AMCEBA, VORTICELLA, PARAMECIUM 31 



just on fho border of vision, and is shaped somewhat lilce a 

 shpper. It may be obtained in abundance from an infusion 

 of hay. 



Tlie body of tiie shpper animalcule is inclosed with a thin 

 cuticle which retains the sliape of the body. All over the 

 body are longitudinal rows of minute, eyelashlike appen- 

 dages, called cilia. The Paramecium moves swiftly through 

 the water by means of the rapid vibrations of cilia. On 

 account of their rapid motion, the cilia are difficult to see in 

 a living specimen. 



On one side of the body is a long, .slightly twisted groove 

 (Fig. 11), known as the oral groove, that extends into Lhe 



Lii^.J^- 



Fig. 11. — Slijipor animalcule mucli enlarged: ?;?,, mouth; g, g.'iUet; 

 w, waste matter; fv, foud vacuole.s ; cv, contractile vehicles; n, large 

 nuclc'U.s. 



body and finally becomes a tube. At the beginning of 

 this tube is the mouth. The pararnecium has two con- 

 tractile vacuoles, one near each end of the body. Two 

 nuclei are present, but difficult to see. 



Paraniecia reproduce by fission in much the same man- 

 ner as the am(el)a. There comes a time, however, when it 

 seems that the jirocess of fission cannot be repeated again 

 until quite a different process has taken jilace. This pro- 

 cess is known as conjugation and may be considered a re- 

 juvenating process. Two individuals come together, and 

 an actual interchange of a part of the substance of the 



