324 



GAEY N. CALKINS 



one another in the posterior part of the connecting bridge of pro- 

 toplasm (fig. 64) and then each continues its migration in the 

 foreign cytoplasm (fig. 66) down to the stationary micronucleus 



Figs. 68 antl 69 Two pairs with pronuclei clo?e together. The 'attraction 

 spheres' have disappeared. X 800. 



Fig. 70 Two pronuclei about to fuse. The difference in size is without sig- 

 nificance. X 3200. 



(figs. 68 and 69). Here the cytoplasmic guide can no longer 

 be made out. The two spherical pronuclei lie close to one an- 

 other, then elongate to form two ellipsoidal nuclei (figs. 70, 76, 

 77 and 78), and finally fuse. 



