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

Date:
1878
Catalogue details

Licence: Public Domain Mark

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

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    PHOTOCHEMISTEY OF THE EETINA. In a recent communication to the Berlin Academy, Herr Fr. Boll announced the beautiful and, beyond doubt, important discovery, that the bacillary layer of the retina of all animals is in the living condition not colourless, as has been hitherto supposed, but of a purple red colour. During life, says Boll, the proper colour of the retina is continually being destroyed by the light which falls into the eye; it is restored in the dark, and after death only remains a few moments. Ani- mals which have been kept in the light are therefore very unsuitable for demonstrating the living colour of the retina, and the eyes of animals which have been exposed to the sun for a long time before death remain absolutely colourless. These facts illustrate the relation of the retinal colour to light on the one hand, and to vital conditions on the other. Whoever has busied himself with the retina will be reminded by Boll's discovery (and thereby receive a wholesome admoni- tion of the limits of his own ability), that he has akeady seen something of the kind before. He will perhaps remember that puzzling blood-clot—which at one moment he saw, or thought he saw, under the retina, and which the next moment disappeared. What he then passed over so lightly was nothing less than the key of the secret, how a nerve can be excited by light. In other words, it was the first fact disclosing the existence of photo-chemical processes in the retina. ]—2