THE PARAMECIUM 



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structure, consisting of one large and one small portion, called 

 respectively the macronucleus and the micronucleus. 



Sometimes a Paramecium may be found in the act of dividing 

 by the process known as fission. In this process the nucleus 

 first elongates and breaks into 

 two, and the halves go to op- 

 posite ends of the cell. The 

 cell elongates, a second gullet 

 appears, and ultimately the 

 cell breaks into two parts, each 

 half provided with a nucleus 

 and a gullet. This is a method 

 of asexual reproduction. 



Frequently another type of 

 reproduction may be observed. 



tile/ , 

 vctcvole 



li^ronwcleus 

 romxcleus 



lace -where 

 torectk- 

 occurs 



Conjugation in Paramecium. Explain 

 how this takes place. 



Cell division in Paramecium. What is the proc- 

 ess called? Describe exactly what happens. 



This is called conjugation, and somewhat resembles conjugation 

 in the simple plants. Two cells of equal size attach themselves 

 Together as shown in the small diagram. The cell membranes 

 dissolve at the point of contact. Complicated changes take place 

 in the nuclei of the two cells thus united. Finally fragments of the 



