ACTION OF ULTRAVIOLET LIGHT ON VIRUSES 



159 



that at the shorter wavelengths less effect on the virus is ob- 

 served, whereas the absorption markedly rises. Since it is 

 thought that this shorter-wavelength rise in absorption is due 

 to the polypeptide absorption of proteins, it would seem as 



Action Liquid 

 Nitrogen 



"2200 2400 2600 ^00 3000 ^00 3400 A 

 Wovelengtti 



Fig. 6.8. Absorption and action spectra, taken by Fluke (1953), for T-1 

 phage. The action spectrum does not follow the absorption spectrum in detail, 

 indicating that T-1 has a morphology, not all of which is concerned with sur- 

 vival. In particular, the quantum yield definitely falls at short wavelengths 

 where polypeptide absorption occurs. 



though either such protein absorption is unimportant or a con- 

 siderable recovery takes place in bonds which have been excited 

 in the polypeptide chain. On the other hand, absorption in the 

 nucleotide or aromatic-amino-acid region seems to be quite 



