  We present a principal components analysis (PCA) of high-quality Lick/IDS
absorption-line measurements for 11 indices in the wavelength range 4100-5400
Ang for 39 Galactic globular clusters (GCs). Only the first principal component
appears to be physically significant. We find that there is a tight linear
relationship between this first component (PC1) and GC metallicity over a wide
range in [m/H] (-1.8 <= [m/H] <= 0), suggesting that PC1 may be used to
accurately estimate metallicities for old extragalactic GCs from their
integrated spectra. The classic GC ``second parameter effect'' is noticeable in
the Balmer indices, though it does not appear in our PCA. We find little
evidence for substantial differences in broad abundance patterns among Galactic
GCs. One implication is that the metal-poor and metal-rich GC subpopulations
formed from very similar physical processes.
