  The microscopic theory of interaction between the heavy fermions and the
crystal field excitations in Kondo lattices is presented. It is shown that the
heavy-fermion spectrum scaled by the Kondo temperature $T_K$ can be modified by
the crystal field excitations with the energy $\Delta_{CF}$ provided the
inequality $\Delta_{CF}<T_K$ is realized. On the base of general description of
excitation spectrum the detailed qualitative and quantitative explanation of
anisotropic inelastic neutron scattering spectra and low-temperature specific
heat of orthorhombic CeNiSn is given. The theory resolves the apparent
contradiction between the metallic conductivity and the gap-wise behavior of
thermodynamic properties and spin response of CeNiSn at low temperatures.
