  This text, written as dissertation within the M.Sc. course in particle theory
at the Centre for Particle Theory, University of Durham, during the academic
year 1993/94, reviews two articles by D.Gross and by D.Gross and W.Taylor which
interpret the 1/N- expansion of the partition function of $QCD_2$ as string
perturbation series. For this required mathematical and physical background is
presented.
