100 



THE PROTOZOA 



Rhizopoda, and to this power of change may be due the fact that 

 fewer species of Flagellidia than of Rhizopoda are known. 1 The 

 development of a flagellate or of a rhizopod throws little light upon 

 the question, for both flagellates with amoeboid swarm-spores, and 

 rhizopods with flagellated swarm-spores, are known. The very close 

 relation of the two groups is also shown by the fact made out by 



Fig. 55. Dimorpha mutans Gruber. [GRUBER.] 

 A. Amoeboid phase. B. Flagellated phase. 



numerous observers, that in the same organism pseudopodia may 

 change into flagella, and flagella into pseudopodia. 



The relations of pseudopodia to flagella have not hitherto been 

 sufficiently emphasized. Not only do flagella become pseudopodia, 

 and pseudopodia flagella, in some forms, but in cases where the 

 mutual change has never been observed, there is morphological evi- 



1 Butschli enumerates 98 genera of Flagellidia and 174 genera of Rhizopoda; Delage 

 and Herouard 314 genera of Rhizopoda and 153 Flagellidia. 



