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Volume 15, Issue 4
Displaying 1-9 of 9 articles from this issue
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J.A. CRAIG1949 Volume 15 Issue 4 Pages 153-154
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
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S. MURAKAMI, S. SHINDO1949 Volume 15 Issue 4 Pages 155-157
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
JOURNAL FREE ACCESSFrom Septembe in 1946 to December in 1947, we made observations on the composition of body length of Trachurus japmicus (Temminck & Schlegel) and its number of rings found in scale at Tomioka to presume its age. As a result of this we could seperate seven age-groups in those individuals below 350mm in body length. Further, according to this consideration, the most part of the eatch at the said districts were under II-age, those over III-age being quite rare.View full abstractDownload PDF (128K) -
S. MURAKAMI, S. SHINDO1949 Volume 15 Issue 4 Pages 158-160
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
JOURNAL FREE ACCESSThe present work was carried out at Tomioka from May to October in 1947 to consider the stock of snapper, Payrosomus major (Temminck & Schlegel) and to observe its variation of fatness. Judging from its growth rate, the mentioned fish of Amakusa is consdered to stand as a distinct stock from those already discussed. The values of k and n in a formula, W=kLn (W, body weight in g; L, body length in mm), are nearly 1.88×10-4 and 2.697 respectively. Then, we computed the value of k for each individual, making n equal to 2.679, and obtained from 1.07×10-4 to 2.86×10-4. With regard to the relation of such a value of k to body length, the following fact can be seen; namely the value of k becomes minimum between 250mm and 300mm in body length, while it shows a maximum between 450mm and 500mm. Moreover, it indicates a seasonal variation, being higher in May and June than in July and August.View full abstractDownload PDF (152K) -
S. MURAKAMI, S. SHINDO1949 Volume 15 Issue 4 Pages 161-165
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
JOURNAL FREE ACCESSWe dealt with three cuttle-fishes, namely Sepioteuthis lessoniana Fèrussac, Loligo bleekeri Kefersteine and Loligo edulis Hoyle, at Tomioka, Amakusa, from September in 1946 to March in 1948, and obtained the following results.
(1) The range of mantle length was generally narrower in female than in male, and large females could not be seen in those three species.
(2) In S.lessoniana, we could seperate six age•groups from O-age to V-age from the distribution of mantle length and the fatness. In L. bleekeri, some age groups were also recognizable from them, but we could not determine their ages for the shortage of materials. With regard to L. edulis, four groups were observable in male from the distribution of mantle length, which are deemed to represent the different ages respectively, but such groups could not be divided in female.View full abstractDownload PDF (980K) -
M. KAWAZIRI1949 Volume 15 Issue 4 Pages 166-172
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
JOURNAL FREE ACCESSI Studyed on the influence of the population density of Killie-fish (Oryzias latipes T & S) upon the number of spawn eggs, hatching-rate, and consequentry upon the reproduction. In the present study these fishes were cultured a pail (1 ?? and -1 ?? ) 1, 2 and 4 pairs respectively in 3 glass bowls (diameter 30cm, depth 15cm) filled with 7 L. of water, and were given food daily into each groups at the ratio of 1, 2, 4, and the rearing water of each bowl were changed 2-3 times in a week at the same ratio as above. Their spawned eggs were counts 3-4 times every day, and transfered into each 3 glass bottles (capacity 200cc) which filled water at the above ratio also, and disinfected by 0.5% of formalin solution every 4-5 days, and the fry which hatch out were counted every day. These experiments were carryed on two times in the same way.
Putting these results together, the number of eggs spawned one female a day decreases, so, accordingly, the number of eggs spawned one female decreases, and besides the hatch-rate have a tendency of depresses, in proportion to the population density of the fishes increases, and by the accumlation of these factors the rate of reproduction of the fish decreases.
Satisfied the equation y=axb, where y represents the number of eggs spawned per i female a day, or hatching-rate, x density of population, a and b are the characteristic constants.View full abstractDownload PDF (348K) -
M. SUGIME, S. FUJITA1949 Volume 15 Issue 4 Pages 173-179
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
JOURNAL FREE ACCESS1. I observed the seasonal variation in species and quantity of plankton appeared in 3 irrigation ponds, O-ike, Sin-ike and Asama-ike, from March to September 1947.
2. The numbers of species of phytoplankton and zooplankton are almost equal: about 67 species in O-ike, 60 in Sin-ike, 45 in Asama-ike.
3. Productivity of plankton is greatest in Sin-ike, and smallest in Asama-ike. The largest number observed was 4828/l in June in Sin-ile, 832/l in September in O-ike, 795/l in April in Asama-ike,
4. Phytoplankton appeared much in Spring and Autumnin Sin-ike and O-ike, but in Asama-ike in Spring only.View full abstractDownload PDF (362K) -
D. YASUDA1949 Volume 15 Issue 4 Pages 180-189
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
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M. UEDA1949 Volume 15 Issue 4 Pages 190-198
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
JOURNAL FREE ACCESSThe present report has been written in the hope to give a preliminary account on the hodrobiological feature of Uranouchi Bay. The data so far obtained shows that Uranouchi Eay behaves like a salt lake though it communieates with outer sea through a narrow and shallow canal The development of thermal and chemical stratifications in this bay are very prominent, the thermal stratification being direct from January to September, and indiroct from October to Febru ?? ry. The direct stratification of dissolved oxygen is set in April when the water temprature is 15.0°C. Such a stratification is kept so long as the upper layer shows low salinity as it makes the stratification stable. It is, however, often disturbed when the density of surface water rises due to the strong evaporation of summer days, which causes the vertical circulation of water.
The saturation percentage of oxygen ranged between 15.7% (August, 1944) and 160.6% (June 1943), the latter value probably being due to Chactoceros boreals which then vegetated. The bulk of the plankton is usu lly composed of Diatoms such as Chaetoceros Schuttii, Ch, decipiens, Ch. dydymus, Ch. diadema, Rhizosolenia hebetata, Rhizo, acuminata, Thatrix. Fraucnfddii, and Nitzschia seriata. The zooplankton which is usually of second importance in quantity, consisted of many Copepods, Euadne, Podon, Penilia, Ceratium fusus, and Noctilaca scintillans. Of zooplankton it was found that Creseis and Bolipnopsis appeared in great abundance during Summer and Autumn respectively.View full abstractDownload PDF (612K) -
Y. OBATA, T. YAMANISHI1949 Volume 15 Issue 4 Pages 199-202
Published: August 25, 1949
Released on J-STAGE: February 29, 2008
JOURNAL FREE ACCESSWe have carried out an experimental research on the change of color in Asakusanori by heat, sunlight, acid and alkali.
The results are as follows.
1. The optimun temperature to broil Asakusanori with the object to give it a bright green color is 160°C.
2. The mechanism of above mentioned change of color is attributed to the transformation of the red-violet phycoerythrin to the blue phycocyan by submitting itself to the dehydrogenation.
3. The reason why Nori becomes red violet when exposed to the sunlight is explained by the disappearance of the unstable phycocyan and chlorophyll are destroyed and more stable phycoeryrhrin remains alone behind.
In this occasion if there are not air and moisture around Nori, the color is not changed even exposed to sunlight for about five months.
4. Under alkaline reaction color of Asakusanori is changed green, and if acid is added it is changed again to red-violet at pH 6.8.View full abstractDownload PDF (259K)
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