28 DESCRIPTION OF PLATES. 



PLATE V. 

 Blattella germanica. 



FIGS. 137-141. Dyads contracting for second maturation mitosis. 



142. Equatorial plate of second maturation spindle, containing II chro- 

 mosomes. 



143-144. Same, with n chromosomes and the element x. 

 145-147. Sections of second maturation spindles; element x dividing in 146 

 and 147. 



148. Telophase of second mitosis. 



149. Telophase of second mitosis, showing masses of chromatin left 



behind in cytoplasm. 



150. Spermatid with extranuclear chromatin (a). 



151. Similar stage; different view of spindle-remains (s~) and of chro- 



matin element (xi). 

 152-153. Spermatid with divided spindle-substance and the corresponding 



double-tailed form. 

 154-155- Stages between 156 and 158. 

 156-157. Older spermatids than 151, showing spindle-remains (s) and cen- 



trosome (c). 

 158-160. Later stages in development of sperm-head. 



161. Ripe spermatozoon. 

 162-168. Degenerate spermatids and spermatozoa. 



