Monday, Apr. 18, 1938
Animal Vision
The old-style method of testing animals' eyesight is to train them to respond to certain visual stimuli. This is laborious, and in the case of some refractory creatures, such as snakes, frogs and Gila monsters, virtually impossible. At the University of Rochester a promising, extravagantly polite young scientist named John Warkentin is investigating animal eyesight with a more efficient technique which requires no training, last week made public some of his findings.
Prime piece of apparatus is a vertical, hollow cylinder, five feet high and four feet in diameter. On the inside wall of the cylinder are alternating black & white stripes, running vertically from top to bottom. These stripes can be adjusted in width from a maximum of five inches down to Moth inch. The animal is placed inside the cylinder, which is then turned slowly by hand. If the animal makes eye or head movements following the rotation, it is assumed that it can see the stripes. Their width is progressively diminished until the animal stops turning its eyes-- thus showing that its threshold of vision has been reached. For sharp-eyed creatures which can easily follow the the 1/16th inch stripes, a further refinement is achieved by using slender threads, the finest of which were especially woven for Warkentin's experiments. The cylinder technique was used in Germany 15 years ago, but only to study reflex eye movements and not to test acuteness of vision. Its adaptation to Warkentin's purposes was suggested by his departmental superior. Dr. Karl Ulrich Smith. Since Mr. Warkentin's animals are inside a cylinder, his experiments of course give no inkling of the distances to which animals can see clearly.
Some findings:
P: White rats, white mice and Gila monsters showed no response at all, presumably have extremely poor vision.
P: Frogs, toads, alligators and opossums showed weak responses, have poor vision.
P: Snakes, contrary to popular supposition, have good vision. Those tested included garter snakes, king snakes, ribbon snakes and rattlesnakes. They see worst just before shedding their skins, best just after shedding, because the snake's cornea grows opaque as shedding time nears and is sloughed off with the skin.
P: Turtles, woodchucks, guinea pigs, rabbits and gophers have good eyesight.
P: Cats and birds see best of all.
P: Guinea pigs and dogs vary greatly from one individual to another. Monkeys could not be tested because they kept peering curiously over the cylinder's top. Wild rabbits see better than tame rabbits; normally pigmented creatures see better than albinos.
John Warkentin was born 25 years ago in Hamburg, Germany, son of a Russian Mennonite preacher and teacher who took a Ph.D. at the University of Chicago and is now a professor of German literature at Bethel College. The elder Warkentin is currently trying to have the Supreme Court pass on his application for citizenship, which has been refused because, abiding by the tenets of his religion, he will take no oath to bear arms. Son John will take no such oath either. He studied at Brown University under Dr. Leonard Carmichael, went along with Carmichael to the University of Rochester, where he expects to receive his Ph.D. this June. Thereafter he will study medicine at Northwestern, specializing in the visual acuity of human infants.
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