General physiology; an outline of the science of life . mass to theopposite side, and collects, as before, at the kathode. This experi-ment, which because of the great exactness of the reaction is veryfascinating to the observer, can be repeated as often as desired STIMULI AND THEIR ACTIONS 457 If the current be broken, the assemblage disappears from thekathode, and the Paramcecia scatter themselves again uniformlythroughout the liquid. If the Paramcecia be put into a largedrop upon a glass plate, and the pointed electrodes be dippedinto the drop, upon making the current the infusorians arrang
General physiology; an outline of the science of life . mass to theopposite side, and collects, as before, at the kathode. This experi-ment, which because of the great exactness of the reaction is veryfascinating to the observer, can be repeated as often as desired STIMULI AND THEIR ACTIONS 457 If the current be broken, the assemblage disappears from thekathode, and the Paramcecia scatter themselves again uniformlythroughout the liquid. If the Paramcecia be put into a largedrop upon a glass plate, and the pointed electrodes be dippedinto the drop, upon making the current the infusorians arrangethemselves in the direction of the curved lines of flow of thecurrent like iron filings above a magnet, and swim in this direction(Fig. 231) until they have reached the kathode, behind which theycollect in a dense swarm. If the kathodic electrode be mademovable, so that its position in the drop can be changed at will, itis possible to direct the Paramcecia with the point of the electrodewherever one wishes, just as tin-fishes may be directed in water. Via. 231. —Galvanotactic curves of swimming Paramcecia, jointed electrodes being used in thedrop of water. A, Beginning of the effect; B, completed assemblage. with a magnet. Since the motion of the Parammcia is directedtoward the kathode, this case may be termed kathodic galvanotaxis. Like Paramecium, the majority of the ciliate Infusoria arekathodically galvanotactic. Among other Protista that showthe same phenomenon, Amaiba alone may be mentioned. AmoebaUmax, when the current is made, abandons its original direction;its pseudopodia flow forward toward the kathode, the whole proto-plasmic mass streams after, and the body assumes the typicalextended creeping form, in which it flows unerringly to the forms of Amosba, such as Amoeba proteus (Fig. 232), Amaibaverrucosa, and Amceba diffluens (Fig. 233), behave in all respectssimilarly. Many flagellate Infusoria show a behaviour opposite to that ofthe above-mentioned
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Keywords: ., bookcentury1800, bookdecade1890, bookidgen, booksubjectphysiology
