FLAGELLATED PROTOZOA 



57 



The processes of feeding, growing and dividing continue for 

 days before other activities occur. Indeed for Chilomonas so 

 far as known they may continue indefinitely, but from analogy 

 with other forms of Mastigophora where the full life history is 

 known, these ordinary vegetative processes are sooner or later 

 replaced by processes involving a simple kind of fertilization 

 or sexual union. In Copromonas, for example, two similar 

 cells after a long period of divisions, meet and fuse; the flagellum 

 of one of them is discarded while that of the other is used as a 

 motile apparatus for the pair. 

 Fusion of nucleus and cell body 

 continue until a single cell results. 

 This then secretes a membrane and 

 becomes quiescent, or it divides and 

 behaves like an ordinary individual. 

 Here there is typical fertilization but 

 no difference between the conjugat- 

 ing cells so far as can be detected 

 (Fig. 22). 



Allied Forms. Many hundreds of FIG. 23 Synura mvlla, a 



.. n ,, colony of flagellated proto- 



species of flagellated protozoa are zoa in which the individuals 



known and may exhibit the most are attached at a common 



center, from a photograph. 



manifold variations in structures 



and functions. Many of them have only one flagellum, 

 as Peranema or Euglena, for example, which are common 

 organisms in infusions of different kinds. It is a remarkable 

 and fascinating sight to see a relatively large cell like Pera- 

 nema drawn steadily forward by the undulations of the tip of 

 its long and easily seen flagellum. In this case the entire 

 flagellum does not vibrate, but only the tip, whereas in Euglena 

 the whole flagellum is in constant motion and almost invisible. 

 Nutrition in Peranema, as in Chilomonas, is saprozoic, but it 

 is entirely different in the case of Euglena which has the power 

 to manufacture its food in the same way that the higher green 

 plants do. This holophytic nutrition is accomplished through 

 the agency of chloroplastids or color-bearing structures distrib- 

 uted throughout the protoplasm of the Euglena cell (Fig. 21). 



