IONIZING RADIATION AND VIRUSES 101 



like, and what factors can be determined by careful radiation 

 study. 



The part of the virus which is needed for infectivity and which 

 can be destroyed by one primary ionization is shown as long and 

 thin, just above the tail of the virus. That it is long and thin is 

 probable, that it is straight is pure guessing mixed with a little 

 laziness in drawing. The smaller killing fraction is drawn 

 double-cross-hatched. The 50 enzyme-like units are shown, 

 crudely to scale, and the whole is encased in some outer part 

 which is seemingly not very radiation sensitive. 



The reader should notice that this is wholly derived from 

 electron microscopy (for the outer shape) and deductions from 

 radiation work. The picture now has to fit other physical and 

 chemical studies but, most importantly, it must check with all 

 the purely biological findings. When a more complete picture, 

 including information from ultraviolet action spectra and surface 

 studies is drawn, an attempt to see whether the resulting picture 

 can work will be made. 



A very good analogy for the kind of information assembled 

 in this way is a series of geographic maps of a nation in which 

 climate, population, height, and mineral deposits are separately 

 indicated. The sum of the maps should tell a lot about the 

 general character of the nation, and all should mutually agree. 

 We have here assembled an early version of one map of a virus 

 in terms of radiation action. Others can be made and all should 

 fit into an inferred, but true, structure. 



References 



For general references on radiation action there are three valuable^books: 

 Lea, D. E., Actions of Radiations on Living Cells (Macmillan Co., New York, 

 1947); Timofeeff-Ressovsky, N. K., and Zimmer, K. G., Das Trejfer Prinzip 

 in der Biologic (Hirzel, Leipsig, 1947); and the Oberlin Symposium Report: 

 Nickson, J. J., Symposium on Radiobiology (John Wiley and Sons, Inc., New 

 York, 1952). The principles of using radiation to study molecular organization 

 are elaborated by Pollard in Advances in Biol, and Med. Phys. 3, 153 (1953). 

 The more detailed references follow below. 



Adams, W. R., and Pollard, E. C, In course of publication (1953). 



Adams, W. R., and Pollard, E. C, Arch. Biochem. and Biophys. 36, 311 

 (1952). 



