  We use deep Chandra observations to measure the emissivity of the unresolved
X-ray emission in the elliptical galaxy NGC 3379. After elimination of bright,
low-mass X-ray binaries with luminosities >10^{36 erg/sec, we find that the
remaining unresolved X-ray emission is characterized by an emissivity per unit
stellar mass L_x/M_stars ~8.2x10^{27} erg/s/M_sun in the 0.5-2 keV energy band.
This value is in good agreement with those previousely determined for the dwarf
elliptical galaxy M32, the bulge of the spiral galaxy M31 and the Milky Way, as
well as with the integrated X-ray emissivity of cataclysmic variables and
coronally active binaries in the Solar neighborhood. This strongly suggests
that i) the bulk of the unresolved X-ray emission in NGC 3379 is produced by
its old stellar population and ii) the old stellar populations in all galaxies
can be characterized by a universal value of X-ray emissivity per unit stellar
mass or per unit K band luminosity.
