26 DESCRIPTION OF PLATES. 



Plate IV. 

 Blattella germanica. 



Fig. 109. Similar stage to figs. 107 and 108; chromosomes U-shaped and not longi- 

 tudinally split; two centrosomes present (c). 

 no. Longitudinally split chromosomes. 

 111-113. Various stages in formation of cross-shaped tetrads. 

 114-117. Bent rods, U-shapes, split rings, pairs of rods, and rod-shaped tetrads 



(116), which are equivalent to the crosses of figs. 112-113. 

 118-122. Metaphase of first maturation division, showing the element x in various 



positions. 

 123-127. First maturation spindle in metaphase. 



128. Same in anaphase. 

 129-132. Late anaphase, showing element x double in 129, and a lagging tetrad 

 in 130. 

 133. Telophase, with the element x in one daughter cell. 

 134-136. Prophase of second maturation mitosis, showing dyads and element x. 



