1. The rates of the growth of bacteria in the solution of the extractive matter of aquatic animals remains practically constant if the concentration of these matter is not very dilute.
2. The process of the formation of fomol titrating nitrogen from the bacterial decomposition of an extractive matter of aquatic animals obeys the law of monomolecular autocatalytic reaction.
3. It appears that in the case of a definite aquatic animal the value of ak remains almost constant irrespective of the increasing or decreasing concentration of the extractive matter but the value of k becomes smaller with the increase of the concentration.
4. In the case of the extractive matter of a definite aquatic animal, the ratio of the total nitrogen (exclusive of the formol titrating nitrogen already present) to the total formol titrating nitrogen produced is nearly the constant if the concentration of a extractive matter is not very dilute.

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The construction and operation of the apparatus used in this test are as shown diagramatically in figure 1.
With the cotton cords having the same linear density but consisting of the yarns of different sizes, it was found that the finer the yarns, the less the resistance of the cord to mechanical wearing. The influence is just adverse to the case of the breaking strength or of the strengh against repeated blows, and is more clearly seen with the thicker cords than the finer.

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I. A netting cord, of which both ends were tied to a horizontal bar-form load, was passed perpendicularly over another stretched and inclined cord of the same kind, and.was made to slide along it. From the critical angle of inclination 0, the static coefficient of sliding friction, tan θ, was determined, which proved to be constant within the experi-mented limit of the weight of the load, not being affected by the difference in diameter of the cord.
2. In C_OULOMB'S method of determining the static coefficient of rolling friction, both of the surfaces in contact were covered with the lines of netting cords arranged in parallel. We obtain nearly the same value of the coefficient for various kinds of the cords, if their arrange-ment, i. e. the number of lines per unit breadth of the surface, is the same.

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By the same method as used in the previous reports, the deformation of amber-fish trap nets under various currents was examined with two models, of which the original nets are as shown in Figs. 1 and 2.
The photographs reproduced in Figs. 4 and 5 show the forms of the two nets respectively, and in each, each column, those under the currents in several directions prevailing in each fishing ground (Fig. 3), while from top to bottom in each column, at the current velocities of 0, 1/4, 1/2 and 1 mile/hour respectively.

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“Genziki-ami” is a fishing appliance for shrimps, operated by the aid of current (Fig. 1). With a model of it, constructed according to T_AUTI'S principle, it was studied, how the dritf-ing speed of and the height assumed by the net are influenced by the velocity of current, the power of the floats, that of the sinkers, as well as the condition of the sea bottom having been varied (Fig. 2).

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The age, body length, body weight, and gonad weight of 2, 063 individuals of Cololabis saira obtained by drift-nets in 1931 to 1935 inclusive in the north-eastern region of Japan were studied with the results nearly the same as those of UNO (this Bulletin, 4 (1), 4 (3), 5 (2)) : -(1) Although somewhat different age compositions of the fish in question were met with during the successive four years, the catch mainly consisted of 3 years and 4 years old indiuidvals. (2) The fi h at the age of 3 years measures 25-26cm in body length and 70-80gr. in body weight, and at the age of 4 years 29-30 cm and 130.140 gr. respectively. (3) In the northern subdivision of the region the gonad of the fish was always found much advanced in maturity than in the southern subdivision, even if in both the subdivisions the age compositions in each year were the same.

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Soon after fertilization eggs of the Europian carassius, Carassius carassius (L_INNAEUS), were put in 20 vials with water. Two of them were then placed in each of 10 compartments (Nos. 1-10) of a S_ENÔ-TAUTI'S serial incubator. They ran at temperatures differing from each other by nearly 2 degrees, No. 1 at the highest (31•5°C) and No. 10 at the lowest (11•8°C.). With a view to determine the effects of temperature variations on the developing eggs one of the two vials in each compartment was interchanged with the corresponding one in another, but the other vial in respective section was kept in situ as control. The interchange was made in 5 pairs, viz., No. 1 with No. 10, No. 2 with No. 9, No. 3 with No.8, No. 4 with No. 7, and No. 5 with No. 6. The results obtained may be summarized as follows:-
1) Water temperature for normal development of the eggs ranges from 15° to 25°C., the optimum for it being at about 20°C.
2) The relation between the temperature (θ) and time in days (T) required for the hatching of the eggs may be experessed, as given by HIGURASHI and TAUTI, by the formula
Te^aθ=constan in which a=0•11. The temperature coefficient for the embryonic development of the Europian carassius was found to be Q₁₀=3•01.
3) Within the range of mean deviations 1•0°-9•8°C. in the series of temperatures 31•5-11•8°C., the larger the temperature deviation the less the hatch-rate of the fry and the less the time required for hatching.
4) T_AUTI'S formula concerning the relation between the mean deviations of the water temperature (M) and time in days (TM) viz.,
T₀/TM-1=a²/2M²
where T₀ is the time when M=O, holds true for the writer's materials with the values of the constants a=0•09. Q₁₀ =2•46.

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Taking microphotographs as are reproduced in the annexed figure, the cavities which were made in frozen fish muscles by ice crystals were observed with respect to their number, area and roundness.
When pieces of fish muscles were stored in frozen state in air, it seems that the larger cavities, though small in number, are contained near the surface of the pieces than in the interior part at any stage of the storage.
The cavities are enlarged by the repetition of refrigeration and thawing.

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The oil obtained by pressing the boiled sardine (Sardinia melanosticta) during the prccess of the sardine cake manufacture was found inferior to the oil extracted from the sardine cake by ether in specific gravity, acid value, content of free fatty acid, and iodine value, but superior in refractive index, ester value, saponification value, and content of unsaponifiable substance. The stearine amounted to 51•3% in the former when kept at 13°C, but it was abundantly present in the latter. Although phosphorus was contained in the latter by the amount of 105•2 mg %, the detection of this substance was beyond the limit of Fiske and Subbarow's phosphorus reaction method even if 6 gr. of the former were used. Therefore, 1 he oil expressed from the boiled sardine does not contain even a trace of phosphatide but ether extract of the sardine cake is rich in this compound. Hence the former oil is the deposite fat and the latter the tissue fat.

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