Word: visione
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Dates: during 1940-1949
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...theories will hardly quiet the old argument as to whether the bull sees red, or merely the movement of the matador's cape. Dog lovers will continue to protest the thought that their pets live in a colorless grey world.* But Biologist Walls outlines a hypothesis of color vision new to the layman. The ability to see colors Dr. Walls links directly to visual acuity-the ability to see well. He points out that the vertebrates with the greatest color vision (bony fishes, reptiles and birds, monkeys, apes and man) are those with the greatest visual acuity-and those...
Cones & Rods. The retina (the screen upon which the lens of the eye casts the image) has two kinds of visual cells: cones, each with its direct line to the brain; rods connected in multiple to the optic nerve fibers. The cones give sharp, color vision, work in bright light only. The rods "gang up" faint and dim impressions in weak light, catch no color. Some animals have cones but apparently no color vision; no known color-seeing animals have rod cells alone...
...Sharp vision and color vision have two other common denominators. One is a highly sensitive dimplelike spot on the retina (the fovea centralis-literally, "central pit"), which acts as a magnifying device to spread the image over a greater number of visual cells. In this dimple, common to the vertebrates with the highest acuity (some birds have two in each eye), there are no rod cells. The cones are slim and tight-packed. The other common denominator is the mechanism for accommodation-ability to focus the eye, maintain a sharp image of a moving object...
Only mammals known to have color vision are the monkeys, apes and man. And they are the only mammals fully equipped with cones, dimples, and accommodation mechanisms. While man uses color vision largely for pleasure, comments Dr. Walls, it was first developed "by animals to whom magazine covers . . mean absolutely nothing...
Schuman is a historian, concentrated-evidently like his author-not only on the vision of freedom, but also on those obstacles to freedom which seem intrinsic in the very effort to achieve it. When he is telling his own story, he offers a perhaps too facile newsreel of the past two decades." When he is talking history and quoting-he quotes, it seems, nearly every man who has ever written well, usually very aptly-Never Call Retreat becomes as rich an anthology of ravenous reading as ever disguised itself as a novel. When he is talking politics, or living them...