The phenomenon of secondary nucleation is illustrated in
a striking fashion by a supersaturated aqueous solution of
an inorganic salt, sodium chlorate [7]. If the solution is
allowed to stand undisturbed in a beaker it deposits a
mixture of enantiomorphic D and L crystals in roughly
equal number. However, if the solution is stirred vigorously
while it is crystallizing, all of the crystals formed in
any one experiment have the same handedness, and they
are equally likely to be all-L or all-D isomers. Vigorous stirring
presumably fragments the first primary nucleus
formed. The secondary nuclei produced in this way grow
and are, in turn, fragmented. Before a second primary
nucleus has time to form, the beaker fills with crystals
‘cloned’ from the first nucleus. Since D-nuclei and
L-nuclei ‘breed true’, one might have been inclined to call
the D and L enantiomorphs ‘strains’ if they were not
simple inorganic structures.