MORPHOLOGY AND TAXONOMY OF MASTIGOPHORA 249 



nized hy all who are familiar with the group. A glimpse of the 

 variety may be possible in a brief summary of the classification which 

 is based in the main upon general organization for carrying out the 

 fundamental activities. The four great groups— Mastigophora, Sar- 

 codina, Infusoria and Sporozoa, are natural groups with the excep- 

 tion of the Sporozoa : The first characterized by motile organs when 

 present in the form of y'lhnxtWe flagella ; the second by protoplasmic 



Fig. 123. — Cristispira anodontce with spirally wound crista; and flagellum insertion 

 in bacteria. (Former from Fantham, latter from Biitsclili.) 



projections known as pseudopodia, some types of which are motile 

 organs. In the third group motile organs are in the form of minute 

 lash-like cilia, which are invariably present in some stage of the 

 life cycle. The Sporozoa finally are characterized by the general 

 absence of motile organs, by the invariably parasitic mode of life, 

 and by the method of reproduction. 

 The four main groups of Protozoa should have the taxonomic 



