138 D. H. WENRICH 



chromatic margin along only apart of the course of the new rod, 

 although presumably it extended the whole distance. In the 

 part which could be made out, however, it remained close to 

 the rod, and hence transversed the deeper protoplasm along 

 with the latter organelle. This deeper position would hardly 

 be expected if the new chromatic margin, or posterior flagellum, 

 had been split off from the peripherally placed old one. 



I have not been able to see evidence of a splitting of the 

 undulating membrane and the chromatic margin, as described by 

 Kofoid and Swezy ('15), although I have searched long and 

 diligently for such evidence. My evidence indicates that the 

 new chromatic margin grows out along the new chromatic basal 

 rod as a new structure just as the other flagella grow out as new 

 structures. In figure 18 I have drawn an individual which 

 appeared to have the old chromatic margin double for the 

 anterior half of its length. The two portions appear to be of 

 equal caliber. The nucleus could not be made out distinctly 

 and there are other indications of degeneration, so that I regard 

 this individual as abnormal, especially since I have carefully 

 examined such large numbers in all stages of division without 

 ever finding any other specimen that indicated a splitting of 

 the membrane. 



Wenyon ('07), Martin and Robertson ('11), and Kuczynski 

 ('14, '18) also find the new posterior flagellum growing out as a 

 new structure, although Dobell ('09) describes the splitting of 

 the undulating membrane in T. batrachorum. I am inclined to 

 agree with Kuczynski that Dobell, and Kofoid and Swezy have 

 been misled by the secondary filament in the undulating mem- 

 brane of T. augusta and T. batrachorum, and I am quite con- 

 vinced that splitting of the undulating membrane does not 

 normally occur in T. muris. 



J-i-. The hlepharoplast. After the new chromatic basal rod 

 has been formed, the new blepharoplast appears, connected to 

 the old one by the paradesmose (Kofoid and Swezy, '15). Figure 

 17 shows a relatively early prophase with the new rod attached 

 to a small granule, which in turn is connected with the old 

 blepharoplast. lii my opinion, this small granule is the new 



