Rapidity gaps have been studied in 3 jet events from hadronic Z decays to
search for colour singlet exchange in $e^+e^-$ annihilation. 
Particle flow and angular separation have been investigated in well separated 
completely symmetric 3 jet events from 77.6 pb$^{-1}$ data collected by the
L3 experiment. Asymmetries, defined with respect to the inter-jet regions,
are found to be sensitive to the exchange of a colour singlet instead of 
a colour octet gluon. From a comparison of the distributions 
between data and Monte Carlo predictions for colour octet and
 colour singlet production, a limit is obtained on the fraction of 
of colour singlet exchange in the data.
The analysis has been extended to study QCD models allowing modifications
of colour topologies in 3 jet events.