Part 8

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.

N. M. S. del.

BLATTELLA GERMANICA.]

PLATE V.

Blattella germanica.

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

142. Equatorial plate of second maturation spindle, containing 11 chromosomes.

143-144. Same, with 11 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 chromatin element (x{2}_).

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 centrosome (c).

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

161. Ripe spermatozoön.

162-168. Degenerate spermatids and spermatozoa.

N. M. S. del.

BLATTELLA GERMANICA.]

PLATE VI.