24 DESCRIPTION OF PLATES. 



Plate III. 



Stenopelmatus. 



Fig. 8o. Telophase of second maturation mitosis. 



8i. Young spermatid, showing spindle-remains at s. 



82. Spermatid showing a conspicuous chromatin element in nucleus, and 



spindle-remains (5) elongated. 



83. Spermatid, showing centrosome (c) and divided spindle-remains 



{s and a). 



84. Older spermatid, showing centrosome (c), axial fiber of tail, and spindle- 



remains (j). 



85. Spermatid, showing acrosome material (a) migrating to side of nucleus 



opposite centrosome. 



86. Slightly older spermatid. 



87. Later stage of spermatid, showing condensed chromatin, elongated cen- 



trosome (c), acrosome material (o), and spindle-remains (j). 

 88-89. Older spermatids, showing formation of acrosome (a) and middle piece (m). 

 90-92. -More advanced stages. 

 93. Mature spermatozoon. 



Blattella germanica. 



Fig. 94. Somatic cell from egg follicle, 23 chromosomes. 



95. Spermatogonium, showing chromatin element (.jr) associated with a 



nucleolus (n). 



96. Same, prophase of mitosis. 



97. Equatorial plate of spermatogonial mitosis, 23 chromatin elements. 



98. Young spermatoc3fte, showing centrosome (c) and U-shaped element (*•). 



99. Young spermatocyte, element x attached to one end of a long, fine spi- 



reme. 

 100. Coarser spireme stage. 

 101-103. Bouquet stage. 

 104-105. Later spireme stage. 



106. Various forms assumed by the combined nucleolus and element x; last 



figure from a giant cell. 



107. Segmenting spireme. 



108. Similar stage to fig. 107, one chromosome longitudinally split ; element x 



present. 



