PLATE 9 



EXPLANATION OF FIGURES 



X 2250 



Tetrad formation. N. insulata (continued) 



103 A, B Small ring. 



104 A-I Formation of cross tetrad; H , in metaphase; I, in anaphase. 



105 A-D Condensation of double rod. 



106 A-D Condensation oi XY; D, late prophase, elements separating. 



Tetrad formation. N. irrorata 



107 A-D Condensation of ring; C, in metaphase, side view; D, polar view. 



108 A-H Formation of cross tetrad; D, in metaphase. 



Prophase figures. N. undulata 



109 A-F Diffuse stage. 



110 A-F Condensed stage. 



118 



