188 



PROTOZOA. 



The fine granules of the protoplasm can enter the pseudopodia 

 and produce here, as they move back and forth, the phenomenon 

 of 'streaming.' Since foreign particles, like grains of carmine 

 taken up by the protoplasm, can participate in this streaming, it 



Fig. mi .—RntaUa frcyeri . (From Lang, after M. Schultze.) 



follows that the movements depend not \\\)o\i the granules but on 

 the protoplasm itself. We have already used the fact (p. 62) 

 that granules in the finest thread can move in opposite directions 

 at the same time, to demonstrate the extraordinary complexity of 

 protoplasmic structure. 



When Ehizopoda, in the free or en- 

 cysted condition, increase by division, the 

 division products frequently exchange the 

 amoeboid motion for that of the Flagellata, 

 and become fiagellate spores or zoospores. 

 The body becomes ova] and develops, on the 

 aiiterior end which contains the nucleus, 

 one or more fiagella. which move more ener- 

 getically than pseudopodia, and are perma- 

 nent as long as the zoosjiore stage persists 

 (fig. 121). Since many Protozoa possess 

 fiagella along with pseudopodia, the 

 Ijoundary between Rhizopods and Flagel- 

 vft rF £ schuizo.) li^tes is not distinct (fig. 118). 

 The Rhizopoda form an ascending series in which the systematic char- 

 acters become more and more pronounced; such are the assumption of a 



Vi ( (/ 



