  The microscopic theory of the Casimir effect in the dielectric is studied in
the framework when absorption is realized via a reservoir modeled by a set of
oscillators with continuously distributed frquencies with the aim to see if the
effects depend on the form of interaction with the reservoir. A simple case of
the one-dimensional dielectric between two metallic plates is considered. Two
possible models are investigated, the direct interaction of the electromagnetic
field with the reservoir and indirect interaction via an intermediate
oscillator imitating the atom. It is found that with the same dielectric
constant the Casimir effect is different in these two cases, which implies that
in the second model it cannot be entirely expressed via the dielectric constant
as in the well-known Lifshitz formula.
