  Comparison of two appropriately chosen screening masses of colour singlet
operators in the pure glue QCD plasma indicates that at sufficiently high
temperature it contains a weakly-interacting massive quasi-particle with the
quantum numbers of the electric gluon. Still in the deconfined phase, but
closer to T_c, the same mass ratio is similar to that at zero temperature,
indicating that the propagating modes are more glueball-like, albeit with a
lower scale for the masses. We observe a continuity between these two regimes.
