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HOW DO WE CLASSIFY ANIMALS? 



..dilicc 



Contractile 

 va6uole> 



.rmcrDnucleus 

 Tnacronueleus 



through which project numerous delicate threads of protoplasm 

 called cilia (sil'i-d). 



Imbedded in the pellicle are many defensive structures called 

 trichocysts (tnk'6-sist), which are shot out like darts when danger 



is near. These structures 

 are composed of cytoplasm, 

 are hollow, and secrete a 

 poisonous substance. 



The locomotion of the 

 Paramecium is caused by 

 the movement of the cilia. 

 The current of water 

 caused by the cilia carries 

 tiny particles of food into 

 the oral groove on one side 

 oral ^5h*?ve of the cell and into a 

 funnel-like opening, the 

 gullet. Once within the 

 cell body, the particles of 

 food materials are gathered 

 within a small area called 

 a food vacuole. Other 

 vacuoles appear to be 

 clear; these are spaces in 

 which food has been di- 

 gested. One or two larger 

 contractile vacuoles may be 

 found ; their purpose seems 

 to be to pass off liquid 

 waste material from the 

 cell body. This is done 

 by the pulsation of the 

 vacuole, which ultimately bursts, passing the fluid waste to the 

 outside. The cell wall breaks at regular intervals to discharge 

 solid food waste. Since the cell membrane breaks at nearly 

 the same place each time, the opening is called the anal spot. In 

 a cell that has been stained, the nucleus is seen to be a double 



. — gullet 

 :r|||"" yoocL vacuole** 



contractile 

 vacixole^ 



The Paramecium. Which end goes first ? Where is 

 the mouth ? How does food get inside the cell ? How- 

 is it circulated ? 



