200 PROTOZOOLOGY 



mal. Trypanosoma, a representative genus of the latter group, in- 

 cludes important disease-causing parasites of man and of domestic 

 animals. 



The Mastigophora are divided into two subclasses as follows : 



With chroraatophores Subclass 1 Phytomastigina 



Without chromatophores Subclass 2 Zoomastigina (p. 263) 



Subclass 1 Phytomastigina Doflein 



The Phytomastigina possess the chromatophores and their usual 

 method of nutrition is holophytic, though some are holozoic, sapro- 

 zoic or mixotrophic; the majority are conspicuously colored; some 

 that lack chromatophores are included in this group, since their 

 structure and development resemble closely those of typical Phyto- 

 mastigina. 



1-4 flagella, either directed anteriorly or trailing 

 Chromatophores yellow, brown or orange 



Anabolic products fat, leucosin Order 1 Chrysomonadina 



Anabolic products starch or similar carbohydrates 



Order 2 Cryptomonadina (p. 213) 



Chromatophores green 



Anabolic products starch and oil. Order 3 Phytomonadina (p. 217) 



Anabolic products paramylon Order 4 Euglenoidina (p. 232) 



Anabolic products oil Order 5 Chloromonadina (p. 243) 



2 flagella, one of which transverse Order 6 Dinoflagellata (p. 245) 



Order 1 Chrysomonadina Stein 



The chrysomonads are minute organisms and are plastic, since 

 the majority lack a definite cell-wall. Chromatophores are yellow to 

 brown and usually discoid, though sometimes reticulated, in form. 

 Metabolic products are leucosin and fats. Starches have not been 

 found in them. 1-2 flagella are inserted at or near the anterior end 

 of body where a stigma is present. 



Many chrysomonads are able to form pseudopodia for obtaining 

 food materials which vary among different species. Nutrition, though 

 chiefly holophytic, is also holozoic or saprozoic. Contractile vacuoles 

 are invariably found in freshwater forms, and are ordinarily of 

 simple structure. 



Under conditions not fully understood, the chrysomonads 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 metabolic activities as 

 well as multiplication (Fig. 88). Asexual reproduction is, as a rule, 

 by longitudinal division during either the motile or the palmella 



