128 



THE PHYSICS OF VIRUSES 



tioii is very strong. Monovalent ions are never as effective, oper- 

 ate at higher concentrations, and again, in excess, cause repulsion. 

 These experiments and the definiteness of this idea for the 

 first attachment phase are relatively new. A complete theory 

 in terms of modern ideas of colloids and ionic atmospheres 

 should be capable of predicting the shape of the curves of Fig. 



Medium Virus Surface Cell Surfoce Result 



Water 



No attachment 



10' M MgClj 



10" M MgCI, 



Attochment 



Mg 



Mg* 



_jMg Mg 

 -'Mg^ Mg"^ 



Mg 



No ottoctiment 



Fig. 5.2. Puck, Garen, and Cline's scheme for explaining the first phase of 

 virus attachment. 



5.1 and should then yield figures for actual charge distributions 

 on the virus or the bacterium. 



One important point which must be cleared up by such a 

 theory is the factor which determines why ions should attach 

 first to one or the other, virus or bacterium, and not equally 

 to both. It seems probable that the final description of the 

 process in terms of ionic-solution theory may be more complex 

 than that just given. 



