INFUSORIA, THEIR CONSOLIDATION. 413 



eluding the Desmidiacece, Diatomacece, Volvocinece, and many other 

 Protophytes, have been transferred by the almost concurrent 

 voice of those Naturalists whose judgment is most to be relied 

 on, to the Vegetable Kingdom. The Rhizopod group, again, 

 must be excluded, as being very distinct in its plan of organiza^ 

 tion from the true Infusoria. And, lastly, it is not improbable 

 that many of the reputed Infusoria may be but larval forms of 

 some higher organisms, instead of being themselves complete 

 animals.' Still an extensive group remains, of which no other 

 account can at present be given, than that the beings of which it 

 is composed go through the whole of their lives, so far as we are 

 acquainted with them, in the condition of isolated cells ; differing 

 from Vegetable cells on the one hand, and from Ehizopods on 

 the other, in this remarkable particular, — that the alimentary 

 particles by which they are nourished are taken into their cavity 

 through a distinct oral aperture, some of them also having an 

 anal orifice for the ejection of indigestible matters. It has been 

 imagined by Prof Ehrenberg, that a distinct alimentary canal 

 exists ; sometimes returning upon itself (as in Vorticella), some- 

 times proceeding straight from one extremity of the body to the 

 other (as in JEnchelis), and sometimes passing round and round 

 in a spiral (as in Leucophrys), having a number of flask-shaped 

 stomachs connected with it, into which the alimentary particles 

 find their way, and in which they undergo digestion. But as he 

 made the like assertions with regard to beings that have been 

 since undoubtedly proved to belong to the Vegetable Kingdom, 

 their authority must be explicitly denied ; and all the best ob- 

 servers of the present time would agree (the Author believes) in 

 the following general account of the organization of Infusoria. 



267. Their bodies consist of " sarcode," of which the outer 

 layer possesses considerably more consistence than the internal 

 portion ; the process of differentiation having here advanced suffi- 

 ciently far to establish a clear distinction between the wall and 

 its contents. Sometimes, as in Paramecium, a distinct pellicle 

 maybe recognized on the surface of the proper coat of the body; 

 and this, which is studded with regularly arranged markings 

 like those of Diatomaceae, seems to be the representative of the 

 carapace of Arcella, &c. (§ 264), as of the cellulose coat of Proto- 

 phytes. The form of the body is usually much more definite 

 than that of Amoeba or Actinophrys ; each species having its 

 characteristic shape, which is only departed from, for the most 

 part, when the animalcule is subjected to pressure from without, 



> Professor Agassiz, indeed, goes so far as to assert (" Ann. of Nat. Hist." vol. ii, 1850 

 p. 157) that, as he has satisfied himsfelf by direct observation, Bursaria, Paramecium, 

 and other Animalcules which are commonly accounted as types of this group, are germs 

 of fresh-water worms, some of which he has seen hatched from eggs of Planaria. No 

 confirmation has yet been given to this statement by other observers; and until details 

 of these observations shall have been published, it cannot be expected that Zoologists 

 should acquiesce in the entire demolition of this class, which Prof. Agassiz thinks him- 

 self warranted by them in proposing. 



