  In the paper we describe complexes whose homologies are naturally isomorphic
to the first term of the Vassiliev spectral sequence computing (co)homology of
the spaces of long knots in R^d, d>=3. The first term of the Vassiliev spectral
sequence is concentrated in some angle of the second quadrant. In homological
case the lower line is the bialgebra of chord diagrams (or its superanalog if d
is even). We prove that the groups of the upper line are all trivial. In the
same bigradings we compute the homology groups of the complex spanned only by
strata of immersions in the discriminant (maps having only self-intersections).
We interprete the obtained groups as subgroups of the (co)homology groups of
the double loop space of a (d-1)-dimensional sphere. In homological case the
last complex is the normalized Hochschild complex of the Poisson or
Gerstenhaber (depending on parity of d) algebras operad. The upper line
bigradings are spanned by the operad of Lie algebras. To describe the cycles in
these bigradings we introduce new homological operations on Hochschild
complexes. It will be proven elsewhere that these operations are related to
Dyer-Lashof homology operations defined for double loop spaces.
