. Animate creation : popular edition of "Our living world" : a natural history. Zoology; Zoology. 586 THE VORTICELLA. Two species of Infusoria, termed Vorticella dtrina and Stentor polyviorpMs, may be found in soft water that has been allowed to remain in the open air, and in which any vegetable matter has been permitted to decay. Both these creatures are affixed by footstalks to some object on which they make their resi- dence, and l)otli agree in having a bell-like mouth, edged with a fringe of cilia. These organs are set upon the edge of the mouth, and their object is indirectly t
. Animate creation : popular edition of "Our living world" : a natural history. Zoology; Zoology. 586 THE VORTICELLA. Two species of Infusoria, termed Vorticella dtrina and Stentor polyviorpMs, may be found in soft water that has been allowed to remain in the open air, and in which any vegetable matter has been permitted to decay. Both these creatures are affixed by footstalks to some object on which they make their resi- dence, and l)otli agree in having a bell-like mouth, edged with a fringe of cilia. These organs are set upon the edge of the mouth, and their object is indirectly to draw food into tlie system by creating certain cur- rents in the surrounding Avater. When the cilia are exposed to a good microscope, they appear to be formed like the cogs of a little wheel, which is rotating with great rapidity ; and it is not until a close examination de- tects tlie real cause of this appearance that its illusory nature is discovered. As in the case of the cilia attached to the higher animals, of which a notice has already been given, each fibril bends in regular succession, so as to pro- duce the effect of waves upon the eye. When the Infusoria are free, the continual movement of the cilia causes them to move with greater or lesser swiftness through the water, each fibril acting as a minute paddle, and having a- distinct feathering movement, like that of an oar handled by a skilful rower. It is a most curious sight to observe the ad- mirable manner in which they make their strokes, the flattened sides striking the water so as to give the greatest force to the blow, and the back stroke being made with the edge, so as to meet -wdth the least possible resistance. In the VoKTiCELLA, the footstalks on which the bell-like cup is seated are of consid- erable length, and capable of being shortened by being coiled into a spiral form. This is by no means an uncommon Inf usorian, and is very liberal in displaying this capability. It is usually found associating in g
Size: 987px × 2532px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbr, bookcentury1800, bookdecade1890, booksubjectzoology
