OXIDATION OF SUBSTANCES OF BIOLOGICAL IMPORTANCE 225 



as in acid solutions. The absorption spectrum of ferricytochrome c in 

 the visible hght was Httle changed, and no reduction was observed even 



Fig. 6. Effect of x-ray irradiation on the absorption spectrum of ferricytochrome c, 



dissolved in 0.005 A' HCl. The Soret band. Abscissa: Wavelength in angstrom units; 



ordinate: optical density E. 



on irradiation with 100,000 r (Fig. 9). Oxidation of Fe++ cytochrome 

 c seems to be produced by the OH radicals alone, for neither catalase 

 nor the absence of oxygen had any effect on the ionic yield. The 



