250 PROTOZOOLOGY 



tained that the Sarcodina are the Protozoa which were most closely 

 related to ancestral forms and which gave rise to Mastigophora, 

 Ciliata, and Sporozoa. 



This concept is however difficult to follow, since it does not agree 

 with the general belief that the plant came into existence before the 

 animal; namely, holophytic organisms living on inorganic substances 

 anteceded holozoic organisms living on organic substances. There- 

 fore, from the physiological standpoint the Mastigophora which 

 include a vast number of chlorophyll-bearing forms, must be con- 

 sidered as more primitive than the holozoic Sarcodina. The class 

 Mastigophora is composed of Phytomastigina (chromatophore-bear- 

 ing flagellates and closely related colorless forms) and Zoomastigina 

 (colorless flagellates). Of the former, Chrysomonadina (p. 256) are 

 mostly naked, and are characterized by possession of 1-2 flagella, 

 1-2 yellow chromatophores and leucosin. Though holophytic nutri- 

 tion is general, many are also able to carry on holozoic nutrition. 

 Numerous chrysomonads produce pseudopodia of different types; 

 some possess both flagellum and pseudopodia; others such as Chrys- 

 amoeba (Fig. 105) may show flagellate and ameoboid forms (Klebs; 

 Scherffel); still others, for example, members of Rhizochrysidina 

 (p. 267), may lack flagella completely, though retaining the char- 

 acteristics of Chrysomonadina. When individuals of Rhizochrysis 

 (p. 267) divide, Scherffel (1901) noticed unequal distribution of the 

 chromatophore resulted in the formation of colorless and colored 

 individuals (Fig. 110, a, b). Pascher (1917) also observed that in the 

 colonial chrysomonad, Chrysarachnion (p. 267), the division of 

 component individuals produces many in which the chromatophore 

 is entirely lacking (Fig. 110, c, d). Thus these chrysomonads which 

 lack chromatophores, resemble Sarcodina rather than the parent 

 Chryosomonadina. 



Throughout all groups of Phytomastigina, there occur forms 

 which are morphologically alike except the presence or absence of 

 chromatophores. For example, Cryptomonas (p. 273) and Chilo- 

 monas (p. 273), the two genera of Cryptomonadina, are so mor- 

 phologically alike that had it not been for the chromatophore, the 

 former can hardly be distinguished from the latter. Other examples 

 are Euglena, Astasia, and Khawkinea; Chlorogonium and Hyalo- 

 gonium; Chlamydomonas and Polytoma; etc. 



The chromatophores of various Phytomastigina degenerate read- 

 ily under experimental conditions. For instance, Zumstein (1900) 

 and recently Pringsheim and Hovasse (1948) showed that Euglena 

 gracilis loses its green coloration even in light if cultured in fluids 



