9S 
THIRTEENTH REPORT. 
EXPLANATION OF FIGURES. 
a camera 
surrounding 
primary spermatogonial 
All figures with the exception of Fig. 1 were made with the aid of 
lucida. Fig. 1 is a freehand drawing x7. 
Portion of testis. 
Apical cell with 
cells. 
Equatorial plate of secondary spermatogonial nucleus, 
showing accessory chromosome (x). 
Metaphase of secondary spermatogonium, showing acces- 
sory chromosome, x. 
Late anaphase of secondary spermatogonium, showing 
limbs of accessory lagging behind. 
Early growth period, the accessory at x, the nucleolus at 
n. 
Later growth period. 
Late growth period, showing polar arrangement of 
spireme* and position of accessory, x, and of the 
nucleolus, n. 
Very late growth period, showing splitting of the spireme. 
The beginning of tetrad formation. Accessory at x. 
Various forms of tetrads. 
Metaphase of first maturation division. 
Late anaphase of first maturation division, accessory at 
x. 
Anaphase of first maturation division. 
Late prophase of first maturation division. 
Metaphase of second maturation division, accessory at x. 
Late anaphase of second maturation division, without the 
accessory chromosome. 
Telophase of second maturation division, nebenkern at y. 
Two spermatids lying side by side, one showing the ac- 
cessory. the other not. Accessory, x. Nebenkern, y. 
Stage in the transformation of the spermatid. 
Nearly mature sperm. 
Figure 
1. 
Figure 
2 
Figure 
O 
O. 
Figure 
4. 
Figure 
5. 
Figure 
C>. 
Figure 
rr 
i . 
Figure 
8. 
Figure 
9. 
Figure 
10. 
Figure 
11. 
Figure 
12. 
Figure 
13. 
Figure 
14. 
Figure 
1 5. 
Figure 
16. 
Figure 
17. 
Figure 
18. 
Figure 
19. 
Figure 
20. 
Figure 
21. 
