\[Fe/H\]$=0.01$ for 5 Gyr. Even so, the general shape of the distribution remains more or less constant with age, and the result that there are few low metallicity stars is secure.

A similar metallicity distribution derived for the POS2 M31 background field is also illustrated in Figure \[fig:hist\], renormalized by a factor of 5.7 so that the total number of stars is the same as that for the corrected POS1. Relative to M32, the M31 population has a peak at similar Z but a higher tail towards lower metallicities. The POS2 M31 diagram resembles the solar neighborhood more closely, with the caveat that the age structure is completely unknown. The paucity of metal-poor stars relative to the closed-box model is also inferred for the nuclei of M31 and M32 (Worthey, Dorman, & Jones 1996), so it is probable that this condition exists at most radii in both M32 and M31.

Worthey et al. (1996) argue that the simplest explanation for the lack of low-mass, metal-poor stars is that normal processes of chemical enrichment typically operate to produce fewer low-metallicity stars than the simplest closed-box model predicts. That is, modifications to the simplest model (like variable yield, spatially inhomogeneous enrichment, or 