6 PROTOZOAN PARASITISM 



larger and necessarily more complex animals is com- 

 monly manifest. 



The bodies, then, of protozoa are organized into 

 specialized systems corresponding to those which we 

 know in higher animals, constructed of specialized 

 materials but not of separate and specialized cells. 



The outer part of the body is called the ectoplasm 

 (outer substance). Here the protoplasm is of more 

 uniform consistency, for a variable width in different 

 forms. There is no separate surface covering or at 

 least only a condensation which keeps the body in- 

 tact. 



From the surface are projected the organelles of 

 locomotion and food gathering. Some of them pos- 

 sess for these purposes the ability to produce pro- 

 trusions from their bodies, called pseudopodia (false 

 foot). These are not permanent features but are 

 projected on proper stimulus toward food materials 

 or in the direction which the body is to travel. When 

 a pseudopodium is used for gathering food it is ex- 

 tended to and wrapped around the article. This is 

 taken directly into the protoplasm through a solution 

 in the continuity of the rim, which immediately is 

 healed. 



When locomotion takes place by pseudopodia the 

 projection of ectoplasm takes place in the desired 

 direction and the inner substance, endoplasm, flows 

 into it, much as a thick-walled flexible bladder of fluid 

 may pass through a small aperture. 



Pseudopodia are thus feet for moving and hands 



