  Two different mechanisms exist in non-perturbative String / M- theory for
enhanced SU(N) (SO(2N)) gauge symmetries. It can appear in type IIA string
theory or M-theory near an $A_{N-1}$ (D_N) type singularity where membrnes
wrapped around two cycles become massless, or it can appear due to coincident
D-branes (and orientifold planes) where open strings stretched between D-branes
become massless. In this paper we exhibit the relationship between these two
mechanisms by displaying a configuration in M-theory, which, in one limit, can
be regarded as membranes wrapped around two cycles with $A_{N-1}$ (D_N) type
intersection matrix, and in another limit, can be regarded as open strings
stretched between N Dirichlet 6-branes (in the presence of an orientifold
plane).
