62 INFUSORIA. 



mistaken for frog's spawn, to which, in consist- 

 ence, it bears some resemblance. 



Anatomically, the bodies of most Infusoria may 

 be regarded as consisting essentially of three dis- 

 tinct structures, viz. : — 



1. The cuticle or integument ("pellicula" of 



Carter) on which are borne the cilia and 

 other locomotive apparatus {fig, 12, c — c) ; 



2. The cortical layer or parenchyma of the body 



(" diaphane " of Carter) (f ) ; and 



3. The chyme mass, abdominal cavity, or in- 



terior of the body (sarcode or "abdominal 

 mucus '' of Carter), wdthin which the particles 

 of the food rotate. 



It is not certain whether the carapace, w^ith 

 which some Infusoria are provided, be distinct 

 from the cuticle properly so called. We have 

 already seen how, in Vaginicola and its allies, it 

 is so far separated from the rest of the body as to 

 act the part of a protective sheath. 



Of the above structures, the second alone pos- 

 sesses any contractile power. 



In those Infusoria which are attached, e. g. 

 Vorticellaf the free extremity of the body which 

 bears the ciliary disk is termed " anterior," the 

 end remote from this being said to be " poste- 

 rior." The term " ventral " is usually ajDplied 

 to that side of the body on which the mouth is 

 placed. 



6. Digestive apparatus. — In all those In- 

 fusoria whose animal nature has been placed above 

 suspicion the presence of a mouth must be re- 

 garded as universal, though the position of this 

 organ varies considerably among the different 



