74 



PROTOZOA 



two in number, i.e. the nucleus divides into two, one of which 



e.vac 



2.Nuclearia 



S.CIafhrulino 



Fio. 20.— Various forms of Heliozoa. In 3, a is the entire animal and 5 the flagellula ; 

 c.vac, contractile vacuole ; g, gelatinous investment ; nu, nucleus ; psd, pseudopodia ; 

 sk, siliceous skeleton ; s-p, spicules. (From Parker and Haswell, after other authors.) 



goes to the surface as the first polar body, and the sister of this 

 again divides to form a second polar body (which also passes to 



