160 KANSAS UNIVERSITY QUARTERLY. 



I'HOTOiMICROtiRAl'HS. 



Fui. A. View of a portion of follicle near its edge. Just above the lower fourth 

 of the picture may be seen the follicular wall. In the lower fourth is the 

 connective-tissue investment of the testis. The large cell in the center is a 

 secondary spermatogonium in prophase. At .r is the accessory chromosome, 

 twisted like a corkscrew, and enclosed in its own membrane. To the left is 

 a very early prophase: below and at the upper right hand are later ones: 

 and below and above, to the left, are prophases of primary spermatogonia. 

 The cyst walls are not in focus. 



Fig. B. Above are secondary spermatogonia in metaphase and anaph-ase : zones 

 of clear karyoplasm may be seen around most of the chromosomes. Below 

 and to the right are secondary spermatogonia in telophase, showing the 

 sacculated nucleus. To the left of these are two primary spermatogonia in 

 resting stage. 



Fig. E. Metaphase of secondary spermatogonium. 



Fig. G. Young cyst of secondary spermatogonia with degenerating primary 

 spermatogonium in the center. Cells of upper half are in anaphase: those of 

 lower half, in middle or late telophase : .v marks a chain of spindle remains 

 extending through three cells. On the left is the follicular wall, within 

 which is the cyst membrane — the latter being plainly visible entirely around 

 the cyst. 



Fig. H. Primary and secondary spermatogonia. Above is the cell shown in fig. 

 18. Below and to the left is a secondary spermatogonium in late prophase. 

 To the right is a primary spermatogonium in prophase, and, below this, an- 

 other in metaphase. 



Fig. C Mass of primary spermatogonia. Cell in the center is in late prophase. 



Fig. D. Primary and secondary spermatogonia. At the upper right hand is a 

 cyst of secondary spermatogonia, while a corner of a similar one may be seen 

 just below. The remaining cells are primary spermatogonia. To the left of 

 the center may be seen the cell from which fig. 7 was drawn. In the lower 

 right-hand corner is a resting stage, and, to the left of this, the metaphase 

 of which fig. 10 is a drawing. At a is an open space formed by the separa- 

 tion of the cell-wall from its enveloping capsule, forming the earliest mani- 

 festation of the future cyst membrane. 



Fig. F. Telophases of secondary spermatogonia. At .r is the vesicular chromo- 

 some. 



Fig. I. Diaster of secondary spermatogonia. Below, an early anaphase. In 

 the lower left-hand corner, a primary spermatogonium in prophase. 



Fig. J. Telophases of secondary spermatogonia. At .r, x, are vesicular chromo- 

 somes. At s. a persisting spindle, with thickenings upon the fibers where 

 they pierce the cell-walls. The spindle passes through the edge and not the 

 center of the partition wall. 



