456 infusokia : INGESTION of food. 



so frequently seen among Protophytes (§ 188). If these creatures 

 are really endowed with consciousness, as their movements seem to 

 indicate, though other considerations render it very doubtful, they 

 must derive their perceptions of external things from the impressions 

 made upon their general surface, but more particularly upon their 

 filamentous appendages. 



341. The interior of the body does not always seem to consist 

 of a simple undivided cavity occupied by soft Sarcode ; for the 

 tegumentary layer appears in many instances to send prolonga- 

 tions across it in different directions, so as to divide it into 

 chambers of irregular shape, freely communicating with each 

 other, which may be occupied either by sarcode, or by particles 

 introduced from without. The alimentary particles which can be 

 distinguished in the interior of the transparent bodies of Infusoria, 

 are usually Protophytes of various kinds, either entire or in a frag- 

 mentary state. The Diatomacese seem to be the ordinary food of 

 many ; and the insolubility of their loricce. enables the observer 

 to recognize them unmistakably. Sometimes entire Infusoria are 

 observed within the bodies of others not much exceeding them in 

 size (Fig. 242, b) ; but this is only when they have been recently 

 swallowed, since the prey speedily undergoes digestion. It would 

 seem as if these creatures do not feed by any means indiscrimi- 

 nately, since particular kinds of them are attracted by particular 

 kinds of aliment ; the crushed bodies and eggs of Entomostraca, 

 for example, are so voraciously consumed by the Coleps, that its 

 body is sometimes quite altered in shape by the distension. This 

 circumstance, however, by no means proves, as some have con- 

 sidered it to do, that such creatures possess a sense of taste and a 

 power of determinate selection ; for many instances might be cited, 

 in which actions of the like apparently-conscious nature are per- 

 formed without any such guidance. — The ordinary process of feed- 

 ing, as well as the nature and direction of the Ciliary currents, 

 may be best studied by diffusing through the water containing the 

 Animalcules a few particles of indigo or carmine. These may be 

 seen to be carried by the ciliary vortex into the mouth, and their 

 passage may be traced for a little distance down a short (usually 

 ciliated) oesophagus. There they commonly become aggregated 

 together, so as to form a little pellet of nearly globular form ; and 

 this, when it has attained the size of the hollow within which it 

 is moulded, is projected into the ' general cavity of the body,' 

 where it lies in a vacuole of the sarcode, its place in the oeso- 

 phagus being occupied by other particles subsequently ingested. 

 This 'moulding,' however, is by no means universal; the aggre- 

 gations of coloured particles in the bodies of these animals being 

 often destitute of any regularity of form. One after another of 

 such particles being thus introduced into the interior of the body, 

 each aggregation seems to push-on its predecessors ; and a kind of 

 circulation is thus occasioned in the contents of the cavity. The 



