THE GILIATE INFUSORIA. 



35 



ers, so that when the organism lias 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 Acinetai a portion of the 

 arms are simply prehensile. 

 These animals are in their 

 adult phase quite unlike the 

 FlageUata or Ciliata, 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 

 Acinetm 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- 

 cium (Fig. 24), observed in 

 infusions, or moving rapidly 



over the bodies of larger ani- view" from the dorHal side, magnified 340 

 1 1 ■ -1 1 J il, diameters. IT, the head; T, the tail; m, 



malS which may be under the the mouth; m to g. the throat; «, the pos- 

 minrnapn-np "PiornrP 94- rP'r\- terior opening of the digestive cavity; c»' 

 microscope. C Igure at rep- jjjg anterior and cv posterior contractile 

 rpspnl-s Pnrrtmprinim rniirin- vesicles; I, II, III, the radiating canals of 

 lebenuB jr ui anwi^iiom cuauu ^,. ^^ jj,^. reproductive organ; v, the 



large vihrating cilia ntthe edge of the ves- 

 tibule.— After H. J. Clark. 



Paramecium caudatam. 



ani- 



tum Ehrenberg. This 

 malcule is a mass of proto- 

 plasm, representing a single cell 



In the body-mass are ex- 



