THE PROTOZOA 



free (Fig. 22). The presence of a firm shell or coating complicates 

 the process, especially if the shell is a secretion (Fig. 23). In many 



Fig. 24. Microgromia sociahs Hert., a gregaloid colony. [HERTWIG.] 



cases the new shell-parts are secreted before the act of division be- 

 gins, and when the protoplasm buds out of the original shell-mouth, 

 they are carried with it, and the bud is covered with the newly formed 



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 fee.* i- ^^^^' ^5% 



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 ***>* *> ^ ^ ^ ^***^5<x- 



Fig. 25. Uroglena americana Calkins, a sphaeroid colony. 



pieces, which are glued together by means of a chitinous or silicious 

 secretion. 



