Measurements of R and search for new thresholds at PETRA

Data are presented from five experiments at PETRA and combined where possible. The measured R values show a constant behaviour for the centre of mass energies between 17 and 36.5 GeV, and are compatible with expectations from the quark parton model including five quarks u,d,s,c,b and QCD corrections. The results of two energy scans are reported. The data exclude any tt threshold below 36.5 GeV of 2/3 charged t quarks decaying into many hadrons. The search for superheavy sequential leptons and scalar electrons yields negative evidence lower mass limits are given