216 



BIOLOGY OF THE PROTOZOA 



Schaudinn's description of division in Heliozoa was confirmed in 

 the main by Zuelzer (1908) in connection with the aberrant form 

 Wagnerella horealis. Here the axopocHa-bearing portion of the cell 

 is free from the silicious mantle which covers the remainder of the 

 animal, the nucleus being in an enlarged pedal portion attached to 

 the substratum. The central granule is in the geometrical center 



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Fig. 102. — Microgromia socialis after Hertwig (A), and Microgromia sp. (J3.) 



original. 



of the "head" and is the focal point of the axopodial filaments. 

 Each of the latter bears a granular enlargement similar to a basal 

 body. In preparation for division these move centripetally toward 

 the central granule forming a zone about it which divides with the 

 division of the central granule. In the meantime the nucleus 

 migrates from the other end of the body and with the spindle formed 

 by the divided central granule forms the mitotic figure. 



