  It is pointed out that the answer on the question about the role played by
spin and charge excitations will help to solve the physical origin of the
heavy- fermion phenomena. Our answer is that neutral spin-like excitations are
responsible for the heavy-fermion phenomena whereas the role of the charge
excitations is negligible.
  Keywords: heavy fermion, spin excitations, charge excitations
  PACS No: 75.20.H
