On the photochemistry of the retina and on visual purple / translated from the German of Dr. W. Kühne ... Ed., with notes, by Michael Foster.

  • Kühne, W. (Willy), 1837-1900.
Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: On the photochemistry of the retina and on visual purple / translated from the German of Dr. W. Kühne ... Ed., with notes, by Michael Foster. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    tlirowing the light on the object with a properly inclined mirror in order that it might act as powerfully as possible. I thus found that in a blue, which seemed to my eye so deep that I was unable to manipulate in it much better than in the dark, the visual purple bleached in two or three hours, while in the gieen, wliich to my eye appeared very luminous, it took from three to four hours. In the red, which produced a most brilliant light, the action first became distinct after the lapse of 16 hours, and it was not till 24 hours that all traces of colour vanished from the retina. An owl's retina with highly-developed purple colour required 72 hours before it became perfectly colourless, and shewed, even after 48 hours, spots not only of yellowish-red and brick-red, but even of real bluish-purple. It will of course be understood that this last preparation, as well as all the others, was carefully protected from drying during the whole time of the long experiment. Several frogs' retinas were, during the experiment, cursorily examined in daylight, and some which happened to be placed under cover-slips were examined with the microscope; and these enabled me to state that in the blue light the stage of orange and yellow colouration was that which was most rapidly passed through. Bearing in mind Boll's already mentioned interesting discovery of the green rods and his remarkable statements about their increase in the eyes of living frogs, after these had been kept exposed to coloured, that is to green light, attention was especially directed to these as well as to the colourless grey opaque rods, which have been already described by me. As far as I could see, the matter was altogether inconstant; grass-green rods were present even in considerable numbers in the preparation which had been ex- po.sed to the three kinds of light. The same was the case also with the grey rods; and where the retina before all exposure to party-coloured light was rapidly examined in darkened daylight, and brought before the lantern still thoroughly well coloured, I have not been a})le to notice any cliange produced by the co- loured light in this direction, ccrtaiidy no increase of tlie green rods at the expense of the red or grey ones. I have however observed tliat the true grass-green rods keep their colour longest in green ligiit, arc less preserved in the blue and least