PROTOZOA 



149 



TIHCHOCY6T3 



S CAHAL9 



them in a warm place for a few days. When observed the liquid 



will be found to be swarming with various kinds of protozoa, of 



which many are paramcecia. Their appearance is due to the fact 



that most protozoa can live 



in a dried condition and so 



are blown around like dust. 



They become attached to 



the hay or leaves and only 



await moisture and warmth 



to begin active life again. 



This is not reproduction 



but only a resting stage to 



carry them over unfavora- 



ble periods. 



Structure. The para- 

 moecium has a cell wall 

 which gives it a definite 

 oval shape. There is .also 

 a funnel-shaped cavity on 

 one side which acts as a 

 mouth. The cell is covered 

 with tiny hair-like cilia by 

 which the paramoecium 

 swims rapidly and also pad- 

 dles food particles toward 

 the mouth cavity. Inside 

 the cell there are, of course, 

 the protoplasm, nucleus, 

 and contractile vacuoles. 

 The latter are two in num- 

 ber and situated in definite 



places at the two ends of 



C 



penisrotif 



MOUTH AHO QVLLET 



FIG. 46. Diagram of structures of Para- 

 caildatum from an individual about 

 125 of an inch in length. From Calkins. 



the cell. 



Specialization. Now you can understand that while the para- 

 moecium and amceba perform similar functions, still, the para- 

 mcecium is much more fully adapted for them, in so much as it 



