We examine the stability of \ell = 1 and \ell = 2 g modes in a pair of nitrogen-rich Wolf-Rayet stellar models characterized by differing hydrogen abundances .
We find that modes with intermediate radial orders are destabilized by a \kappa mechanism operating on an opacity bump at an envelope temperature \log T \approx 6.25 .
This ‘ deep opacity bump ’ is due primarily to L-shell bound-free transitions of iron .
Periods of the unstable modes span \sim 11 - 21 hr in the model containing some hydrogen , and \sim 3 - 12 hr in the hydrogen-depleted model .
Based on the latter finding , we suggest that self-excited g modes may be the source of the 9.8 hr -periodic variation of WR 123 recently reported by .