THE PROTOZOA 



151 



T. 



spermatozoa, and still others grow large, becoming macrogametes or 

 eggs. The eggs are fertilized by the spermatozoa, and, after a resting 

 stage, develop into new colonies. 



16. Order 2. Choano- 

 flagellata ( ) 

 Mastigophora with a con- 

 tractile protoplasmic collar 

 from the bottom of which 

 extends a single flagellum. 



Examples : Monosiga, 

 Proterospongia. (Fig. 68.) 



17. Order 3. Dino- 

 flagellata ( ) 

 Mastigophora w i t h two 

 flagella, one at the anterior 

 end, the other passing 

 around the body, often in a 

 groove. 



Examples : Peridinium, 

 Ceratium. (Fig. 69.) 



18. Order 4. Cystoflag- 

 ellata ( ) 

 Mastigophora with two 

 flagella, one resembling a 

 tentacle, the other lying in 

 the gullet. 



Examples : Noctiluca, 

 Leptodiscus. (Fig. 70.) 



Enormous numbers of 

 Noctiluca ( ) 



are often found floating near 

 the surface of the sea, giving 

 it the appearance, as 

 Haeckel says, of "tomato 

 At night they are 



longicollis more enlarged; IV copulation of gametes; V phosphorescent, emitting a 



longicolhs more enlarged; IV, copulation of gametes; V, v . r \ 



A, Clepsidrine, blattarum. 1-4, Monocystis magna. 1, blllish OT PTCCnish li"ht. 



two individuals copulating while in the spermatheca of 



an earthworm, surrounded by spermatozoa; 2, encysted; 19. The SpOTOZOa 



3 and 4, parts of cysts, formation and conjugation of the 



more enlarged gametes, cu, cuticula ; dm, deutomerite ; ( ) are 



ek, ectosarc ; en, entosarc ; g, gametes; gl, zoospores ; -,-j . 



g2, oospore; pm, protomerite ; n, nucleus; r, residual -TTOtOZOa WltflOUt motile Or- 



body ; s, sperm of earthworm; z, zygote. (From Hertwig <-!-! - 



after various authors.) gans. 1 hey are parasitic in 



Metazo*?. Reproduction is 



mainly by spore formation. The following classification is simplified 

 from Minchin's account in Lankester's Treatise on Zoology, Part 1 : 



Different Gregarina. I-VII, development of Stylor- 

 hynchus; 1, S. longicollis; II, encysted S. oblongatus (two 

 animals) beginning gamete formation; ///, same later 

 when the sexually differentiated gametes are copulating ; gOUD 

 IV -VI I, formation and development of zygote of S. 



