It is odd that total color blindness, a subject of such elementary importance to so many branches of medicine, physiologic optics, neurology, psychology, heredity and the like, has been almost overlooked in this country. Bell's1 exhaustive bibliography, issued two years ago, cites only one report2 from this continent out of the 119 cases recorded.3 One factor doubtless is that the name total color blindness in no way suggests the interest of this subject, nor is it at all adequate in describing its nature. Clearly, the color defect is only a small part of this affliction, yet the popular textbooks fail to portray it as anything other than a combination of the regular forms of color blindness. For a clear understanding of the subject, this distinction should be made plain at the outset. The other varieties of impaired color perception, the ones continually run across in practice, cause