A critical inquiry respecting a new membrane in the eye : discovered by Mr. George Hunsley Fielding, and described by him in a lecture delivered at Oxford, before the late meeting of the British Association for the Advancement of Science / by William Gordon.
- Gordon, William, 1800-1849.
- Date:
- 1832
Licence: Public Domain Mark
Credit: A critical inquiry respecting a new membrane in the eye : discovered by Mr. George Hunsley Fielding, and described by him in a lecture delivered at Oxford, before the late meeting of the British Association for the Advancement of Science / by William Gordon. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![ciently powerful impulse from the image repre- sented upon it. On what account, then, does Mr, Fielding suppose that this image is too faint for producing vision ? Has he ascertained what is tiie precise nature of the effect tliut light has upon the Retina ? Does he know >vhether it is a mechanical, a chemical, a magnetic, or uu electrical effect ? Has he, or has any physiolo- gist, become so well acquainted Avith the struc- ture and functions of nervous matter, as to inform us with accuracy what quantity of light is ne- cessary to make an impression upon the Retina, or to tell us how vivid the image of an external object depicted upon this delicate nervous expan- sion should be, in order to create the perception of sight ? I fear, that, on these abstruse points, Mr. Fielding has acquired no correct know- ledge, nor, indeed, any knowledge at all. His doctrine, then, is left unsupported both by facts and arguments, and, on this account, no one am hesitate (in direct opposition to it) to conclude that the image upon the Retina, hoAvever faint and nebulous it may appear, is sufficiently vivid and energetic for all the purposes of vision. As Mr. Fielding supposes that the Retinn is incapal)le of retaining a distinct image, lio conceives that the Membrana Versicolor, l)eing opalie, forms the part appropriated r-.n- its recc].-](https://iiif.wellcomecollection.org/image/b22285933_0035.jp2/full/800%2C/0/default.jpg)
