m- 



Fig. i. Diagram of horizontal section through testis (enlarged 20 diameters) 

 showing arrangement of cysts in the lobes. Openings of vas deferens cut obliquely 

 at a and b, longitudinally at c. 



Fig. 2. Early prophase of last spermatogonial division. 



Figs. 3, 4. Polar view of last spermatogonial metaphase. 



Figs. 5, 6. Side views of metaphase and of telophase (optical sections). 



FlGS. 7-10. Various stages in spireme formation ; appearance of plasmosome. 



Figs, ii, 12. Concentrated stage of spireme. 



Fig. 13. Height of spireme stage. 



Figs. 14-16. Stages in breaking up of spireme. 



Fig. 19, a-e. Various views of plasmosome from nuclei similar to Fig. 18. 



