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THE PROTOZOA 



FIG. 81. General life-cycle of Trichosphcerium sieboldi, as an example of dimor- 

 phism in the adult condition combined with alternation of generations. 

 A, Sohizont or non-sexual form, distinguished by the possession of rod-like 

 bodies in the envelope (compare F) ; this form may multiply by simple or 

 multiple fission (plasmotomy) in a " vegetative " manner, or by the process 

 of sporulation (schizogony) seen in B and G, in order to give rise to the gamete- 

 producing form ; B, division of the body of the schizont into as many cells 

 (" sporogonia ") as there are nuclei ; G, rupture of the envelope and escape 

 of the sporogonia as active amoebulae, each of which forms an envelope for 



[Continued at foot of p. 183. 



