recapture data of Japanese common goby, Acanthogobius flavimanus in the northern part of Tokyo bay, from 1955 to 1959. The results showed that the population size of this goby in the area were about 1 ?? 2 hundred millions at the period from middle of September to beginning of October, though of course there were some yearly variation. Otherwise, the results obtained by common PETERSEN method, based on the same data, were clearly overestimates, caused by the successive diminution of tags.
The average value of weekly natural mortality coefficient, obtained by the tagged ratio method and BEVERTON method together, was about 0.0519 at the prime fishing season from middle of September to beginning of November in this area.
Furthermore, 0.10 ?? 0.20 for the exploitation rate, (1×10^-6 for the catchability coefficient), and 0.60 ?? 0.70 for the survival rate during same period, were calculated respectively.

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The present paper deals with an attempt to find the satisfactory method to permit rapid growth of Artemia and to maintain their survival at a high ratio.
Dried eggs of Artemia obtained commercially were used for the material. Dried eggs were allowed to hatch in the artificial sea water (Table 1). The culture was started by inoculating 300 or so newborn larvae into 500ml of the culture medium. During the culture, the medium was incubated at 28°C and aerated 20ml per min., and fine ground food was added 100mg per 100 individuals every day.
The results obtained are summarized as follows:
1) The larvae hatched from dried eggs under aerated condition showed more successful results than those nnder stationary condition.
2) Artemia were allowed to grow rapidly to adult and multiply enormously in the culture nedium added NaCl and chelated metals to artificial sea water (Table 2).
3) The most suitable specific gravity of the medium was restricted to the range of about 1.04 (Fig. 1).
4) The addition of chelated metals caused raising the survival ratio, accelerating the speed of growth and increasing the egg production (Fig. 2).
5) The beneficial actions of chelated metals were mainly due to chelated iron and manganese (Fig. 3).
6) Baker's yeast was a good food, while “WAKAMOTO” composed of yeast and vitamin B complex materials in addition was the better food than the former (Fig. 4).
7) The acetone-butanol fermentation waste was a very good food from the point of view of practical utility (Fig. 5).
8) The newborn larvae grew to adults (at 50-65% survivals) and began to copulate after 6-7 days. The copulated females began to spawn after following 3-4 days. The number of eggs produced by a female was 100 on an average. The hatching out of the fresh eggs took place within several hours in the culture medium (Table 3).

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The frequency distribution of hooked-rate in tuna longline operation had been known already as a form of negative binomial distribution by previous authors. Here, the authors tried to find out the schooling intensity of albacore, represented by a parameter k in formula (1) of negative binomial distribution, from the data about the fishing operation in Southern Pacific, 18°-30°S and 170°E-170°W, during July to November 1955. The fishing ground was devided by a unit area of 4° square, and the hooked-rate (number of fish caught by 1000 hooks in a long line) of each operation during a certain month in a unit area was grouped to be an unit block for analysis of the authors. Among 48 blocks obtained from operation data, merely 18 blocks which has more than 40 operations data were selected for the analysis. The results of analysis are as follows.
1) Frequency distribution of the hooked-rate of albacore seems to be represented by negative binomial distribution from the results of F test of Poisson distribution's divergense coefficient (formula (3)) and test of goodness of fit against the theoretical negative binomial distribution (Table 2, Column 6).
2) Values of k calculated in each blocks using the formula (2) were variable from 2.133 to 7.161 (Talbe 2, Column 10). About k, SUDA (1958) reported already 2.0-4.4 of albacore in North Pacific.
3) The authors calculated a common value of k through out 18 blocks by four methods independent from unit area and month. i) The most likelihood method ( ?? ₁=3.817), ii) Nonweighted mean method ( ?? ₂=4.573), iii) Mean weighted by number of sample ( ?? ₃=4.435), iv) The regression coefficient method ( ?? =3.998) (formula (5)). ?? ₁ is the best theoretically, but this method is troublesome to calculate. ?? ₄by the regression coefficient method is easy to obtain and not so different from ?? 1 in this case. The round estimate of value for k is 4.

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