16 The Life Cycle of the Single Cell 



CONJUGATION 



When culture conditions are adverse (notably, when the Faramecia 

 are starved) these animals come together in pairs and undergo sexual 

 union or conjugation. The steps in conjugation are outlined below (see 

 Fig. 6). 



Fig. 6. Conjugation in Paramecium aurelia. 



Animals pair 

 nd becorne attached 



undergo meiosi: 



The bridge 



between the onimals 



dissolves 



'/: :\ 



: :» 



Moting 

 is complete 



Each gamete nucleu 

 divides mitotically 



Nuclear fusion 

 to yield diploids 



Micronuclei divide; 

 cells begin to divide 



7 of 8 haplold nuclei disapped?^ 



the 8th moves Into area of the bridge 



between the animals 



Mitotic division to M 

 yield 4 nuclei 



2 nuclei become macronuclei; 

 2 become micronuclei 



