  By adopting the empirical constraints related to the estimates of Helium
enhancement ($\Delta Y$), present mass ratio between first and second stellar
generations ($M_{1G}/M_{2G}$) and the actual mass of Galactic globular clusters
($M_{GC}$), we envisage a possible scenario for the formation of these stellar
systems. Our approach allows for the possible loss of stars through evaporation
or tidal interactions and different star formation efficiencies. In our
approach the star formation efficiency of the first generation
($\epsilon_{1G}$) is the central factor that links the stellar generations as
it not only defines both the mass in stars of the first generation and the
remaining mass available for further star formation, but it also fixes the
amount of matter required to contaminate the second stellar generation. In this
way, $\epsilon_{1G}$ is fully defined by the He enhancement between successive
generations in a GC. We also show that globular clusters fit well within a
$\Delta Y$ {\it vs} $M_{1G}/M_{2G}$ diagram which indicates three different
evolutionary paths. The central one is for clusters that have not loss stars,
through tidal interactions, from either of their stellar generations, and thus
their present $M_{GC}$ value is identical to the amount of low mass stars ($M_*
\le$ 1 M$_\odot$) that resulted from both stellar generations. Other possible
evolutions imply either the loss of first generation stars or the combination
of a low star formation efficiency in the second stellar generation and/or a
loss of stars from the second generation. From these considerations we derive a
lower limit to the mass ($M_{tot}$) of the individual primordial clouds that
gave origin to globular clusters.
