360 



Marine Microbiology 



similar to that in sea water peptone water, Figure 1. Inactivation 

 in all the NaCl solutions was, however, much more rapid. This 

 does not appear to have been due to a positive action of the NaCl, 

 at least up to a concentration of 2.75 per cent, approximately that 

 in sea water, as the rates of inactivation were similar to tliat 

 in distilled water. A more likely cause is the presence in sea 

 water of some factor which reduces the effect of sodium cloride 

 on thermal inactivation. The results shown in Figure 3 indicate 

 that the magnesium ion, present in sea water as MgCL at a 

 concentration of 0.495 per cent, serves this pui-pose, and that 



• • SCA water. 0-— O 2-75°/o NaCl -t- Q- 495 "/o MgClj. 



O 



a. 

 a 



h- 

 z 



o 

 u 



UJ 



3 



d 

 < 



o 



5 ▲ A 0'495°/oMgCI A A 0-9 97o MgCI, 



(O 



TIME OF EXPOSURE -MINUTES. 



Fig. 3. The thermal inactivation at 40 C of phage P/T4 suspended in various 



inorganic media (11). 



