HYLUM PROTOZOA 



43 



process of binary fission (Fig. 14, 2b\ which may take place 

 either in the active or in an encysted condition. In some 

 cases the fission is multiple, the protoplasm dividing not 



Fu,. 17. VolVQX globator. A, entire colony, enclosing several daughter-colonies ; 

 B, the same during sexual maturity ; C, four zooids in optical section ; D 1 D 5 , 

 asexual formation of daughter colony ; K, zooid which has become converted 

 into a mass of microgametes ; F, microgamete ; G, megagamete surrounded by 

 microgamstes ; H, zygote ; a, early stages in the formation of daughter-colonies ; 

 fl, flagellum ; ov., ovy. megagametes. ; pg. pigment spot ; sf>y. zooids containing 

 microgametes. (From Parker's Biology, after Cohn and Kirchner.) 



merely into two, but into a greater number of parts, each 

 destined to develop into the adult form. 



We also meet in the Mastigophora with what may be 

 regarded as the simplest mode of sexual reproduction. In 



