In a quasi-neutral sheet the tearing mode is strongly stabilized by electron compressibility. We demonstrate that previous attempts to remove the compressibility by wave turbulent pitch-angle scattering or by non-adiabatic stochastic first invariant diffusion are incorrect since these processes do not change the perturbed number of particles on a flux tube. Only spatial diffusion of electrons across magnetic flux surfaces can remove the stabilizing effect of compressibility; in this case, the electron, but not the ion, tearing mode may exist. ¿ American Geophysical Union 1991