Show M MANY P PERSONS ER si 0 N S COLOR BLIND tests testa used by railroads show that almost everybody Is slightly color blind tho rho various tests for color blindness have come coma into practical uso use in ill ule ho examination of railroad engineers an and d t it like k e where 0 tho the ability to distinguish colors Is necessary so BO that these tests aro are no longer pecullar peculiar to the laboratory but it la IR not gener acner ally known outside the laboratory that everybody ta Is partially color blind that Is in cortale parts of tho the field of vision tho the most normal individual can see all the colors colora only when it lie looks directly at them it looked it at from an angle of about fifteen debrew red and green call no longer bo be econ coon but in their places will appear shades of yellow or blue tills this region of the oyos eyes la Is known us its tho the yellow blue zone if the color tio be moved still farther to tho side the yellow and blue will din appear and only gray can bo be seen title region Is known tie na tho the zone of complete color blindness an inter theory in regard to these zones la is that every normal oyo eye represents three stages of evolution the zono of complete color blindness to Is tho the low est stage and appears in such auch animals its as tho the frog whose vision la IS known as shadow vision the blue yellow zono zone la Is one step higher in the scale although not clearly in marked arke oft in the animal kingdom and the a appearance ppe aranco or of reu red green zono aono tho the highest stage of evolution cases ot of color blindness are according to this theory a lack of develop mont beyond tho the early stage ot at individual life strand magazine |