  We interpret Minkowski black holes as world-sheet {\it spikes } which are
related by world-sheet { \it duality} to {\it vortices } that correspond to
Euclidean black holes. These world-sheet defects induce defects in the gauge
fields of the corresponding coset Wess-Zumino descriptions of
spherically-symmetric black holes. The low-temperature target space-time foam
is a Minkowski black hole (spike) plasma with confined Euclidean black holes
(vortices). The high-temperature phase is a {\it dense} vortex plasma described
by a topological gauge field theory on the world-sheet, which possesses
enhanced symmetry as in the target space-time singularity at the core of a
black hole. Quantum decay via higher-genus effects induces a back-reaction
which causes a Minkowski black hole to lose mass until it is indistinguishable
from intrinsic fluctuations in the space-time foam.
