Wilcox. — Spermatogeuesis. 



PLATE I. 



Cicada tihicen. 



Fig. 1 a-e. Spermatids in various stages of metamorpliosis. 



Fig. 2. Spermatid with nucleus Nebenkurper and small red body. 



Fig. 3. Spermatid, tail undeveloped. 



Fig. 4. Spermatid immediately after second division of spermatocytes. 



Figs. 5, 6. Spermatids. 



Fig. 7. Spermatogonium witii centrosomes near nucleus. 



Fig. 8. Spermatogonium after amitotic nuclear division. Degeneration. 



Figs. 9, 10. Spermatids. 



Fig. 11. Spermatogonia. 



Figs. 12, 13, 21, 22. Stages in development of giant spermatozoa. 



Fig. 14. Longitudinal section of testicular follicle. 



Figs. 15-18, 24-43. Stages in the metamorphosis of spermatids. See also Figs. 44, 

 45 (Plate II.). 



Fig. 23. Part of compartment c of Figure 14. To the left of the connective tissue 

 dissepiment are spermatogonia ; to tlie right, belovif, are spermato- 

 cytes of the first order; above, spermatids. 



Figs. 19, 20. Degenerating spermatogonia. Fig. 19 with two extranuclear bodies, 

 centrosomes ? 



