PROTOZOA 37 



dysentery and are thought to be concerned with certain ulcers of the 

 large intestines. 



Opalina (see Figure i^B) is parasitic in the intestine of the frog 

 (Metcalf). Several species of ectoparasitic infusoria are known to 

 attack fishes, causing inflammation and death. Ichthyophthirius 

 attacks steel-head-trout fingerlings, catfish, bass and perch. The 

 common stickleback is one of the carriers for the parasite. 



Cyclochaeta and Chilodon are parasites of goldfish, brook trout 

 and small mouth black bass but apparently do not infest salmon, 

 steel-head trout or perch. Cyclochaeta thrives best when the 

 temperature of the water is low, below 50° F., but Chilodori cy print 

 requires a higher temperature (Guberlet). 



, • ■ ' f .• 





oneme around moafh 

 Phoryngeol boskef 



\r^:^^:^-^m-^- "^ol/road track' 



Fig. 15. Neuromotor apparatus of Chlamydodon. (After M. S. MacDougall. Biol. 



Bull., vol. 54, p. 473, 1928.) 



Class 4. Sporozoa. Type — Plasmodium vivax. — The Sporozoa 

 lack organs of locomotion and are characterized by their method of 

 reproduction by spore formation. They are all parasitic forms at 

 the active stages of their life cycle. 



The malarial Plasmodia include three species. One, P. vivax., 

 produces chill every 48 hours; another, P. malariae, causes chill 

 every 72 hours; while the third, P. falciparum., produces attacks 

 daily or at irregular intervals (Fig. 16). 



Infected/d-zw^/^ mosquitoes of the Anopheline group are able to 



