Charles J. Chamberlain 19 



Fig, 17. — The two centrospheres are practically alike, but the upper one is shown in 

 median section, while the lower one appears in surface view, the fibers having the appearance of 

 granules within a centrosphere. 



Fig. 18. — The more usual appearance of an early prophase at the third mitosis; prominent 

 caps, but no centrospheres or very definite aster. 



Fig. 19. — An exceptionally prominent centrosphere and aster at the third mitosis; no cen- 

 trosphere or aster at the other pole. 



Fig. 20. — Transverse section of mitotic figure at the third mitosis, just before the splitting 

 of the chromosomes, showing nine chromosomes. 



PLATE XXVII 

 (Figs. 21-9, second mitosis in the germinating spore.) 



Fig. 21. — Cap more prominent at upper pole; nuclear membrane intact. 



Fig. 22. — Nuclear membrane has broken down at the poles, but is still intact at the sides 

 of the nucleus. 



Fig. 23. — Tripolar figure. 



Figs. 24, 25. — Lower cap much broader than the upper; the granular matter within the 

 nucleus is derived largely from the nucleolus and stains with gentian violet. 



Fig. 26. — Late prophase; the achromatic figure evidently consists of two half-spindles. 



Fig. 27. — Spindle very broad at the poles; a rather common form at this stage in the first 

 three mitoses; no radiations or centrospheres. 



Fig. 28. — The caps have kept the ends of the spindle rounded for an unusually long 

 period; no centrospheres or radiations. 



Fig. 29. — Telophase; radiations, but no centrospheres have reappeared. 



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