24 • DESCRIPTION OF PLATES. 



Plate III. 



Stenopehnatus. 



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 {s) 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 {s). 



85. Spermatid, showing acrosome material (o) 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 (a), and spindle-remains {s). 

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

 90-92. More advanced stages. 

 93. Mature spermatozoon. 



Blattella germanica. 



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



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



nucleolus («). 



96. Same, prophase of mitosis. 



g7. Equatorial plate of spermatogonial mitosis, 23 chromatin elements. 



98. Young spermatocyte, showing centrosome (c) and (J-shaped element (x). 



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. 



