The lustrous particles in epidermis of hair-tail has been utilized as a principal source of pearl essence in making imitation pearl in Japan. In the process of refining the raw particles, first necessaries, of coures, will be to know the content and properties of impurities in the particles. But, little satisfactory analysis of the raw material was found out. Then, the writer attempted to investigate the chemical constituents of raw particles. In this paper, some peculiarities of them were reported. The results obtained were summarized as follows:
1) The particles contained co siderable amount of ash and fat besides nitrogenous compounds which hold the greater part of moisture free particles.
3) The nitrogenous compounds of particles were almost insoluble in water and soluble in the solution of acid and alkali as in the case of guanine which was already identified as a chief constituent of partcles. Most of the nitrogenous compounds of particles dissolved in both acidic and alkaline solution, were precipitated by the neutralization of the solution. Only a little common protein were present in the solution.
3) Phosphorus content of the extractives obtained with organic solvents, varied acording to the sort of the solvent used for extraction and it was the largest in that of alcohol, though there was little difference in the amount of extracives.
4) The composition of ash of particles differed significantly that of common fish scale or fish bone. Namely, the ash of particles was rich in P and Mg, and relatively rich in S, Cl, Na, K, Ca, Fe and Al.

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The investigation on the nitrogenous compounds of lustrous particles was performed, with the following results.
1) The nitrogenous matter in the raw particles proved positive in both murexide reaction and reaction with uric acid reagent. The former reaction appeared to be due to the presence of guanine which was generally noticed as a chief constituent of the lustrous particles, but the latter was observed to be due rather to the presence of uric acid than that of guanine.
2) From the particle, uric acid and guanine were each isolated first with 1% borax solution and next with 4% sodium hydroxide solution, and identified by paper chromatographic and other analysis.
It was, consequently, confirmed that uric acid of about 30% per guanine content was contained in the part cles.

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Butter and lard are seldom subject to rusting even they have become rancid. When oily fishes are dried and stored, however, they suffer rusting, often becominga little rancid. In the present work the authar has dealt with difference in chemical mechanism between “rancidity” and “rusting” of fish oil and obtained a result supporting the Nonaka's assumption.¹⁾²⁾

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We studied, by means of fish-delector, the behavior of the sardine schools in waters and their reaction to fishing light.
From the experiments we found that sardine schools were not atracted by light when the water temperature did not seem to be suitable for the fish (Figs. 2-5 and 9)

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The fish jellies have a characteristic elasticity, called the “Ashi”.
Since the strength of the Ashi has a remarkable effect on the quality of the products, the makers are labouring to strengthen the Ashi. The investigator of fish jellies should, therefore, know the nature of the Ashi. Yet it has been investigated incompletely.
The present writers investigated whether the Ashi may be represented mechanically. The measuring apparatus devised by us is shown in Fig. 1. The principle of this apparatus consists in measuring the pressure (mm, Hg) and the distance (w) at the moment the plunger, which has been pushed to a sample (S) by compressing air, has run into the sample. The pressure represents the “Jelly Strenth”, and the distance “Softness”. This is a simple apparatus which may be constructed with the instruments of ordinary laboratory, being employed with a good accuracy.
Using this apparatus, we tested at first the measuring methods, and found that the size of the sample should strictly be limited and that the effect of temperature was remarkable. Secondary we have selected several makers and let them grade the Renseihin following the strength of the Ashi, and investingated whether certain relations exist between the grades and the mechanical properties, or not. From this investingation, we found that though the strength of the Ashi might be represented approximately with the jelly strength, other elements should be added to, in order to understand the nature of the Ashi itself.

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Sardines generally sampled do not offer enough knowledge of their own living environments. Here the author investigated the growth rate of sardine in relation to the environmental factors. The samples were taken from the Yosanaikai and Kumihama Bay, where larvae of sardine move from the open sea in spring and stay till autumn. The results obtained are summarized as follows.
1). The factor influenced the growth rate of sardine in 1952 is the quantitative and qualitative difference of plankton production in inlets waters.
2). Where the sardines develop into the “Chuba (=middle)-stage”, they migrate to the open sea. At their “Chuba-stage” sardines find their favourable living condition in waters of higher salinity and lower temperature than in inlets waters, to which they adapt themselves at their “Koba(=small)-stage” (Thus classification of sardine according to its growth stages has been widely known among Japanese fishermen. Its ecological importance was recently emphasized by Tsuzita.)
3). As mentioned above, the physiological function of sardine changes essentially in accordance with each stage of its growth, and this physiological change has influence on the ring formation of scales. For instance, many individuals staying in the Yosanaikai for a while after “Chubastage” have two concentric contiguous rings on each of their scales. These rings means continuous physiological change for sardines in adapting themselves to the inlet waters of lower salinity.

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In the previous paper we have reported that the changes in the chemical components of the body tissues during the spowning migration.
In this paper we studied the changes in the depot fats component during this period.
The material of the present investigation was taken from the male salmon captured at Ishikali Village facing the estuary of the Ishikali River and at a spowning ground in one of the upper reaches of the river situated at Chitose Village approximately 48 miles from the estuary.
The results of our research thus far obtained are summarized as follows.
(1) The amount of C₁₈ and C₂₀ acids were decrease, while that of C₂₂ and C₂₄ acids were increase in the material from Chitose than that from Ishikali.
(2) The increases and decreases of the amount of C₁₄ and C₁₆ acids were difference between the part of body.

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In the pr ?? vious paper we have reported that the changes in the chemical components of the body tissues and changes of the components of the body fats during the spawning migration.
In this paper we studied the changes of the component of liver fats during this period.
The material of the present investigation was taken from the salmon captured at Ishikari Village facing the esturay of the Ishikari River and at ?? spawning ground in one of the upper reaches of this river situated at Chitose Village approximately 48 miles from the esturay.
The results of our research thus far obtained are summarized as follows.
(1) The Saponification value, Ester value, Iodine value and Unsaponifiable matter were higher in the material from Chitose than that from Ishikari.
(2) The amount of C₁₈, C₂₀ and C₂₂ acids were decrease, but that of C₁₄, C₁₆ and C₂₄ acids were increase in the material from Chitose than in that from Ishikari.

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In the case of the fish-culture-pond we have hitherto no appropriate direct method to measure and denote the amount of phytoplankton which plays an important role upon the productivity of the pond. Although the fact that the close relation exists between the water transparency measured by the Sccchi disk and the amount of seston is well known, such a large disk as the Secchi is not available in the shallow water of ordinary fish ponds. The author deviced a practical, convenient method for the prerent purpose. Using a white china disk, 5cm in diameter, the transparency is measured by dipping it into the water and reading the depth where it becomes invisible. A Relationship represented by the hyperbolic curve exists between the observed transparency and the precipitation volume of the phytoplankton. Some transparency measurements in ponds at Ikawazu, Aidprefecture are shown.

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