would show the ‘back-reaction’ of the D2- or NS5-brane on the D6-brane. Certainly, a brane-charge argument indicates that, for example, any $\tilde{F}_4$ or $H_3$ flux falling on the D6-brane must result in the creation of F1- or D4-branes. However, one does not see this in the solutions of [@GM]. Instead, there seems to be a ‘flux-expulsion’ effect associated with D6-branes which is reminiscent of the ‘superconducting branes’ phenomenon [@sup].

To begin to understand this effect, consider any massless type IIA solution containing D6-branes. This of course provides a solution to 11-dimensional supergravity in which the D6-branes are replaced by the cores of Kaluza-Klein monopoles. This solution has a Killing field $\lambda^{11}$ which vanishes at the core of each monopole. The natural boundary condition to impose on the D6-branes is that the corresponding 11-dimensional solutions (or an appropriate multiple cover in the multiply charged case) be smooth at these cores. But now consider the 11-dimensional four-form field strength $F_4^{\{11\}}$. If it is smooth then $F_4^{\{11\}} \cdot
\lambda^{11}$ must vanish when $\lambda^{11}$ does and in particular at any core. Since $H_3 = F_4^{\{11\}} \cdot \lambda^{11}$, it follows that $H_3$ will vanish at any D6-brane. Note that since the lowest Fourier mode around 