T. Caspersson, Skand. Arch. Physiol. 73, Suppl. 8, 1 (1936); Chromosoma 1, 147 (1939); J. Roy. Microscop. Soc. 60, 8 (1940).
Recent general discussions of microspectrophotometry will be found in "Optical Methods of Investigating Cell Structure," Discussions Faraday Soc. No. 9, (1950); E. R. Blout, Advances in Biol. and Med. Phys. 3, 285 (1953); H. Swift and E. Rasch, in Physical Techniques in Biological Research, edited by G. Oster and A. W. Pollister (Academic Press, Inc., New York, 1956), Vol. 3, p. 353; and P. M. B. Walker ibid., Vol. 3, p. 401. For recent contributions to the art, see B. Chance, R. Perry, L. Åkerman, and B. Thorell, Rev. Sci. Instr. 30, 735 (1959); and G. K. Strother and J. J. Wolken, Science 130, 1084 (1959).
We wish to thank Mr. Frank White of the Biological Laboratories of Harvard University for making the photographs shown as Figs. 1 and 2.
This attachment and the stands for the macroscope and microscope were built in the machine shop of the Biological Laboratories by Mr. Robert Chapman and his assistant, Mr. Bernard Dillon. We wish to thank Mr. Chapman for many helpful suggestions regarding the design and machining of the apparatus.
The quartz condenser lenses, which are identical, were made by the Jones Optical Company of Cambridge, Massachusetts and were mounted by Mr. Kenneth A. Dawson of Belmont, Massachusetts.
It should be said at once that we were encouraged to prepare to make measurements of this type by the pioneer work of E. J. Denton at the Marine Biological Station in Plymouth, England. Denton showed that spectrophotometric measurements on intact retinas can yield spectra of visual pigments that rival in accuracy the best work done in solution [cf. E. J. Denton, in Visual Problems of Colour, National Physical Laboratory, Teddington, England, Symposium No. 8 (Her Majesty's Stationary Office, London, 1958), p. 177; also Proc. Roy. Soc. (London) B150, 78 (1959)].
G. Wald, J. Opt. Soc. Am. 41, 949 (1951).
G. Wald and P. K. Brown, J. Gen. Physiol. 37, 189 (1953–54).