disruption.

In gas-poor elliptical galaxies and the halos of spirals, equation (\[eq:210\]) reduces to ${\hbox{$\widehat\epsilon$}}_{\rm cl}\simeq M_{\rm gcs}/M_{\rm stars}$, so that—as was mentioned above—the cluster formation efficiency can be obtained directly from obervations of the global GCS specific frequency (cf. eq. \[\[eq:23\]\]). More generally, however, ellipticals can contain large amounts of hot, X-ray emitting gas (e.g., Forman, Jones, & Tucker 1985), and when it happens that $M_{\rm gas}$ is non-negligible relative to $M_{\rm stars}$, measurements of $S_N$ are only low-order approximations to ${\hbox{$\widehat\epsilon$}}_{\rm cl}$ (which is itself only an estimate of the real efficiency $\epsilon_{\rm cl}$). Keeping this in mind, the observed systematics of both global [*and local*]{} GCS specific frequencies provide a useful starting point for an examination of the extent to which cluster formation efficiencies might vary from galaxy to galaxy, or from place to place within a single system.

The Specific Frequency “Problems”
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As was intimated in the discussion around equation (\[eq:23\]), not all galaxies have the same globular cluster specific frequency. There are several aspects to this: (1) Spiral galaxies tend to have lower $S_N$—at least when their GCS populations are normalized to their [*total*]{} (bulge plus disk) light—than do average ellipticals (Harris 1991). (2) 