PROBABLY the demand most frequently made of those who have had experience in testing for color blindness is for a simple means of detecting the presence of defective color vision—in other words, for a simple screening test adequate to differentiate between normal and defective color vision. The demand comes from the military services; from ophthalmologists; from industry, with its increasing use of color, and from vocational high schools, where too often a boy is trained for a trade only to find near the end of his training that he cannot meet the requirements for color vision. Tests have been produced which when properly administered and the critical scores established will meet this need, as was shown by us in previous reports1; but these tests are of foreign make and are not now available in quantity. Therefore, their evaluation has at present more theoretic than practical value. Other tests are