JOHN I. NURNBERGER, M.D. The Institute of Living, Hartford, Conn., and the Departments of Medicine (Neurology) and Psychiatry, Yale University School of Medicine, New Haven, Conn.
ACKNOWLEDGMENTSFrom the Cytochemistry Laboratory, The Institute of Living, Hartford, Conn. This work was supported, in part, by the Medical Research and Development Board, Office of the Surgeon General, Department of the Army, under Contract DA-49-007-MD-204.
The writer wishes to express his deep gratitude and indebtedness to Professor Torbjörn Caspersson. under whom he was privileged to work during 1949-1950 at the Institute for Cell Research and Genetics. Stockholm, Sweden. The author likewise is deeply indebted to Professors Arne Engström and Bo Thorell, Stockholm, Sweden, for their many stimulating discussions and original conceptions about problems considered in this paper. Much of the biochemical data recorded here was obtained in collaboration with Malcolm W. Gordon, Ph.D., Research Associate in Biochemistry and Enzymology, The Institute of Living. He has generously given of his time in assisting the author to arrive at a sober estimate of some of the chemical problems involved.
The development of monochromatic quartz microscopic objectives of superb quality and high numerical aperture (NA) by Köhler and von Rohr (21, 123, 137) and their wide-scale production by the Zeiss optical works provided stimulus for a major revolution in microscopic technique in the first years of this century. The design of a satisfactory, high-intensity monochromatic ultraviolet light source by Köhler of Zeiss at about the same time presented the microscopist with complete and efficient ultraviolet equipment. With such tools, biologists, anatomists, and pathologists began to explore previously elusive problems in finer cell structure. Both living and fixed unstained tissues (52, 135, 147) were studied. The facts that such optics approximately doubled the resolving power realized with conventional glass systems in visible light and that staining was unnecessary because of selective ultraviolet absorption in the region 250 to 310 mμ for which the quartz systems were designed, presented advantages of the greatest importance for