90 



PHYSIOLOGICAL ACTIVITIES OF THE PROTOZOA 



These various modifications of the process of division or reproduc- 

 tion in its broadest sense may be conveniently summarized as follows: 



Binary division 



/-Cells dissociated (Protista). 



J f Undifferentiated (Protozoa 



Cells associated -j 



Reproductio 



. 



f Simple - 



I phyta). 

 [ Budding division (Euglypha, etc.). 



I Exogenous. 

 ( Gemmation _ 



I , . i . - \ (_ Endogenous. 



I Schizogony (without fertilization) 

 I. bporulation < a . . . .. 



(. Sporogonv (after fertilization). 



colonies). 

 Differentiated (Metazoa, Meta- 



FIG. 28 



Trypanosoma gambiense; stages in longitudinal division. 



by F. W. Baeslack. 



Original from a preparation 



In a number of protozoa, the cell before division draws in or throws 

 off its motile organs, rounds out into a sphere, and then divides into two 

 equal parts. This is the case in some of the heliozoa, a nuclearia, for 

 example, which is very plastic with freely moving and often branching 

 pseuclopodia, becomes spherical and then divides through the middle, 

 the entire operation, as seen under the microscope, taking not more 

 than a minute. 



The process becomes more complicated in those forms with com- 

 plex motile organs. In some cases, as in some forms of trypanosoma, 

 the flagellum is divided throughout the entire length, but in other 

 cases the basal body alone divides, a second flagellum being formed 



