海産橈脚類Tigriopus japonicus MORIの雌雄性に及ぼす外界の影響 : (I) 鹽素酸加里及び鹽化加里の影響
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These experiments were carried out at the Seto Marine Biological Station on material collected in its vicinity. This material was slightly different in its physiological state from that of the same species collected at Misaki and Simoda and used in the previous study (this magazine, 51, 1-13). All the experiments were carried out at 23℃ which was confirmed to be the optimum temperature for the life of this copepod. Throughout these experiments no intersex was found, at least so far as the external characters were concerned. I. The Influence of Potassium Chlorate The larvae were transferred at various stages from sea water into the medium, KClO_3 0.15gr.+ordinary sea water 100cc. (the repetition of a part of the previous study). The lot which had been brought into the medium at the nauplius stage III, showed some tendency to feminization. The tendency was more marked in the lot reared in the medium from nauplius stage V or from the former part of the stage VI. The same tendency was recognizable, though less definitely, in the lot brought into the medium at the latter part of nauplius stage VI, but from the copepodid stage I on, no tendency to feminization or musculinization was perceived. When the larvae were reared from the copepodid stage I in the medium, KClO_3 0.3gr.+sea water 100cc., they showed neither feminization nor masculinization; even in the latter part of nauplius stage VI, no evident change in sexuality was perceived. Although the results obtained here are not quite identical with those in the previous study, they coincide with the latter as regards the following points:-1. The sex of the copepod is determined rather abruptly in the copepodid stage I; the larva is practically indifferent with respect to sexuality in the preceding stage (nauplius stage VI), and the physiological state in the latter part of nauplius stage VI seems to play a decisive role to whether the larva should become a male or a female. 2. Further it has been ascertained that when the copepodid I stage is attained, the sex can no longer be altered, even if the quantity of potassium chlorate added to the sea water is increased. 3. The conclusion obtained in the previous study that, the agent which acts for the increase of the developmental velocity in the latter part of nauplius VI stage, induces masculinization, while that which decreases it induces feminization, seems true for the present study on the whole, except that no clear masculinizing tendency was perceived in the present case, apparently because there was no increase of developmental velocity. II. The Influence of Potassium Chloride In the experiments described in the preceding section potassium chlorate added to sea water was found to influence the sexuality of the copepod, and this was assumed to be due to the increase of K-ion in the sea water. In the present experiments potassium chloride was used for the same purpose. All the experiments were carried out at 23°, as in the other experiments. Potassium chloride added to sea water also influenced the sexuality of the copepod. When the larvae of the nauplius stage VI were brought into the medium, KCl 0.15gr.+sea water 100cc., the developmental velocity in the latter part of nauplius VI stage decreased, and a clear feminizing tendency was perceived; but the copepodid stage I larvae in the same medium showed neither feminizing nor masculinizing tendency. As in the case of potassium chlorate the sex of the copepod seems to be fixed rather abruptly in the copepodid stage I, and the decrease of the developmental velocity in the latter part of the nauplius VI stage, apparently induces feminization in this case also.
- 1941-01-31
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関連論文
- 海産橈脚類Tigriopus japonicus MORIの雌雄性に及ぼす外界の影響(II) : クロレトン, 抱水クロラール及びヂヨードチロジンの影響
- 海産橈脚類Tigriopus japonicus MORIの雌雄性に及ぼす外界の影響 : (I) 鹽素酸加里及び鹽化加里の影響
- 海産橈脚類Tigriopus japonicus MORIの雌雄性に及ぼす外界の影響 : I.鹽素酸加里の作用に就て(豫報)