Show MANY PERSONS COLOR BLIND tests testa used by railroads show that almost everybody to Is slightly color blind tile the various tests for color blindness have como come into practical use in aiho ho examination of rail railroad rond engineers and tho the like khero the ability to distinguish ting colors la III necessary necos sary so BO that clinso tests aro are no longer peculiar to tho the laboratory but it Is not generally known outside tho the laboratory that everybody la Is partially color blind that la is in certain parts 0 of tho the field 0 at vision the most normal in individual divIdu ai can see all tho the colors colora only when lie ho looks directly at them it if looked it at from nn an angle of nebout fifteen red ana green can no longer bo be seen boon but in their places will appear shades of yellow or blue this region of tho the eyes Is known as aa the yellow blue zone it the color bo be moved stilt still farther to the blile bide tho the yellow and blue will disappear and only gray can bo be seen this raglon melon III IB known na as tho the zone of complete comp loto color blindness an interesting ting theory in regard to these zones Is that every normal eyo eye represents throe stages of evolution tho the zono 0 of complete color blindness Is the low ost cat and appears in such auch animals na as tho the frog whose vision Is if known na as shadow vision tho the blue yellow zono zone la Is ono one stop step higher in tile the scalo scale although not dearly marked oft off in tile tho animal kingdom ara and I 1 the appearance of the red green zone sone markru the highest stage of 0 evolution cases of color blindness are according to this theory a lack of at development beyond tha early stage of individual lifo life strand magazine |