  We point out that the abelian projection theory of quark confinement is in
conflict with certain large-N predictions. According to both large-N and
lattice strong-coupling arguments, the perimeter law behavior of adjoint Wilson
loops at large scales is due to charge-screening, and is suppressed relative to
the area term by a factor of $1/N^2$. In the abelian projection theory,
however, the perimeter law is due to the fact that $N-1$ out of $N^2-1$ adjoint
quark degrees of freedom are (abelian) neutral and unconfined; the suppression
factor relative to the area law is thus only $1/N$. We study numerically the
behavior of Wilson loops and Polyakov lines with insertions of (abelian) charge
projection operators, in maximal abelian gauge. It appears from our data that
the forces between abelian charged, and abelian neutral adjoint quarks are not
significantly different. We also show via the lattice strong-coupling expansion
that, at least at strong couplings, QCD flux tubes attract one another, whereas
vortices in type II superconductors repel.
