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One of the most obvious global tests of mechanical feedback is to identify the parent stellar populations, or their remains, with the superbubbles. M31 (Brinks & Bajaja 1986) and M33 (Deul & den Hartog 1990) both show correlations of OB assocations with H i holes. However, Ho II shows contradictory results, based on the H i hole catalog compiled by Puche et al. (1992). Tongue & Westpfahl (1995) found that the SN rate implied by radio continuum emission is consistent with the hole energetics in that galaxy. However, Rhode et al. (1999) carried out a direct, BVR search for remnant stellar populations within the H i holes, and found little evidence for the expected stars. But Stewart et al. (2000) used far-UV data from the Ultraviolet Imaging Telescope and Halpha images to conclude that a significant correlation between the H i holes and recent star formation does indeed support a feedback origin for the holes.

It is perhaps unsurprising that studies of Ho II yield these confusing results in view of that galaxy's distance of 3 Mpc. The LMC, which is 60 times closer, presents much better spatial resolution and should therefore yield less ambiguous results. Kim et al. (1999) examined the correspondence between their H i shell catalog, catalogued H ii regions (Davies et al. 1976), and Halpha imaging. Not only do they find a correspondence, but they are also able to identify an evolutionary sequence with respect to the relative sizes, expansion velocities, and Halpha emission. Further investigation of the Magellanic Clouds should confirm and reveal more quantitative details of the mechanical feedback process (Oey, Gerken, & Walterbos, in preparation).