Retinal insensibility to ultra-violet and infra-red rays / by L. Webster Fox and Geo. M. Gould.

  • Fox, Lawrance Webster, 1853-1931.
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: Retinal insensibility to ultra-violet and infra-red rays / by L. Webster Fox and Geo. M. Gould. 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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    media as such may be proved not to have this filtering action, and criticism is not checkmated by many moves; the layer of axis cylinders, highly complex and organized structures, of which there are some 800,000 spread out over the concave surface of the globe, may exercise an absorbent or modifying agency; not only does the entering light have to pass through these structures (except at the fovea) but it has also to pierce the still more highly organized and extensive eight or nine distinctly recognized strata of the retina before reaching the tips of the rods and cones or the pigmentary substance into which these extend. It seems wholly beyond the possibility of experiment to determine whether these may not, when instinct with quivering life, exercise an in- fluence upon the transmitted rays. The inexplicable and appar- ently unnatural arrangement whereby the points of the retinal end organs are turned away from instead of toward the entering stimulus may not be disconnected from this interesting question. It must certainly have been another great task to make so complex an organizism as the retina so wonderfully transparent. Its transparency, however, may only be to the light rays, and it may possibly be wholly opaque to the infra-red. If it were proved that the rays in question do reach the pigment masses about the cone tips, it would conform to the theory of heat as the retinal intermediate that we have previously set forth, to suppose no receptive substance were there secreted whose vi- bratory phases corresponded to those of the infra-red rays. Lastly, it may not be held improbable that there is retinal re- sponse to these stimuli but no neural transmission to the brain; or, supposing there be such reports sent up, that, even as a final resort, the brain refuses to notice intimations that, from their inconstant, weak, or confusing character, are more wisely ig- nored. A thousand facts of experimental psychology show the cerebral co-ordinating centre to have such powers and to habitu- ally exercise them. The Retinal Stimulus of the Lower Animals. An interesting question here presents itself, and may be alluded to in passing: Does the visual mechanism of other orders of an- imal life differently situated from ourselves respond to other