The temperature dependence of hopping conduction through a one-dimensional chain of localized states has been studied in small-area (S=2 mu m*2 mu m) thin (L=280 AA) amorphous silicon layers. If the average number (N) of states in the chain is less than five, then the conductivity was observed to obey not an exponential but a power law. From these data the values of N have been extracted in a set of microstructures. It was found that chains with different numbers of states are realized in different devices. Chain reorganization with variation in the temperature has been studied. At low temperatures (T<40-60 K), resonant tunnelling through localized states was observed. It was shown that the electronic spectrum of microstructures can be affected by external parameters: the electric field, temperature and light illumination.