  We investigate the natural involutive structure on the blow-up of ${\Bbb
R}^n$ in ${\Bbb C}^n$ extending the complex structure on the complement of the
exceptional hypersurface. Our main result is that this structure is
hypocomplex, meaning that any solution is locally a holomorphic function of a
basic set of independent solutions. We show this by an elementary power series
argument but note that the result is essentially equivalent to the Edge of the
Wedge Theorem. In particular, we obtain a relatively simple new proof of this
classical theorem.
