168 CONJUGATION, MATURATION, AND FERTILIZATION 



by longitudinal but by transverse division, and this division is hetero- 

 polar, so that the resulting nuclei are of different sizes. The smaller 



Fig. 72 



Tlie niicronucleu.s of Paramecium aurelia during cnnjugatinn. .4, concentration of chro- 

 mcsomes after the cre.'^cent phase. Accumulation of kinopla.sm at upper pole; B, early 

 anapiiase of first maturation division; C, late anaphase of first maturation division; D, 

 jirophase of second maturation di^■ision. (.\fter Calkins and Cull.) 



is the migratory nucleus, the larger the stationary. Each migratory 

 nucleus wanders through the connecting lundge of protoplasm and 



'egi 



nucleus wauuers luiougu lue couueciuig oruige or proiopiasm ana 

 fuses with the opposite stationary nucleus, the fusion beginning at one 



