The correspondents are:
James A Saba, Professor Horst Sackmann (Dr Jack Dunitz), Dr Carl Sagan (directed panspermia), Dr Fred Sanger, Professor V Sasisekharan, Dr Howard A Schneiderman, Dr Arnold B Scheibel, Professor A L Schwarzenberg, Scientific American (split infinitive), The Sciences (Rosalind Franklin and "How to live with a golden helix"), Dr Terrence J Sejnowski, Jane K Setlow (New York Times crossword containing "Sir" Francis Crick), Dr Gordon Shaw, Dr John Shepherd, Professor S Murray Sherman, Mikio Shimizu (C4N model, including two colour photographs), Dr P G Shinkman, Akin Shofoyeke, Robert L Sinsheimer, Simon & Schuster (Lucy: The Beginnings of Humankind), Alfred P Sloan Foundation, Dr Steve Smale (Christopher Zeeman and catastrophe theory), R L Small, Dr Gerald R Smith, Dr Roulette W Smith (includes Smith, "Long-term memories"), Dr Temple F Smith, Dr John R Smythies, Parti Socialiste, A J Soderberg, David Solomon, Dr Veikko Sorsa, Professor Roger Sperry ("Very many congratulations on your Nobel Prize"), Professor Arthur Springer (Michael Dowler), Christopher Starr ("evolution is a lot cleverer than we are"), Dr Lawrence G Crowley, Dr Gunther Stent, Professor Peter Sterling, Dr W K Stell, Professor Leon M Stock, Dr T D Stokes, Hilton Stowell (includes two papers by Stowell), Bernard Strauss, Lubert Stryer (Roger Kornberg / Eli Lilly Award), Dr Mriganka Sur, Dr Stuart Sutherland, Richard Sutton, Dr Nicholas V Swindale, and Professor Waclaw Szybalski (split genes and RNA splicing).