  Certain static soliton configurations of gauge fields in 4+1 dimensions
correspond to the instanton in 4-Euclidean dimensions ``turned on its side,''
becoming a monopole in 4+1. The periodic instanton solution can be used with
the method of images to construct solutions satisfying D-brane boundary
conditions. The $\theta$-term on the brane becomes a topological current
source, yielding an emission amplitude for monopoles into the bulk. Instantons
have a novel reinterpretation in terms of monopole exchange between branes.
