56 



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 socialis 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 







£>'eY v.* 





lM^:©:-„->> si, ■•■■. fl -.-""':,^ : ^|V 





«■ © -'.■«_*, 



^^>*^' 



«> • « o ^ .. s>: 

 « © 



<? 



o 



■«► 



&&^, 





SV " 9 " " ® ® 

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



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

 secretion. 



