CONGENITAL COLOR DEFICIENCIES
In a minority of persons the form of color vision hitherto discussed, with the exception of a few individual variations which do not detract from its general character, is not applicable. These are the so-called color defectives—of whom, as modern investigations show, several types are distinguishable.
The majority of recent authors agree that besides the true partly color blind, who do not perceive certain definite colors, e. g., red and green, there are persons who are able to perceive all color qualities but whose color sense is, nevertheless, different from that of the normal person. These are called anomalous.
Concerning the vision of the congenitally color blind: It is generally accepted that it is impossible to conclude from the fact that they correctly name the colors of certain objects that they experience the same color sensations as do normal persons. The color blind have from childhood