98 FUNDAMENTAL STRUCTURE OF PROTOPLASM 



origin and the same kind have a strong tendency to combine with 

 one another. 



The combination between virus and the host cell must be raised 

 by complementarily arranged polar groups between them, w^hilst there 

 appears to exist a common antigenic structure or structures between 

 a virus and the host cell protoplasm as mentioned in Part I, indicating 

 that the complementary pattern is attributed to such common struc- 

 tures. Thus, a virus may be able to com.bine readily wuth a cell if 

 the cell and the virus share a structure or structures in common. 



The structures common to a virus and the host give rise to the 

 combining force between them, whereas when they are drawn near by 

 the combining force, uncommon structures present between them may 

 exert a mutual electrostatic repulsion, and if the virus has a structure 

 strong enough to rearrange the structure of the host cell protoplasm, 

 the virus can assimilize the cell. Viruses must have such strong struc- 

 tures not present in the host cell protoplasm. 



