76 



THE PARAMECIUM 



(i) Paramecia may be found in the process of conjugation, but 

 such pairs swimming about adhering together by their buccal grooves 

 do not show the nuclear changes which are occurring. Examine and 



A. Two individualt unlti 6y 

 buccal grooves. The micro 

 nuclei a»parate from tht 

 macronuclei. 



B. The macronucleua begins to 

 degerterate. The micyonucleua 

 diuidea. 



C. The micronuclei divide 

 again. Three of each four 

 disappear. 



D. The remaining micronuclei 

 divide to form migratory and 

 atationary nuclei. Exchange 

 of migratory nuclei. 



E. The migratory and atationary 

 nuclei unite. 



f The fualon nucleua ia 

 thua formed. 



C. The Indluiduala separate. 



H. Diviaion of the fualon nueleua. 



I. Diuialon, at thown. 



J. Differentiation into maero-and 

 micronuclei occurs and dis- 

 appearance of three micronuclei. 



K. Cells and nuclei 

 dwidt as shown tt> 

 produce the original 

 condition. 



Fig. 37. — Conjugation in Paramecium caudatum; diagrammatic. 



(Redrawn from H. S. Jennings, "Life and Death. Heredity and Evolution in Unicellular 

 Organisms," copyright. 1920, Richard G. Badger, printed by permission.) 



draw demonstrations showing: (1) A pair of conjugants, with a single 

 micronucleus in each, in which the macronuclei are beginning to show 

 some irregularity. (2) Conjugants in which the original micronuclei 



