play in producing a frothy medium in galaxies?

SUMMARY AND CONCLUSIONS
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We have presented the results of an ongoing investigation to provide a detailed view of the processes by which massive stars shape the surrounding ISM, from pc to kpc scales. In this paper we have focused on studying the environments of WR stars to find evidence for WR wind-ISM interactions in M31, through imaging ionized hydrogen nebulae surrounding these stars.

We have classified the morphology of the H$\alpha$ emission near 48 WR stars into two groups, Group I and Group II. The first category (Group I shells) consists of shells, or shell fragments, in which the WR star is at or near the center of a single shell (Ia), or concentric limb brightened shells (Ib). We consider Group I shells as potentially being causally associated with a WR star (i.e. E- or W-type shells). There are 17 WR stars within Group Ia shells, and 7 stars within Group Ib shells. The second category (Group II stars) consists of WR stars where there is no clear causal relation with nearby H$\alpha$ emission (IIa), or a lack of nearby H$\alpha$ emission (IIb). Group IIa consists of WR stars that are 