the image shows the number 44, but people who have deuteroanopia, cannot see it. ------ -->--In 1794: Dalton wrote, " Extraordinary Facts Relating to the Visions of Colors" what makes his paper so remarkable is during that time period, color blindness wasnt formally described until Dalton wrote about his own visual problem.
[ because of his research into it, color blindness is now commonly recognized as Daltonism.]
-- In 1995, the perserved eye of John Dalton showed he had the less common type of color blindness, deuteroanopia. [defect of vision in which the retina fails to respond to the color green.]
