infusoria: — movements. 455 



drawing-together (somewhat after the fashion of the tentacula of 

 Zoophytes), than of reducing them by any kind of masticatory 

 process. 



340. The modes of movement which Infusory Animalcules 

 execute by means of these instruments, are extremely varied and 

 remarkable. Some propel themselves directly forwards, with a 

 velocity which appears, when thus highly magnified, like that of 

 an arrow, so that the eye can scarcely follow them, whilst others 

 drag their bodies slowly along like a leech. Some attach them- 

 selves by one of their long filaments to a fixed point, and revolve 

 around it with great rapidity, whilst others move by undulations, 

 leaps, or successive gyrations : in short, there is scarcely any kind 

 of animal movement which they do not exhibit. There is no suffi- 

 cient reason, however, to regard such actions as indicative of con- 

 sciousness ; indeed, the very fact that they are performed by the 

 instrumentality of Cilia seems to imply the contrary, since we know 

 that ciliary action takes-place to a large extent in our own bodies 

 without the least dependence upon our consciousness ; and that it 

 is also used as a means of dispersion among the Zoospores of the 

 lowest Plants, which cannot for a moment be supposed to be en- 

 dowed with this attribute. We can only regard it, therefore, as 

 indicative of a wonderful adaptation, on the part of these simple 

 organisms, to a kind of life which enables them to go in quest of 

 their own nutriment, and to introduce it when obtained into the 

 interior of their bodies. — The curious contraction of the foot-stalk 

 of the Vorticella (Fig. 239), however, is a movement of a different 

 nature, and is due to the contractility of the tissue that occupies 

 the interior of the tubular pedicle. This stalk serves to attach the 

 bell-shaped body of the Animalcule to some fixed object, such as the 

 leaf or stem of duck-weed ; and when the animal is in search of 

 food, with its cilia in active vibration, the stalk is fully extended. 

 If, however, the Animalcule should have drawn to its mouth any 

 particles too large to be received within it, or should be touched 

 by any other that happens to be swimming near it, or should be 

 ' jarred ' by a smart tap on the stage of the Microscope, the stalk 

 suddenly contracts into a spiral, from which it shortly afterwards 

 extends itself again into its previous condition. The central cord, 

 to whose contractility this action is due, has been described as 

 muscular ; but it does not possess the characteristic structure of 

 either kind of muscular fibre, and is probably nothing else than a 

 portion of sarcode specially endowed with the property. Nothing 

 but the rapidity of its contraction and relaxation differentiates it 

 from the pseudopodia of the Rhizopods. — There is no reason what- 

 ever to believe that these Animalcules possess any organs of 

 special sense. The red spots which may be seen in many of them, 

 and which have been designated as eyes by Prof. Ehrenberg, from 

 their supposed correspondence with the eye-spots of Rotifera (§356), 

 really bear a much greater resemblance to the red spots which are 



