THE CILIATE INFUSORIA. 



35 



ers, so that when the organism has by means of its hollow 



arms or tentacles caught some 



Infusorian, the arms con- 

 tract, draw the victim nearer 



to the Acineta, and when the 



sucking disk at the end of the 

 ^arms has penetrated the skin, 



the contents of the body of 



the Infusorian are sucked into 



the food-cavity of the Acine- 

 ta ; on the other hand, in 



some Acinetse a portion of the 



arms are simply prehensile. 



These animals are in their 



adult phase cpiite unlike the 



Flagellata or Giliata, but the 



young are developed within 



the parent and are provided 



with cilia, being at first free- 

 swimming, and afterward 

 fixed by a long stalk. The 

 Acinet(B sometimes self -di- 

 vide, sending off from the 

 free end of the body a ciliated 

 Acinete ; they have also been 

 seen to conjugate. 



Order 3. Ciliata (Infuso- 

 ria). A common type of this 

 group and one easy to obtain 

 by the student is Parame- 

 cinm (Fig. 24), observed in 

 infusions, or moving rapidly 



. Fi- 24 Paramecium cauaaium. -n. 



Over the bodies Of larger am- view from the dorsal side, magnified 340 

 , . , j i.1 diameters. //, the head; 7', the tail; m, 



mala which may be under the the mouth; m to gMhe throat; a,thepos- 



-nv ft A terror opening of the digestive cavity; cv l 



miCrOSCOpe. f IgUl'e /J* rep- the anterior and cv posterior contractile 



resents Parcunecium cauda- ^| c ^' t he reproductive organ; , the 



*. T?U,./vi-.l-vr>vrr Tliis -mi- large vibrating cilia at the edge of the ves- 

 tUin -EjllienDClg. tibule.- -After R. J. Clark. 



malcule is a mass of proto- 

 plasm, representing a single cell. In the body-mass are ex- 



2l.Paramecium caudutum. 



