  We find the following improved laboratory bounds on the coupling of light
pseudoscalars to protons and neutrons: $g_p^2/4\pi < 1.7 \times 10^{-9}$ and
$g_n^2/4\pi < 6.8 \times 10^{-8}$. The limit on $g_p$ arises since a nonzero
$g_p$ would induce a coupling of the pseudoscalar to two photons, which is
limited by experiments studying laser beam propagation in magnetic fields.
Combining our bound on $g_p$ with a recent analysis of Fischbach and Krause on
two-pseudoscalar exchange potentials and experiments testing the equivalence
principle, we obtain our limit on $g_n$. (PACS number(s):
14.20.Dh/14.80.-j/12.20.Fv/04.90.+e)
