  We have observed variations in the optical emission lines from the X-ray
binary Circinus X-1. These variations may be attributed both to orbital
variations and to long term secular changes in line strength. We have detected
double-peaked H-alpha emission lines on two occasions, providing the first
direct evidence for an accretion disk in the system. The separation of the
peaks was different on the two occasions, suggesting that the disk might have a
different size. The equivalent width of the emission lines dropped by more than
a factor of three between 1999 and 2000; this continues the trend seen in
earlier data, so that the H-alpha equivalent width has now declined by a factor
of twenty since 1976. The emission lines do not appear to show signature of
orbital motion, except for the data taken near phase 0, which show a
significant velocity shift.
  We have observed an absorption component to the He I lines on one occasion.
We suggest that, unlike the P Cygni profiles seen in X-ray spectra, this
absorption does not arise in the accelerating zone of a radiatively driven
wind. Instead, the absorption arises in material previously ejected from the
system. It was only seen on this one occasion because the strength of the
emission line had dropped dramatically.
