Phvluiii Proto::oa 371 



O' 



Fig. 120. — Diagram of conjugation in Paramecium caudatuin. A, Two mated 

 individuals with oral surfaces together; B, micronuclei elongate; C, micronuclei di- 

 vide; D, micronuclei divide again, resulting in four in each conjugant; E, three 

 micronuclei degenerate in each conjugant leaving one; F, each remaining micro- 

 nucleus divides and one-half of each moves into the other conjugant; G, the "male" 

 and "female" fuse in each conjugant; H and H', the conjugants separate; / and /', 

 each micronucleus divides, the macronucleus degenerates; J and J', each micro- 

 nucleus divides again; K and K', each micronucleus divides again, resulting in a 

 total of eight; L and L', four micronuclei enlarge to become macronuclei, three 

 micronuclei degenerate; M and M', four macronuclei and one micronucleus present; 

 N and A^', division of cell and micronucleus, resulting in two cells, each with two 

 macronuclei and one micronucleus; O and O', division of each cell and each micro- 

 nucleus, resulting in four cells, each with a single micro- and a single macronucleus. 

 Cytoplasm of one conjugant and its progeny is stippled; the other is clear. 



