  We study a cofibrant E-infty operad generated by the Fox-Neuwirth cells of
the configuration space of points in the Euclidean space. We show that, below
the `critical dimensions' in which `bad cells' exist, this operad is modeled by
the geometry of the Fulton-MacPherson compactification of this configuration
space. We analyze the Tamarkin bad cell and calculate the differential of the
corresponding generator. We also describe a simpler, four-dimensional bad cell.
We finish the paper by proving an auxiliary result giving a characterization,
over integers, of free Lie algebras.
