•PLATE 6 



Fig. 7. Vertical view of centroblepharoplast complex in rounJed-up form. 

 Cuplike depression and operculum have disappeared. Oblique fibers radiating out 

 from lobes of centroblepharoplast. 



Fig. 8. Cross-section of distorted individual showing relative extent of endo- 

 plasm and ectoplasm. X 300. 



Fig. 9. Lateral view of anterior end showing centroblepharoplast complex, 

 oblique fibers and alveolar layer. 



Fig. 10. Centroblepharoplast complex of individual in early prophase. Oper- 

 culum and depression have disappeared, end of centroblepharoplast drawn out to 

 a point. 



Fig. 11. Vegetative nucleus showing the central region of chromatin granules, 

 the heterochromosome and its vesicle, the alveolar zone and the outer, granular 

 region. 



Fig. 12. Cross-section of anterior end of body showing the centroblepharo- 

 plast, myonemes and surface ridges. 



Fig. 13. Vertical view of centroblepharoplast complex of the early prophase 

 stage. 



Fig. 14. Vegetative nucleus showing the chromatin-encrusted network. Other 

 parts as in figure 11. 



Figs. 15-22. Nuclei of the early prophase stages in individuals which present 

 no other sign of division. 



Fig. 15. Early prophase; alveolar zone has disappeared, chromatin moving 

 out from the granules along the threads of the network. 



Fig. 16. Later stage of the same. Note size of heterochromosome and its 

 vesicle. 



Fig. 17. Formation of chromosomes; vesicle surrounding heterochromosome 

 has disappeared. 



Fig. 18. Appearance of distinct, paired chromosomes. 



Figs. 19-22. Various figures of fully formed chromosomes. 



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