Fifteen months of new particles

An account of the discovery in November 1974 of the psi particle is given and the model of the psi that consists of two charm quarks, one as an antiparticle, orbiting around one another, is discussed. The further discoveries of the psi prime, the decays of charmed particles and the e-mu events are described. It is suggested that recent months may have seen not just the discovery of some more particles but the discovery of two more fundamental constituents of matter, a new quark and a heavy lepton. (U.K.)