PLATE 2 



EXPLANATION OF FIGURES 



Notonecta irrorata 

 X2250 



15-16 Metaphase of first division, polar view, showing 13 chrom.osomes, one 

 small one in center. 



17 A, B, C Serial sections of spindle in side view, early anaphase, first divi- 

 sion. 



18 Components of central pair on different fibers. 



19 ^, jB, C Serial sections of spindle in side view, initial anaphase, second 

 division, showing 12 chromosomes, XY in center. 



20 Metaphase of second division, polar view. 



21 A, B, C Complete spindle, X and Y on different fibers. 



22 Same, polar view. 



23 A, B Sister anaphase groups of second division, from same spindle. 



24 Spermatogonial group, showing 24 chromosomes. 



104 



