EXPLANATION OF PLATE 10 



Binary and multiple fission in Hexamitus ovatiis sp. nov. (figs. 13-20) and 

 H. batrachorum sp. nov. (figs. 21-24). X 2583. 



Fig. 13. Completion of division of organelles; note persistence of para- 

 desmose. 



Fig. 14. A later stage: paradesmose has disappeared. 



Fig. 15. Complete reorganization of nuclei preparatory to final separation 

 of two individuals. 



Fig. 16. Beginning of multiple fission: axostyles divided; karyosome brealc- 

 ing up. 



Fig. 17. Migration of blepharoplasts to opposite sides of nuclei before 

 spindle formation. Paradesmoses formed. 



Fig. 18. Somatella of five sets of organelles of individuals the product of 

 multiple fission and subsequent disintegrative separation of a part of the 

 trophozoites. 



Fig. 19. The same, with four individuals. 



Fig. 20. The same stage: note variation in size. 



Figs. 21-24. Hexamitus hatrachonim sp. nov. from Eana pipiens. 



Fig. 21. Trophozoite showing characteristic nuclear appearance. 



Fig. 22. Somatella with four pairs of nuclei, product of multiple fission. 



Fig. 23. The same, with three pairs of nuclei. 



Fig. 24. The same, with two pairs of nuclei. 



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