タマミジンコの趨光性に及ぼすアルコホルの影響

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It has been shown by Loeb and others that some Crustaceans those are indifferent to light can be made intensely positive heliotropic by adding the alcohols to the fresh water. Moina macrocopa retains the behavior of positive phototropism in the dilute solution of alcohols, as in the case of fresh water. So I made the following experiments to observe the effect of alcohols on the velocity of phototropic locomotion of this water-flea. The experiments were carried out from the late spring to the early summer of every year from 1937 to 1939. Apparatus and methods The main parts of the experimental apparatus are shown in fig. 1. A trough (C) is made with a glass tube of 16mm in inside-diameter and 21cm long, by grinding off its upper side along the long axis. The trough containing alcoholic solution was put horizontally in the dark room. A beam comes from the sourceof light (L)-Mazda lamp 100V 5W-and passes through the small pores (p_1p_2p_3) of the screens, and penetrates into the experimental trough along its long axis. The intensity of illumination at the side (AB) of the trough is 4.94 meter candle power. The materials were preserved in a crystallizing-dish with 18cm of diameter. The dish was put on the base of a box with the erea of 20cm square and 30cm high, and was illuminated by the lightof a lamp-100V 30W-from its upper side. In this state, the water-fleas crowd near the center of the dish, so that they can easily be picked up with a pipette. In the experiment, the source-lamp was put out, and the other one near the opposite side was tern on, and then one individual was picked up from the preserving dish and put into the experimental trough near the opposite side of source-lamp. Then, turning on the source-lamp and puting out the other one of opposite side, the water-flea begins to swim towards the source of light and reaches the end (AB) of the trough after a definite time. This time was measured and the velocity of locomotion was calculated. The temperature of solution in the trough was between from 20° to 23.5°, and that of the preserving dish was from 25° to 28°. 5 kinds of alcohol and the different percentages of those were used for this experiment (table 1). The velocity (at c/s) of the water-flea for different percentage of different alcohol is shown on the table 2, and graphically on the fig. 2. The following facts may be summarized fromthe results of this experiment:-Results (1) The velocity of locomotion increases gradually according to the increase of percentage of the alcohols, and then decreases again after arriving at the maximum. (2) In the case of metylalcohol, the water-fleas become remarkably indifferent to light, when its concentration reaches about 4%. But in the case of other alcohols, they still retain the phototropic behavior during the decrement of velocity after arriving the maximum, and even they up to die. (3) The velocity of locomotion in the fresh water is 0.26 c/s. So it is evident that the alcohols, in limited concentration, act upon the phototropic locomotion of the water-fleas, as an accelerating factor. (4) At the same percentage, the higher alcohols are more effective than the lower ones, and the former increase much more locomotive velocity. (5) The minimum percentage of differnt alcohols being accelerate the locomotive velocity of the water-flea decreases according to the increase of their molecular weight. (6) The effect of amylalcohol on the locomotion of the water-flea resembles that of the butylalcohol. The concentration of the both alcohols which gives the maximum effect corresponds to that of the other lower alcohols which gives the minimum effect. (7) The propylalcohol of about 4% is the most efficient medium as the accelerating agent of the locomotive velocity of water-flea to light.
1939-12-15

タマミジンコの趨光性に及ぼすアルコホルの影響

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