PROTOZOA 



33 



Reproduction. — Paramecium reproduces by simple binary fission 

 and frequently conjugates. Isolated daily, the offspring of a single 

 Paramecium have been kept running since 1907 by Woodruff of 

 Yale University. Over 13,500 generations have been produced by 



FiffST MATURATION DIVISION OF MICRONUCLEUS 



3EC0N0 AND TMIRn 

 DIVISION OF MICRONUCLEUS 



THREE 5OMAT1C DIVISIONS OF FERTILIZED NUCLEUS 



rERTIUZATlON 



TWO CONSECUTIVE DIVISIONS 

 GIVING FOUR NORMAL CELLS 



Fig. II. Conjugation in Paramecium caudatum. (After Calkins.) 



division without an opportunity for conjugation with a different 

 line^ (Fig. 10, J and B). 



* Woodruff, L. L. 1929. Thirteen thousand generations of Paramecium. Proc. 

 Soc. Exp. Biol, and Med., vol. 26, pp. 707-708, May. 



