OR COLOUR BLINDNESS. ’ 179 
A problem which had not hitherto been attempted to be solved, 
is that of the difference which must exist between a daltonian 
and a person of normal vision in the perception of the comple- 
mentary colours. In order to obtain some results on this point, 
I presented to D*** a sheet of paper on which were painted the 
colours of the spectrum with their complementary ones opposite. 
I give in Table III. by the side of their true names those which 
he assigned to them. This table proves clearly, and as might 
have been expected, that the colours which we regard as com- 
plementary do not appear such to the daltonian*. 
TaBLe III. 
Experiments on Complementary Colours. 
Names of the Natural Colours. 
According to me. According to the daltonian. 
| 
1. Red. Red (rose leaf). 
2. Orange. Reddish yellow. 
3. Yellow. Chrome yellow. 
4. Green. Weak green. 
5. Blue. Deep blue. 
6. Indigo. Blue (reddish tinted). ? 
7. Violet. Full blue. 
8. Black (Indian). Brown. ? 
9. White. White. 
Names of the Complementary Colours. 
According to me. According to the daltonian, | 
/ | 
| 1, Greenish blue. Light red (flower of the rose). | 
2. Blue. Bright blue. 
| 3. Indigo. Indistinct blue. 
4. Reddish violet. Red. ? 
| 5. Red orange. Yellow. ? 
6. Yellow orange. Deeper yellow, 
7. Greenish yellow. Light yellow. 
8. White. White. 
9. Black (Indian). Brown. ? 
D***’s eye is not however insensible to the accidental co- 
lours ; but the fatigue which results in their production from 
the voluntary and sustained fixation of the illuminated object 
seems to be more painful to him than to us. The following are 
two of the experiments in which I succeeded best. 
I placed a disc of rose-coloured paper 0™:05 in diameter on 
a 3 b : 
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N 2 
