376 Marine Microbiology 



cell culture fluid. This inhibition seemed to be removed after 48 

 hours. The original seed was recovered. The reason for the large 

 decrease in the amount of poliovirus in the presence of starving 

 ciliates remains to be determined. 



TABLE 5 



Exposure of Feeding and Starving Ciliates (T16) to Polio Virus (Fish 

 Tissue Cultures as Food) 



DISCUSSION 



It is a well established fact that some viruses pass through 

 invertebrate or arthropod hosts without loss of infectivity. Virus 

 transfer between fish, if carried out by a vector, calls for a faculta- 

 tive parasite. Such an organism should be able to live periodically 

 independent in seawater, either in a motile phase or in the form 

 of cysts. Thus far we have not found encystation in our two 

 strains of ciliates. We have, however, shown that they can em- 

 ploy two feeding systems, the carnivorous way of life representing 

 the parasitic phase and the saprozooic way of life representing 



TABLE 6 

 Osmotic Pressure of Natural and Experimental Environment 



MOsM ! 



Seawater 



Hank's BSS 



Grunt Serum 



Human Scrum 



Melnick's monkey kidney medium 



Melnick's seawater medium 



1245 

 290 

 410 

 310 

 320 

 983 



