Economic Importance of Animals 531 



A number of Protozoa produce a variety of human diseases, of which 

 the following are typical and representative: Balantidium coli (class In- 

 fusoria) (Fig. 262) produces intestinal ulcers and a type of dysentery. 



Fig. 257. — Various species of Foraminifera of the class Sarcodina (phylum 

 Protozoa). (Courtesy of Victor Animatograph Corporation.) 



Peristome 



— Cilia 



uM:)f— Nucleus 



Flagella 



Matrix- — -Mil 



_ YaaJo\& 



Fig. 258. 



Fig. 259. 

 gophora). 



Fig. 258. Fig. 259. 



-Bursaria truncatella of the class Infusoria, phylum Protozoa. 

 -Spherical colony of the protozoan Uroglena americana (class Masti- 



