A histological basis to explain constant differences in action-current response from certain points on the retina of the horned toad, Phrynosoma cornutum
✍ Scribed by Clyde E. Keeler
- Publisher
- John Wiley and Sons
- Year
- 1930
- Tongue
- English
- Weight
- 675 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0362-2525
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✦ Synopsis
Abstract
The retina of Phrynosoma cornutum bears fovea, pecten, and many varieties of cones. The light band visible in fresh retinae beneath the slit of the eyelid corresponds to a zone of action current responses characterized by a low ‘B’ rise (negative response of Chaffee.) The lack of response from pecten and fovea is due to leakage and failure to tap ganglionic fibers.
Relief maps for ‘on’ and ‘off’ effects of the ‘B’ rise were prepared.
Diagrams of retinal response in cross‐sections were compared with corresponding curves showing density of cone distribution. In general, the height of response is inversely proportional to the density of cone distribution.
The potential change due to photochemical reaction in the average rod is on the order of 23 billionths of a volt for the ‘on’ effect and 11 billionths of a volt for the ‘off’ effect.