CHAPTER V 

 EUGLENA OF CLASS MASTIGOPHORA 



Habitat and Characteristics 



The most common species are Euglena viridis and Euglena gracilis 

 which are found abundantly in fresh water. This genus is also quite 

 well represented among marine animals ; many Euglenae possess 

 chloroplastids which give them the possibility of photosynthesis. 

 They are usually found living in the surface waters of ponds, slug- 

 gish creeks, and lakes. Euglenae are sometimes classified as plants by 

 botanists because of the presence of chlorophyll. It is a form which 

 illustrates certain plant characteristics and animal characteristics in 

 the same organism. 



Structure 



The microscopic, single-celled body has about the shape and pro- 

 portions of a cigar with a blunt anterior and a sharp posterior end. 

 At the anterior end, attached near the mouth, it bears a very 

 slender, almost transparent, whiplike filament, the flagellum. This 

 is an extension of the cytoplasm. The superficial layer of the cell or 

 ectosarc (ectoplasm) is covered by an extremely thin portion, the 

 cuticle. Most of the euglenoid forms have spiral markings (stria- 

 tions) on the surface of the body. The mouth of the cell is near the 

 anterior end, and extending inward from it is the gullet or cyto- 

 pharynx. Beside the cytopharynx is the reservoir or large vesicle. 

 Just anterior to this is the stigma, which is red in many individuals 

 of E. viridis. Bodies of collected protein material may be seen in 

 eoiuiection with most of the chloroplasts which are distributed 

 through the cytoplasm. These bodies are called pyrenoid dodies. 

 Within the inner portion of the cell or endosarc (endoplasm) is lo- 

 cated the nucleus. It is usually obliterated from view by the abun- 

 dant chloroplasts. Small contractile vacuoles empty from the endo- 

 plasm into the reservoir. 



Food and Assimilation 



The food problem among Euglenae as a group is interesting from 

 the biological standpoint. It seems that some Euglenae are able 

 to ingest other small organisms through the mouth and cytopharynx 



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