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THE NATURE OF FOVEAL DARK ADAPTATION.
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MedLine Citation:
PMID:  19871919     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
1. After a discussion of the sources of error involved in the study of dark adaptation, an apparatus and a procedure are described which avoid these errors. The method includes a control of the initial light adaptation, a record of the exact beginning of dark adaptation, and an accurate means of measuring the threshold of the fovea after different intervals in the dark. 2. The results show that dark adaptation of the eye as measured by foveal vision proceeds at a very precipitous rate during the first few seconds, that most of the adaptation takes place during the first 30 seconds, and that the process practically ceases after 10 minutes. These findings explain much of the irregularity of the older data. 3. The changes which correspond to those in the fovea alone are secured by correcting the above results in terms of the movements of the pupil during dark adaptation. 4. On the assumption that the photochemical effect of the light is a linear function of the intensity, it is shown that the dark adaptation of the fovea itself follows the course of a bimolecular reaction. This is interpreted to mean that there are two photolytic products in the fovea; that they are disappearing because they are recombining to form anew the photosensitive substance of the fovea; and that the concentration of these products of photolysis in the sense cell must be increased by a definite fraction in order to produce a visual effect. 5. It is then suggested that the basis of the initial event in foveal light perception is some mechanism that involves a reversible photochemical reaction of which the "dark" reaction is bimolecular. Dark adaptation follows the "dark" reaction; sensory equilibrium is represented by the stationary state; and light adaptation by the shifting of the stationary state to a fresh point of equilibrium toward the "dark" side of the reaction.
Authors:
S Hecht
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of general physiology     Volume:  4     ISSN:  0022-1295     ISO Abbreviation:  J. Gen. Physiol.     Publication Date:  1921 Nov 
Date Detail:
Created Date:  2010-06-22     Completed Date:  2010-06-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985110R     Medline TA:  J Gen Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  113-39     Citation Subset:  -    
Affiliation:
Marine Biological Laboratory, Woods Hole.
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Journal Information
Journal ID (nlm-ta): J Gen Physiol
ISSN: 0022-1295
ISSN: 1540-7748
Publisher: The Rockefeller University Press
Article Information
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Copyright © Copyright, 1921, by The Rockefeller Institute for Medical Research
Received Day: 15 Month: 8 Year: 1921
Print publication date: Day: 20 Month: 11 Year: 1921
Volume: 4 Issue: 2
First Page: 113 Last Page: 139
ID: 2140462
PubMed Id: 19871919

THE NATURE OF FOVEAL DARK ADAPTATION
Selig Hecht
From the Marine Biological Laboratory, Woods Hole.


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