GENERAL CLASSIFICATION 135 



Infinitely minute, gelatinous, transparent, contractile, almost homo- 

 geneous and incapable of the possession of any special organ on 

 account of the very delicate consistency of their parts, the infusoriana 

 are in truth mere rudiments of animalisation. 



These fragile animals are the only creatures which do not have to 

 carry on any digestion when feeding, and which in fact only feed by 

 absorption through the pores of their skin and by an internal 

 imbibition. 



In this they resemble plants, which live entirely by absorption, 

 carry on no digestion and in which the organic movements are only 

 achieved by external stimuh ; but the infusorians are irritable and 

 contractile and perform sudden movements which they can repeat 

 several times running ; this it is that indicates their animal nature and 

 distinguishes them essentially from plants. 



TABLE OF INFUSORIANS. 

 Order 1. — Naked Infusorians. 

 They are destitute of external appendages. 

 Monas. — 



Volv^o-ç. Buraaria. 



Proteus [Amoeba. H. E.]. Colpoda. 



Vibrio. 



Order 2. — Appendiculate Infusorians. 

 They have projecting parts, like hair, kinds of horns or a tail. 

 Cercaria [Trematode. H. E.]. 

 Trichocerca. 

 Trichoda. 



Remarks. The monas, and especially Monas termo, is the most 

 imperfect and simplest of the known animals, since its extremely 

 minute body is nothing but a point which is gelatinous and trans- 

 parent, but contractile. This animal then must be the one with 

 which the animal series begins, when arranged according to the 

 order of nature. 



POLYPS. 



(Class II. of the Animal Kingdom.) 



Gemmijoarous animals, with gelatinous, regenerating bodies, and having 

 no internal organ except an alimentary canal with a single aperture. 



Terminal mouth, surrounded by radiating tentacles, or furnished with 

 ciliated or rotatory organs. They mostly adhere together, are in com- 

 munication by their alimentary canal, and then form compound 

 animals. 



