1912] SHARP— SPERMATOGENESIS IN EQUISETUM 119 



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Fig. 5. — Blepharoplasts at upper side of nucleus; other single and paired 

 bodies present in cytoplasm; exceptional condition. 



Fjg. 6. — Blepharoplasts beginning to separate; central spindle present; 

 the radiations on the side toward the nucleus form a distinct cone. ' 



Fig. 7. — Later stage; no cone of rays present. 



Fig. 8. — Still later stage; central spindle fading out. 



Figs. 9-12. — Stages in the divergence of the blepharoplasts. 



Fig. 13. — Blepharoplasts lying at a greater distance from nucleus; the 

 radiations on the side toward the nucleus form two well marked cones; the 

 chromatin network becoming coarser. 



Fig. 14. — Spirem stage: nuclear membrane beginning to break down; 

 astral rays much shorter. 



Fig. 15. — Late prophase: the spindle fibers have been formed from the 

 radiations of the blepharoplasts, which occupy the poles. 



Fig. 16. — Telophase: blepharoplasts have enlarged and become vacuolate. 



plate vni 



Fig. 17. — Pair of spermatids differentiated: blepharoplasts have the form 

 of irregular rings; plastids present in cytoplasm. 



Fig. 18. — Spermatid: blepharoplast beginning to fragment. 



Fig. 19. — Blepharoplast broken up to several pieces. 



Fig. 20. — Granules formed by fragmentation of blepharoplast beginning 

 to draw out into a row; nucleus again in resting condition. 



Fig. 21. — Blepharoplast granules arranged in a long row; cilia beginning 

 to grow out from them; plastids present. 



Fig. 22. — Blepharoplast granules fusing at right end of chain; still separate 

 at left end; degenerating plastids in cytoplasm. 



Fig. 23. — Blepharoplast now a continuous thread; cilia partially 

 developed; nucleus beginning its metamorphosis. 



Fig. 24. — Portion of a similar cell viewed from the direction a, showing 

 proximity of nucleus and blepharoplast ; cilia not drawn. 



Fig. 25. — Later stage: nucleus and blepharoplast have elongated spirally; 

 chromatin network very coarse. 



Fig. 26.— Entire cell similar to that of fig. 25 viewed from the direction a, 

 showing independence of nucleus and blepharoplast; cilia not drawn. 



Fig. 27.— Section of similar cell in plane ab: n, nucleus; 6, blepharoplast; 

 cilia not drawn. 



Fig. 28. — Mature spermatozoid still in antheridium: the blepharoplast 

 makes 1.4 turns, the nucleus 0.7 of a turn; deeply staining globules in cyto- 

 plasm near nucleus. 



Fig. 29. — Smaller spermatozoid in another antheridium, viewed from a 



different direction. 



Fig. 30.— Spermatozoid fixed in the swimming state over osmic fumes: the 

 dark spiral band bearing the cilia is the blepharoplast; the lighter, homo- 

 geneous portion the nucleus; the vacuolate portion the cytoplasm; length 

 exclusive of cilia, 19. 7 /x. 



