  Various galaxy properties are not continuous over a large range in mass, but
rather reveal a remarkable transition or `bimodality' at a stellar mass of 3 x
10^{10} Mo. These properties include colors, stellar populations, Xray emission
and mass-to-light ratios. This behavior has been interpreted as the transition
from hot to cold flows by Dekel & Birnboim (2005).
  Here we explore whether globular cluster (GC) systems also reveal a bimodal
nature with regard to this critical mass scale. Globular clusters probe star
formation at early epochs in the Universe and survive subsequent galaxy mergers
and accretions. We use new data from the ACS Virgo Cluster Survey (Peng etal
2005), which provides a homogeneous sample of the GC systems around one hundred
Virgo early-type galaxies covering a range of five hundred in galaxy mass.
Their classification of the GC color distributions is taken to examine a key
quantity -- the number of GCs per unit galaxy luminosity. Below the critical
mass, this quantity (called the GC specific frequency) increases dramatically
in its mean value and spread. This increase may be due to regulated star
formation in low mass galaxies, which in turn is due to mass loss via winds and
the transition from hot to cold gas accretion flows. We also note that above
the critical mass, galaxies possess two GC subpopulations (with blue and red
mean colors) but below this mass, galaxies reveal an increasing proportion of
single (blue) GC systems.
