Davis. — Spermatogenesis. 



PLATE 4. 



All figures magnified 966 diameters. 



Figs. 57-63. Dissosteira Carolina. 



Figs. 57, 58. Stage g, primary spermatocyte. The loop-shaped monosome 



is shown in both cases. 

 Figs. 59-60. Stage h, primary spermatocytes. The tetrads are already 



formed. The rod-shaped monosome is seen in each cell. The 



irregular deeply staining body in the upper part of the nucleus 



in Figure 59 is a plasmosome. 

 Fig. 61. Stage i, primary spermatocyte. The monosome is seen at the 



right applied to the nuclear membrane. 

 Fig. 62. Late prophase of first maturation division. 

 Fig. 63. Metaphase of first maturation division. The rough rod-shaped 



element lying at an angle to the spindle axis is the monosome. 

 Fig 64. Metaphase, first division of Arphia tenebrosa. A monosome lies 



near each spindle pole. 



Figs. 65-6S. Dissosteira Carolina. 



Fig. 65. Early anaphase of first division. The monosome lies near the left 

 spindle pole. 



Fig. 66. Late anaphase of first division. 



Fig. 67. Group of cells fi-om the distal end of the follicle. The apical cell 

 is seen below and at the right — the one nearest the numerals "67." 

 Surrounding the apical cell aliove and at the left are three pri- 

 mary spermatogonia in different stages. Above and at the left 

 of the primary spermatogonia are four connective-tissue cells. 



Fig. 68. Young spermatocyst from near distal end of follicle. Several con- 

 rective-tissue cells surround the spermatogonia. 



