Figure 147. Diagram of ciliate conjugation. 1, two ciliates joined ventrally, micro- 

 nuclei in prophase parachute stage; 2, first meiotic (equational) division; 3, second 

 meiotic (reduction) division in which the chromosome number is reduced from diploid 

 to haploid, and the macronucleus begins to degenerate ; 4, third maturation division, 

 involving only one of the four nuclei in each animal, the other three degenerate; 5, 

 migration of the wandering ( $ ) pronuclei into the apposed animals, $ and $ pro- 

 nuclei of left conjugant stippled to indicate common origin; 6, fusion of wandering 

 and stationary pronuclei to form synkaryon and restore diploid condition; 7, conjugants 

 separate, first division of amphinucleus in exconjugants; 8, second amphinuclear division; 

 9, four nuclei produced by the two amphinuclear divisions, the old macronucleus dis- 

 integrates; 10, two of the four new nuclei develop into new micronuclei, two into new 

 macronuclei; 11 and 12, first fission of the exconjugant separates out one micronucleus 

 and one macronucleus to each daughter cell reestablishing the vegetative condition. 



