โ Scribed by Ragnar Granit
No coin nor oath required. For personal study only.
In the first volume (1938) of Documenta Ophthalmologica I wrote an article "Processes of adaptation in the vertebrate retina in the light of recent photochemical and electrophysiological research". Professor Missotten has kindly asked me for a brief comment on how I felt re-reading that paper now, fifty years later.
My first experience was to recall the air of general excitement that stimulated so many physiologists in Europe and the United States to suddenly undertake experimentation on the long neglected primary visual processes. Retinology then got a push from which it never has recovered. The field has remained fertile, and has attracted numerous highly competent adepts.
My paper was divided into two sections: (i) photochemistry; (ii) electrophysiology. The major achievements presented in (i) concerned rhodopsin, the visual purple of the previous generations 1850-1907, headed by Kfihne, K6nig and Garten: Now its photochemical properties and constants became finally established by Lythgoe and Goodeve in London. Bleaching and regeneration of rhodopsin were the subjects of a large number of studies. Rhodopsin chemistry had received a directive hint by a paper in 1925 in which two Danes, Fridericia and Holm, showed that rats became nightblind when deprived of vitamin A in their food. The subsequent chemical approach of Wald had at the time (1938) led to the conclusion that a carotenoid retinene, so named by him, was the likely chromophore of rhodopsin and that the end result of bleaching rhodopsin was vitamin A. Six years later the matter was settled by Morton and Goodwin who proved retinene to be vitamin A aldehyde, now called retinal.
The renewal of retinal electrophysiology started with the papers by Adrian and Matthews in the late twenties on the mass discharge from the optic nerve of the Conger eel, with my own analysis of the vertebrate electroretinogram (1932) with the subsequent discovery that light also could inhibit the mass discharge in the optic nerve (1934 with Therman) and with Hartline's studies of the activity in single fibres of the optic nerve of Limulus' ommatidial eye. An immediate sequence, though too early for my article, was Hartline's isolation of single fibres in the frog eye and our comparisons
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