Endomi&is 



31 



study of life and reproduction in these creatures. We must 

 therefore examine it with care. 



In their race of Paramecium that lived indefinitely with- 

 out conjugation, Woodruff and Erdmann found that the 

 active macronucleus is replaced at rather short intervals 



B 



Figure 9. Diagram showing what occurs in endomixis, or the replace- 

 ment of the old active macronucleus by a part of the reserve nucleus 

 (micronucleus) in Paramecium aurelia. Constructed from the figures 

 and description of Woodruff and Erdmann. 



The earliest stage (condition before the process begins) is shown at 

 the top; successive later stages from above downward. The larger black 

 bodies represent the macronuclei; the smaller ones the micronuclei. The 

 clear circles are the micronuclei that degenerate. 



