Particles, quarks, leptons and coloured glue

In considering the current situation in particle physics it is shown that protons and neutrons are no longer thought of as fundamental, they are made of quarks, and pions are no longer thought of as being agents of the nuclear force, as the proper agents of the strong force are gluons. The subject is examined under the headings; the Bohr atom and beta decay, particle population explosion, quarks, leptons and gauge fields, partons, coloured gluons, and electroweak interaction. Having given a picture of the presently envisaged fundamental particles the outstanding problems are listed. (U.K.)