72 B. F. LUTMAN. 



EXPLANATION OF PLATE II. 



13. Longitudinal diagram of the entire mature testes. 



14. Section of one of the follicles showing size, shape, and distribution of the 

 cysts. 



15. Formation of the spireme in a spermatocyte. 



1 6. Synapsis. 



17. Nucleus showing nucleolus on spireme. 



1 8. Nucleus showing nucleolus on spireme. 



19. Entire cell showing same. 



20. Enlarged views of the nucleolus at this same stage showing the split. 



21. Chromosomes formed by the transverse split. 



22. Chromosomes lying free in the nucleus; also the split nucleolus. 



23. Chromosomes forming the tetrads; nucleolus at n. 



24. Tetrads. 



25. Metaphase, first division. 



26. Anaphase, first division. 



27-28. Polar view of the equatorial plate. 



29. Metaphase, second division. 



30. Polar view, equatorial plate. 

 31-32. Anaphase, second division. 



33-35- Transformation stages of the spermatid. 

 36. Sperm. 



