Chapter 9 

 Order 3 Phytomonadina Blochmann 



THE phytomonads are small, more or less rounded, green 

 flagellates with a close resemblance to the algae. They show 

 a definite body form, and most of them possess a cellulose mem- 

 brane, which is thick in some and thin in others. There is a defi- 

 nite opening in the membrane at the anterior end, through which 

 1-2 (or seldom 4 or more) flagella protrude. The majority possess 

 numerous grass-green chromatophores, each of which contains 

 one or more pyrenoids. The method of nutrition is mostly holo- 

 phytic or mixotrophic; some colorless forms are, however, sapro- 

 zoic. The metabolic products are usually starch and oils. Some 

 phytomonads are stained red, owing to the presence of haemato- 

 chrome. The contractile vacuoles may be located in the anterior 

 part or scattered throughout the body. The nucleus is ordinarily 

 centrally located, and its division seems to be mitotic, chromo- 

 somes having been definitely noted in several species. 



Asexual reproduction is by longitudinal fission, and the daughter 

 individuals remain within the parent membrane for some time. 

 Sexual reproduction seems to occur widely. Colony formation 

 also occurs, especially in the family Volvocidae. Encystment and 

 formation of the palmella stage are common among many forms. 

 The phytomonads have a much wider distribution in fresh than in 

 salt water. 



Solitary 



Membrane a single piece; rarely indistinct 



2 flagella Family 1 Chlamydomonadidae 



3 flagella Family 2 Trichlorididae (p. 193) 



4 flagella Family 3 Carteriidae (p. 194) 



5 flagella Family 4 Chlorasteridae (p. 196) 



6 or more flagella Family 5 Polyblepharididae (p. 196) 



Membrane bivalve Family 6 Phacotidae (p. 196) 



Colonial, of 4 or more individuals; 2 (1 or 4) flagella 



Family 7 Volvocidae (p. 197) 



Family 1 Chlamydomonadidae Biitschli 



Solitary; spheroid, oval, or ellipsoid; with a cellulose mem- 

 brane; 2 flagella; chromatophores, stigma, and pyrenoids usually 

 present. 



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