In fishing aided with a lamp light there should be many factors determining an effect of the fishing light in use. However, if other factors are assumed the same between operations comparable one another, important variables may include the length of lighting hours, age of the moon, and conditions of the tide. As few works have been made available for these practical aspects of light fishing, the present paper deals with the relationship between these factors and effects of an electric lamp and a kerosene one. The data used for the study have been obtained from purse seine fisheries for the anchovy, Engraulis japonicus, operated in a part of the Seto Inland Sea during July and August 1953 (Table 1).
1) When the amount of catch was examined in relation to age of the moon, the relation was found to have nearly the same tendency between the electric light and the kerosene lamp fishing. Because between two succeeding periods of dark night, one from the dark to the first quarter of the moon and another from the last quarter to the dark, the catch by each type of fishing was greater in the former than in the latter (Table 1 and Fig. 1).
2) In the both kinds of lamp, efficiency of attracting fish seems to be accelerated in a parabolic curve with progress of the lighting hour (Fig. 2). It is interesting to note that a vertex on the parabola tells the time when a seining operation comes near to an end.
3) The fishing harvests under report may be classified into three categories: good fishing, poor fishing and no catch, where good fishing is represented by catch greater than 500 kans (1 kan=3.75kg) in a few hours, and poor fishing by catch at lower levels. In order to see whether fluctuations in the tide had an effect upon the harvests, these categories of catch have been arranged in relation between the mean fluctuation of tide (cm/hr) and the order of ebb and flow that occurred between two consecutive mornings. In Fig. 3 it is evident that the tide patterns for poor fishing and no catch resemble each other, but they are different from the pattern for good fishing.
4) The fishing hours may be sorted into N, M, and NM, where N stands for 6hours before midnight (2:00 a.m.), M for hours following N till daybreak, and NM for those of all-night operation, In regard to frequency of effective fishing when catch was more than 50 kans per hour, the electric light fishing showed little difference regardless whether it was operated in N, M or NM (Table 3). In the kerosene lamp fishing, however, ratio of the frequency of good catch based on the total number of that operation was 65% for NM, 50% for M and 25% for N. Although the numbers of operation made during N, M, and NM were different depending a kind of lamp, one lamp seems to have been used oftener than the other in one of the categorized hours when an efficient fishing was apparently expected from its use.
5) In regard to a question as to whether one type of lamp is ultimately more efficient than the other under report, further studies have to be made on a comparable base before drawing any conclusion.

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Examining the graphic representations of body-length distribution by KIMURA³⁾ for catches of saury pike, it was noticed a peculiar situation that in fishing seasons extending every year from September to December, during which the fish continues to increase in body-length, the values for the most predominant body-length characteristic of every mode of body-length distribution changes in some cases suddenly from a route to another and in other cases stepwise from a higher level to a lower (see Fig. 1).
In the light of the relationship found between body-length and time of scale-ring formation or granographically assessed age of saury pike, which is now in preparation to be published, the abovementioned peculiar phenomena about body-length distribution were interpreted as a reflection of that any school of saury pike is possible to be replaced by or mingled with that of another age. As to the fishing ground where such replacing or mixing is realized, its yearly change in geographic position seems to be negligible. It may be regarded, therefore, that a school of saury pike temporarily form separate schools on the way of their migration toward the north and the south along the coast of Japan proper.

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Developmental processes of teleostean intraocular structures were studied in Salmo gairdnerii irideus and Channa argus which have falciform process and vitreal vessels, respectively.
In Salmo, an intraocular vascular net originating from the hyaloid artery appears temporarily around the hatching stage and covers the whole retina just as the vitreal vessels do. When it degenerates succeedingly, its communication with the choroid through the embryonic fissure develops in turn and forms the definitive falciform process, being accompanied by pigmentation commencing from the lens muscle.
In Channa, however, there occurs no degeneration of intraocular vessels at any stage. To branches developing over the retina is added a peripheral annular vessel along ora terminalis and the embryonic fissure closes from the optic disc to the base of the lens muscle. Thus the definitive vitreal vessels are completed.
In both cases, the main vessel supplying the lens muscle is not present at first. Later, from branches along the embryonic fissure, it becomes separated and grows in size, concurrently with the development of the lens muscle.

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The author has examined the vertebral length curves (VLC) of one hundred species of teleosts, mainly perciform fishes, and got the following results:
1) It seems that the fishes examined at present have their own type of VLC respectively, so VLC may be useful for the systematic study of fishes.
2) VLC of fishes vary gradually according to the progress of body growth, but in some fishes such as mackerels, dorados, etc., they are unvarying.
3) VLC of fishes may be divided into three main groups, the premodal, the postmodal and the bimodal being supposed to have close systematic relations each other.
4) VLC of bottom fishes are generally steeper than those of surface fishes.

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This is an important problem when considered with practical fisheries, especially to find out the movements of fishes inside the net when they are gathered. Many investigations had been carried out regarding this problem (See references).
For this experiment, Japanese Killifish Aplocheilus latipes was used. The equipments were 5 tanks of different sizes and two cylinders of diameter 13cm of which one was transparent made out of celluloid and the other was painted white inside so that the fishes were not allowed to see the environment. About 15 individuals were liberated in each cylinder and it was lifted above after some times. The time lapses from then to when they moved out were observed (Tables 3-5). Staying times were particularly to find out the difference of effects between the transparent cylinder and the cylinder painted white inside.
The result obtained is as follows: ……
Staying time, the time between lifting up of cylinder and swimming out of fish.
??
In the case of the transparent cylinder, it was observed that when the keeping time was increased, the staying time also increased.
So it may be suggested that the fishes get more well accommodated the transparent cylinder than the painted cylinder. On the other hand, in the case of the painted cylinder even if the keeping time was increased, the staying time was found to be increased only by a few seconds. The sudden outburst of the fish that are kept in the painted cylinder, could be the result of the stimulus produced when they are allowed to escape suddenly from an enclosed place to a more open space.

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1) Procedure and method for the estimation of total catch, total fishing effort, and catch per unit of effort were presented in case of creel census in river.
2) Survey for the estimation required two systems, one was creel census and the other was check survey.
3) The former prepared apparent total catch and apparent effort together with representative time for the application of corrective coefficient, while the latter corrective coefficients.
4) Three kinds of corrective coefficient were offered, corrective coefficient for total catch, for total effort, and for catch per unit of effort.

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1. Estimation of population size was made directly through observation with water-glass in an experimental area settled in a mountain brook.
2. The research period was divided into four periods owing to the occurrence of principles having influence on the errors of observation.
3. The flood was defined newly.
4. With use of errors of observation measured, a deviced procedure of correction of apparent survival or mortality rate was actually applied.
5. Some adjustment were applied tb apparent observed data including the population size of naturally propagated fingerlings of rainbow trout together with that of stocked rainbow trout fingerlings.
6. The change of behavioristic character made a cause to change the method of adjustment. Change of fishing method involved also made a cause to change the method of adjustment. (However, as the fishing method is subordinate to the change of behavioristic character of fingerlings, the actual principle should be taken to be the latter.)
7. Floods caused a large mortality showing the measures of 50.4 to 62% in rainbow trout fingerlings, and 67.9 to 83.7% in brook trout fingerlings at each flood.
8. Floods had scouring effect on mortality, and of decreased fingerlings 75.3 to 95.5% with rainbow trout and 99.0 to 100% with brook trout were estimated to be swept away from the experimental area, though some of them were expected to remain over some downstream area.
9. The intervals of measuring date in survivor survey before and after the occurrence of flood was thought to have some influence on the measure of scouring effect as well as on that of mortality caused by flood. In this case, the dispersion of fingerlings made on the days of usual flow was considered to be the actual agency to reduce the apparent impression of violence of flood, the action of which emerged in mortality of fingerlings and scouring effect.

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Marlins and tunas immigrating in respective fishing grounds (SAISHUTO Gr., MESHIMA Gr., TURBULENT Gr. and UOTSURIJIMA Gr., AMAMIOSHIMA Gr., DAITOJIMA Gr., KUMEJIMA Gr. and MIYAKONANBU Gr. belonging to Okinawa Region) (Fig. 1), and caught by long line, were analized by the rank correlation of Spearman with the following results -:
1. Significant difference was found to exist in the species composition in the East China Sea and Okinawa Region (Fig. 2). Catch of marlins amounts to 95% of the total in the former region, and that of tunas over 60% in the latter (Fig. 3, Table 2).
2. Composition of kinds of marlin slightly varies all year round in the East China Sea. Fish composition in a ground bears a close resemblance to that of adjoining ground, but discrepancy is evident between two grounds which are rather widely spearated from each other (Fig. 4).
3. Sudden change in fish composition takes place in two periods, viz., April and October-November. Thus two types are recognized in the species composition for the whole year; the 1st type is composed of typical species, Albacore, Yellowfin tuna and Bigeye tuna, former whereas the 2nd one is comprised in Bluefin tuna, Yellowfin tuna and Striped marlin. The is easily seen from December to March, but the latter from May to July.

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Taking marlin's number of individuals caught per one operation as school size, analyses were tried with the following results: -
1. It was recognized that frequency of school lineally decreases with size of school, as given in Fig. 1.
Therefore, these two variables are brought out in the following equation
y=Ae^-bx (1)
where y denotes frequency of school (x) is 1, 2, 3, …• m, and A is a constant of zero haul operation.
Now, when the above equation is integrated with respect to x, we have
I_S=∫^∞ ₀ Ae^-bxdx (2)
which gives total number of school.
Therefore, when the equation (1) is integrated with respect to x, we have an expression giving total yield number
Ic=∫^∞₀Axe^-bxdx (3)
Thus average size of school is given by
?? =Axe^-bxdx/Ae^-bxdx (4)
and rate of zero haul operations is given by ?? =A/Ae^-bxdx (5)
Values of the equations (4) and (5) are approximated to 1/b (Fig. 2) and to b (Table 3) respectively.
2. It is suggested that the discrepancy between theoretical (b) and observed values of rate of zero haul operation (r. z. h.) (Table 4) was caused by localized fishing in the general grounds.
3. Schools caught by long line in the Eastern China Sea and Okinawa Region attain to fol lowing amounts: -
Fish name Eastern China Sea Okinawa Region
Striped marlin 3, 005 1, 951
White marlin 4, 102 94
Sailfish 2, 463 624
Black marlin 491 1, 048
Swordfish 368 703
4. Rate of zero haul operations referred to species as well as to water areas runs as follows: -
Fish name Eastern China Sea Okinawa Region
Striped marlin 55.8% 55.2%
White marlin 39.7% 97.8%
Sailfish 63.8% 85.6%
Black marlin 92.8% 75.9%
Swordfish 94.6% 83.9%

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A chlorination product of shark oil dissolved in carbontetrachloride with or without addition of benzoyl peroxide was subjected to irradiation with γ ray by 3.3×10⁷ r in a sealed glass tube in order to obtain a product improved in the stability against heat.
The irradiation proved, however, to have little effect on the melting point. The melting point of the product was raised to some extent only when the air in the sealed tube had been replaced by nitrogen before the irradiation, irrespective as to whether benzoyl peroxide had or had not been added to the sample.

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Fire-retardative property given on coating materials by mixing a chlorination product of fish oil therewith was examined by comparing a combustion curve of a wooden test plate, which had been painted with test paint, with that of a control plate. Combustion curves were obtained by observing the time required to bring about inflammation of wooden plates heated at specified temperatures. As shown in Fig. 4, it is obvious that coating materials, except boiled oil, mixed with the chlorination product are fire-retardative at heating temperatures lower than about 450°C. In the case of boiled oil and when heating temperature was higher, test plates began to burn in shorter time than control plates did. But combustion of test plates was gentle, and the flame was dim and not persistent, disappearing as soon as the heating of the plates was stopped. On the contrary, combustion of control plates was vigorous and continued even after the heating was stopped. Therefore, the chlorinated fish oil will probably be used with effect for conferring fire-retardative property on ordinary paint.

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As a part of studies for predicting the green meat appearance in canned albacore and yellow-fin tuna, various kinds of methods chiefly comprising known ones were examined of their reliability. After a number of examinations it was discovered that a certain compound, which is occasionally contained in flesh of albacore and yellow-fin tuna and gives a yellow ninhydrin paperchromatographic spot from alcoholic extracts, is closely connected with the occurrence of green meat. This compound, though it is still opened to be identified, has been presumed as a sort of peptide from some results of examination. The judgement from color of kidney, on the other hand, proved to be little reliable except when the flesh examined was that of yellow-fin tuna, especially of large body-lengths. The chromatographic judgement, in turn, despite of its far greater reliability as compared with the criticism referred to the kidney color seems also not perfectly satisfying as it requires time in its practice.
Since the greening tendency latent all over the muscular system of fish body was confirmed to be predicted from the behavior of small pieces of flesh on cooking, judgement by cooking test of small flesh pieces may be said for the time being to be a most practicable method of predicting the tendency. It must be noticed, however, the appearance of greenish color in the sample pieces depends upon the time of cooking. Too short a time of cooking proved always to fail in causing the color to develop irrespective as to whether the pieces were boiled in aqueous common salt or in plain water or canned and subjected to the routine heating in retort.

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Preliminary studies were made on the method of cultivation for marine nitrifying bacteria and on the distribution of them.
A. Some results on the methods of cultivation were obtained, as follows;
1. Marine nitrifying bacteria don't grow in the ordinary media for soil ones, and grow hardly even in the media prepared by using sea water instead of fresh water.
2. Marine nitrifying bacteria grow well in the medium prepared as follows: (NH₄)₂SO₄; 30mg (for nitrite formers) or KNO₂; 30mg (for nitrate formers), KH₂PO₄; 2mg, and chelated iron (EDTA-Fe); 0.2mg are added to 1 litter of sea water, and this solution is adjusted to pH=8.4 by the addition of 50% K₂CO₃, and then autoclaved. This medium is very low in the concentration of (NH₄)₂SO₄ or KNO₂, comparing with the media for nitrifying bacteria of soil, that is, the concentration of the former is about 1/100 of that of the latter.
3. Further marine nitrifying bacteria grow very well, when small amounts of sand are added into the above mentioned media.
B. Researches on the distribution were made by using of the method of cultivation as described above, and some results were obtained, as follows:
1. In the sea water in nature, there are very few nitrite formers and nitrate ones, i. e. both of them are similarly fewer than 0.3cell/ml. In the sea bottom muds, they are the maximum in bacterial counts at the surface layer of the muds, i. e. both of them are similarly 10³-10⁴cells/g, and they decrease with the length distant from the surface layer, i. e. are fewer than 10²cells/g at the layer bellow 15cm in depth from the surface one.
2. In the breeding sea water in the aquariums of circulating system, nitrite formers and nitrate formers are markedly more than those in the sea water in nature, i. e. both of them are similarly 10²-10³cells/ml.
3. In the filter-sand of the aquariums of circulating system, both of nitrite formers and nitrate formers are similarly 10⁴-10⁵cells/g and these counts are almost unchanged by the length from the surface layer.

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Total nitrogen (TN) and amino nitrogen (AN) of kombu extractives extracted with 70% ethyl alcohol were quantitatively determined (Table 1). By means of computing the coefficient of rank correlation (r), the contents and the ratio of both nitrogens (AN/TN) were compared with market price and the quality which was evaluated in the previous paper¹⁾. Most of them, except the relation between AN/TN and market price, were found to correlate highly to each other.
By studying the difference of first year and second year plants, the locality of harvest and the sampling parts of the plant, it was ascertained that the contents of TN, AN and the ratio of AN/TN are higher in good quality kombu than in the poor.

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Twenty-two kinds of kombu were extracted with 70% ethanol. Then the extractives were passed through a column filled with an ion exchange resin, Dowex 50 X-4 (H-type, 20-50 mesh) to remove inorganic salts which were contained in high concentration in the seaweed; otherwise the growth of the test microorganisms would be disturbed. In this process, large amounts of arginine remained in the column when displaced with 0.2N-NH₄OH because the compound is strongly alkaline.
Seventeen amino acids in the extractives were determined by the microbiological assay method. The resulte are shown in Table 1. In order to clarify if the contents of any amino acid be one of the quality-influencing factors, these data were analyzed statistically in relation to the following 8 items: (1) Difference between ichiban-dashi and niban-dashi; (2) Harvesting season; (3) The grade in the market; (4) The sampling position of kombu lamina; (5) Locality of kombu plant; (6) Whether growing offshore or seashore; (7) First year or second year plant; (8) Kombu species.
It was revealed through the analysis that the quality did not seem to be entirely influenced by the difference of amino acid composition.

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Amino acid composition of the protein of the external mucous substance from 6 kinds of fishes (2 fresh water and 4 sea water fishes) was determined by the column chromatographic method using an ion-exchange resin and the results obtained are shown in Table 1. Although some different features were observed on several amino acids, the pattern of amino acid distribution in the mucous proteins examined was similar to each other, all of them, except Dasyatis akajei, being rich in aspartic acid, leucine and glutamic acid, medium in valine, serine, isoleucine, threonine, phenylalanine and arginine, and poor in cystine, tyrosine, tryptophan and histidine. The mucous protein of Dasyatis akajei showed the considerably higher value of threonine and lower ones of leucine, methionine, alanine and arginine than those of the other fishes.

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The component sugars of the mucus-polysaccharide from the external mucous substance of loach was reported in the previous paper¹⁾: mucus-polysaccharide acid hydrolyzate was separated into three fractions based on R_f values by paper chromatography, and the component sugars was identified.
In the present paper, the hydrolyzate was divided into neutral, basic and acidic fractions by using ion-exchange resins (Fig. 1), and the component sugars in each fraction were analyzed qualitatively. The results obtained are as follows:
1) In the neutral fraction, ribose, galactose and glucose were identified. Although the presence of arabinose was reported in the previous paper¹⁾, this sugar could not be detected clearly (Fig. 2).
2) In the basic fraction, glucosamine and galactosamine were identified indirectly as arabinose and lyxose, respectively, after degradation of the fraction with ninhydrin.
3) In the acidic fraction, a hexuronic acid was detected by the WILLIAMS's method (Fig. 3). The acid seemed to be glucuronic acid, as judged from the DISCHE's reaction (Fig. 4).

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Mucus-polysaccharide acid hydrolyzate of 7 kinds of fishes was divided into neutral, basic and acidic fractions by using ion-exchange resins. The component sugars in each fraction were analyzed qualitatively and the results showed that all mucus-polysaccharides contain the same components except glucose, the presence of which was not confirmed in some species (Table 1).
Due to the fairly close R_f values of galactose and glucose in this study, it was difficult to detect glucose. There remains, therefore a possibility that glucose is also present in all the fishes tested. So, the present results suggest that the mucus-polysaccharides mostly consist of the same component sugars irrespective of the differences in their living circumstances (fresh water or sea water) and in classification system (teleost or cartilaginous fish).

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