  We consider the chiral expansion for the reaction $\pi N \to \pi \pi N$ in
heavy baryon chiral perturbation theory. To order $M_\pi$ we derive novel
low--energy theorems that compare favorably with recent determinations of the
total cross sections for $\pi^+ p \to \pi^+ \pi^+ n$ and $\pi^- p \to \pi^0
\pi^0 n$.
