  The model of dense lattice polymers is studied as an example of non-unitary
Conformal Field Theory (CFT) with $c=-2$. ``Antisymmetric'' correlation
functions of the model are proved to be given by the generalized Kirchhoff
theorem. Continuous limit of the model is described by the free complex
Grassmann field with null vacuum vector. The fundamental property of the
Grassmann field and its twist field (both having non-positive conformal
weights) is that they themselves suppress zero mode so that their correlation
functions become non-trivial. The correlation functions of the fields with
positive conformal weights are non-zero only in the presence of the Dirichlet
operator that suppresses zero mode and imposes proper boundary conditions.
