430 BOTANICAL GAZETTE [November 



6. Sharp, L. W., Spermatogenesis in Equisetum. Bot. Gaz. 54:89-119. 

 pis. 7, 8. 1912. 



7. Shaw, W. R., Uber die Blepharoplasten bei Onoclea und Marsilia. Ber. 

 Deutsch. Bot. Gesells. 16:177-184. pi. 11. 1898. 



8. Walker, N., On abnormal cell-fusion in the archegonium; and on sperma- 

 togenesis in Polytrichum. Ann. Botany 27:115-132. pis. 13, 14. 1913- 



EXPLANATION OF PLATES XXXIII AND XXXIV 



All figures were drawn at the level of the stage with the aid of an Abbe 

 camera lucida, figs. 1-1 1 under a Spencer achromatic objective 2 mm. N.A. 1 . 30 

 with Zeiss compensating ocular 4, and figs. 13-42 under a Zeiss apochromatic 

 objective 2 mm. N.A. 1.40 with compensating ocular 18. They have been 

 reduced one-half in reproduction, and now show magnifications as follows: 

 figs, i-ii, X368; figs. 13-42, X1400. 



PL A TE XXXIII 



Fig. 1. — Microspore at time of liberation from sporocarp: starch grains in 

 cytoplasm. 



Fig. 2. — First mitosis in microspore, cutting off prothallial cell (wall 1). 



Fig. 3. — Prothallial cell completed. 



Fig. 4. — Second mitosis in microspore, forming wall 2 (fig. 8). 



Fig. 5. — Third mitosis in microspore, forming walls 3. 



Fig. 6. — Fourth mitosis in microspore, forming walls 4. 



Fig. 7. — Fifth mitosis in microspore, forming walls 5. 



Fig. 8. — Diagram to show sequence of wall formation: the two primary 

 spermatogenous cells marked with nuclei. 



Fig. 9. — Two primary spermatogenous cells enlarged. 



Fig. 10. — Two-celled stage. 



Fig. 11. — Eight-celled stage. 



Fig. 12. — Sixteen-celled stage (spermatids). 



Fig. 13. — First spermatogenous mitosis: late prophase; spindle poles in- 



pole 



definite. 



Fig. 14. — Anaphase: cytoplasm denser about poles. 



Fig. 15. — Late anaphase: dense regions and radiations present at 

 but no definite centrosomes. 



Fig. 16. — Telophase: remnants of polar radiations visible. 



Fig. 17. — Second spermatogenous mitosis: late prophase; cytoplasm becom- 

 ing dense and granular at poles of spindle. 



Fig. 18. — Anaphase: centrosomes present. 



Fig. 19. — Late anaphase: centrosomes and radiations prominent. 



Fig. 20. — Telophase: centrosome at upper pole beginning to divide. 



PLATE xxxiv 



Fig. 21. — Cell of four-celled stage: centrosome undivided. 

 Fig. 22. — The same: centrosome divided. 



