100 



THE PHYSICS OF VIRUSES 



Structural Inferences from Radiation Studies 



In Fig. 2.13 we showed the appearance of two plant viruses 

 which results from studies of sedimentation, diffusion, and X-ray 

 scattering. Since the most detailed radiation studies have been 

 made on bacterial viruses, we show in Fig. 3.11 what can be 



Infectivity 



11 "'"" 



g power 

 Latent period 



Fig. 3.11. Schematic representation of the various radiation cross sections 

 of a T-series bacteriophage. The various factors are not put in place, but their 

 relative areas are indicated. 



inferred about bacterial virus structure from the considerations 

 outlined in this chapter. The picture is unfortunately a composite 

 of T-1 and T-2 bacteriophage, which is probably an unjustified 

 synthesis of two very different viruses. This is no great detri- 

 ment since careful enough studies of any one virus have yet to be 

 made. The picture is, therefore, meant to give a general impres- 

 sion of two things — what the internal structure of a virus may be 



