30 



INVERTEBRATE ZOOLOGY 



Class Mastigophora 



The presence of one or more flagella is practically the only 

 character common to all Mastigophora. More than superficial 

 examination is necessary to distinguish some Mastigophora 

 bearing numerous flagella from ciliates, and on the other hand 

 the boundary between Mastigophora and Sarcodina is obscured 

 through the presence of temporary flagella on some of the 

 Sarcodina and of pseudopodia on some of the Mastigophora 

 (Fig. 15). In addition to these confusing relationships with other 

 classes of Protozoa, there are some forms which are so distinctly 



Fig. 



-MastlgcUa vitrea. 

 Goldschmidt) . 



{After Fig. 16. — Isolated flagellum of 

 Euglena showing axial filament within 

 surrounding sheath. {After Butschli). 



plantlike that they are claimed alike by zoologists and botanists. 

 Body shape is far from constant in many forms, the degree of con- 

 stancy depending upon the character of the body surface. In 

 some, the pellicle is either wanting or so thin as to permit of 

 free amoeboid movements. Limitation to change in shape is 

 secured in some by the presence of supporting structures of 

 organic matter such as the axostyle (Figs. 21 and 22). 



Each flagellum (Fig. 16) consists of a firm axial filament, part 

 of which is encased in a more fluid contractile sheath. Distally, 

 this filament extends a short distance beyond the sheath and 

 constitutes an "end piece." Proximally, the axial filament con- 

 tinues through the cytoplasm to the blepharoplast, though in 

 some instances the basal granule from which the flagellum arises 

 may be separate from the blepharoplast and connected with it 



