  We present a solid relationship between the neutral hydrogen (HI) disk mass
and the stellar disk mass of late-type galaxies in the local universe. This
relationship is derived by comparing the stellar disk mass function from the
Sloan Digital Sky Survey and the HI mass function from the HI Parkes All Sky
Survey (HIPASS). We find that the HI mass in late-type galaxies tightly
correlates with the stellar mass over three orders of magnitude in stellar disk
mass. We cross-check our result with that obtained from a sample of HIPASS
objects for which the stellar mass has been obtained by inner kinematics. In
addition, we derive the HI versus halo mass relationship and the dependence of
all the baryonic components in spirals on the host halo mass. These
relationships bear the imprint of the processes ruling galaxy formation, and
highlight the inefficiency of galaxies both in forming stars and in retaining
their pristine HI gas.
