NO. 2 EFFECT OF ULTRAVIOLET ON ALGAE MEIER II 



that much weight should be given to this point. Therefore, in draw- 

 ing the smooth curve, a questionable value of .380 is ascribed to this 

 wave length. 



Table 7. — I.cthal Radiotoxic Threshold and Radiotoxic Spectral Sensitivity 



2300 A. No algae were killed at 2300 A by an exposure of 600 

 seconds. Lethal effect appears for the first time with one exposure 

 at 720 seconds, which gives a radiotoxic spectral sensitivity value 

 of .283. If it is assumed that there is lethal eft'ect at 650 seconds' 

 exposure, the lethal factor becomes .313. 



