The volume focuses on the line of research which led from the Italian physicist, Antonino Zichichi's contribution to the study of the muon (g-2) to the threshold of the discovery of the heavy lepton. This volume includes the reprints of the afticles and of some published laboratory reports, documenting the extraordinary constaney of Ziehiehi in a scientific programme which spanned more than a decade and laid the foundations for the subsequent discovery by M; Perl of the heavy lepton ML (now called r), first proposed and searched for at CERN and Frascati.