Capt. W. de W. Abney. Examination for [May 14, 



Taking the intensity carve of the light reflected from the red it was 

 found to contain a great deal of the part of the spectrum which she 

 called brownish, viz., from 53'5 to 48 on the scale, whereas the blue 

 reflected a trifle of this portion of the spectrum, as did also the green, 

 and this may account for her making a match to grey of U and G, and 

 not of R and G, but it is hard to see why she matched U alone and 

 also R with the grey. 



Reviewing the case, it seems that any perception of colour is very 

 small, and that the sensations are green and red, together with white. 

 Experiments which I have described in my book on " Colour Measure- 

 ments and Mixture," 1891, show that a large proportion of colour may 

 be mixed with white without being perceived, but this colour so hidden 

 has still the capability of neutralising a certain quantity of the com- 

 plementary colour thrown on the white, which, by itself, would not 

 be masked by the white. It would seem then that in N. W.'s case 

 the two colours perceived were very much diluted, and at parts of the 

 spectrum so diluted as not to be perceived, but that the latent colour, 

 if it may be so called, has the power of forming a grey with the green 

 which she sees more strongly. 



Case VI. This case is that of Miss W., who was brought before 

 the Committee by Dr. Lindsay Johnson, on -April 29. The right 

 eye was apparently normal for colour, but with the other she saw 

 nothing but shades of white. 



Miss W., it appears, has had a slight stroke of paralysis, which 

 affected her left side, and subsequently she discovered that colour 

 sensation in the left eye had disappeared. Mr. Brndenell Carter, 

 the day after the meeting of the Committee, examined her and pro- 

 nounced hers to be a case of atrophy of the optic nerve. 



I examined her with the spectrum colours on the 5th May, and 

 found her left eye totally blind to every colour, though her per- 

 ception of light was very fair. She had very little difficulty in 

 comparing the luminosity of the most brilliant spectrum colours 

 with the white patch of light placed alongside them. In making the 

 measurements she experienced a certain amount of fatigue, but, by 

 resting the eye for short intervals, her readings were very constant. 

 The following is the table of her readings : 



