In summary, the spectroscopic and photometric variations observed in 1985 show the transition of the star from a quiescent state to an active state. Our data confirm the results of the observations of previous authors.
In particular our spectra clearly show that the 1985 state has a lower level of activity with respect to the one observed in 1987.
In 1989 Z CMa returned to approximately the 1984 brightness level, but the spectrum still shows evidence of residual activity.
The most important result of our spectroscopic observations of Z CMa is given
by the very peculiar profile change of H
observed in January 1996. The
appearance of a double emission profile might be explained by geometric effects
due to variation of the opening angle of the bipolar outflow.
Furthermore a strong decrease of the circumstellar
envelope density may explain the observed decrease in the B-V index.
Further and higher dispersion spectroscopy is proposed for the future in order
to allow a much more detailed description of possible geometric effects causing the
peculiar morphology of the 
emission line profile.
Acknowledgements
We are indebted to Dr. J.A. Mattei who provided us with photometric observations of Z CMa in the period 1976-1996. We thank Dr. Krautter for allowing us to obtain the CASPEC spectrum. We are indebted to Prof. A. Guarnieri of Bologna Astronomy Department for giving us precious help with BFOSC observations at the Loiano 1.52 m telescope. We wish to thank also Dr. Kevin Reardon for carefully reading our manuscript.