VIRUS GENETICS, MXTI.TIPLICATION, AND PHYSICS ^219 



in more specific attractive forces due to special arrangements of 

 charges on the surfaces of the virus chains which act to make 

 the attraction of subunits considerably less unless the whole 

 chain is complete. 



It can be seen that the multiple mating process falls into this 

 scheme. Each genetic unit is thought of as being one of the 

 nucleoprotein building blocks shown in Fig. 8.10. It is quite easy 

 for the separation of two chains to carry away part of the first; 

 in fact, the whole process is one of ordered assembly of separate 

 units rather than of the si)litting of one individual into two 

 halves. So it is not surprising if a genetic unit which started in 

 one chain finds itself part of another chain. 



It is also clear that the generations need not be synchronized, 

 but only approximately so. 



This last part of this chapter has been frankly speculative. In 

 truth, all that can be said is that we have some small idea of the 

 probable nature of the virus precursors, that there exist attrac- 

 tive forces between large molecules up to a certain size, and also 

 repulsive forces due to ionic atmospheres, which are somewhat 

 controllable by the cellular state. What has been done above is to 

 try to invent a scheme using these ideas. 



The interest and value of such a scheme is not essentially in 

 its truth but rather in its suggest! veness. We have said before 

 that virus multiplication may form an elementary test of the 

 adequacy of physical laws to explain fully biological processes. 

 Using some simple facts regarding large molecules in solution, it 

 can be seen that known physical laws contain at least some of the 

 necessary features demanded of them. This is encouraging, but 

 it remains for the virologist to provide fuller information about 

 the parts and pieces and the biological processes, for the virus 

 physicist to make their information fully quantitative and handy 

 for accurate thought, and for the theorist to put all the informa- 

 tion correctly together to see whether known natural laws can 

 accurately interpret and predict events in virus development. 



Physical studies of viruses aid in this goal, and it is because 

 they aim toward a solution of an outstanding problem of hu- 

 manity that even preliminary steps, as we have described here, 



