174 



PROTOZOOLOGY 



Under conditions not fully understood, the Chrysomonadina 

 lose their flagella and undergo division with development of 

 mucilaginous envelope and thus transform themselves often into 

 large bodies known as the palmella phase and undertake meta- 

 bolic activities as well as multiplication (Fig. 84). Asexual re- 

 production is, as a rule, by longitudinal division during either 

 the motile or the palmella stage. Incomplete separation of the 

 daughter individuals followed by repeated fission, results in 

 numerous colonial forms mentioned elsewhere (p. 141). Some 



Fig. 84. The life-cycle of Chromulina, X about 200 (Kiihn). a, en- 

 cystment; b, fission; c, colony-formation; d, palmella-formation. 



resemble higher algae very closely. Sexual reproduction is en- 

 tirely unknown in this group. Encystment occurs commonly; in 

 this the flagellum is lost and the cyst is enveloped by a sihcious 

 wall possessing an opening with a plug. 



The chrysomonads inhabit both fresh and salt waters, often 

 occurring abundantly in plankton. 



Motile stage dominant Suborder 1 Euchrysomonadina 



Palmella stage dominant 



Sarcodina-like; flagellate stage unknown 



Suborder 2 Rhizochrysidina (p. 181) 



Palmella phase dominant Suborder 3 Chrysocapsina (p. 182) 



Suborder 1 Euchrysomonadina Pascher 



With or without simple shell 



One flagellum Family 1 Chromulinidae (p. 175) 



2 flagella 



Flagella equally long Family 2 Syncryptidae (p. 177) 



Flagella unequally long Family 3 Ochromonadidae (p. 179) 



