44 



RADIATION BIOLOGY 



national Commission on lllnmination (ICI), Berlin (11)35). Both curves 

 are plotted with the relative effect at the optimum wave length as 100 per 

 cent. The relative 100 per cent bactericidal elTcctiveness of 2V)'){) A and 

 the 85 per cent relative effectiveness of 2537 A energy shown in Fig. 2-1 

 should not be confused with the possibility of a 100 per cent absolute kill 

 by 2537 A energy shown in Figs. 2-2 and 3. The ICI factors for the 

 erythemal-action curve and tentative factors for the bactericidal-action 

 curve proposed in Fig. 2-1 are shown for indixidual mercury lines in Table 

 2-1. These factors are useful for calculating the relative effectiveness and 



Table 2-1. I^kytiikmal- and Bactericidal-action Factors 



efficiency of mercury sources whose relative line intensities are known 

 (see Tables 2-3 and G). 



ACTION CURVE TENTATIVE AT SHORTIHl WAVE LENGTHS 



The germicidal-actioii i-nvvc for wave lengths less than 2500 A is still 

 tentative since theory and some research suggest that the action continues 

 to increase at shorter wave lengths (greater frequencies and greater energy 

 content of the quanta). A rather rapid drop in the curve at wave lengths 

 less than 2500 A is, on the other hand, characteristic of the absorption 

 curve of nuclear protein and very representative of practical germicidal 

 effects in which nearly all the liquid and gaseous elements in the environ- 

 ment of an organism absorb the ultraviolet of shorter wave lengths and 



