The correspondents are:
Professor Ole Maaløe, Professor Donald MacLeod, John Maddox (Editor, Nature), Professor Henry R Mahler, Dr Arthur J Mandell, Dr A K Mann, Margaret Markham (Rosalind Franklin), Mark Twain Journal, Dr Alvin Markovitz, Dr R F Marsh, Dr John C Marshall, R F Matagne (Chlamydomonas and triploid strains), John I Mattill (Editor, Technology Review and Michael Feirtag), Dr Andrew Matus ("structural difference at the molecular level between axon and dendrite"), Michael McClure, Dr A Patrick McLaughlin, Dr Bruce McConnell (includes McConnell, "A model for the specific site melting of DNA in vivo"), Theodore Melnechuk, Dr Richard B Middleton, Dr R Mikelsaar (includes Mikelsaar, "C-A - a novel wobble base pair in nucleic acids?"), Daryl Millar, Dr Jeffrey H Miller, Dr Mortimer Mishkin, Professor R K Mishra, Professor W F H M Mommaerts, Dr Lawrence J Mononen (Russian work on ECT), Howard J Morgan (Dr Hayes), Dr A Richard Morgan, Dr Vernon B Mountcastle, Dr Charles Schwartz ("pursuing the possibility of making a movie"), and Professor Walter H Munk.