"Colorblindness" includes all forms of color deficiency. "Daltonism" was first discovered by the English biologist-schoolmaster (Dalton) who determined that he saw things differently. The most common type of color deficiency (red-green) is inherited by men from their Mothers, who do not have it, but might be called carriers. We miss the ability to see 'green'. Other types are inherited differently and miss different colors. One may also lose colorvision by taking certain drugs or getting diseases, such as Alzheimers or diabetes (low blood sugar).