32 



AMCEBA, VORTICELLA, PARAMECIUM 



nucleus of each animal takes place. After conjugation 

 occurs they reproduce rapidly by fission as before. 



Bell animalcule, or vorticella. — These animals occur in 

 infusions of hay and in bodies of fresh water attached to 



leaves, sticks, and pond 

 scums. The body is 

 shaped like an inverted 

 bell and has a long, 

 slender stalk by which 

 it is fastened to objects 

 in the water. The body 

 is invested with a trans- 

 parent cuticle, but the 

 cilia are confined to the 

 edges of the bell and 

 vestibule. On the mar- 

 gin of the bell is a deep 

 Oral groove, the vestibule, 

 that extends downward 

 toward the center of the 

 body (Fig. 12) and ends 

 with the mouth. The 

 long, slender stem is 

 composed of an outer 



Fig. 12. -Bell animalcule, or vorticella: transparent sheath and 

 e, gullet ; n, nucleus ; cv, contractile vacu- an inner mUSCular rod, 

 ole ; a, axis ; ., sheath ; /,;, food vacuole. ^j. ^^jg^ j^^ j^^^^j.^^ ^^^^ 



little animals are constantly pushing out and darting back 

 to their places of support by means of the uncoiling and 

 coiling of the slender stems. As one darts back, the edges 

 of the bell become inverted and turned inward so far that 

 the body assumes a globular shape. As it slowly pushes 



