  This paper presents some new statistical correlations between the properties
of disks and spiral arms with some physical properties of galaxies. Our results
show that the thickness of spiral disks tend to diminish along the Hubble
sequence in the sense that disks of Sc galaxies are 40% thinner than disks of
Sab-Sb galaxies. Moreover, the thinner disks tend also to be bluer. We also
find that there exists a correlation between HI linewidths and arm pattern
within each Hubble type, which suggests that the arm shape is partially
determined by the mass of a galaxy. Total mass luminosity ratios and total mass
surface densities also have correlations with pitch angles, i.e., for disks
with lower surface densities and lower total mass luminosity ratios, the pitch
angles tend to be greater.
