% THE PHYSICS OF VIRUSES 



relationship, symptomatology, virus classification, growth of 

 viruses in different species to produce attenuated viruses, im- 

 munological properties of viruses, chemical contents, and 

 genetics. A very valuable and impressive body of knowledge 

 has resulted. Nevertheless, the contribution of physics has not 

 been small and is rapidly growing. The size and shape, degree 

 of hydration, absorption spectra, and thermal properties of 

 viruses are all being studied with very interesting results. Physics 

 is beginning to tell something about the viruses themselves. 

 Furthermore, viruses are so small that they represent one of the 

 desirable extremes of study. If, indeed, the processes of the 

 cell are by the present known laws of nature, by electrical and 

 quantum-mechanical forces, by the processes of the molecular 

 theory, it ought to be possible to see the action of these in the 

 processes of virus multiplication. A very valuable start in this 

 direction has been made by Puck, Garen, and Cline, who have 

 shown the role of electrostatic forces in virus attachment to 

 bacteria. 



Therefore, even if the past direction of virus research has 

 been primarily biological and chemical, it looks as though 

 physical experimentation and theoretical speculation on viruses 

 is well worth while. The aim of this book is to collect together 

 the knowledge which bears on the physics of viruses in the hope 

 that it can serve as a starting point for still more penetrating 

 studies. 



Because it is hoped that physicists and physical chemists 

 will read this book, and because a summary is often a means of 

 clarification, a brief outline of virology, slanted to suit our 

 needs, is here given. 



Outline of Virology 



The first and most important fact about viruses is their 

 apparent intimate concern with some host. So far, all attempts 

 to secure virus multiplication on any kind of medium other 

 than an intact organism have failed. This failure does not mean 

 that all future attempts will fail, but it does mean that, whereas 

 a plant will grow if supplied with water, air, light, and a few 



