ORIGIN OF THE METAZOA 



45 





.•••I.C-'-'V ••.'"■ .■' N - 



Fig. 16. Sporozoan structure. Spore cases of gregarines. The 

 Cnidosporidea are not the only forms to have complex spore cases ; 

 the gregarines have them too. (a) shows the complete spore case, 

 (b) shows details of the tube through which the spores are dis- 

 charged, (c) shows the tube everted and the spores being discharged 

 through it. Such a reproductive spore case with its evertible tubes 

 has something in common with the spore case of the Cnidosporidea. 

 (a) Gregarina munieri after Schneider, (b and c) Gregarina ovata 

 after Schnitzler. (Both from Grasse.) 



