CAMP LE JEUNE, NORTH CAROLINAIN early 1960, at a meeting of the Armed Forces Epidemiological Board, one of us (G.L.C.) asked a member, "What are your thoughts on the etiologic significance of the pleuropneumonia-like organisms in relation to human disease?" The following reply came without hesitation:This group of organisms may very well be the next area of important breakthrough in infectious disease. There is a great need for more basic research confined to this area, for the biology of the pleuropneumonia-like organisms is still not well understood. Much conscientious and careful work has already been done, and it . . .