  A survey is presented of the work done so far to check earlier claims that a
fine structure may be observed to occur under certain circumstances in the
impurity spectral range of the optical absorption spectra of silver halides
following photostimulation in the intrinsic range. This structure, associated
with the photochemical formation of silver specks, has been questioned over the
years. We now weigh carefully the experimental evidence on the silver halides
against a background of similar data on the alkali halides, where competing
processes run slower. We come to the conclusion that present day advances in
experimental techniques may be quite adequate for providing a solid
experimental basis to solve the problem unambiguously.
