Either the ejecta from IM-AGBs pollute the proto-cluster gas from which the present cluster members form or the ejecta are accreted by present cluster members. The strongest evidence for this “primordial scenario” has come from observations of main-sequence stars in which abundance variations of O, Na, Mg, and Al have been found [@gratton01; @ramirez03; @cohen05]. In these unevolved stars, the internal temperatures are too low to run the Ne-Na or Mg-Al chains which therefore precludes internal mixing as a viable explanation for the star-to-star composition differences.

In M 4, @smith05 found that F varied from star-to-star and that the F abundance was correlated with O and anticorrelated with Na and Al. Since destruction of F is expected to take place during HBB in IM-AGBs [@lattanzio04], the observed dispersion of F is in qualitative agreement with IM-AGBs being responsible for the globular cluster abundance anomalies. However, a quantitative test involving recent yields for AGB stars combined with a standard initial mass function showed that the observed abundance variations cannot be reproduced via pollution from AGB stars [@fenner04]. @denissenkov03 and @denissenkov04 also find flaws in the AGB pollution scenario based on calculated yields from AGB models. @ventura05 caution that theoretical yields from 