  We present internal velocity dispersion determinations from high-resolution
spectroscopic observations of a sample of nine globular clusters in M31.
Comprehensive numerical simulations are used to show that the typical
uncertainty of our velocity dispersion measurements is about 5%. Using these
new velocity dispersions together with structural parameters derived from HST
observations, we estimate the mass-to-light ratios of these clusters and find
that they are typical of those measured for Galactic clusters. We show
relations between velocity dispersion, luminosity and physical scales for
globular clusters belonging to the Galaxy, the Magellanic clouds, Fornax, M31,
and Centaurus A. The mean relations and the degree of scatter are similar in
all galaxies. This reveals remarkable similarities, in term of structure and
mass-to-light ratio, between the globular clusters belonging to these different
galaxies. We briefly discuss the possible use of individual globular clusters
as extragalactic distance indicators.
