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
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概要
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In the other experiments of the same series carried out by the writer the larvae were reared in the sea water to which potassium chlorate or potassium chloride was added; the sexuality was influenced in such a way that the percentage of females was raised dignificantly. This influence was probably correlated with the fact that in this artificial medium the developmental velocity in the latter part of the nauplius VI stage was reduced. Conversely, when this velocity was increased, a tendency towards masculinization appeared. To see whether this relation holds good for other agents producing similar effect on development, the present experiments were carried out. Chloretone, chloral hydarate or diiodotyrosin were chosen as such agents. All the experiments were carried out at 23°, which had been confirmed to be the optimum temperature for the life of this copepod. No intersex was produced throughout these experiments. When the larvae were kept in the medium, chloretone 0.005 gr.+sea water 100 cc., for one day from the nauplius stage VI, the developmental velocity in the latter part of nauplius VI stage decreased, and dignificant feminizing tendency appeared. But when the larvae were exposed to this artificial medium for a day from the copepodid stage I, they showed neither feminizing nor masculinizing tendency. Exactly similar effect was found in the medium, chloral hydrate 0.01gr.+sea water 100 cc. Next as a substance abringing about the increase of the developmental velocity, diiodotyrosin was used. When the nauplius stage VI larvae were put in the medium, diiodotyrosin 0.01 gr.+sea water 100 cc., for one day, the developmental velocity in the latter part of this stage increased, and the larvae showed tendency towads masculinization. But when the copepodid stage I larvae were kept in the artificial medium for a day, neither feminizing nor masculinizing tendency appeared. These experiments show that these substances exert rather clear influence on the determination of the sex of the copepod, also that the sex is determined rather abruptly at the onset of the copepodid stage I exactly as it was found in the case of potassium chlorate or potassium chloride. Thus the above relation holds good for all the five organic or inorganic substances tried. This finding has induced the writer to perform another series of experiments of rearing the larvae under different temperatures. Nauplius II stage larvae of the same brood were separated in two lots and kept one in the 18° and the other in the 23° thermostat respectively. Significant feminizing tendency appeared in the 18° lot as vompared with the 23° lot. But no such tendency was perciived in the experiments where the larvae had been separated in copepodid stege I. Thus, it seems safe to conclude that: The sex is determined rather abruptly in the copepodid stage I, and any substance or condition which increases the developmental velocity in the latter part of the nauplius VI stage, induces masculinization, while that which decreases it induces feminization.
- 1941-03-15
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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)