258 0. M. WKNYON. 



1 jx. These cysts will withstand drying at ordinaiy Iaboratoi-y 

 temperatures, and are capable of giving rise to fresh cultures 

 when broiiglit into suitable media. 



Nomenclature. 



It is certain that Dujardin's original description of the 

 genus Cei'comouas is incomplete, but it seems to me quite 

 clear from liis account that he was dealing with flagellates 

 similar to the one described in this paper. Though he did 

 not definitely state that the fine drawn-out posterior extremity 

 of the body was a tlagellum, still, he says that it was at times 

 so fine as to resemble the anterior Hagellum, and that it was 

 capable of independent movements. Further, in his table of 

 classification he divides the Monads into two groups. In the 

 first he includes forms with'"'uu seul filament flagelliform," 

 while in the second tiiose with " pleusieurs filaments ou 

 appendices." The genus Cercomonas appears in the second 

 of these groups as a foi-m with '' un second filament ou 

 appendice posterieur." It is therefore quite evident that 

 Dujardin regarded this posterior termination of the body as 

 of the nature of a flagellum. Stein and J^iochmann describe 

 the genus Cercomonas as having a drawn-out posterior end, 

 though they do not describe a definite flagellum. 'J'he genus 

 Cercomonas was not accurately defined by Kent or Biitschli, 

 and to Klebs the confusion seemed so great that he proposed 

 the rejection of this generic name and the substitution of 

 G ruber's name Dimorpha, Avhich was created for a bi- 

 Hagellate showing" at certain staofes definite heliozooid 

 characters. In this genus Dimorpha Klebs included forms 

 which he identified with those described originally by 

 Dujardin as Cercomonas, and he suggests that this observer 

 has overlooked the second flagellum. We have seen how 

 near Dujardin was to definitely describing this second 

 flagellum, so that the action of Klebs in rejecting this 

 genus is hardly sound. It seems to me clear that the forms 

 described by Dujardin really possessed two flagella, though 



