Show MANY PERSONS COLOR BUND tests aeed by railroads show that almost everybody Is slightly color bund the various tests for color blind ness have come into practical use in the examination of railroad engineers and the like where the ability to distinguish colors Is necessary that these tests are no longer peculiar to the laboratory but it Is not generally known outside the laboratory that everybody is partially color blind that Is in certain parts of the field 0 vision the most normal individual can see all the colors when he looks directly at them looked at from an angle of about fifteen degrees red and green can no longer be seen but in their places will appear shades of yellow or blue this region of the eyes Is known as ohp yellow blue zone it the color be moved still farther to the side the yellow and blue will dis appear and only gray can be seen this region Is known as the zone ot complete color blindness an interesting theory in regard to these zones is that every normal eye represents three stages of evolution the zone of complete color blindness Is the low est stage and appears in such ani neals as the frog whose vision la known as shadow vision the blue yellow zone Is one step higher in the scale although not clearly marked oil in the animal kingdom and the appearance of the red green zone marks the highest stage of evolution cases of color blindness are accord ing to this theory a lack of development beyond the early stage of andl vidual life strand magazine |