32 SPECIAL CHARACTERS 



Protozoa move by several methods. Some possess 

 short, delicate, hair-like projections from the wall, 

 which exhibit a slow, wavy motion. These are cilia. 

 Others have one, two, or three long coarser threads, 

 the flagella (sing., flagellum) arising from various 

 parts of the structure and producing locomotion by a 

 thrashing or whip-like motion. Perhaps the simplest 

 and surely the most primitive form of motion is to be 

 seen in what are called pseudopods or false feet, a 

 phenomenon characteristic of the amebse. This is a 

 pushing out or budding of a portion of the cell wall 

 into which the cytoplasm of the protozoon flow, 

 enlarging the false foot until it embraces all the con- 

 tents of the cell. The space formerly occupied by 

 the protozoon is vacated, the cell having moved to a 

 position directed by the pseudopod. In some protozoa 

 a portion of the body has muscular power and drives the 

 organism. Again, a portion of the cell wall may be 

 fitted with a sucking apparatus, serving either to drive 

 the protozoon or to attach it to another body. Pro- 

 tozoa gain their food by simple absorption through 

 the wall or by possessing definite vacuoles or open- 

 ings for this purpose. Excretion takes place the same 

 way. 



Reproduction may occur by simple division as in 

 bacteria. Protozoa may divide by simple budding 

 with breaking oft' of the smaller piece similar to the 

 first stages of the pseudopod. The higher protozoa 

 go through a complicated process of division such as 

 is seen in the higher animal cells, or there may be 

 male and female elements with conjugation. 



