292 



Descriptive Zoology. 



or in vases where flowers have been standing for some 

 time, a film of scum is likely to appear. Just underneath 

 this film is a good place to look. Often the naked eye 

 may detect small white objects moving about. These are 

 paramecia. On examining some of the water with a low 

 power of the microscope, one discovers that these tiny 

 white specks are oval or elliptical, that they swim actively, 



Course of food vacuoles 



Contractile vacuole 



Contractile vacuole 



Ventral view 



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ANTERIOR MACRO- MICRO- ^UTH GULLET 

 END NUCLEUS NUCLEUS 



SPOT 



CONTRACTILE 

 VACUOLE 



POSTERIOR 

 END 



Mouth gullet Food ball 



FK5, 171. PARAMECIUM, THE SLIPPER ANIMALCULE. 



usually with the same end foremost, and that when they 

 run against an obstruction they back off quickly. They 

 evidently have the power of moving and the sense of 

 touch. Looked at with a higher power, the shape may be 

 determined more definitely. They are somewhat flattened, 

 and one end is more pointed than the other. The dif- 

 ference between the clear ectoplasm and the more 

 granular endoplasm is more marked than in the amoeba. 



