THE PATHOGENIC PROTOZOA 



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reproduction by spores. Genera pathogenic for man. 

 Coccidia, Sarcosporidia, Nosema, Babesia, Plasmodia. 

 4. Ciliata. Movement by means of cilia; reproduction by 

 transverse division. Germs parasitic for man. Balanti- 

 dium. 



AMEB.ffi 



The amebae are characterized by their ability to project por- 

 tions of their protoplasm into pseudopodia, or " false feet " which 

 serve as organs of locomotion 

 and nutrition. The pseudo- 

 podia may protrude from any 

 portion of the cell or from dif- 

 ferent parts at the same time ; 

 they are quite irregular in 

 form and are called forth only 

 in response to some physical 

 or chemical stimulus. When 

 such a stimulating object may 

 be used as food the pseudo- 

 podia flow around it and 

 eventually absorb it into the 

 cell protoplasm. All forms of ameba possess one or more nuclei 

 and usually a contractile vacuole. Multiplication takes place by 

 simple division or by encysted brood formation (Fig. 43). 



Saprophytic forms are abundant in nature ; they may be found 

 wherever moisture and decaying vegetable matter exist. Yet, not- 

 withstanding their common occurrence, little is known of their 

 life history. Not all forms of protozoa showing ameboid move- 

 ment can be classified as rhizopodia until most of their life history 

 is known, since members of other classes may pass through an 

 ameboid stage. Some flagellates, for example, during one period 

 of their existence develop blunt pseudopods and crawl along as 

 typical ameba. 



Three forms of ameba have been described as parasitic in man : 

 Entameba histolytica, E. coli, and E. gingivalis. 



FIG. 43. Ameba. 



