Report of the Committee on Colour-Vision. 369 



incapacity to distinguish between different shades of one colour, 

 or even of an inability to distinguish between such colours as 

 blue and violet or blue and green, when these are the sole defects. 

 It is perfectly and clearly distinguished from a defective naming- 

 of colours, and from deficient acuteness of vision." 



The actual results of examination are stated as follows :— 

 "The total number of persons examined was 18,088, of whom 

 16,431 were males and 1,657 females. 



" The examination of certain classes of persons was undertaken 

 in the expectation of some peculiarities, which the result amply 

 justified. 



M Deducting these, we have 14,846 males, of whom 617 were 

 colour-blind, giving an average percentage of 4*16. Making- 

 similar deductions in the case of the females, we have 489 

 persons, with 0-4 per cent. And even this small percentage is 

 entirely made up of persons with very slight individual defects. 



" Taking the exceptional groups of females, we find those of 

 Jewish extraction, the members of the Society of Friends, and 

 the inmates of deaf and dumb asylums, to be more defective 

 as regards colour than the average. Thus, among the first (730) 

 examined as high a percentage as 3-1 was touched, though the 

 cases were almost entirely of slight character. Among the 

 members of the second group who happened to be the subjects 

 of examination (216 in all) the percentage was even somewhat 

 higher (5*5), though the cases were clearly even slighter still. 

 Among the deaf and dumb females (122 examined) there was a 

 somewhat high percentage (2*4) of slight cases. 



" Colour defects exceeded the average in the male members 

 also of the same classes. It is possible to draw more exact 

 comparisons between the normal and colour-blind males than of 

 females, because the former show much more pronounced cases. 

 Thus, the slight individual differences of examiners will cease to 

 be a source of error for males, for no examiners, however low 

 the standard they exact, could omit to detect and record as 

 colour-blind those persons who matched red, or the full shades 

 of brown or grey, with green. 



" Enumerating in this manner, we have — 



"Among males generally (14,846 examined) 3*5 per cent, of 

 pronounced cases. 



" Among male Jews (949 examined) 4-9 ditto, ditto. 



" Among male Friends (491 examined) 5*9 ditto, ditto. 



" Among male deaf and dumb (145 examined) 13-7 ditto, ditto. 

 " It must be noted, however, that the Jews were, on the 

 average, in a poorer condition of life than any other class 

 examined. The deaf-mutes were mostly poor. The Friends 

 were mostly of the middle class; their mistakes were chiefly 

 confined to the paler shades, and were therefore, in general, 

 slight in degree, especially as compared with the Jews, whose 

 defects, though less numerically, were usually well pronounced 

 in character. The wealthier Friends are much less liable to 



