260 Walter Gordy 



kind provides temporary abode for the disrupted children to prevent their 

 disturbing the neighbors. Our Hving systems probably have already built in 

 both types of protective agents in sufficient quantity to provide reasonably 

 good protection from ionizing radiation encountered in normal living of the 

 past. For the future we may need to add some. 



I have not space to discuss radiation damage to other substances — such as 

 fatty acids, nucleic acids, and hormones — for which our group has obtained 

 many spin resonance data similar to that described here. I have not space to 

 discuss the important effects of oxygen on radiation damage to molecules, 

 about which we have obtained information from spin resonance, of the type 

 shown in Fig. 13. I hope that I have described enough of the results to convince 

 you — and the biologist who rode with me in the car — that microwave electron- 

 spin resonance is an important new way of 'seeing into' biological things. 



ACKNOWLEDGEMENTS 



The experimental results I have discussed here were obtained largely by 

 my students — W. B. Ard, H. W. Shields, C. G. McCormick, H. N. Rexroad, 

 A. VAN RoGGEN and C. F. Luck. Others now active in the project are J. H. 

 Hadley, F. W. Patten, and Dr. I. Miyagawa. For their valuable assistance I 

 am grateful. Our research is supported by the Office of Scientific Research, 

 U.S. Air Force, and the Office of Ordnance Research, U.S. Army. 



Without implying that he is to any degree responsible for any misinterpreta- 

 tions I may have made, I wish to acknowledge with thanks some stimulating 

 and enlightening discussions with Dr. James Franck during the preparation of 

 this paper. 



REFERENCES 



1. E. Zavoisky: Paramagnetic relaxation of liquid solutions for perpendicular fields. 

 /. Phys., Moscow 9, 211-216 (1945); 



E. Zavoisky: Spin magnetic resonance in the decimetre-wave region. /. Phys., Moscow 

 10, 197-198 (1946). 



2. C.A.Hutchison: Paramagnetic resonance absorption in crystals colored by irradiation. 

 Phys. Rev. 75, 1769-1770 (1949). 



3. J. CoMBRissoN, and J. Uebersfeld: Detection de la Resonance Paramagnetique dans 

 Certaines Substances Organiques Irradiees. C.R. Acad. Sci., Paris 238, 1397-1983 (1954); 

 W. Gordy: Quadrupole couplings, dipole moments and the chemical bond. Disc. 

 Faraday Soc. 19, 14-29 (1955). 



4. W. Gordy, W. B. Ard, and H. Shields: Microwave spectroscopy of biological 

 substances. I Paramagnetic resonance in x-irradiated amino acids and proteins. Proc. 

 Nat. Acad. Sci., Wash. 41, 983-996 (1955). 



5. G. McCormick, and W. Gordy: Electron-spin resonance in x-irradiated peptides. Bull. 

 Amer. Phys. Soc. 1, 200 (1956). 



6. W. Gordy, W. B. Ard, and H. Shields: Microwave spectroscopy of biological 

 substances. II Paramagnetic resonance in x-irradiated carboxylic and hydroxy acids. 

 Proc. Nat. Acad. Sci., Wash. 41, 996-1004 (1955). 



7. H. Shields, and W. Gordy: Electron-spin resonance of x-irradiated nucleic acids. 

 Bull. Amer. Phys. Soc. 1, 267 (1956). 



8. W. Gordy, and H. Shields: Electron-spin resonance in x-irradiated proteins. Bull. 

 Amer. Phys. Soc. 1, 199 (1956). 



9. H. N. Rexroad, and W. Gordy : Electron-spin resonance in x-irradiated hormones and 

 vitamins. Bull. Amer. Phys. Soc. 1, 200 (1956). 



