General physiology; an outline of the science of life . tending indifferent directions. B, Creeping, with a long pseudo-podium in one direction (forni of Amaba Umax). (\ Contracted to a ball upon chemical stimulation. 368 GENERAL PHYSIOLOGY brought into contact with these stimuli, likewise gradually drawsin its pseudopodia, the protoplasm becoming contracted intonumerous, small globules and spindles, which slowly flow centripetallyinto the cell-body l (Fig. 159). Upon the effect of chemical stimuli upon ciliary motion,Engelmann (79, 1) and Rossbach (71) especially have carried outdetailed inve
General physiology; an outline of the science of life . tending indifferent directions. B, Creeping, with a long pseudo-podium in one direction (forni of Amaba Umax). (\ Contracted to a ball upon chemical stimulation. 368 GENERAL PHYSIOLOGY brought into contact with these stimuli, likewise gradually drawsin its pseudopodia, the protoplasm becoming contracted intonumerous, small globules and spindles, which slowly flow centripetallyinto the cell-body l (Fig. 159). Upon the effect of chemical stimuli upon ciliary motion,Engelmann (79, 1) and Rossbach (71) especially have carried outdetailed investigations. Here also the greatest variety of sub-stances, such as acids, alkalies and salts, carbonic acid and variousalkaloids, have like effects, which always consist in an augmentationof the activity of the cilia or flagella, the rate of their beat beingconsiderably increased. The result is a considerable augmentationof the motor effect, which can be clearly observed in free-livingciliated cells, such as Infusoria, in a great acceleration of their. A B Fig. 159.—Actinosphwrium under chemical stimulation. A, Unstimulated ; B, at the beginningof the stimulation; C, after the stimulation has continued for some time (the pseudopodiaare almost entirely drawn in). motion. After the addition of chemical reagents the Infusoriaby the strokes of their cilia rush madly through the field of view. Numerous chemical stimuli act upon the different forms ofmuscle-fibres (myoids, smooth muscle-fibres, cross-striated muscle-fibres) in a manner analogous to that upon naked protoplasmicmasses, by calling out contractions. If to a drop of water in whichmany Vorticellw exist, waving their bodies gracefully upon theirextended stalk-muscles, chemical substances of the above-mentionedkinds be added, all the Vorticellw immediately draw together, theirstalk-muscles suddenly contracting in their elastic sheaths, andcoiling up into delicate spirals (Fig. 160, b). Cross-striated muscleslikewise contra
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Keywords: ., bookcentury1800, bookdecade1890, bookidgen, booksubjectphysiology
