212 ANIMAL PARASITES 



Protozoa. 



Sarcodina. 



Rhizopoda. 



Gymnamcebida Amoebae. 

 Mastigophora. 

 ~^ Flagellata. 



Monadida, Cercomonas, Trypansosoma, Poly- 



mastigida, Trichomonas. 

 Some authors separate a family Spirochaetidae to include 



Spirochaeta and Treponema. 

 Sporozoa. 



Gregarinida gregarines. 

 Coccidia coccidia. 

 Hemosporidia. 



Plasmodium malaria. 

 Infusoria. 

 Ciliata. 



Heterotrichida Balantidium. 



The protozoa are always, in every stage of development, primi- 

 tive unicellular bodies. They consist essentially of a cell-body or 

 sarcode, a nucleus, and a nucleolus. All of the vital functions of the 

 cell are carried out by the cell-body, the protoplasm of which digests 

 and assimilates food. Particular parts of the protoplasm have 

 special functions, these parts are called organelles. The living 

 protoplasm is finely granular, is viscid, and exhibits a distinct 

 movement. The motility of protozoa is supplied variously. In 

 the Rhizopoda progression takes place by pseudopods or false feet, 

 a phenomenon in which a section of the cell wall and protoplasm 

 are extended like a bud. Into this the latter then flows with a 

 shrinkage of the main body. At last the pseudopod is large enough 

 to hold all the protoplasm and the former place of the protozoon is 

 vacated for the new. Motility is also supplied by the lashing or 

 vibratory action of flagella or the fine vibration of the circum- 



