ABSTRACT
Some individuals are born with physical disabilities which make it impossible for them to live as do ordinary individuals. A person who is born blind, for example, must adjust himself to space relations through the use of such senses as he has. He learns to locate objects in a way very different from that in which a person does who enjoys normal vision. Some persons are born with retinas that do not respond differently to different colors, as normal retinas do. These persons are said to be color blind. The structures of the normal retina which make possible different sensory reactions to different colors are highly developed. In the case of color-blind individuals, the retina is not developed to the normal degree of complexity. The most common type of color blindness is that of individuals who are unable to distinguish red and green. Such individuals are handicapped unless they find ways of adjusting themselves through sensory experiences not ordinarily employed by normal individuals. One interesting case was that of a chemist who was red-green blind. While chemists ordinarily depend on color to recognize the chemical reactions of substances which they mix, this chemist had to develop a substitute for color vision. As a matter of fact, he cultivated the ability to recognize chemical reactions through their odors.
