Conjugation 25 



to be a sort of reserve of nuclear material. The large part, 

 or macronucleus, seems to take a part in the physiological 

 processes of the daily life of the cell. The reserve nucleus, 

 or micronucleus, seems to lie inactive, save at the time when 

 the creature divides ; then both the large, active nucleus and 

 the small reserve nucleus divide, so that both the new indi- 



c v 



ma 



c v 



Figure 7. Diagram of the process of division in Paramecium; suc- 

 cessive stages, c. v., Contractile vacuoles; m., Mouth; ma., Macro- 

 nucleus; mi., Micronucleus. 



viduals produced contain half of each (Figure 7, c, d). 

 Sometimes there are several of the small reserve nuclei. 



Now at the time of conjugation (Figure 8), in each of the 

 mated individuals the old active nucleus breaks up and 

 gradually disappears, being apparently absorbed like so 

 much food, by the rest of the body. The reserve nucleus 

 (mi., Figure 8), on the other hand, divides several times; 

 in Paramecium caudatum, for example, each divides twice 



