CILIA TED 



3541 



CILIATED INFUSORIA Order 



ClUATA 



The organisms of this group 

 are provided with cilia, limited 

 either to the under side of the 

 body, or forming a circle or spiral 

 at one end, or arranged uniformly 

 over the surface. Cilia are slender 

 hair-like processes of the body, 

 which move by bending and 

 straightening themselves in uni- 

 son; flagella are larger whip-like 

 organs, and act more independ- 

 ently, the range of motion is not 

 so restricted, and there are usu- 

 ally only one or two present on 

 a cell. A few typical and com- 

 mon species are described. 



The mussel animalcule (Sty- 

 lonychia), common in stagnant 

 water, has the flattened oval body 

 one-hundredth of an inch in 

 length; on the under side is a ring 

 of cilia, and at one end a funnel- 

 shaped depression or mouth (a) 

 with ciliated margin, leading 

 through the dense outer proto- 

 plasm into the more fluid inner 

 mass. The two dark oval bodies 

 (c) are nuclei, and the clear spot 

 () is the contractile vacuole 

 which contracts rhythmically 

 once in about every ten seconds. 

 The creature can stalk along on 

 the large bristle-like processes, in 

 addition to swimming by means 

 of its cilia; the oral cilia set up 

 currents which converge to the 

 mouth funnel, and carry in 

 other infusoria, diatoms, etc. 



The bell animalcules usually 

 possess stalks, and are either 

 solitary or form branching colo- 

 nies. Vorticclla, whose outline 



ROSEI/S TRUMPET ANIMALCULE, Stentor. 

 (Magnified 200 diameters.) 



