新东方英语背诵美文50篇 第四十六篇 Vision
Vision
Human vision like that of other primates has evolved in an arboreal environment. In the dense complex world of a tropical forest, it is more important to see well that to develop an acute sense of smell. In the course of evolution members of the primate line have acquired large eyes while the snout has shrunk to give the eye an unimpeded view. Of mammals only humans and some primates enjoy color vision. The red flag is black to the bull. Horses live in a monochrome world .light visible to human eyes however occupies only a very narrow band in the whole electromagnetic spectrum. Ultraviolet rays are invisible to humans though ants and honeybees are sensitive to them. Humans though ants and honeybees are sensitive to them. Humans have no direct perception of infrared rays unlike the rattlesnake which has receptors tuned into wavelengths longer than 0.7 micron. The world would look eerily different if human eyes were sensitive to infrared radiation. Then instead of the darkness of night, we would be able to move easily in a strange shadowless world where objects glowed with varying degrees of intensity. But human eyes excel in other ways. They are in fact remarkably discerning in color gradation. The color sensitivity of normal human vision is rarely surpassed even by sophisticated technical devices.
_小精灵 儿童网
新东方英语背诵美文50篇 | |
- 新东方英语背诵美文30篇 第一篇 Youth 青春
- 新东方英语背诵美文30篇 第二篇 Three Days to See(Excerpts) 假如给我三天光明
- 新东方英语背诵美文30篇 第三篇 Companionship of Books 以书为伴
- 新东方英语背诵美文30篇 第五篇 Ambition 抱负
- 新东方英语背诵美文30篇 第四篇 If I Rest, I Rust 如果我休息,我就会生锈
- 新东方英语背诵美文30篇 第六篇 What I have Lived for 我为何而生
- 新东方英语背诵美文30篇 第七篇 When Love Beckons You 爱的召唤
- 新东方英语背诵美文30篇 第八篇 The Road to Success 成功之道
- 新东方英语背诵美文30篇 第九篇 On Meeting the Celebrated 论见名人
- 新东方英语背诵美文30篇 第十篇 The 50-Percent Theory of Life 生活理论半对半