  We investigate, in a certain decoupling limit, the effect of having a
constant C-field on the M-theory five-brane using an open membrane probe. We
define an open membrane metric for the five-brane that remains non-degenerate
in the limit. The canonical quantisation of the open membrane boundary leads to
a noncommutative loop space which is a functional analogue of the
noncommutative geometry that occurs for D-branes.
