CHAPTER IX 

 FLAGELLATE AND CILIATE PROTOZOA 



(MASTIGOPHORA ET INFUSORIA) 



BY H. W. CONN AND C. H. EDMONDSON 



Professor of Biology, Wesleyan^University Assistant Professor of Zoology, University of Oregon 



BY early observers the term Infusoria was applied to all minute 

 organisms found in water, including not only unicellular animals 

 but many minute plants and not a few multicellular animals, as 

 rotifiers, sponges, etc. Later the term was restricted to those one- 

 celled animals which are commonly found in standing water and 

 which move by means of long whip-like processes called flagella 

 or by shorter, hair-like structures called cilia. 



At the present time the flagellated forms are included under the 

 subphylum Mastigophora and those possessing cilia, throughout 

 their entire existence or during their embryonic stage only, are 

 grouped under the subphylum Infusoria. Mastigophora and 

 Infusoria are of almost universal distribution, occurring in fresh 

 and salt water, abundant in clear pools and streams as well as 

 in stagnant bodies of water and also in infusions of plant or animal 

 macerations. Some are parasitic, living upon or within the bodies 

 of other animals. 



In the Mastigophora flagella are the characteristic structural 

 features. These structures are slender, flexible, whip-like processes 

 drawn out from the body, commonly at one end. The flagellum 

 when single is usually directed forward, and by a lashing movement, 

 a corkscrew twisting, or a mere vibration of its free distal end 

 draws the body forward. Flagella may be numerous and often 

 one or more are directed backward or trail at the side in addition 

 to those extended in advance. 



That a close relationship exists between flagella and pseudopodia 

 is easily observed in a number of forms. Some low flagellates 



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