VI. FACTORS INTERFERING WITH GENES 



261 



somewhat different with the kind of particles, the gradient of the 

 effect of various ions is almost similar regardless of the kind of 

 particles, and so the result similar to that shown in this figure can 

 be attained likewise with phage, rennin particles, and also with 

 protoplasm particles having no virus action (70). 



The inorganic salts which have particularly great effects upon the 

 turbidity also exert remarkable deleterious influences upon the virus 

 activity. Thus vaccinia virus particles are particularly injured by 

 salts, such as KaSO^, KI, KNO, KBr, etc. while these salts have 

 striking effects upon the turbidity. The virus remains active for the 

 longest if preserved in water containing no salt. 



Since a single active particle is regarded as producing a single 

 plaque on agar, the deleterious action of inorganic salts on phage can 

 be easily indicated in numerical values as seen in Fig. 25. In this 



-1.0 



-2.0 



-3.0 



-4.0 



Hours 



Fig. 25. 

 Influences of various potassium salts and also of NaF upon phage. 



figure the degrees of the phage inactivation following the heating to 

 50"C. in the presence of various salts are shown. 



The rennin sample prepared by the writer consisted of virus-like 



