Reproduction and Life-Cycles 



89 



necessary to restore the normal nuclear situation. Therefore, the final 

 result of typical conjugation is the formation of 2-8 reorganized ciliates 

 from a pair of exconjugants. In Metopus sigmoides (201), the pronucleus 

 of one conjugant (the "donor") is accompanied by a large amount of 

 cytoplasm during migration. After separation of the conjugants, the donor 

 eventually dies. Conjugation in Opisthonecta (211), Urceolaria (67), and 

 Vorticella (88) also produces only one functional exconjugant. One con- 

 jugant is a microconjugant, produced by budding, and the other is a 

 macroconjugant. In Vorticella ynicrostoma (Fig. 2. 22), a microconjugant 



Fig. 2. 22. Conjugation in Vorticella microstoma. A. Formation of micro- 

 conjugant by budding. B. Fusion of microconjugant and macroconjugant; 

 micronucleus of former in the first pregamic division; second pregamic divi- 

 sions of the microconjugant have produced four nuclei. D. Two spindle- 

 shaped pronuclei are distinguishable. E. Synkar)'on and remnants of de- 

 generating macronuclei. F. One micronucleus in division; seven developing 

 macronuclei. xl050 (after Finley). 



