152 



General Biology 



cells produce by division a great number of minute microgametes or 

 spermatozoa, and still others grow large, becoming macrogametes or 

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

 ing 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. O r d e r 3. Dino- 

 flagellata ( ) 

 Mastigophora with 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 

 soup." At night they are 

 phosphorescent, emitting a 

 bluish or greenish light. 



19. The Sporozoa 

 ( ) are 

 Protozoa without motile or- 

 gans. They are parasitic in 

 Metazoa. Reproduction is 



mainly by spore formation. The following classification is simplified 

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



Fig. 71. 



Different Gregarina. I-VII, development of Stylor- 

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

 animals) beginning gamete formation; 777, same later 

 when the sexually differentiated gametes are copulating; 

 IV-VII, formation and development of zygote of S. 

 longicollis more enlarged; IV, copulation of gametes; V, 

 A, Clepsidrina blattarum. 1-4, Monocystis magna. 1, 

 two individuals copulating while in the spermatheca of 

 an earthworm, surrounded by spermatozoa; 2, encysted; 

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

 more enlarged gametes. cu, cuticula; dm, deutomerite; 

 ek, ectosarc; en, entosarc; g, gametes; gl, zoospores; 

 g2, oospore; pm, protomerite; n, nucleus; r, residual 

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

 after various authors.) 



