  We test the evolution of the correlation between black hole mass and bulge
velocity dispersion (M$_{\rm BH}-\sigma$), using a carefully selected sample of
14 Seyfert 1 galaxies at $z=0.36\pm0.01$. We measure velocity dispersion from
stellar absorption lines around Mgb (5175\AA) and Fe (5270\AA) using high S/N
Keck spectra, and estimate black hole mass from the H$\beta$ line width and the
optical luminosity at 5100\AA, based on the empirically calibrated
photo-ionization method. We find a significant offset from the local relation,
in the sense that velocity dispersions were smaller for given black hole masses
at $z=0.36$ than locally. We investigate various sources of systematic
uncertainties and find that those cannot account for the observed offset. The
measured offset is $\Delta \log M_{\rm BH}=0.62 \pm 0.10 \pm 0.25$, i.e.
$\Delta \log \sigma=0.15 \pm 0.03 \pm 0.06$, where the error bars include a
random component and an upper limit to the systematics. At face value, this
result implies a substantial growth of bulges in the last 4 Gyr, assuming that
the local M$_{\rm BH}-\sigma$ relation is the universal evolutionary end-point.
Along with two samples of active galaxies with consistently determined black
hole mass and stellar velocity dispersion taken from the literature, we
quantify the observed evolution with the best fit linear relation, $\Delta \log
M_{\rm BH} = (1.66\pm0.43)z + (0.04\pm0.09)$ with respect to the local
relationship of Tremaine et al. (2002), and $\Delta \log M_{\rm BH} =
(1.55\pm0.46)z + (0.01\pm0.12)$ with respect to that of Ferrarese (2002). This
result is consistent with the growth of black holes predating the final growth
of bulges at these mass scales ($<\sigma>$=170 km s$^{-1}$).
