. A text-book of human physiology . n thecurrent is turned on the head end isalready near the anode, the changein position is effected by a forwardmovement; if the tail end lies nearerthe anode, it is effected by a back-ward movement. The following examples of gal-vanotaxis may be mentioned. Cer-tain echinoderms in their youngestand oldest stages (free-swimminggastrulae and the creeping matureanimals) exhibit no galvanotaxis,while in the intermediate stages(free-swimming plutei and bipen-naria) they exhibit very marked gal-vanotaxis, and wander to the cathode(Carlgren). The majority of ciliate
. A text-book of human physiology . n thecurrent is turned on the head end isalready near the anode, the changein position is effected by a forwardmovement; if the tail end lies nearerthe anode, it is effected by a back-ward movement. The following examples of gal-vanotaxis may be mentioned. Cer-tain echinoderms in their youngestand oldest stages (free-swimminggastrulae and the creeping matureanimals) exhibit no galvanotaxis,while in the intermediate stages(free-swimming plutei and bipen-naria) they exhibit very marked gal-vanotaxis, and wander to the cathode(Carlgren). The majority of ciliate Infusoria and Amoebae assemble at thecathode, if an electric current is conducted through the vessel in which they arecontained. Many flagellate Infusoria show the opposite reaction by moving tothe anode. Finally, it has been observed that the ciliate Infusorian Spirostomumplaces itself its long axis at right angles to the current (Verworn). Allthese differences find an explanation according to Wallengren in the general fact. Fig. 34.—Showing the effects of a constant cur-rent on the shrimp PoUi-ivonetes, when thecurrent passes trans\ersely through the ani-mals body, after Loeb and Maxwell. Thelegs on the side of the anode are stronglyflexed, those on the side of the cathode arestrongly extended. THE EFFECT OF EXTERNAL INFLUENCES ON CELLS 61 that in all ciliate Infusoria the cilia on the side of the cathode beat toward theanterior end, those on the side of the anode, toward the posterior. For example,as long as its anterior end is directed toward the cathode, Opalina ranarum(Fig. 35) always turns toward the right as indicated by the arrow. Organisms are killed by strong electric currents. Concerning the changeseffected by such currents on the higher animals, Prevost and Battelli especiallyhave made extensive investigations, of which the following, relating to thedog only, will be mentioned here. With an induc-tion current of lower tension (up to 120 volts)death results
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