Davis. — Spermatogenesis. 



Explanation of Plates. 



All drawings have been made at the level of the base of the microscope 

 with the aid of a camera lucida. The combination used, Leitz /o inch objective 

 and No. 4 ocular, was the same in all cases. All figures with the exception 

 of Plate 4 are magnified 1450 diameters. The figures in Plate 4 have been 

 reduced |, giving a final magnification of 966 diameters. 



PLATE 1. 



Fig. 1. Apical cell of Dissosteira Carolina. 



Fig. 2. Apical cell of Stenobothrus curtipennis. 



Fig. 3. Apical cell of Melanoplus femoratus. 



Fig. 4. Apical cell of Steiroxys trilineata. 



Figs. 5-15. Dissosteira Carolina. 



Fig. 5. Resting stage of primary spermatogonium. 



Fig. 6. Resting stage of secondary spermatogonium. 



Figs. 7, 8. Prophase of secondary spermatogonia. 



Fig. 9, 10. Same stage as Figs. 7 and 8, but the sections are cut in such a 



way as to show only one side of the nucleus. 

 Fig. 11. Late prophase of secondary spermatogonium. 

 Fig. 12. Polar view, metaphase of secondary spermatogonium. 

 Fig. 13. Side view of the same stage as Fig. 12. 

 Fig. 14. Anaphase of secondary spermatogonium. 

 Fig. 15. Telophase of secondary spermatogonium. 

 Fig. 16. Prophase of secondary spermatogonium of Steiroxys trilineata. 



The monosome is shown inclosed in a separate vesicle. 

 Fig. 17. Prophase, secondary spermatogonium of Stenobofhrus curtipennis. 



