48 



TYPICAL ANIMAL CELL 



The physiological functions of the Paramecium are somewhat 

 more complex than those of the amoeba because of the increasing 

 complexity of structure. 



Nutrition. Bacteria and any other tiny plants or protozoa that 

 are small enough are swept by the current created by the cilia 



into the oral groove. These 

 ^M\\mm/A. ^j.g driven through the gul- 



let, where they are made 

 into a food ball and dis- 

 charged into the cytoplasm 

 of the cell. The food ball 

 is carried around as a vac- 

 uole by the streaming cyto- 

 plasm. The processes of 

 digestion, circulation, as- 

 similation, growth, and res- 

 piration in the animal are 

 similar to those described 

 for the amoeba. As the 

 food is gradually digested, 

 any material that cannot be 

 digested is collected at a 

 certain small area of the 

 plasma membrane in the 

 posterior end of the animal. 

 The membrane breaks at 

 regular intervals to throw 

 off the solid food wastes. 

 This mechanism is called 



Note in this diagram the strHctures that you were i i • t) 



unable to see in your microscopic study of the Para- tllC anal OpCUUlg. rJccaUSe 



cilice 

 |-tricKocy5ts 



ite en'SLo pi cc s m 



_^ . ^ J^^Racronuccleirs 



^-^^^^■a, vacuole. 



■c V. cocrtaL 

 anal epot^ 



mecium. 



the wall always breaks in 

 the same region to let out the solid material, it is frequently called 

 a weak spot. The wastes, carbon dioxide, water, and urea, formed 



