The Scale of Structural Units in Biopoesis 



393 



The existence under certain circumstances of this equihbrium results in the 

 division of the solution containing them into two parts whenever the overall 

 concentration of particles is less than that which would ensure the equilibrium 

 distance. In the more concentrated regions this critical concentration is main- 

 tained: in the rest there is in general a far more dilute solution. 



Table i 

 Types of inter particulate forces 



The long-range forces are undirected, but the shapes of mutual equipotential 

 surfaces around flat or elongated particles ensure a tendency towards parallelism. 

 This leads, in the case of identical particles such as viruses, to a liquid-crystal 

 condition for equilibrium sols of such particles with one- or two-dimensional 



